中国生态农业学报(中英文)

Effects of temperature and moisture on soil CO₂ release potential under three typical land use types in the hill-gully area of the Loess Plateau

ZHANG Hong, HUANG Yi-Mei, QI Jin-Hua, AN Shao-Shan

2011, 19(4): 731-737. doi: 10.3724/SP.J.1011.2011.00731

Abstract(2075) PDF(1810)

Abstract:
The most important greenhouse gases in the atmosphere are CO₂ , CH4 and N2O, which in total contribute approximately 80% to greenhouse effect. Soil respiration generally accounts for one half of total CO₂ emission into the atmosphere, adding to greenhouse effect. In addition to other factors, soil respiration is highly related with temperature, moisture and soil type. However, few studies have investigated soil respiration under different land use types in the hill-gully area of the Loess Plateau. The objective of this experiment was to determine the effect of temperature, moisture and other related factors on soil respiration. For that purpose, undisturbed soil samples were collected from different land use types in the hill-gully area of the Loess Plateau. The study covered three land use types — 15-year old apple orchard land at Changwu, Shaanxi Province; 6-year old retrieving grass land at Guyuan, Ningxia Hui Autonomous Region; and 140-year old forest land at Fu County, Shaanxi Province. We used the S-distribution method to collect soil samples and the infrared absorption CO₂ analyzer to measure soil respiration. CO₂ release rate was analyzed in the laboratory using undisturbed soil samples under four temperatures of 5 ℃,15 ℃,25 ℃ and 35 ℃; and five moisture contents of wilting water holding capacity, natural water holding capacity, fracture capillary water holding capacity, field capacity, and saturated water holding capacity. The aim was to determine the correct relationship among the factors and soil respiration rate. Factors that influenced soil CO₂ release potential under different land use types in the Loess hilly-gully area were then determined. The results showed that under different land use types in the loess hilly region, the rates of soil respiration under different moisture contents were mainly driven by temperature variation. The “Ra=ae^bT” exponential model precisely forecasted the changes in respiration rate as affected by temperature. Though, soil moisture slightly influenced soil respiration rate, it greatly affected Q₁₀, which indicated the sensitivity of soil respiration to temperature. Both high and low moisture contents inhibited the sensitivity of soil respiration. While the rates of soil respiration substantially differed, it generally tracked the following order: forest land soil > grass land soil > orchard soil. Organic carbon significantly contributed to the variation in soil CO₂ release, followed by organic nitrogen. Furthermore, microbial biomass carbon might indirectly affect rate of soil respiration.

Yield and nutrient balance of lettuce as influenced by reduced and optimized nitrogen application

QUAN Zhi, QIN Hong-Ling, LI Ming-De, ZHU Yi-Jun, LIU Xin-Liang, WEI Wen-Xue, WU Jin-Shui

2011, 19(4): 738-744. doi: 10.3724/SP.J.1011.2011.00738

Abstract(1422) PDF(1307)

Abstract:
Environment and health quality of vegetable are closely related with food quality and human health. Most farmers use excessive chemical fertilizers to maximize yield. This practice, along with high irrigation and multiple cropping, results in soil degradation, nitrogen (N)/phosphorus (P) loss, and other severe environmental issues. A field experiment was carried out in a vegetable field of suburban Changsha City to determine the effects of reduced and optimized application of N fertilizer on soil nutrient balance and yield of lettuce. N was reduced by 20% under optimized fertilization strategies of slow-release urea (80%N+CRU), urease/nitrification inhibitor (80%N+QD) and soil conditioner (80%N+SC). The results showed that the three optimized strategies reduced soil NO₃^--N, Olsen-P content and nitrification rate. This reduced N/P loss into the environment and enhanced nitrogen use efficiency. It also increased lettuce biomass and farmers’ real income, with obvious economic and environmental benefits. The 80%N+CRU strategy significantly reduced soil NO₃^--N, Olsen-P contents and the loss of N and P into the environment. Compared with conventional fertilizer treatment (CF) and national standard (GB18406.1—2001) (P<0.05), however, it increased nitrate in the stem of lettuce at harvest. The 80%N+QD strategy had no significance effects on soil Olsen-P and nitrate in edible parts of lettuce. It, however, significantly reduced soil nitrification rate (P<0.05) and increased biomass yield by 21.7% for stem, 7.6% for leaf; and increased total revenue by 13.0%, farmers’ real income by 14.0%, and output/input ratio by 14.2%. The 80%N+QD strategy was therefore recommended as the optimal strategy. Although the effect of 80%N+SC treatment was not completely satisfactory, it improved the nutrient use efficiency. On accounts of comprehensive production effects, health safety and ecological benefits, it was suggested that the application of urease/nitrification inhibitors with reduced nitrogen fertilizer should be adopted in fertile vegetable soils.

Yield and competitive response of intercropped wheat and faba-bean to water and allelochemical dose

ZHENG Li-Long, CHAI Qiang

2011, 19(4): 745-749. doi: 10.3724/SP.J.1011.2011.00745

Abstract(1355) PDF(1273)

Abstract:
Academic evidence showing negatively effects of allelochemicals on optimized intercropping systems are largely lacking. To that end, a pot experiment was conducted to study the mechanism of allelopathy in intercropping systems. Three modes of cropping systems (monocropped wheat, monocropped faba-bean and intercropped wheat/faba-bean) were designed with three irrigation rates (45%, 60% and 75% of field capacity). The effects of irrigation rates and 3-methyl-phenol on yields of the different cropping systems were analyzed. Competition between wheat and faba-bean in the wheat/faba-bean intercropping system was also determined. Results indicated that intercropping significantly influenced the biological and economic yields of wheat. Compared with monocropped wheat, yield of intercropped wheat increased under irrigation rates of 60% and 75% filed capacity. However, the reverse was noted in economic yield under irrigation rate of 45% filed capacity. The yield of intercropped faba-bean was significant higher than that of the monocropped faba-bean under different irrigation rates. Allelopathic effects of 3-methyl-phenol on the yield of wheat and faba-bean were negative. Intercropping mitigated the degree of negative allelopathic effect on faba-bean. 3-methyl-phenol significantly enhanced the competitive capacity of wheat over faba-bean in intercropped systems. The competitive capacities of wheat over faba-bean in intercropping system with 3-methyl-phenol were 24.82%, 19.26% and 79.30% higher than those of intercropping systems without 3-methyl-phenol under irrigation rates of 45%, 60% and 75% of field capacity, respectively. On the other hand, increasing irrigation rate weakened the competitive capacity of wheat in intercropping systems. The competitive capacities of wheat over faba-bean in their intercropping systems with and without 3-methyl-phenol under 75% irrigation rates were 158.08% and 79.67% lower than that under 45% irrigation rate, respectively.

Response of hedysari radix nitrogen absorption and polysaccharide accumulation to fertilizer application

LIN Hai-Ming, LIU Xue-Zhou, CHENG Wei-Dong, YANG Jian-Jun

2011, 19(4): 750-754. doi: 10.3724/SP.J.1011.2011.00750

Abstract(1430) PDF(1312)

Abstract:
It is critical to establish a standard cultivation procedure for hedysari radix, and explore new ways of using less fertilizer for high yields of Chinese herbal crops, and provide theoretical basis for the application of palygorskite in cultivating Chinese traditional medicine. To that end, a field experiment was conducted to study the dynamics, absorption and distribution of nitrogen and polysaccharides in hedysari radix. The effects of palygorskite application rates of 750 kg·hm^-2 (P1), 1 500 kg·hm^-2 (P2) and 2 250 kg·hm^-2 (P3) with NPK fertilizer on nitrogen absorption and polysaccharide accumulation in hedysari radix were also analyzed. The results showed that the critical period of nitrogen nutrition in aboveground part of hedysari radix was late June to late July. However, increased nitrogen requirement by the root system of hedysari radix was noted in late August. From late September to late October, nitrogen transfer occurred from aboveground part to belowground tissues. Also from late June to late August, the content of polysaccharides sharply increased in the root system of hedysari radix plant. Compared with only NPK application, combined application of palygorskite and NPK fertilizer increased N content at the late growth stage of the plant. It also increased N content in roots and active aboveground growth tissues. Compared with NPK treatment, NPK+P3, NPK+P2 and NPK+P1 treatments increased hedysari radix N accumulation at harvest by 45.22%, 29.45% and 20.06%, respectively. N accumulation in the aboveground part of the plant under NPK+P3 treatment increased by 71.99%, compared with NPK treatment. N accumulation in the root system under NPK+P3 and NPK+P2 treatments increased by 38.72% and 26.07%, respectively. NPK+P3 treatment promoted N accumulation and prolonged the period of N accumulation in the aboveground part of hedysari radix at the early growth stage. It also delayed N de-accumulation in the aboveground part of the plant at the late growth stage. NPK+P3 and NPK+P2 treatments enhanced the rate of N accumulation in roots. They also increased single plant root N accumulation over NPK treatment. The content of polysaccharides under NPK+P1, NPK+P2 and NPK+P3 treatments increased by 50.74%, 62.95% and 40.63%, respectively, over NPK treatment. The combined application of palygorskite and NPK prolonged accumulation time of polysaccharides in hedysari radix. While it delayed polysaccharide de-accumulation in roots, and improved overall polysaccharide yield of the plant. The comprehensive performance of N absorbing capacity under combined application of palygorskite and NPK was in the following order: NPK+P1 (high rate) > NPK+P2 (medium rate) > NPK+P3 (low rate). The further studies on this observed correlation between palygorskite and polysaccharide output were recommended.

Effect of conservation tillage on wheat and soil nutrient distribution and absorption

YANG Pei-Pei, YANG Ming-Xin, DONG Wen-Xu, CHEN Su-Ying, HU Chun-Sheng

2011, 19(4): 755-759. doi: 10.3724/SP.J.1011.2011.00755

Abstract(1623) PDF(1458)

Abstract:
Conservation tillage technology improves soil environment, reduces wind and water erosion, and mitigates sandstorm. As a mode of agricultural technology, conservation tillage is drawing more and more global attention. Agricultural soils are increasingly managed through conservation or no-tillage. The objective of this study was to identify the effects of different conservation tillage patterns on N, P, K distribution in both soil and wheat, and also on their absorption of wheat in the North China Plain. The investigated tillage patterns included no-tillage with crushed straw (NC), no-tillage with entire straw (NW), traditional tillage with crushed straw (MC) and rotary tillage with crushed straw (X). The 6-year experiment showed significant differences in soil nutrient distribution and absorption, and also in wheat distribution among different tillage patterns. Rotary tillage significantly increased organic matter, total nitrogen and available N, P, K contents in the 0~5 cm surface soil. The contents of these nutrients gradually decreased with increasing soil depth. Soil organic matter, total and available N contents were lower under rotary tillage than NC in the 20~30 cm soil layer. The contents of total N, P and K in plants under the two modes of no-tillage (NC and NW) were significantly lower than that under traditional tillage (MC) and rotary tillage (X) at seedling stage. The differences among these modes of tillage were most significant at reviving stage. At jointing and flowering stages, the differences in total N, P, K contents of plants between the non-tillage (NC and NW) and tillage (MC and X) treatments gradually dropped; and finally significantly influenced grain nutrient content.

Nicotine accumulation and distribution in tobacco under continuous cropping

ZHANG Ji-Li, GUAN Xin, WANG Xiao-Ye, JIAO Feng, WANG Peng

2011, 19(4): 760-764. doi: 10.3724/SP.J.1011.2011.00760

Abstract(1548) PDF(1311)

Abstract:
Continuous cropping of tobacco affects the growth and quality of flue-cured tobacco. This study investigated the effect of continuous tobacco cultivation on the accumulation and distribution of nicotine with aim of developing suitable cultivation methods. The study also discussed the theories and obstacles of continuous tobacco production. For that purpose, experiments were conducted in natural and fertilized soils with different periods (0, 3 and 5 years) of continuous cultivation in Yongsheng Town, Zhaozhou County, and the relationships among nicotine content, accumulation and distribution in flue-cured tobacco were analyzed. The results showed that nicotine gradually accumulated during the first 3~11 weeks after transplanting with the 3-year and 5-year continuous cropping under the natural fertility. After 11~17 weeks of transplanting, nicotine accumulated very rapidly in the 3-year and 5-year continuous cropping under the natural fertility. Nicotine accumulation for 0-year continuous cropped tobacco under the natural fertility was two weeks earlier, compared with that for the 3-year and 5-year continuous cropped tobacco. Nicotine accumulation was respectively 87.56 kg·hm^-2, 64.79 kg·hm^-2, 38.35 kg·hm^-2 under natural fertility, and 128.31 kg·hm^-2, 90.09 kg·hm^-2, 53.71 kg·hm^-2 under fertilization in the 0-year, 3-year and 5-year continuous cropped tobaccos at leaf harvest, approximately 17 weeks after transplanting. Continuous cultivation decreased nicotine adsorption and accumulation in both fertilized and natural soils. While nicotine distribution in roots and stems decreased with increasing period of continuous cropping, it increased in leaves with increasing period of continuous cropping in both natural and fertilized fields. The contents of nicotine in the continuous cropping systems were: 3-year > 5-year > 0-year, 3-year > 0-year > 5-year and 0-year > 3-year > 5-year in the lower, middle and upper leaves of tobacco, respectively. The nicotine content of leaves in different positions of plant of tobacco continuously cropped for 5 years was not up to the scratch of high quality tobacco. Continuous tobacco cultivation severely affected nicotine accumulation and distribution, and also the quality of flue-cured tobacco.

Nitrification inhibition and dose-dependent effect of dicyandiamide on sandy, loamy and clayey soils

LIU Qian, CHU Gui-Xin, LIU Tao, WANG Jian, YE Jun, WANG Fei, LIANG Yong-Chao

2011, 19(4): 765-770. doi: 10.3724/SP.J.1011.2011.00765

Abstract(1619) PDF(1590)

Abstract:
Ammonium and nitrate are the main forms of available nitrogen (N) for plant. Nitrate is the dominant form of N in upland soils in arid regions. However, nitrate can easily leach through soil profiles. Furthermore, N can easily be lost in the form of NOx via (de)nitrification. Inhibiting the processes of nitrification in soil through nitrification inhibitors is therefore critical for optimizing soil NH₄⁺/NO₃^- ratio and improving the efficiency of N fertilizers. As one of the most common nitrification inhibitors, dicyandiamide (DCD) was applied at different rates (0%, 1.0%, 2.0%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 6.0% and 7.0% of applied N) in this study. And incubation experiment was conducted in sandy, loamy and clayey desert soils at 25 oC to investigate the inhibition effect, dose-dependent effects of DCD on soil nitrification in arid regions. The study may further enhance our existing knowledge on the mechanisms of DCD inhibited nitrification. The results showed that during 30 days of incubation, DCD exhibited significant inhibition effects on nitrification in all the tested soil types. Nitrification inhibition rates were 96.5%~99.4% in sandy soil, 66.9%~85.6% in clayey soil and 49.3%~79.4% in loamy soil. For the three soil types, DCD nitrification inhibition efficacy was in the following order: sandy soil > clayey soil > loamy soil. When DCD application rate increased from 1.0% to 7.0% of applied nitrogen, nitrate concentration in sandy soil merely increased from 1.9 to 10.7 mg·kg^-1. This suggested that DCD dose did not significantly affect nitrification in sandy soils. However, soil nitrate concentration in loamy and clayey soils decreased sharply with increasing rates of DCD, indicating significant dose effect on soil nitrification. In conclusion, DCD significantly inhibited soil nitrification in calcareous desert soils. The recommended optimum application rates of DCD in sandy, clayey and loamy soils were 6.0%, 7.0% and 7.0% of applied nitrogen, respectively.

Concentration change and migration characteristics of nitrogen in the paddy field of Ningxia Yellow River Irrigation Area

YI Jun, ZHANG Qing-Wen, YANG Zheng-Li

2011, 19(4): 771-777. doi: 10.3724/SP.J.1011.2011.00771

Abstract(1484) PDF(1145)

Abstract:
Excessive use of nitrogen and irrational irrigation are the primary drivers of aggravated non-point farmland pollution. It is therefore urgent to develop effective coupling modes of water and nitrogen use in agricultural production in Ningxia Yellow River Irrigation Area that reduces non-point farmland pollution of the Yellow River. To that end, an experiment was conducted in typical paddy fields of the area to study the effect of irrigation and nitrogen use on non-point pollution. Based on the results, high concentrations of NH₄⁺-N and NO₃^--N were noted in surface water of paddy fields after fertilization. Compared with NH₄⁺-N, the peak concentration of NO₃^--N was a little delayed and built up more slowly. During the periods of topdressing and the entire experimentation, NH₄⁺-N average concentration in field surface waters was obviously related with nitrogen input and irrigation amount. The average concentration of NO₃^--N in field surface water was significantly related with nitrogen input, and not irrigation amount. The concentrations of NH₄⁺-N in seepage waters at depths of 30 cm and 60 cm were strongly influenced by fertilizer dose. The dynamics of NH₄⁺-N concentration in the seepage waters were similar to that of NH₄⁺-N in field surface water. There were larger lags in the peak concentration of NH₄⁺-N at 90 cm soil depth, and which was much lower than that in the upper soil layers. The concentration of NH₄⁺-N at 120 cm soil depth steadily increased. The average concentration of NH₄⁺-N in the different layers over the entire period of experimentation was significantly related with nitrogen input, and not irrigation amount except at the depth of 30 cm. The concentrations of NO₃^--N in seepage water at 30 cm and 60 cm soil depths dropped sharply after the first irrigation, but gradually increased after each fertilization. The concentrations of NO₃^--N at 90 cm and 120 cm soil depths slowly dropped. A significant correlation between NO₃^--N concentration and nitrogen input was only noted in seepage water at 30 cm soil depth. The overall result suggested that deficit irrigation limited nitrogen leaching.

Effect of combined frozen saline water irrigation and soil amendment on coastal saline land reclamation

CHENG Wen-Juan, PAN Jie, XIAO Hui, LU Wen-Long, WANG Li-Yan

2011, 19(4): 778-782. doi: 10.3724/SP.J.1011.2011.00778

Abstract(1398) PDF(1425)

Abstract:
Frozen saline water irrigation (FSWI) in winter is a kind of irrigation that utilizes natural cold conditions and abundant saline water. Natural melting of frozen brackish water separates salt from soil via salt water leaching that leaves behind fresh water, leading to saline soil desalinization. In accordance with water desalinization via freezing and thawing of saline water, a field experiment was conducted to study the principle of water and salt transfer following FSWI and soil amendment application. The results showed that FSWI in winter reduced rhizosphere soil salinity. The amount of irrigation water was positively correlated with soil moisture. FSWI caused soil alkalization in initial stage of saline water ice melt, although this trend gradually weakened with ice melt under different treatments. Application of phosphogypsum decreased soil HCO₃^- content, increased soil SO₄^2- and Ca²⁺ contents, and effectively reduced ratios of Cl^- and Na⁺ in total salt content. With increasing phosphogypsum application rate, rhizosphere soil pH decreased while soil water retention capacity increased (7 500 kg·hm^-2 phosphogypsum > 4 500 kg·hm^-2 phosphogypsum). High FSWI along with phosphogypsum application enhanced the growth of Chinese tamarisk. The best treatment combination was FSWI in winter at 1 350 m³·hm^-2 saline water + 7 500 kg·hm^-2 phosphogypsum. Combined FSWI and phosphogypsum application improved coastal saline land reclamation efficiency. It also amended soil alkalization induced by FSWI and provided favorable conditions for early seed germination and plants growth.

Effects of NH₄⁺-N/NO₃^--N ratio on pak-choi nitrogen metabolism and enzyme activity under weak-light

HUANG Jun, ZHOU Xu-Yan, LIU Li

2011, 19(4): 783-787. doi: 10.3724/SP.J.1011.2011.00783

Abstract(1374) PDF(1101)

Abstract:
Pak-choi (Brassica campestris ssp. chinensis Makino) is a native vegetable of China, which is critical for vegetable consumption. Pak-choi cultivation is often under weak-light environments. Studying the effects of different forms of nitrogen fertilizer on the growth, nitrogen uptake and related enzymes under weak-light conditions benefits proper application of ammonium nitrate for the optimum production of pak-choi. In this experiment, low-light environment was imitated using black shade net covers with the light intensity at about 20% of natural light. Then the natural light condition was used as the control. A controlled hydroponics experiment was conducted to determine the effects of five NH₄⁺-N/NO₃^--N ratios (0/100, 25/75, 50/50, 75/25 and 100/0) on nitrogen metabolism and key enzymes [glutamine synthetase (GS) and nitrate reductase (NR)] activities of pak-choi under weak-light conditions. The indicators for nitrogen metabolism and key enzymes were determined after 0 d, 5 d, 10 d and 15 d of treatments. The results showed that under weak-light, plant fresh weight, leaf nitrogen content, and GS and NR activities were significantly lower than under the natural light. Appropriate NH₄⁺-N/NO₃^--N ratio promoted pak-choi growth, maintained high nitrogen absorption, and higher enzyme activity. The total fresh weight, total nitrogen content, and NR and GS activities were highest at NH₄⁺-N/NO₃^--N ratio of 25/75, and lowest at NH₄⁺-N/NO₃^--N ratio of 100/0. Sustained high levels of NR enhanced the absorption of NO₃^--N, which in turn improved the growth and quality of the plant. High GS activity promoted the growth of pak-choi under weak-light conditions. The results suggested that increasing the proportion of NH₄⁺-N reduced energy consumption during nitrogen absorption, which enhanced the plant to adapt to weak-light conditions. The best effect was achieved under NH₄⁺-N/NO₃^--N ratio of 25/75.

Effects of irrigation and fertilization coupling on protein and amino acids contents in grains of winter wheat

ZHENG Zhi-Song, WANG Chen-Yang, NIU Jun-Yi, ZHANG Mei-Wei, ZHANG Jie, YAO Yu-Qing

2011, 19(4): 788-793. doi: 10.3724/SP.J.1011.2011.00788

Abstract(1487) PDF(1271)

Abstract:
To evaluate effects of different water, nitrogen and phosphorus fertilizers and their interactions on grain quality of winter wheat in semiarid region, the experiment was carried out in rain-sheltered condition in Luoyang, west part of Henan Province during crop season of 2009~2010. Grain protein content and contents of amino acid components were tested. The results indicated that irrigation, application of nitrogen had significant effects on grain protein and amino acids contents (P≤0.01) of winter wheat. The interaction of irrigation and nitrogen fertilization also presented significant effects (P≤0.05 or ≤0.01). No significant effect of P fertilization on protein and amino acids contents was observed. Protein and amino acids contents in wheat grains increased with increasing nitrogen fertilization rate, but dropped with increasing of irrigation amount. However, as irrigation amount was above 282.0 mm, and nitrogen fertilization rate was above 179.2 kg·hm^-2, the changes became less obvious. Protein content decreased as the nitrogen fertilization rate above 179.2 kg·hm^-2. The trend of ETT/ATT (percent of essential amino acids to total amino acids) was contrary to that of amino acids contents. The contents of protein and amino acids in wheat grains reached the highest in treatment of N₁₀₅P₄₂W₁₂₇ with nitrogen fertilization rate of 105 kg(N)·hm^-2, phosphorus fertilization rate of 42 kg(P₂O₅)·hm^-2 and irrigation amount during growing season of 127 mm. While ETT/ATT reached the highest in treatment of N_30.8P₁₂₆W₂₈₂ with nitrogen fertilization rate of 30.8 kg(N)·hm^-2, phosphorus fertilization rate of 126 kg(P₂O₅)·hm^-2 and irrigation amount during growing season of 282 mm. The grain yield increased with the increasing of irrigation, and water use efficiency was higher with high yield. Overall, N_179.2P₁₂₆W₂₈₂ with nitrogen fertilization rate of 179.2 kg(N)·hm^-2, phosphorus fertilization rate of 126 kg(P₂O₅)·hm^-2 and irrigation amount during growing season of 282 mm was the best treatment.

Effects of enriched atmospheric CO₂ on the growth and uptake of N and C in mung bean

HAO Xing-Yu, LI Ping, YANG Hong-Bin, HAN Xue, LIN Er-Da

2011, 19(4): 794-798. doi: 10.3724/SP.J.1011.2011.00794

Abstract(1394) PDF(2003)

Abstract:
The inter-governmental panel on climate change projects that atmospheric [CO₂] will reach 550 μmol·mol^-1 by 2050. Elevation of [CO₂] will invariably influence the growth and yield of mung bean. Research on the growth and uptake of C and N in mung bean in response to elevated [CO₂] will benefit the study of the balance of nutrients under future climate change. This could provide the scientific basis for high-value mung bean production through the implementation of climate-oriented policies. Contrary to recent studies of crop response to elevated [CO₂] in chambers and other enclosures, FACE (Free Air CO₂ Enrichment) was used in this study. In the study, mung bean was planted under ambient [CO₂] of 389±40 μmol·mol^-1 and FACE regimes of 550±60 μmol·mol-1, respectively. The results showed that leaf, stem, pod, root, above-ground part and total biomass, and root/shoot ratio increased under elevated [CO₂]. Elevated [CO₂] increased the weight of leaf by 17.15%~80.20% and that of stem by 25.29%~97.38%, compared with ambient [CO₂]. Under FACE, the weight of pod significantly increased by 24.50% at harvest. The weight of root increased by 34.17% and 60.41% at pod-filling and harvest stages, respectively. Elevated [CO₂] increased above-ground biomass weight by 12.90%~83.09%. Total biomass weight increased by 13.98% and 25.79% at pod-filling and harvest stages, respectively. Root/shoot ratio increased by 18.68% at pod-filling stage. N concentration in above-ground part of mung bean decreased by 10.39%~21.06% under FACE compared with ambient [CO₂]. Elevated [CO₂] increased C concentration and C/N ratio by 0.41%~1.13% and 12.23%~26.68%, respectively. The change in seed N and C concentration and C/N ratio was insignificant. N and C uptake by above-ground part of mung bean increased by 1.99%~50.87% and 14.43%~92.69%, respectively. Biomass increase suggested higher crop assimilation of C and absorption of soil N under elevated [CO₂] conditions. This implied that mung bean production could be benefitted from increased levels of soil fertilization which ensures sufficient nutrient supply under elevated [CO₂] conditions.

Growth response and tolerance of potato (Solanum tuberosum L.) seedlings to root-zone hypoxia stress

LI Ya-Ling, SUN Zhou-Ping, SHI Xue

2011, 19(4): 799-804. doi: 10.3724/SP.J.1011.2011.00799

Abstract(1625) PDF(1301)

Abstract:
In order to analyze the waterlogging resistance of different potato varieties and screen waterlogging resistant genotypes, this paper investigated the effects of root-zone hypoxia stress on seedling growth of 14 potato varieties under pot-cultured waterlogging condition. The waterlogging-tolerance of these potato varieties was comprehensively evaluated according to the adversity resistance coefficient (ARC), waterlogging index (WI) and cluster analysis. The results showed that compared with normal cultivation (control), waterlogging significantly decreased plant fresh weight, dry weight, new leaf number, height and maximum length of new root of “Wuyangyu”, “Zaodabai”, “Favorita” and “Vagor” with the average ARC of 0.61~0.68, which indicated that those four varieties were sensitive to root-zone hypoxia stress. The plant growth was not significantly inhibited for “Zhugen”, “Zangshu-1” and “Kexin-12” under hypoxic conditions with the average ARC of 0.90~0.93, those three species showed higher waterlogging tolerance. “Kexin-16”, “Kexin-18”, “713NS51-5”, “717NS78-7”, “Cersa”, “458 DTO-33” and “Chuanyu” had a certain degree of tolerance to hypoxia stress with the average ARC of 0.75~0.83. After 8 days for waterlogging treatment, “Vagor” and “Favorita” showed the lowest waterlogging tolerability, with the highest WI of 3.0 and mortality rate of 47% and 50%. “Kexin-18”, “Wuyangyu” and “Zaodabai” were poorly waterlogging resistant with the WI of 2.5~2.8; while “Zhugen”, “Zangshu-1”, “Kexin-12” and “Kexin-16” had higher waterlogging tolerance with the WI of 0.2~0.8. “713NS51-5”, “717NS78-7”, “Cersa”, “458 DTO-33” and “Chuanyu” were intermediately waterlogging tolerant with the WI of 1.4~1.9. The comprehensive evaluation on hypoxia stress tolerance with ARC, WI and cluster analysis divided 14 potato varieties into four groups, the high tolerant varieties of “Zhugen”, “Zangshu-1” and “Kexin-12”; medium tolerant varieties of “Kexin-16”, “713NS51-5”, “717NS78-7”, “458DTO-33”, “Chuanyu” and “Cersa”; no-tolerant varieties of “Kexin-18”, “Wuyangyu” and “Zaodabai”; sensitive varieties of “Favorita” and “Vagor”.

Effect of limited irrigation on diurnal variation in flag-leaf photosynthesis and yield of dryland wheat

TAN Nian-Tong, LIN Qi, JIANG Wen, LIU Yi-Guo, LI Ling-Yan

2011, 19(4): 805-811. doi: 10.3724/SP.J.1011.2011.00805

Abstract(1459) PDF(1358)

Abstract:
A field experiment was conducted to study the effects of five irrigation treatments on diurnal variations in flag-leaf photosynthesis and yield of “Qingmai 6” dryland wheat variety. The results showed that diurnal variations in net photosynthetic rate (Pn) in each treatment followed a double-peak curve. However, the degree of midday depression in photosynthesis increased with increasing amount of irrigation. Increasing irrigation amount enhanced flag-leaf Pn and net stomatal conductance (Gs) under ≤3 irrigation times. The maximum Pn and Gs appeared in W3 treatment (i.e., 60 mm irrigation each at jointing, booting and grain-filling stages). With increasing supplementary irrigation, intracellular CO₂ concentration and stomatal limitation (Ls) decreased. Flag-leaf Pn under W4 treatment (i.e., 60 mm irrigation each at sprouting, jointing, booting and grain-filling stages) was significantly lower than that under W3 treatment. This suggested that superfluous irrigation had negative effects on flag-leaf photosynthesis in dryland winter wheat at grain-filling stage. In all the treatments, yield under W2 treatment (i.e., 60 mm irrigation each at jointing and booting stages) was the highest. The difference in yield between W2 and W1 (i.e., 60 mm irrigation at jointing stage) treatments was insignificant. Under ≤2 times of irrigation, yield increased with increasing irrigation amount. Yields under W3 and W4 treatments were lower than that under the dryland control treatment. This suggested that superfluous irrigation was unsuitable for high yield dryland winter wheat cultivation. In all the treatments, water production efficiency (WPE) declined with increasing irrigation amount. The experiment suggested that irrigation at jointing, booting and grain-filling stages was crucial for high flag-leaf Pn in dryland winter wheat. However, the effect of irrigation at sprouting stage on flag-leaf photosynthesis of dryland winter wheat was insignificant. Jointing was the most pivotal stage for high yield of wheat. Jointing and booting were the most essential stages for irrigating of winter wheat. Dryland wheat irrigation at these stages was very important for high yield and WPE. In terms of yield and WPE, the optimal supplementary irrigation mode for high yield in dryland winter wheat was 60 mm at jointing stage.

Effect of soil moisture on water use and appearance of green eggplant in greenhouse conditions

LIU Hao

2011, 19(4): 812-817. doi: 10.3724/SP.J.1011.2011.00812

Abstract(1374) PDF(1048)

Abstract:
With rapid economic development and improved living standard, the Chinese have shifted their attention to food quality and safety. Also with increasing water shortage, water-saving irrigation technologies such as drip irrigation have been increasingly used in greenhouse vegetable production. On this basis, the effects of soil moisture at different growth stages on water uptake, yield, water use efficiency, and appearance quality of green eggplant were studied in plot experiments under drip irrigation in greenhouse conditions. The experiment was conducted in 2009 at the experimental station for water requirement of the Institute of Farmland Irrigation Research. Green eggplants were transplanted in wide and narrow rows. The experiment was divided into three growth stages (seedling, flowering/fruit-setting and fruit maturation stages) based on the growth characteristics of eggplants. In the experiment, four different irrigation rates (with soil water content to be kept at 50%, 60%, 70% and 80% of field capacity) were applied at each growth stage. Furthermore, adequate water treatment (with soil water content to be kept at 80% of field capacity) was designed as the control of the experiment. This study was important for high efficiencies in water and fertilizer utilization, and significant environmental and economic benefits. Results showed that water deficit at any growth stage reduced water uptake by green eggplants. Fruit size, number and yield dropped with increasing water deficit. A quadratic parabola correlation existed among yield, water use efficiency and water consumption; with an optimal water consumption of 307.12~339.59 mm. Fruit count, total yield and water use efficiency were higher when the lower limit soil moisture content was kept at 60%~70% of field capacity at seedling stage, 70% of field capacity at flowering/fruit-setting stage and at fruit maturation stage. This was recommended as the optimum soil moisture index for drip irrigation management in green eggplants under greenhouse conditions.

Effect of regulated irrigation on input-output benefits of pear jujube

LI Xiao-Bin, WANG You-Ke, ZHAO Chun-Hong, WANG Ying, ZHANG Yong-Yong, WANG Xing, ZHANG Jian-Guo

2011, 19(4): 818-822. doi: 10.3724/SP.J.1011.2011.00818

Abstract(1643) PDF(1230)

Abstract:
Jujube is the main cash forest species in the Loess Plateau region. It is now the preferred and dominant cultivated tree species in the region due to its huge economic and ecological benefits. In this region, however, rainfall-fed and overland flooding remain the principal modes of irrigation, leading to low yield and poor fruit quality. This is a par with societal development, where emphasis has from quantity to quality of fruits/vegetables. It is therefore vital to develop water-saving irrigation systems that ensure high quality/yield in water-deficient regions for high economic benefits. In this paper, five irrigation gradients (to maintain soil water content as 70%, 60%, 50%, 40% of field capacity, and non-irrigation) were set up to investigate the influence of regulated irrigation on the quality of pear jujube fruit. The pear jujube trees were irrigated twice during sprouting and leaf-expansion, flowering and fruit setting, and fruit swelling periods, respectively. The fruit quality and input-output benefits of jujube production under the regulated irrigation system were analyzed. The results showed that: (1) fruit swelling, and flowering and fruit setting periods were the critical water demand periods that influenced fruit quality and economic benefits; (2) appropriate irrigation significantly improved not only fruit flavor and nutritional quality, but also increased weight per pear jujube fruit and number of fruit harvest; excessive irrigation also not only increased production cost, but resulted in no improvement in fruit quality and yield; (3) reasonable regulated irrigation during high water demand periods ensured a balance between input (production cost) and output (high yield and quality of fruits). Further analysis showed that proper irrigation significantly improved yield, quality and economic benefits of pear jujube. Under drought conditions, the economic benefits of jujube forest effectively improved by reasonable irrigation system at critical water demand and transfer periods. The study suggested that the reasonable irrigation system in the region for pear jujube was to keep 60% of field capacity.

Comparison of photosynthetic eco-functions of water hyacinth and their environmental factors in different areas

LI Xia, REN Cheng-Gang, WANG Man, CONG Wei, SHENG Jing, ZHU Pu-Ping, ZHENG Jian-Chu, YAN Shao-Hua

2011, 19(4): 823-830. doi: 10.3724/SP.J.1011.2011.00823

Abstract(1269) PDF(2371)

Abstract:
Eichhornia crassipes Solms, commonly known as water hyacinth, is a bundler aquatic plant. It is widely used in sewage purification due to its well developed root system, strong reproductive ability and ultra-strong absorbency. Introduced into China as feed, it is recently moderately consumed as cultivation substrate of edible fungus and methane fermentation materials. In fact, it is now an importantly modern, low-carbon eco-agricultural resource. An experiment was therefore conducted to determine the physiological and ecological characteristics of different types of water hyacinth in different ecological environments. The experiment was carried out at the Jiangsu Academy of Agricultural Sciences experimental sites in Xueyan of Taihu Lake, Nanjing and Dianchi Lake in 2009. Different plant indices such as plant height, root length and dry weight were measured. Also photosynthetic parameters of leaves at different sits were measured using LI-6400 portable photosynthetic system. The related environmental factors such as light intensity, air temperature and relative humid were recorded as well. Different water hyacinth phenotypes were noted in different areas. Short shoot with long root water hyacinths were noted in Dianchi Lake (with shoot/root height ratio of 0.4±0.1). Then medium-long shoot with short root water hyacinths were observed in Nanjing (with shoot/root height ratio of 7.1±0.3). Also long shoot with medium- long root water hyacinths existed in Taihu Lake (with shoot/root height ratio of 2.0±0.2). Compared with those in Nanjing and Dianchi Lake, Pn (25.9~35.3 μmol·m^-2·s^-1) of water hyacinth at Taihu Lake was the highest for different leaf positions. The correlation coefficients between Pn and relative humidity in Nanjing, Pn and stomatal conductance (Gs) in Dianchi Lake, and relative humidity and transpiration rate (Tr) in Taihu Lake were -0.831^*, 0.769^* and -0.818^* (n=6), respectively. Correlation analysis showed that after light intensity, relative humidity was the next most important ecological driving factor of Pn. Difference in phenotype of water hyacinth in different areas had affected maximum photosynthetic potentials of water hyacinth. The strongest plant growth of water hyacinth in Taihu Lake was related with high photosynthetic capacity (P_max=36.29±1.21 μmol·m^-2·s^-1) and light saturation point (LSP=2 350.0±69.0 μmol·m^-2·s^-1). Plant height and light compensation point (LCP), as well as shoot length and LSP were all positively correlated with correlation coefficients of 0.998^* and 0.997^* (n=10), respectively. The findings of the study were critical for high yield artificial stocking of water hyacinth. It was recommended that future breeding should focus on extensive adaptability of E. crassipes to light and temperature conditions.

Effect of stubble height on collectable amount of rice straw under different cultivation patterns

GU Ke-Jun, YANG Si-Jun, ZHANG Si-Mei, XU Bo, CHEN Juan, ZHANG Heng-Gan

2011, 19(4): 831-835. doi: 10.3724/SP.J.1011.2011.00831

Abstract(1329) PDF(1349)

Abstract:
There has been a significant inconsistency in research results regarding the effects of stubble height on collectable amounts of rice straw under different cultivation patterns. This study was therefore investigated 23 rice cultivars (including 19 Japonica rice and 4 Indica rice) with desirable yield and widely cultivated in Jiangsu Province. The effects of varietal genotype, planting pattern and yield on resource availability and collectable amount of rice straw under different stubble heights (5 cm, 15 cm, 20 cm and 25 cm) were determined. The results showed that straw amounts of Japonica rice were 11.4% higher than that of Indica rice. The amounts of straw from Japonica and Indica rice were 7 874.17 kg·hm^-2 and 7 066.83 kg·hm^-2, respectively. For different planting patterns, mechanical transplanting yielded the highest amount of rice straw. Hand planting ranked the second, and parachute transplanting had the least straw yield. The yield of rice straw for mechanical transplanting was 34.2%, 23.7% and 18.5% higher than those of parachute transplanting, direct seeding and hand planting, respectively. The collectable amount of rice straw in high yield field was more than that in low yield field. However, no significant difference was noted between high and low yield fields. There were no significant differences in straw/grain ratios for yields with 6 750~9 000 kg·hm^-2. However, significant differences existed among fields with grain yields below 9 000 kg·hm^-2 and above 9 000 kg·hm^-2. Under similar stubble height, the effects of yield levels and varieties on ratio of collectable straw to total straw were insignificant. However, there were significant differences among different planting patterns, and parachute transplanting exhibited the least collectable straw ratio. Under different cultivation patterns, the variation in collectable straw ratio changed with increasing stubble height. Collectable straw ratio was 0.815~0.868 for 5 cm stubble height, 0.668~0.732 for 15 cm stubble height, 0.600~0.669 for 20 cm stubble height, and 0.533~0.618 for 25 cm stubble height. In conclusion, collectable rice straw ratio under the same stubble height was mainly driven by planting pattern. Yield and varietal differences had little effect on collectable rice straw ratio. It suggested that collectable amounts of rice straw should be estimated based on planting pattern, and the stubble height.

Effects of pollination by different bees on peach fruit development and quality under greenhouse conditions

DONG Jie, AN Jian-Dong, HUANG Jia-Xing, ZHOU Zhi-Yong, ZHAO Ya-Zhou, XING Yan-Hong

2011, 19(4): 836-842. doi: 10.3724/SP.J.1011.2011.00836

Abstract(1415) PDF(1887)

Abstract:
Honeybee Apis mellifera and bumblebee Bombus hypocrita are the two main pollinators of greenhouse peaches in China. The effects of pollination by the two bee species on peach fruit development and quality were studied in greenhouse conditions in Pinggu of Beijing City for 2008~2010. The results showed that the diameter growth rate of peach fruit pollinated by B. hypocrita was significantly higher (P<0.05) than that of peach fruit pollinated by A. mellifera. The developmental duration of peach fruit pollinated by the two bee species differed, with B. hypocrita pollinating fruits ripening on the average by seven days earlier than A. mellifera pollinating fruits. While a di-peak physiological fruit-drop was noted in B. hypocrita pollinating fruits, a tri-peak physiological fruit-drop was observed in A. mellifera pollinating fruits. The rate of fruit setting of B. hypocrita pollinating peaches under greenhouse conditions did not significantly changed with the distance of peach trees to beehives. The rate of fruit setting of A. mellifera pollinating peaches under greenhouse significantly declined with increasing distance to beehives. There existed no significant difference (P>0.05) in fruit quality between fruits pollinated by different pollinator species. However, the quality of fruits pollinated by bees was significantly better (P<0.05) than that of the control (artificial pollination). Compared with A. mellifera pollination, B. hypocrita pollination resulted in higher single fruit weight and lower rate of malformed fruit (P<0.05) of peach fruits. In conclusion, the Chinese native bumblebee B. hypocrita was a better pollinator of greenhouses peach than the honeybee A. mellifera.

Effects of bagging on “Hanfu” apple aroma compounds

LI Hui-Feng, WANG Hai-Bo, LI Lin-Guang, LU De-Guo, YANG Jian-Ming

2011, 19(4): 843-847. doi: 10.3724/SP.J.1011.2011.00843

Abstract(1484) PDF(1181)

Abstract:
Bagging is a key apple production technology in China. Present research on fruit bagging has focused mainly on fruit micro-environment, structure, resistance capacity to adverse environmental elements, quality, etc. There has been less credible research on the effects of fruit bagging materials on fruit taste. Fruit aroma, a critical fruit taste indicator that determines fruit flavor, was investigated in this study in relation to fruit bag materials. The study used static headspace and meteorological chromatography- mass spectrometry technology to analyze the effects of bags of different materials (e.g., plastic film bag, double-layer paper bag, and reflective film bag) on aromatic compounds of “Hanfu” apple fruits. Although the effects of different bag materials on fruit aromatic compounds were different, bagging generally reduced the total content of aromatic compounds in “Hanfu” apple fruits. The total content of aromas in plastic film bagged fruits was slightly lower than that in non-bagged (CK) fruits (0.792 μg·g^-1). The total contents of aromas in fruits with double-layer paper and reflective film bags were 40.03% and 20.33% lower than that of CK, respectively. While bagging increased the total content of esters, it decreased the total content of alcohols and aldehydes. The aroma compounds of “Hanfu” apple characteristically contained 2-methylethylbutyrate, ethyl butyrate, 2-methylethylhexylbutyrate, ethyl hexanoate and hexaldehyde; all of which were ester aromas. The characteristic aroma compound of apple fruits with plastic film and double-layer paper bags was 2-methylethylbutyrate. While ehylbutyrate and 2-methylethylbutyrate were the characteristic aroma compounds of apple fruits with reflective film bags, 2-methylethylbutyrate and hexaldehyde were the characteristic aroma compounds of CK fruits. Fruit bagging limited production of important aroma compound (E)-2-hexenal, causing lower aroma quality of apple fruit under bagging than under CK conditions. The study of aromatic compounds laid the basis for research-driven selection and innovation of fruit bagging materials in fruit production.

Research on technology of grain production under double-cropping system in Yantai City

YU Kai, ZHANG Yu-Qiu, HAN Shou-Liang, MU Mei-Cai, SHAN Yu-Shan

2011, 19(4): 848-853. doi: 10.3724/SP.J.1011.2011.00848

Abstract(1472) PDF(1185)

Abstract:
Yantai (a city in Shandong Province) is a strong base for winter wheat-maize double-copping system. A previous double- copping system experiment involving single-stem late wheat intercropped with late-maturing maize in Longkou (a county of Yantai City) yielded 22 770 kg·hm^-2. Other studies have reported grain yields excess of 22 500 kg·hm^-2 in North China. For various reasons, however, replicating these experiments at field scales has not been feasible. As one of the first institutions to develop super- high-yield experiments, the Grain and Food Safety Research Center of China Agricultural University was founded in July 2004 in Yantai City, Shandong Province, at where we conducted a 3-year experiment on high-yield technology system of double-cropping system. Based on weather analysis in Longkou and Laizhou Counties of Yantai City, where super-high-yield experiments were first conducted, this paper put forward a new research direction that makes rational use of the abundant light, heat and species resources in Yantai for high-yield wheat-maize double copping system. The strategy delayed the sowing time of wheat to get the effective temperature (≥16 oC) for maize to fully exploit yield potential of longer growth period maize varieties. Two modes of double-cropping system cultivation techniques with suitable improved varieties were designed and selected. Based on the design, Longkou was best fitted for a double-copping system of mid-late wheat intercropped with mid-late maturing maize with Oct. 10 → Oct. 10 crop-rotation periods. Laizhou, on the other hand, was best fitted for double-copping system of single-stem late wheat variety mixed with mid-late maturing maize with Oct. 15 → Oct. 15 crop-rotation periods. Furthermore, the corresponding suitable varieties were incorporated into the experiments. The results of the double-copping system experiments were as follows: Longkou was suitable for the mid-late wheat “Liangxing 99” intercropped the mid-late maturing maize “Jinhai No. 5” of double-copping system with Oct. 10 → Oct. 10 crop-rotation period. Laizhou was suitable for directly sowed single-stem late wheat “Liangxing 99” mixed with the mid-late maturing maize “Jinhai 607” of double copping with Oct. 15 → Oct. 15 crop-rotation period. The results of three-year high-yield experiments in Laizhou and Longkou showed that yields were above 21 000 kg·hm^-2 per year. Yields for the last year reached the expected target of 22 500 kg·hm^-2. Yields for the area of 0.074 hm² reached 24 792.45 kg·hm^-2 for the two seasons. The study showed that wheat-maize double-cropping system technology that made full use of light, heat and variety resources was more rational for Yantai, which brought local potential productivity to full realization.

Influence of global warming on winter wheat yield in Henan Province

CHENG Lin, LIU Rong-Hua, MA Zhi-Hong

2011, 19(4): 854-859. doi: 10.3724/SP.J.1011.2011.00854

Abstract(1424) PDF(1339)

Abstract:
Agriculture is one of the industries that is most sensitive to global warming. Crop yield analysis is an efficient approach to evaluating the impact of climate change on agriculture. Henan Province (which is in the south region of North China Plain) is one of the most important production bases of winter wheat, a crop that is sensitive to global warming. This study used historical climate data and average winter wheat yield to determine the trends in precipitation and temperature during winter wheat growing season in Henan Province. It then utilized the extracted climatic productivity and Mann-Kendall mutation testing method to separate two distinct stages of the effects of climate change on agriculture. For each of the stages, regression equations were also established among temperature, climate change and yield. Then the impact of warming climate on unit yield of winter wheat was eventually analyzed at each stage using the equations. While there was no drastic change in precipitation during the 1961~2007 winter wheat season in Henan Province, the temperature rose continuously. In comparison with precipitation, temperature showed significant correlations with climate and unit yield of winter wheat. For the period of 1961~1981, the correlation between winter wheat yield and temperature departure was significant and positive. This correlation weakened after 1987, after which time yield fluctuation was limited. Since the mid 1980s, air temperatures during winter wheat seasons in Henan Province increased dramatically, with an average temperature increase of 0.81 oC per decade. In comparison with 1961~1981 (the pre-warming stage/period), wheat yield increased by 173.4%~245.9% in 1991~2000 and 2001~2007, and the contribution rate of temperature rise was 15.6%~20.7%. Average temperatures were relative higher in wintering, re-greening, heading and flowering stages. Warming positively influenced unit yield of winter wheat, as average temperatures were lower than the suitable temperature range. In the conspicuous 2001~2007 warming period, however, only 1.0% of the yield increase was due to temperature rise. This showed that unit yield of winter wheat increased with improved cultivation techniques. The study showed that while the sensitivity of yield to temperature variation decreased, the adaptability of agriculture to environment factors increased.

Drought indices and prediction models for winter wheat

KANG Xi-Yan, SHI Yin-Shan, GU Guang-Qin

2011, 19(4): 860-865. doi: 10.3724/SP.J.1011.2011.00860

Abstract(1624) PDF(1335)

Abstract:
Drought is one of the meteorological hazards that severely affects winter wheat production in Hebei Province. Accurate monitoring and prediction of drought occurrence provides the scientific basis for hazard control decision-making. This paper analyzed drought conditions in the winter wheat production belt of Nangong County, South Hebei Province. The study used observed agro-meteorological data and regular meteorological data for 1991~2007 to establish a drought index and prediction model for winter wheat. The water sensitive coefficients of winter wheat during re-greening to jointing, jointing to heading, heading to milky maturity and milky maturity to grain maturity stages were calculated using the Jensan model. Then percent yield reduction and relative evapotranspiration at each growth stage were used as index value to determine light drought, moderate drought, heavy drought and severe drought. A simulation test for 12 years (1991~2005) with 2006 and 2007 as evaluation periods was conducted. The results showed that the established index values for drought degree in different growth periods objectively reflected the active drought degree in the region. The criteria for drought degree took into account of the sensitivity of winter wheat at different growth stages. Regression models were used to predict drought in the four growth stages of winter wheat. The established drought prediction model results were significant at P=0.05. The correct rate of model simulating was 70.8%, correct rate of prediction was 75.0%, and the average correct rate was 71.4%. Assuming that drought was classified as level-one drought (light drought) and level-two drought (medium, heavy and severe droughts), then the model simulating correct rate was 81.3%, correct rate of prediction was 75.0%, and average correct rate was 80.4%. In summary, model calculations and predictions were in good agreement with observed data. Thus the prediction model had practical application in early warning and control of the impact of drought in winter wheat production.

Impact of warming climate on crop water requirement in Gansu Province

WANG He-Ling, WANG Run-Yuan, ZHANG Qiang, NIU Jun-Yi, LU Xiao-Dong

2011, 19(4): 866-871. doi: 10.3724/SP.J.1011.2011.00866

Abstract(1634) PDF(1693)

Abstract:
Global warming is an increasingly worrisome environmental and climatic phenomenon. Global average temperature increased by 0.60~0.70 oC over the last centuray, with an average temperature rise of 0.80~1.50 oC in China. Northwest China is one of the most sensitive areas to climate change. Temperature (a critical factor of global warming) is often used in an integrated method to calculate crop water demand. In other words, temperature afftects climate change, which in turn affects crop water needs. Crop water requirements in Northwest China is therefore critical in farm water cycle. It is also an important hydraulic and water-saving parameter in agricultural research, planning and design. This study addressed issues such as: the effect of climate change on agricultural water demand in different regions, and current lack of systematic and quantitative data to support crop water requirement research in the face of global warming. This study analyzed the effects of warming climate on crop water requirement in Gansu Province under different temperature scenarios (future temperature increases of 1~4 oC). The results showed that the effects of warming climate on crop water requirement were different for different crops. Warming climate greatly afftected water requirement of winter wheat, followed by spring wheat and maize. When future temperatures rose by 1~4 oC, water requirement of winter wheat increased by 3.05%~12.90%, which was the equivalent of 13.2~81.2 mm. That of maize increased by 2.49%~10.80%, the equivalent of 9.9~60.6 mm. Then spring wheat water requirement increased by 2.74%~11.69%, the equivalent of 6.7~40.0 mm. Regional differences were noted in the impact of warming climate on crop water requirement. The impact of warming climate on crop water requirement was highest for arid regions, followed by semi-arid regions, and then semi-humid regions. The least effect was for humid regions. When future temperatures rose by 1~4 oC, the temperature scenario caused additional irrigation water requirement of 1 243, 1 302, 1 374 and 1 465 million m³ for winter wheat; 794, 832, 878 and 930 million m³ for maize; and 497, 516, 542 and 576 million m³ for spring wheat, respectively. Warming climate worsened water shortage problems in the study area.

Response of Sophora alopecuroides and Thermopsis lanceolata seed germination and growth to drought stress

WANG Jin, WANG Ju-Hong, ZHANG Yong, MA Zhao-Yuan, YAN Xia

2011, 19(4): 872-877. doi: 10.3724/SP.J.1011.2011.00872

Abstract(1475) PDF(1229)

Abstract:
Seed germination and seedling stages are not only crucial stages of the life span of plants, but also important adaptation stages to different environmental conditions. The response of Sophora alopecuroides L. and Thermopsis lanceolate L. seed germination and seedling growth to drought stress in border desert lands of the Hexi Corridor were investigated under simulated drought conditions of polyethylene glycol-6000 (PEG) with -0.03 MPa, -0.10 MPa, -0.24 MPa, -0.42 MPa, -0.65 MPa and -0.94 MPa osmotic potentials. The main objectives of the study were to reveal the adaptive mechanisms of desert plants and to provide further technical guidance on seedling cultivation and restoration of desert vegetation. The result showed that the rate of seed water uptake, germination percentage, germination index, vigor index, seedling height, root length and plant water content decreased with increasing PEG drought stress. However, seedling and root dry weight and root/shoot ratio initially increased followed by a decrease. Furthermore, seed germination was sensitive to drought stress. The lowest osmotic potential threshold was -0.65 MPa for S. alopecuroides seeds and -0.42 MPa for T. lanceolate seeds. For seeds incapable of germination under drought stress, germination percentage was high once water was recovered. The results suggested that response of seed germination and seedling growth to drought stress was ecologically essential for later establishment of seedlings and vegetation. In artificial cultivation, however, a key step for successful planting was guaranteed soil moisture.

Research on Tripterygium wilfordii Hook. f. rhizosphere microbial characteristics

LI Jian, TANG Jia-Dong, WU Cheng-Zhen, HONG Wei, FENG Lei, SONG Ping

2011, 19(4): 878-882. doi: 10.3724/SP.J.1011.2011.00878

Abstract(1495) PDF(1283)

Abstract:
Rhizosphere is the zone of soil surrounding a plant root, which provide a conducive special environment for a wide range of microorganisms. Root secretions at different plant growth stages provide nutrition and energy for microorganisms, thereby notably influencing their number, composition and activity. Metabolism of microorganisms in the rhizosphere promotes or limits plant nutrient absorption and growth, and also influences the transformation of substances in rhizosphere soil. Tripterygium wilfordii Hook. f. has well-developed root systems, and is frequently planted along with other trees. This makes the study of rhizosphere microorganism activity very important for soil fertility and growth of T. wilfordii. This paper used three different T. wilfordii forest stands [mixed Cunninghamia lanceolata (Lamb.) Hook (Chinese fir) and T. wilfordii forest, mixed Magnolia officinalis Rehd. et Wils. and T. wilfordii forest, and natural T. wilfordii forest) in Taining County, Fujian Province as experimental materials and the dilution-plate technique to determine the number of bacteria, fungi and actinomyces in rhizosphere and non-rhizosphere soils. The results showed that: the number of rhizosphere microorganisms was much larger than non-rhizosphere microorganisms. In the three forest stands, the number of microorganisms in either rhizosphere or non-rhizosphere soil was in the order of: bacteria > actinomyces > fungi. Rhizosphere microorganisms were more active than non-rhizosphere microorganisms. In three forest stands, rhizosphere to non-rhizosphere ratio of microorganisms number was higher than 1. The activity of microorganisms in the three forest stands was in the order of: mixed M. officinalis and T. wilfordii forest > mixed Chinese fir and T. wilfordii forest > natural T. wilfordii forest. This suggested that mixed forest modes enhanced the activity of microorganisms.

Effects of exotic plant Ageratina adenophora invasion on mycorrhizal fungal community

YU Wen-Qing, LIU Wan-Xue, WAN Fang-Hao

2011, 19(4): 883-889. doi: 10.3724/SP.J.1011.2011.00883

Abstract(1540) PDF(2049)

Abstract:
The invasion of exotic plants and probability of successful invasion are affected by the interaction between exotic plants and soil microbes in invaded habitats. Furthermore, interactions among mycorrhizal fungi (MF) and exotic plants have been the focus of the response of soil microbial mechanisms to plant invasion. This study used nested PCR to detect MF in roots and rhizosphere soils of native weeds and A. adenophora in native weeds dominated community, A. adenophora and native weeds mixed community, and A. adenophora dominated community in A. adenophora invaded habitats. The results showed that MF community structures were different for different invasion phases. Glomus intraradices clones were detected in roots of native weeds grown in native weeds dominated community. G. intraradices clones were also noted in roots of A. adenophora grown in A. adenophora and native weeds mixed community. Only one Glomus (Glomus sp 2) clone was found in the roots of native weeds grown in A. adenophora and native weeds mixed community. No MF was detected in the roots of A. adenophora grown in A. adenophora dominated communities. Also two Glomus (Glomus sp 1 and Glomus sp 2) clones were obtained in the rhizosphere soils of A. adenophora dominated community. Trichoglossum hirsutum, Tricholoma saponaceum, Xylobolus subpileatus and Sarcodon imbricatus were detected in rhizosphere soils of A. adenophora grown in A. adenophora and native weeds mixed community. Camarophyllopsis hymenocephala, Lepista irina, T. saponaceum and Panellus serotinus were found in rhizosphere soils of native weeds grown in A. adenophora and native weeds mixed community. T. saponaceum was found in rhizosphere soils of native weeds grown in native weeds dominated communities. MF communities were changed by A. adenophora invasion and ectomycorrhizal fungi (EMF) more likely habited native weeds rhizosphere soils than A. adenophora rhizosphere soils. Arbuscular mycorrhizal fungi (AMF) accumulated more in rhizosphere soils of exotic A. adenophora than in native weeds rhizosphere soils. The probability of invasion changed MF community response to A. adenophora invasion, which suggested that A. adenophora heartened AMF in rhizosphere soils and induced positive AMF feedback, which enhanced A. adenophora invasiveness. The study highlighted one of the important soil microbial mechanisms of A. adenophora invasion in southeast China.

Effects of dimethyl disulfide on microbial communities in protectorate soils under continuous cropping

WANG Fang-Yan, WANG Qiu-Xia, YAN Dong-Dong, MAO Lian-Gang, GUO Mei-Xia, YAN Ping-Mei, CAO Ao-Cheng

2011, 19(4): 890-896. doi: 10.3724/SP.J.1011.2011.00890

Abstract(1706) PDF(1345)

Abstract:
Soil fumigants are widely used to protect agricultural and high-value cash crops from soil-borne diseases. As broad-spectrum agents, however, fumigants also have side effects on non-target organisms. Dimethyl disulfide (DMDS) is a new alternative to methyl bromide (MeBr) that reduces plant fungal pathogens and nematodes. DMDS is therefore recommended by the Methyl Bromide Technical Options Committee of the United Nations Environment Program (UNEP). This study was an attempt to identify the effects of DMDS on microbial communities in protectorate soils under continuous cropping. The efficacy of DMDS was evaluated by bio-assay in the laboratory. The efficacy of DMDS on the Fusarium spp. and Phytophthora spp. was observed after fumigations. The LC₅₀ of DMDS with different concentrations (170.00 mg·kg^-1, 85.20 mg·kg^-1, 42.50 mg·kg^-1, 21.30 mg·kg^-1 and 10.62 mg·kg^-1) was 42.08 mg·kg^-1 and 115.15 mg·kg^-1, respectively to Fusarium spp. and Phytophthora spp. Microbial community structures after DMDS fumigation were evaluated using BIOLOG Ecoplates under laboratory conditions. Compared with the untreated/control plants, the average well color development (AWCD) of the DMDS 10.62 mg·kg^-1, 42.50 mg·kg^-1 and 170.00 mg·kg^-1 respectively increased by 8.46%, 6.02% and 19.31%, 0 day after fumigation and 120 h after sample incubation. AWCD increased by 1.87%, 3.47% and 8.01%, respectively, 240 h after incubation; which indicated that DMDS promoted the growth of microbes. AWCD of treated samples were close to the control at 14 days after fumigation. The indices of Shannon and Simpson at 0 day after fumigation were higher than that of the control, recovering to the levels of the control 7 days after fumigation. Based on McIntosh index, there was no significant difference between the fumigation treatments and the control. Principal component analysis of substrate reaction reflected that the use of carbon sources by microbial community was obviously different in the treatments immediately after fumigation. It was, however, close to the control 14 days after fumigation. The study showed that DMDS fumigation promoted microbial activity, and affected the carbon sources consumption of microbe. However, effects became very weak and the indicators recovered to the levels of the control treatment at 14 days after fumigation. It indicated that DMDS fumigation not only effectively controlled soil-borne pathogen spread, but was also environmentally safe. The study laid the basis for a scientifically-guided use of fumigants.

Effects of fluoride on soil properties and yield and quality of maize

CUI Xu, WANG Xiao-Dong, FAN Wen-Hua, WANG Jian-Ming, CUI Ke-Yong

2011, 19(4): 897-901. doi: 10.3724/SP.J.1011.2011.00897

Abstract(1546) PDF(1425)

Abstract:
Fluorine is good for animal and human health, however, its excessive use is harmful for both animal and human health. A pot experiment was conducted to study the effects of fluorine on soil properties (pH, water soluble Ca and microbes) and on yield and quality of maize. The fluorine was added into the soil in form of NaF of 0, 100 mg·kg^-1, 200 mg·kg^-1, 500 mg·kg^-1, 1 000 mg·kg^-1 and 1 500 mg·kg^-1. The results showed that maize yield significantly decreased with increasing fluoride dose. Compared with the control, maize yield dropped on the average from 9.9% to 85.4%. However, maize grain protein content significantly increased on the average from 91.8 g·kg^-1 to 108.8 g·kg^-1. Under fluoride doses of 100~200 mg·kg^-1, starch content decreased. It, however, increased at fluoride doses of 500 mg·kg^-1, 1 000 mg·kg^-1 and 1 500 mg·kg^-1. Fluoride content in different parts of the maize plant increased with increasing fluoride dose. Fluoride contents in maize root, grain and leaf were significantly positively correlated with fluoride dose, coefficients were 0.998^**, 0.915^** and 0.852^*, respectively. The order of fluoride content in different parts of the maize plant was: root > leaf > leaf-sheath > stem > grain. With 200 mg·kg^-1 of fluoride dose, fluoride content in grains exceeded the safe agricultural product standard. Soil pH increased (from 8.05 to 8.70) and water soluble Ca decreased (from 2.71 g·kg^-1 to 1.02 g·kg^-1) with increasing fluoride dose. Compared with the control, actinomyce quantity decreased by 0.92%~65.22% with increasing fluoride dose. Low fluorine dose promoted bacteria and fungi growth, while the reverse inhibited bacteria and fungi growth.

Effects of fluazinam on soil sucrase activitiy and respiration

LUO Ai-Lan, YU Xiang-Yang

2011, 19(4): 902-906. doi: 10.3724/SP.J.1011.2011.00902

Abstract(1556) PDF(1544)

Abstract:
Despite beneficial impacts such as improving and sterilizing agricultural products via pest and disease control, pesticide pollution of soils continues to be a huge and growing environmental problem. Repeated and extensive application of pesticides ultimately percolates into the soil, which in turn interact with soil organisms and affect their metabolic activities. Biological activities under continuous pesticide inputs constitute an important aspect of agro-ecological research. To better understand the potential environmental risks of pesticide fluazinam on soil microbial activity and soil quality, the residues and degradation dynamics of fluazinam in soils were determined in a laboratory simulation method. The effects of fluazinam pollution on soil basal respiration, and kinetic and thermodynamic parameters of sucrase were analyzed. Significant fluazinam degradation rates were noted under higher application rates of fluazinam. The half-life of soil fluazinam degradation was 0.38~0.59 d. With increasing concentrations of fluazinam (50 mg·kg^-1, 100 mg·kg^-1 and 1 000 mg·kg^-1), the degrees of inhibition effect on sucrase activity increased. However, inhibition-activation-inhibition curves were fitted at lower concentration (1 mg·kg^-1, 5 mg·kg^-1) treatments with large ranges of fluctuating. 10 mg·kg^-1 of fluazinam initially inhibited and later enhanced soil sucrase activity with a great fluctuation. The maximum rate of enzymatic reaction (V_max) of sucrase was noted along with different Michaelis constant (K_m) under different fluazinam concentrations. The activation energy (E_a) of sucrose was higher under 1 mg·kg^-1 fluazinam than that under the control (CK), but lower under other fluazinam concentrations than under CK. Activation enthalpy change (ΔH) decreased with increasing fluazinam concentrations (from 5 mg·kg^-1 to 1 000 mg·kg^-1). Sucrase activation entropy change (ΔS) under fluazinam concentration of 1 mg·kg^-1 was lower than under CK for the same temperature conditions, though insignificant changes in free energy of activation (ΔG). The maximum velocity constant (Q₁₀) was in the thermodynamic temperature range of 320~330 K, and minimum in 290~300 K. Soil microbial basal respiration initially decreased, followed by a increase under lower fluazinam concentration treatments. However, inhibition effects were noted in higher concentration treatments all through incubation period. The findings had useful applications in future research on enzymatic mechanisms in relation to pesticides pollution and soil integrity.

State of pesticide residue in litchi orchard soils in Guangxi and Fujian, China

YAO Li-Xian, HUANG Lian-Xi, LI Guo-Liang, YANG Bao-Mei, HE Zhao-Huan, ZHOU Chang-Min, GUO Bin

2011, 19(4): 907-911. doi: 10.3724/SP.J.1011.2011.00907

Abstract(1386) PDF(1200)

Abstract:
Litchi, a famous (sub)tropical fruit, originated in South China. After Guangdong Province, Guangxi is the second largest litchi production base, and Fujian is also another main litchi production base in China. The state of pesticide residue in litchi fruit has been of great concern to researcher and consumers. In fact, the state of pesticide residue in litchi orchard soils has been related to the quality and safety of litchi fruit. This work therefore investigated the state of common pesticide residues in Guangxi and Fujian litchi orchards to guide safe production of the crop in these regions. A total of 210 soil samples were collected in litchi orchards in Guangxi and Fujian after harvest. The samples were analyzed for commonly used pesticides, including metalaxyl, mancozeb, carbendazim, deltamethrin, cypermethrin, cyhalothrin, dipterex, dimethoate and dichlorvos. Based on the results, carbendazim was the most frequently detectable pesticide in litchi orchards in both Guangxi and Fujian. The detection rates of carbendazim in Guangxi and Fujian litchi orchard soils were 48.1% and 84.0%, respectively. While mancozeb, dipterex and dimethoate were not detected in Guangxi orchard soils, the detection rates of the other five pesticides were less than 10%. Metalaxyl and cypermethrin were observed in 24.0% of the soil samples from Fujian orchards. The other six pesticides were at least not detectable. Litchi orchards numbered with zero or one detectable pesticide accounted for 48.6% and 38.4% of the total litchi orchards in Guangxi, and 56.0% and 8.0% in Fujian, respectively. Litchi orchards with two detectable pesticides accounted for 11.4% and 32.0% of the total investigated litchi orchards in Guangxi and Fujian respectively. The pesticide with the highest mean concentration in orchard fields of Guangxi was cypemethrin (5.0 μg·kg^-1), followed by dichlorvos (1.9 μg·kg^-1). The concentrations of the other detectable pesticides were less than 1.0 μg·kg^-1. The ranked order of average detectable pesticides was carbendazim (0.77 μg·kg^-1) > metalaxyl (0.65 μg·kg^-1) > cypermethrin (0.48 μg·kg^-1) in Fujian. Although higher concentrations and detection rates of pesticides were detected in Fujian, the state of pesticide residues in both Fujian and Guangxi was still minimal. Hence, soil pesticide residues in litchi orchards posed no harm to litchi quality in both Guangxi and Fujian.

Effects of outlet positions and plant species on rural domestic sewage purification in engineered vertical flow wetland

LIU Fen-Fen, WANG De-Jian

2011, 19(4): 912-917. doi: 10.3724/SP.J.1011.2011.00912

Abstract(1254) PDF(1301)

Abstract:
In this study, four different types of engineered vertical flow constructed wetland (VF-CW) — Canna indica Linn wetland (M), Pennisetum alopecuroides (Linn.) Spreng wetland (L), Sorghum sudanense (Piper) Stapf wetland (S) and control wetland without plant (CK) — were used to determine the effects of outlet positions (high, middle and low position) and plant species on pollutant removal efficiency in rural domestic sewages. Domestic sewages from anaerobic tanks in the Changshu Agro-ecological Experimental Station were intermittently used to irrigate VF-CW at hydraulic loading rate of 0.15 m³·m^-2·d^-1. Results showed that the outlet position significantly determined the removal efficiency of NH₄⁺-N, NO₃^- -N and COD (chemical oxygen demand) in rural domestic sewages. The removal rate of NH₄⁺-N significantly increased with lowering of the outlet position. The maximum removal rate of NH₄⁺-N was 98.3%. However, the removal rate of NO₃^--N and COD significantly decreased with lowering of the outlet position. The removal rates of NO₃^--N and COD of the highest outlet were -47.4% and 64.5%, respectively. The removal rate of total nitrogen (TN) of the high outlet increased by 22.5%~27.6% compared with that of the middle and low outlets. On the contrary, the removal efficiency of total phosphorus (TP) of the high outlet was 20.6%~28.9% lower than that of middle and low outlets. Compared with the control treatment (CK), the removal rates of NO₃^--N, TN, TP and COD in VF-CW with C. indica, P. alopecuroides and S. sudanense significantly increased by 74.4%~98.6%, 11.3%~17.8%, 8.60%~16.3% and 14.1%~19.0%, respectively. However, no significant differences were noted among VF-CWs with three plant species regarding the removal of NO₃^--N, TN, TP and COD. In term of the removal rate of NH₄⁺-N, C. indica wetland performed significantly less than the other plant species VF-CWs. These results suggested that pollutant removal efficiency improved by controlling outlet position and growing plants in VF-CW systems.

Population dispersal of parasitoid Coccobius azumai (Hymenoptera: Aphelinidae) introduced from Japan in Fujian pine forest of China

CHEN Shun-Li, ZHANG Fei-Ping, HONG Bing-Huang

2011, 19(4): 918-924. doi: 10.3724/SP.J.1011.2011.00918

Abstract(1308) PDF(1084)

Abstract:
Parasitoid Coccobius azumai is an important biological agent against Hemiberlesia pitysophila had pine armored scale imported from Japan in the late 1980s and released in Fujian pine forest of China. This paper analyzed the dispersal ability, post-release parasitic ratio and the driving factors of parasitoid population using a series of observations in selected pine forests in Fujian Province of China for the period 2007~2009. The parasitoid population dispersed much slowly in the field and spread at an approximate velocity of 200 m per year. Even though jerk dispersal of the population was occasionally observed in the field experiment, generalized linear model analysis showed that a displacement dispersal trend which increased with the time of release. The interaction of forest stand and dispersal time significantly influenced population dispersal. High parasitoid release initially, ♀∶♂=7∶1 mixture and release in the upper/middle forest slopes enhanced population dispersal. Linear regression analysis revealed that C. azumai parasitic ratio on H. pitysophila adult females significantly decreased with increasing distance from parasitoid population dispersal site. Parasitic ratios were 41.8%, 34.7%, 19.8%, 11.0% and 3.8% for initial release intervals of 0, 50 m, 100 m, 150 m and 200 m, respectively. No significant effects of the number of initial release and sex-mix pretreatment were observed on parasitic ratio at 100 m site. It suggested that interaction of high pest-controlling efficiency and low dispersal capability of parasitoid population was disadvantageous to parasitoid stability and sustaining in the field. The long-term efficient control was not sustainable for present releases in small geographic ranges. An effectively considerable measure was to release parasitoids at greater number of sites with reasonable spatial intervals in large geographic ranges, and periodically do so at logical time intervals. In order to fully utilize the parasitoids, useful and detailed methods of release were suggested, involving spatial layouts of release sites, complementary releases, parasitoid collection modes, initial released number and sex-mix pretreatment.

Coupling mechanism and countermeasure of compound rural-urban eco-economic system in karst areas — A cast study of Qianxinan Region

LUO Kun-Yan, ZHOU Guo-Fu

2011, 19(4): 925-931. doi: 10.3724/SP.J.1011.2011.00925

Abstract(1535) PDF(1361)

Abstract:
Guizhou is one of the provinces with the most widely distributed carbonate rocks and extensive karst systems. The area under karst is 120 000 km², and ≈1/3 of the area is rocky desert. About 5.85 million people of the rural population are poor, which is a growing concern for fast-developing country. Using eco-economy and systematic coupling theories, this paper developed an evaluation index system for Qianxinan Region, Guizhou Province. About 15 years of data, spanning for 1994~2009, were used in the study. Modeling was used to explain the interactions/coupling mechanisms of compound rural-urban eco-economic system in karst regions which was in turn used to develop a material foundation/dynamic mechanism. The results suggested that preface parameters in the compound urban-rural eco-economic systems of Qianxinan Region were growing. This was mainly due to rapid growth of the urban eco-economic system. While the positions of rural and urban economies changed in the compound system, urban economy showed a great momentum with a gradually strengthened dynamic human input. Environmental elements were damaged to some degree, especially in rural area environmental factors changed greatly. The coupling function was used to calculate the coupling degree (DC) and coupling coordination (CC) of the compound urban-rural eco-economic system in karst areas. The calculation showed that DC of the compound urban-rural eco-economic system was 0.39~0.49 with a CC of 0.18~0.42, they were considered not high, but with gradual built up of subsystems synergy. DC of the rural eco-economic system in karst areas was 0.48~0.50 with CC of 0.18~0.29, it suggested non-adaptation of ecological environment to rural economic development. DC of the urban eco-economic system in karst areas was 0.15~0.50 with CC of 0.05~0.33, they was not high, but indicted a rapid phase of development. This brought about negative influences on the environment. Based on the present conditions of the compound system, it was advanced that rural eco-economic system growth should promote urban eco-economic construction, to realize healthy development of the compound system.

Determining the dynamic of energy consumption in rural Heilongjiang Province from ecological footprint

HUANG Jing-Qiang, SHANG Jie, YU Fa-Wen

2011, 19(4): 932-935. doi: 10.3724/SP.J.1011.2011.00932

Abstract(1605) PDF(1186)

Abstract:
Rapid rural development needs a great amount of energy, which conflicts with the demand of less CO₂ release for relieving global climate changing. Rural energy consumption is therefore important and is predicted to significantly increase energy demand. This paper used ecological footprint (EF) to evaluate and analyze energy consumption dynamics and efficiency in rural Heilongjiang Province in 1998~2007. Straw and biogas EF was also calculated and integrated into the total EF. The results suggested increasing trends in all forms of energy consumption during the 1998~2007 period. For all the forms of energy, the highest consumption increase was noted in electric power, increasing from 183.51 kWh per capita in 1998 to 279.03 kWh per capita in 2007. This was followed by biogas, increasing from 0.001 m³ per capita in 1998 to 2.445 m³ per capita in 2007. Because of the increases in consumption of these forms of energy, EF of all the forms of energy also increased over the period. Total energy EF per capita was 0.278 9 hm² in 1998 and 0.549 8 hm² in 2007. Under the same energy consumption dynamics, increase in electric and biogas energies were higher than in other forms of energy. This resulted from the development of government policies to regulate rural power and bio-energy consumption. Ecological efficiency increased with increasing energy consumption. It increased from 2 472.34 Yuan·hm^-2 in 1998 to 5 192.58 Yuan·hm^-2 in 2007 indicating improved resources efficiency. Because of continuous increase in energy consumption, government should institute regulation polices and adjust capital flow to support renewable energy technology and biomass energy development, which reduced petroleum energy consumption and improved energy efficiency.

Dynamic evaluation of sustainable development in Jiangxi Province

ZHAO Xian-Gui, MA Cai-Hong, XIAO Ling, LAN Ye-Xia

2011, 19(4): 936-939. doi: 10.3724/SP.J.1011.2011.00936

Abstract(1591) PDF(1156)

Abstract:
Appraisal of sustainable regional development has attracted much attention in recent years. Conventional appraisal of sustainable development is routinely based on representative overall index system. The principal weakness of this approach is the large number of appraisal factors. The index weight also needs artificial evaluation and subjective factors may drastically affect the overall results. Furthermore, the evaluation indicators and division rank standard are often too difficult to unify. The overall results are therefore not often commensurate to the individual components in space and time. Recently, an ecology trail theory is proposed for appraising sustainable regional development. However, this method merely relies on ecological deficits (which are insufficiently available) in judging the sustainability of development conditions. Using ecological footprint theory, this paper advanced a sustainable development evaluation model that was designed on ecological tension (ETI), occupancy (EOI) and economic coordination (EECI) indices. ETI is the ratio of per-capita regional ecological footprint of renewable resource to ecological carrying capacity. This represents the degree of tension that can safely be absorbed by a regional ecological environment. EOI is the ratio of a per-capita regional ecological footprint to per capita global ecological footprint. It reflects the degrees of both national/regional socio-economic development and per-capita consumption. EECI is the ratio of EOI to ETI. It depicts the level of coordination between regional ecological environment and regional socio-economic development. The sum of ETI, EOI and EECI is a standardized measure of sustainable development index of a region. This paper dynamically evaluated ecological safety, people’s consumption level, and ecological/ economic development in Jiangxi Province for the period 1990~2007. The results showed an enhancement in ETI from 1.56 in 1990 to 1.96 in 2007. About 25.64% of this enhancement occurred during the period of research. This implied that the ecology was in an unsafe state (2 grade). The increase in EOI from 0.79 in 1990 to 0.88 in 2007 also implied a very poor state of occupancy (2 grade). The decrease in EECI from 0.50 in 1990 to 0.45 in 2007 suggested a bad state of coordination (1 grade). Sustainable development index (SDI) decreased from 0.19 in 1990 to 0.13 in 2007, suggesting a bad state ecological sustainability (1 grade).

Emergy analysis of vegetable ecosystem in Pei County, Jiangsu Province

FU Wei, JIANG Fang-Ling, LIU Hong-Wen, WU Zhen

2011, 19(4): 940-946. doi: 10.3724/SP.J.1011.2011.00940

Abstract(1523) PDF(1208)

Abstract:
The theory of emergy analysis is based on the premise that all forms of energy are from the sun. Different and incomparable forms of energy are therefore unifiable into solar emjoules. In this study, environmental resources and economic characteristics of vegetable ecosystems in Pei County (one of the main production bases of vegetable in Jiangsu Province) were quantitatively analyzed using the theories and methods of ecosystem emergy analysis. A series of emergy indices were developed for evaluating the environment resources and development characters of the vegetable ecosystem in Pei County. These indices simultaneously provided scientific basis for sustainable development of vegetable industry in Pei County. The study showed that: in 2007, vegetable emergy input in Pei County was 1.22×10²¹ sej. Industrial auxiliary energy input was 7.18×10²⁰ sej, accounting for 58.85% of the total vegetable ecosystem emergy, which suggested that the development of vegetable industry in Pei County relied mainly on industrial auxiliary energy, and had developed beyond traditional agriculture relied mainly on natural conditions. Vegetable ecosystem output in Pei County was 3.20×10²¹ sej, accounting for 39.65% of total agriculture emergy yield, indicating that vegetable industry was one of the strongest pillars of industries in Pei County. Emergy outputs from solanaceous fruits and roots, tuber vegetables were relatively higher, accounting for 35.63% and 23.63% of total vegetable emergy yield, respectively. Foreign exchange earning vegetables such as burdock and Chinese yam accounted for 18.61% of total vegetable emergy yield. Emergy self-sufficiency ratio of vegetable ecosystem in Pei County was 2.67%, which was lower than that of arable land ecosystems of Jiangsu Province (10.12%), illustrating that environmental resources were no longer the main determinants of vegetable development. The resistance of vegetable ecosystem in Pei County to natural disasters was sufficiently strong. The proportion of industrial auxiliary emergy of vegetable ecosystem in Pei County was 58.85%, which was lower than that of arable land ecosystems in Jiangsu Province (73.16%). There was a huge consumption of chemical fertilizers in vegetable production in Pei County, accounting for 69.42% of industrial auxillary emergy. This was considered unfavorable to sustainable development of vegetable industry in the county. Organic auxiliary emergy ratio of vegetable ecosystem in Pei County was 38.61%, which was higher than that of arable land ecosystems of Jiangsu Province (16.72%). Purchased emergy ratio of vegetable ecosystem in Pei County was 97.54%, which was higher than that of arable land ecosystems of Jiangsu Province (89.88%), suggesting that the development of vegetable industry in Pei County almost totally depended on buying emergy of the socio-economic system. The high emergy purchase promoted rapid development of vegetable industry in Pei County. Emergy investment ratio of vegetable ecosystem in Pei County was 36.61 and that of arable land ecosystems in Jiangsu Province was 8.88. This further suggested a rapid development of vegetable industry in Pei County. However, net emergy output ratio of vegetable ecosystem in Pei County was only slightly higher than that of arable land ecosystems in Jiangsu Province. This was due to insufficient promotion of high output new technologies. Environmental loading ratio of vegetable ecosystem in Pei County was 1.43, which was lower than that of arable land ecosystems in Jiangsu Province (2.83). Pesticide input only accounted for 0.21%, indicating that vegetable industry in Pei County was strongly sustainable with a high development potential. Further strengthening of vegetable industry infrastructure would enhance comprehensive benefit and sustainable development of county-level vegetable industry. It was also recommended that the development of vegetable processing industry and popularization of science and technology should be enhanced, which could benefit emergy output increase of vegetable ecosystem in Pei County.

Evaluation of ecological conservation importance via GIS approach in the middle reaches of Nujiang watershed

LI Hui, YANG Shu-Hua, YAO Wen-Jing, WANG Si-Qi, YI Na, LIU Da-Bang

2011, 19(4): 947-953. doi: 10.3724/SP.J.1011.2011.00947

Abstract(1748) PDF(1348)

Abstract:
The importance of ecological conservation at regional level is reflected in the sustainability and protection of valuable/ fragile ecosystems. Several factors (e.g., soil erosion, eco-hydrological environment, stone desertification and geological disaster) influence ecological conservation. This paper used Geographic Information System (GIS) technology to build a combined multi- factor approach to evaluate ecological conservation. The approach combined one fold factor overlay method with logical reasoning method to formulate a comprehensive systems approach. The concept of ecological sensitivity was extended to ecological conservation importance, which is a critical factor of ecological conservation. The paper discussed the concept of importance of ecological conservation and evaluated the ecological conservation importance of the middle reaches of Nujiang watershed from soil erosion sensitivity and biodiversity. The results showed that the ecological conservation extremely important zone lied in the river valley region. This region was situated at an altitude over 1 300 m and covered 11.43% of the total studied area. The ecological conservation highly important zone covered about 48.02% of the studied area, and was at an altitude of 1 800~3 100 m. The ecological conservation moderately important zone was 35.22% of the studied area, located at an altitude of 3 100 m. The ecological conservation slightly important zone was small, accounting for 5.29% of the studied area, and with patched distribution. The ecological conservation unimportant zone was the smallest zone, covering only 0.04% of the total area and mainly distributed in residential areas. This evaluation work provided the basis for prioritizing ecological conservation efforts, with the main focus on ecological protection, recovery and construction.

Calculation and analysis of water footprint in Beijing City

WANG Yan-Yang, WANG Hui-Xiao, CAI Yan

2011, 19(4): 954-960. doi: 10.3724/SP.J.1011.2011.00954

Abstract(1595) PDF(1871)

Abstract:
Individual or community water footprint (WF) is defined as the total volume of water used to produce goods and services consumed by the individual or community. Virtual water content of a product (a commodity, good or service) is the volume of water used to produce the product. It is the sum of water used in the various stages of the production chain. Total water footprint (TWF) includes real water consumption, and more importantly virtual water consumption. By analyzing the volume and structure of WF, the consumption of water resources in any given region in terms of finished products can be determined. This paper calculated TWF of Beijing City for 2002 based on water input-output table. It also analyzed TWF composition in the city. The analysis showed that Beijing’s TWF in 2002 was 8.626 billion m³. About 70% of TWF was used in resident consumption and 30% in government consumption. The per capita average WF of Beijing was 606.208 m³, that of urban residents was 537.690 m³ and the per capita average WF of rural residents was 197.123 m³. Real water consumption accounted for 8% of TWF, whereas virtual water consumption accounted for 92% of TWF. Virtual water net inflow was 1.498 billion m³, which accounted for 17.4% of TWF. The results illustrated that virtual water accounts for the bulk in the water consumption structure. Percent of entity water of Beijing was very small. Because of differences in production chains and trades, the content of virtual water in commodities and services varied significantly. Virtual water import reduced possessed water resources in Beijing. However, the volume of water consumption did not reduce the pressure on water resources, which just was transferred to the surrounding regions. This paper provided valuable modes of water-saving and water recourses management in Beijing.

Development of apiculture modernization in China

LIU Meng, WANG Yong, LUO Shu-Dong

2011, 19(4): 961-965. doi: 10.3724/SP.J.1011.2011.00961

Abstract(1882) PDF(1593)

Abstract:
Apiculture is a form of traditional agriculture that is critical for modern agricultural development in China. Generally, bees are pollinators of crops and producers of honey. Bees assume an increasing importance in modern agriculture. This is because apiculture focuses not only on increasing crop yields and farmers' income, but also ensures ecological balance. However, beekeeping technology in China still lags behind that in developed countries. This paper analyzed the relationship between apiculture and modern agriculture. It illustrated that bee pollination increased yield and quality of crops. Bees were also an important monitors and protectors of food-chain and agro-environment. The paper also highlighted the obstacles in apicultural development in China. China’s apiculture had mainly focused on bee production, and has largely neglected crop pollination. Most bee products were raw materials or semi-processed products. The nomadic beekeeping was the main mode of apiculture, with single bee instead of stereoscopic bee breeding. Apicultural research has mainly focused on the application aspect, at the expense of the theoretical aspect of beekeeping. Based on the above findings, the study suggested intensive industrialization of insect pollination, development of circular mode of apiculture, stationary beekeeping, intensive processing of bee products and enhancement of theoretical research.

Research advances on source/sink intensities and greenhouse effects of CO₂, CH₄ and N₂O in agricultural soils

ZHANG Yu-Ming, HU Chun-Sheng, ZHANG Jia-Bao, DONG Wen-Xu, WANG Yu-Ying, SONG Li-Na

2011, 19(4): 966-975. doi: 10.3724/SP.J.1011.2011.00966

Abstract(5664) PDF(6993)

Abstract:
Climate change is an increasing global challenge. Greenhouse gas emission via anthropogenic processes is the main cause of global warming. CO₂, CH₄ and N₂O are the main greenhouse gases, accounting for ≈80% of greenhouse effect. It is estimated that each year, 5%~20% of CO₂, 15%~30% of CH₄ and 80%~90% of N₂O in air are emitted from soils. Agricultural soils are the main sources of greenhouse gas emission. This work expatiated the mechanisms and affecting factors of greenhouse gas formation, emission and absorption in agricultural soils. And the contribution of farmland ecosystem to greenhouse effects was discussed. It was indicated that anthropogenic factors such as land use and agricultural activity influenced greenhouse gas formation, emission and absorption in agricultural soils. Because anthropogenic processes affected agricultural ecosystems, greenhouse gas emission reductions for stabilized carbon and nitrogen were possible through improved agricultural cultivation and production systems. This study summarized the latest research advances in source/sink intensities of greenhouse gas emissions from farmlands and how that contributes to greenhouse effect. The study suggested that accurate estimation of source/sink intensities of greenhouse gases and appropriate assessments of greenhouse gas effects were the theoretical basis for reducing greenhouse gas emissions and uncertainties in predicting climate change.

Research progress in soil water/salt dynamics and crop growth under saline water irrigation

YANG Jing, YANG Ming-Xin, DONG Bao-Di, QIAO Yun-Zhou, SHI Chang-Hai, ZHAI Hong-Mei, LIU Meng-Yu

2011, 19(4): 976-981. doi: 10.3724/SP.J.1011.2011.00976

Abstract(1901) PDF(2386)

Abstract:
Fresh water resource is scarce and unevenly distributed in China. The use of saline water is therefore an effective way of solving the fresh water shortage. This article summarized the impacts of saline water irrigation on water/salt movement in soil, and on crop growth and changes in crop physiological metabolism. It discussed water/salt distribution in the soil profile, the effect of different degrees of saline water on water/salt movement, and the role of irrigation methods on salt distribution in soil. The paper also epitomized the effects of saline water irrigation on the growth, yield and quality of crops. It further noted effects of saline water irrigation on physiological metabolism; including the changes in praline content, antioxidant enzyme activities, malondialdehyde content, chlorophyll content and photosynthesis.

Herbicidal activities of different organs of Pittosporum tobira (Thunb.) Ait.

WANG Xia, LUO Xiao-Yong

2011, 19(4): 982-984. doi: 10.3724/SP.J.1011.2011.00982

Abstract(1440) PDF(1349)

Abstract:

2011 Vol. 19, No. 4