中国生态农业学报(中英文)

Fundamental classification of eco-agricultural models

LUO Shi-Ming

2009, 17(3): 405-409. doi: 10.3724/SP.J.1011.2009.00405

Abstract(2301) PDF(2653)

Abstract:
Following the basic organization hierachy of biology, eco-agricultural models can be classified into the following fundamental classes: landscape model (at landscape level), in which agricultural land arrangement pattern is essential; cycling model (at ecosystem level), in which the core model is linked to different compartments of agro-ecosystems through energy and material flow; the vertical model (at community level), in which structural arrangement of species is important; food-chain model (at population level), which relates to the structural design of food-chain; and variety structure model (at individual and gene level), which relates to the choice of plant and animal species. Models in upper levels interact with models in lower level forming a complex system of model. This fundamental classification of eco-agricultural models does not rule out other methods of classification for specific purposes. However it provides understanding and enhances analysis of other classification methods. This fundamental classification benefits identification of important developmental processes of eco-agriculture. It also benefits the improvement, selection, standardization and research on eco-agricultural models.

Evaluation of soil quality in reclaimed coastal regions in North Jiangsu Province

YANG Jin-Song, YAO Rong-Jiang

2009, 17(3): 410-415. doi: 10.3724/SP.J.1011.2009.00410

Abstract(1982) PDF(1307)

Abstract:
Soil quality in reclaimed coastal regions in North Jiangsu Province was quantified using comprehensive indexing method and selected soil physico-chemical property and crop growth index. Weight values were accordingly determined by correlation and principal component analysis method from which soil quality maps were developed. Results indicate a generally poor state of soil quality across reclaimed lands, with a substantial level of soil salinity. Soil organic matter (SOM) and N content is relatively low, with severe deficiency in alkali-hydrolysis N. SOM is the most important enabling factor of soil quality while soil salinity and groundwater mineralization are the limiting factors of soil quality. Both correlation and principal component analyses of soil quality have a similar and consistent result (r²=0.933 9**). Soil quality in different areas of reclaimed lands differs significantly and soil quality in cotton fields is generally superior to that in rice fields. There exists significant spatial similarity between soil quality maps developed from different methods. The findings of the study are important references for precision fertilization in moderate-to-low yield farmlands and in scientific management of problematic soils in coastal regions.

Distribution of trace elements in Holocene loess-paleosol sequence and environmental change in the upper reaches of Jinghe River

LI Yu-Qin

2009, 17(3): 416-422. doi: 10.3724/SP.J.1011.2009.00416

Abstract(1407) PDF(1325)

Abstract:
Based on field survey, samples of Holocene loess-paleosol sequence were systematically collected at the Zhaojiacun (ZJC) site in the upper reaches of Jinghe River. The contents of Ba, Zn, Cu, Pb, Cr, Rb, Sr, Co, Th and Zr were then determined by X-Ray fluorescence and compared with magnetic susceptibility and particle-size distribution. It is noted that most of the trace elements including Ba, Zn, Cu, Rb, Co, Th and Zr accumulate in paleosol layer (S0) and drop in Malan loess layer (L1). The correlation coefficients of element content with magnetic susceptibility and clay (<0.005 mm) content are positive, while they are negative with coarse silt (0.01~0.05 mm) content. But the trace elements of Pb, Cr and Sr are high in Malan loess, low in paleosol. They have a negative correlation with magnetic susceptibility and clay content, but are positively related with coarse silt content. During Holocene megathermal epoch, the contents of trace elements are higher in paleosol than in loess because of strong pedogenesis, adsorption and complexity. Cr is largely stable, only weakly fluctuating in the entire sequence. Sr content is high in Holocene loess (L0) layer and the topsoil (TS) because of warming and drying climate, strong topsoil alkalescence and weak CaCO3 eluviation. High Pb content in the topsoil is mainly due to human activity such as “three-waste” discharge, mining and smelting of metals, coal and petroleum combustion, and automobil exhaust emission.

Carbon and nitrogen mineralization of incubated sweet maize

ZHU Chun-Mao, LI Zhi-Fang, WU Wen-Liang, YANG Pei-Zhu

2009, 17(3): 423-428. doi: 10.3724/SP.J.1011.2009.00423

Abstract(1837) PDF(1563)

Abstract:
Organic fertilizer derived from intercropped legume and grain crops supplies substantial soil nutrient under intensive cropping system. Microbial biomass carbon and microbial biomass nitrogen, respiration CO₂ and mineralized nitrogen in plant straw fertilized soil were determined under laboratory incubation conditions of constant temperature and moisture based on field aboveground yields of intercropped sweet maize straw and white clover straw. Results show that microbial biomass carbon and microbial biomass nitrogen in fertilized soil peak in the first several days, and then decline. Intercropping Incubating both sweet maize straw and white clover have the highest yield, maxima of 529.57 mg·kg^-1 and 75.50 mg·kg^-1 respectively. They also release the most respired CO₂ the most among all treated soils. The best mineral nitrogen release is in white clover intercroppingincubating, with a maximum of 29.81 mg·kg^-1 under a 26-day culture, and then keeping 1.60 times the control and reaching 2.48 times at 80-day culture. Sweet maize incubatingintercropping has the least mineral nitrogen release. It is 13%~53% of the control under a 26-day culture, with a maximum of 7.51 mg·kg^-1. Soil nitrogen mineralizatiomineralization is insignificant under sweet maize incubatingintercropping with urea in short-term. It is concluded that plant straw intercropping fertilizing enhances soil organic matter turnover. Intercropping Incubating of sweet maize and white clover may induce significant higher soil microbial biomass. White clover incubating intercropping activates soil microbe which is beneficial to soil nitrogen mineralization.

Response of P accumulation in wheat and maize seedlings to different substrate P levels

HUA Rui, SHEN Yu-Fang, LI Shi-Qing, ZHANG Fu-Suo

2009, 17(3): 428-435. doi: 10.3724/SP.J.1011.2009.00428

Abstract(1468) PDF(1230)

Abstract:
Wheat (Triticum aestivum L.) and maize (Zea mays L.) are very sensitive to phosphorus at seedling stage. Two varieties of wheat (“Xiaoyan 22” and “Lankao 4”) and maize (“Tunyu 65” and “Hudan 4”) were grown in Hoagland solution under different phosphate concentrations [0, 0.05 mmol (P₂O_{5)·L^-1, 0.3 mmol (P₂O_{5)·L^-1, 0.5 mmol (P₂O_{5)·L^-1] to investigate the response of P accumulation in wheat and maize at seedling stage to P levels in substrate. The results show a significantly difference in P accumulation in two corps under different substrate P levels. Variation in P accumulation is dependent on crop genotype, organ and the measurement time. The optimal level of P in wheat substrate is higher than that in maize during early seedling stage (25 days after seed emergence). There is, however, no observable difference between the two crops during later seedling stage (40 ~ 50 days after seed emergence). When 0.05 mmol·L^-1 treatment is used as the control, P accumulation in the entire plant of maize becomes more sensitive to substrate P level than in wheat. “Lankao 4” is more sensitive than “Xiaoyan 22” and there exists no observable difference between “Tunyu 65” and “Hudan 4”. P efficiency in wheat is higher than in maize under zero phosphate treatment, while the reverse is the case under phosphate treatment. There is no consistent relationship between different genotypes.}}}

Impact of mowing on plant regrowth under different resource conditions

PAN Sheng-Wang, WANG Hai-Yang, DU Guo-Zhen, LEI Shu-Qing, WEI Shi-Qiang

2009, 17(3): 436-442. doi: 10.3724/SP.J.1011.2009.00436

Abstract(1570) PDF(1431)

Abstract:
10 common species of subalpine meadow communities in Gannan Province were selected as experimental materials to analyze the impact of grazing on plants at different growth stages under different field resource conditions of fertilization through simulated mowing experiment. The results show positive correlation between plant palatability and compensation ability. Elymus nutans,Avena sativa, Astragalus polycladus and Kobresia humilis exhibit a relatively lower biomass compensation capacity in high resource conditions than in low resource conditions. Medicago rythenica, Polygonum viviparvum, Festuca sinensis, Swertis bimaculata, Taraxacum tibetanum and Ajania tenuifolia exhibit the reverse response. F. sinensi, A. tenuifolia and P. viviparvum exhibit a relatively high reproductive compensation ability under high resource conditions while the reverse is true for the other seven plant species. The comprehensive compensation index analysis presents the biomass compensation ability order of the 10 plant species under fertilized/non-fertilized conditions is the same as that for biomass standing. This indicates that the comprehensive compensation index adequately reflects plant recovery potential. It then implies that evolutionary strategy is the most dominant factor affecting plant recovery, whereas comprehensive compensation index is a useful tool for predicting the effect of grazing on plant community dynamics.

Effect of palygorskite coating on various forms of nitrogen urea

LIU Xue-Zhou, LIN Hai-Ming, WANG Di, QIU Dai-Yu, JIN Hao, ZHANG Peng-Fei

2009, 17(3): 443-447. doi: 10.3724/SP.J.1011.2009.00443

Abstract(1650) PDF(1239)

Abstract:
Static absorption and soil column leaching methods were used to study and analyze the difference of N form between from applied urea coated with three different thicknesses of palygorskite and uncoated urea. The results show that coating urea with palygorskite decreases ammonia volatilization by 10.38%~26.24% compared with uncoated urea. Coating also reduces N (NO₃^--N+N+NH₄⁺) leaching by 5.88%~27.74%. With 20% palygorskite coating treatment, urea significantly increases the NH₄⁺-N in column soil. The three different palygorskite coatings lead to a significant increase in NO₃^--N in column soil. Urea coated with palygorskite decreases ammonia volatilization and N (NO₃^--N+NH₄⁺-N) leaching, increases NH₄⁺-N and NO₃^--N in the soil. More importantly, palygorskite coating of 20% induces optimal ecological conditions.

Effect of conservation tillage and fertilization on photosynthetic physiology of soybean at full-bloom stage

HUANG Mao-Lin, LIANG Yin-Li, WEI Ze-Xiu, ZHOU Mao-Juan, WU Yan

2009, 17(3): 448-453. doi: 10.3724/SP.J.1011.2009.00448

Abstract(1874) PDF(1161)

Abstract:
Based on field plot experiments in the Ansai region, Shaanxi Province, the paper analyzed net photosynthetic rate, stomatal conductance and water-use efficiency in soybean leaves at full-bloom stage under different tillage and fertilization. The LI-6400 portable photosynthesis system was used in the analysis. The treatments included plow tillage with chemical fertilizer (CF), plow tillage with organic fertilizer (CM), non-fertilized plow tillage (CN), fertilized no-tillage (NF), no-tillage with organic manure (NM) and non-fertilized no-tillage (NN). The results show that diurnal variation of net photosynthetic rate of soybean follows the typical bimodal curve in the different treatments; peaking at 11:30 and 16:00. NM and NF treatments, especially NM, significantly enhance net photosynthetic rate of soybean. A significant correlation exists between stomatal conductance and net photosynthetic rate (P<0.01), with a correlation coefficient of 0.999 4. Diurnal variation of stomatal conductance is also a bimodal; peaking at 11:30 and 16:00. In different treatments, water-use efficiency of soybean follows a uni-peak curve; highest at 10:00 and lowest after 13:00. NM and NF treatments have a significantly enhancing effect on soybean water-use efficiency. Correlation analysis shows that stomatal conductance (Cond>), evaporation ratio (Tr), leaf temperature (Tl), photosynthetically active radiation (PAR) and supplemental vapor pressure deficit (Vpdl, based leave temperature) are positive factors of photosynthesis in soybean. On the other hand, inter-cell CO₂ concentration (Ci), air CO₂ concentration (CO₂R ) and air relative humidity (RH-R) mainly limit photosynthesis in soybean. CF & NF at 8:30~10:20 and 13:00; CM & NN at 8:30, 11:30~13:00 & 17:30; and CN & NM at 8:30 & 13:30 have significant correlation between impacting factors and net photosynthetic rate, with a correlation coefficient of ±0.9. The optimum management modes for growing soybean in dry farmlands on the Hilly Loess region are NM and NF.

Effect of slow-release fertilizer on the root system and photosynthesis of flue cured tobacco

ZHANG Xue-Qin, PENG Ke-Qin, WANG Shao-Xian, LI Zai-Jun

2009, 17(3): 454-458. doi: 10.3724/SP.J.1011.2009.00454

Abstract(1651) PDF(1093)

Abstract:
The effect of slow-release fertilizer on the root system, photosynthetic characteristics and dry-matter accumulation in flue-cured tobacco was studied. The yield and output value of flue-cured tobacco leaf were also analyzed in the experiment. The results show that slow-release fertilizer increases tobacco root activity, chlorophyll content, net photosynthetic rate and dry-matter accumulation while reducing inter-cellular CO₂ concentration in flue-cured tobacco leaf. 45.45 g slow-release fertilizer for per plant has the most favorable impact on roots, leaf photosynthetic characteristics and dry-matter accumulation. Also 38.63 g slow-release fertilizer for per plant positively influences these variables. Yield and output value of the leaf are enhanced by slow-release fertilizer. Although yield of tobacco leaf decreases with decreasing application amount of slow-release fertilizer, tobacco output value increases due to the production of high quality tobacco leaf. 38.63 g slow-release fertilizer for per plant has the best effect on tobacco output.

Effect of intercropping summer and spring maize on photosynthesis and yield of summer maize

NING Tang-Yuan, JIAO Nian-Yuan, ZHAO Chun, SHAO Guo-Qing, WEI Jing, JIN Fu-Shen, LI Zeng-Jia

2009, 17(3): 459-464. doi: 10.3724/SP.J.1011.2009.00459

Abstract(1731) PDF(1428)

Abstract:
Three cultivars of maize (the early maturity cultivar of “Luyuandan14”, the medium maturity cultivar of “Yedan22” and the late maturity cultivar of “Yedan13”) were selected to study the effect of maize cultivars on the photosynthetic characteristics and yield of summer maize intercropped with spring maize and monocropped one. The results show that late maturity spring maize cultivar reduces leaf area, light interception rate, chlorophyll content, nitrate reductase activity, and the rate of photosynthesis of summer maize after anthesis under intercropping. To further analyze the relationship between photosynthetic characteristics and the yield of summer maize, the concept of “photosynthetic productivity product (PPP)” was developed. PPP is the product of two or more factors including photosynthetic leaf area, photosynthetic capacity and photosynthetic duration. Compared with single photosynthetic character, PPP is more significantly correlated with yield. Furthermore, the arithmetic product of leaf area, ear leaf chlorophyll content and days after anthesis, and that of leaf area, photosynthetic rate of ear leaf and days after anthesis are more closely related to yield than the arithmetic product of leaf area and days after anthesis. In conclusion therefore, the differences in yield under different cropping systems are the common actions of photosynthetic leaf area, capacity and duration. Thus medium maturity cultivars of spring maize and late maturity cultivars of summer maize are beneficial to total yield under intercropping. PPP provides a new and efficient analytical dimension for yield and quality superiority in intercropping.

Light distribution in wheat population and its effect on leaf photosynthetic rate under raised-bed planting method

LI Sheng-Dong, WANG Fa-Hong, SI Ji-Sheng, KONG Ling-An, FENG Bo, ZHANG Bin, LIU Jian-Jun, QIN Xiao-Sheng

2009, 17(3): 465-468. doi: 10.3724/SP.J.1011.2009.00465

Abstract(1675) PDF(1358)

Abstract:
A comparative study was conducted on the distribution of light in wheat population and leaf photosynthetic rate in four wheat genotypes (the large-spike cultivars of “Yanfu188” and “Zimai12”, and the multi-spike cultivars of “Jimai22” and “Jimai20”) under raised-bed and conventional flat planting methods. The results show a significant improvement in canopy light vertical reception, leaf photosynthetic rate, 1000-kernel weight and per-spike grain number under raised-bed planting method (RBP), in comparison to conventional flat planting (CFP). RBP can significantly decrease the canopy temperature of the multi-spike cultivars, while it is not significant for the large-spike cultivars. The normalized difference vegetation index (NDVI) of the multi-spike cultivars is higher under RBP than CFP, showing significantly promoting effect of RBP on plant growth. Wheat cultivars that develop more tillers and spikes are more suitable to RBP conditions.

Effect of branch and stem pruning on photosynthetic characteristics of Platanus acerifolia L.

CHENG Jian-Feng, JIANG Kun, SHEN Yun-Gang

2009, 17(3): 469-473. doi: 10.3724/SP.J.1011.2009.00469

Abstract(1483) PDF(1353)

Abstract:
Photosynthetic characteristics of south-facing single full-leaf in one-year branch of Platanus acerifolia L. with branch and stem pruning (BSP) or under natural conditions (NG) were determined using Li-6400 portable photo-meter. The results show that diurnal variations in net photosynthetic rate (Pn) of P. acerifolia single full-leaf under BSP and NG follows a di-peak curve. The first peak appears at 11:00, the second at 15:00, while the minimum peak occurs at 13:00 (when light intensity is highest). This indicates a remarkable midday depression. The leaves under both conditions suffer from photo-inhibition. Pn [μmol(CO₂)·m^-2·s^-1] of the first peak, second peak and the minimum peak of P. acerifolia leaf under BSP are 12.16, 9.21 and 6.47, which are respectively 27.06%, 69.93% and 159.84% higher than those under NG. This implies that BSP improves photosynthesis, while at the same time reduces photo-inhibition. Best-fit response curves for Pn to photosynthetic photon flux density (PPFD) in P. acerifolia leaf under BSP and NG are expressed as Pn = 12.30 (1-1.135 3 e^{-0.030 2PPFDD/12.30}) (R²=0.989 1**) and Pn = 10.92 (1-1.130 7e^{-0.030 5PPFD/10.92}) (R²=0.984 9**) respectively. The values of max Pn (Pmax), light compensate point, light saturation point and PPFD range of P. acerifolia leaf under BSP are 12.30 μmol(CO₂)·m^-2·s^-1, 51.67 μmol·m^-2·s^-1, 1 927.32 μmol·m^-2·s^-1 and 1 875.65 μmol·m^-2·s^-1 respectively; which are 12.64%, 17.33%, 13.85% and 13.76% higher than those under NG, respectively. This suggests that BSP treatment could increase utilization of light energy in P. acerifolia. The best-fit response curves for Pn to CO₂ concentration (Ci) of P. acerifolia leaf under BSP and NG are expressed as Pn=11.96(1-1.471 6e^{-0.028 7Ci/11.96}) (R²=0.982 4**), Pn=10.70 (1-1.465 7e^{-0.029 2Ci/10.70}) (R² = 0.981 0**), respectively. Pmax, CO₂ compensate point and CO₂ saturation poing and Ci range under BSP are respectively 11.96 μmol(CO₂)·m^-2·s^-1, 67.54 μmol·mol^-1, 872.02 μmol·mol^-1, and 804.48 μmol·mol^-1; which are 11.78%, -27.44%, 0.39% and 3.73% higher than those under NG, respectively. This indicates that BSP treatment increases CO₂ assimilation ability of P. acerifolia under low CO₂ concentration condition.

Diurnal variation in net photosynthetic rate and influencing environmental factors of Elaeagnus mollis Diels leaf

LIU Qun-Long, NING Chan-Juan, WANG Duo, WU Guo-Liang, ZHANG Hong-Mei, CHU Cui-Ying

2009, 17(3): 474-478. doi: 10.3724/SP.J.1011.2009.00474

Abstract(1880) PDF(1467)

Abstract:
Diurnal variation in net photosynthetic rate (Pn) of Elaeagnus mollis Diels leaf was measured and the relationships between Pn and the photosynthetic parameters of transpiration rate (Tr), intercellular CO₂ concentration (Ci), stomatal conductance (Gs) and environmental factors analyzed. The results indicate that diurnal variation in Pn exhibits a dual-peak curve ranging between 1.25 ~ 11.35 μmol·m^-2·^s-1. The curve has an obvious midday depression, with the dual peak occurring at 9:00 and 15:00 respectively. Decline in Pn during 11:00 ~ 12:00 is caused by stomatal limitation factor, but by non-stomatal limitation factors during 9:00 ~ 11:00 and 15:00 ~ 19:00. The relationship between Pn and photosynthetic parameters varies with time during the day. 6:00 ~ 9:00 and 15:00 ~ 19:00, Pn exhibits a significantly positive correlation with Tr and Gs, but a significantly negative correlation with Ci. 9:00 ~ 12:00, Pn shows a significantly positive correlation with Ci> and Gs, and a negative correlation with Tr. 12:00 ~ 15:00, Pn is significantly positively correlated with Tr and Gs, while it is positively correlated with Ci. The main environmental factors and their degree of influence on Pn are photosynthetically active radiation (PAR, positive effect) > Ci (negative effect) during 6:00 ~ 9:00; PAR (negative effect) > Ca (atmospheric CO₂ concentration, positive effect) during 9:00 ~ 12:00; relative humidity (RH, positive effect) during 12:00 ~ 15:00; and PAR > Ta (atmospheric temperature, both positive effect) during 15:00 ~ 19: 00.

Effect of crop rotation and irrigation on wheat yield and water-use efficiency

CUI Huan-Hu, WANG Juan-Ling, MA Bu-Zhou, WANG Yu-Zhi, JING Hua, LU La-Hu

2009, 17(3): 479-483. doi: 10.3724/SP.J.1011.2009.00479

Abstract(1362) PDF(1114)

Abstract:
To efficiently utilize water resources and to ensure reasonable irrigation systems of winter wheat in rotation with different crops, the effect of rotation and irrigation on wheat yield and water-use efficiency was determined under plot design experiment. From the results, the order of average wheat yield for maize, sunflower, soybean and fallow rotation under three irrigation treatments is maize>sunflower>fallow>soybean. On the basis of water-use efficiency, the order is sunflower>maize>soybean>fallow. Wheat yield and water-use efficiency increase with increasing irrigation amount for all the rotation systems. Soybean-wheat rotation has the most impact on wheat yield and water-use efficiency with irrigation at wheat grain filling stage, while the other rotation systems are most advantageous with irrigation at wheat jointing stage. The dynamics of the characteristics of water storage and consumption in each rotation system at different growth stages and irrigation schemes simultaneously play out.

Change in crop evapotranspiration and associated influencing factors under screenhouse conditions

LIU Hai-Jun, HUANG Guan-Hua, Shabtai COHEN, Josef TANNY

2009, 17(3): 484-488. doi: 10.3724/SP.J.1011.2009.00484

Abstract(1429) PDF(1342)

Abstract:
A field experiment was conducted in a banana-cultivation screenhouse to study the change and relationship between crop evapotranspiration and reference crop evapotranspiration (ET0). The effects of microclimatic factors inside the screenhouse on ET0 were also analyzed. Results show that ET0 and Class-A pan-evaporation inside the screenhouse respectively decrease by 39% and 42% in comparison with those in the open field. Also, banana transpiration in the screenhouse decreases by 53% in comparison with those in the open field. Reductions in banana transpiration, ET0 and pan-evaporation inside the screenhouse are mainly due to the decreases in net radiation and wind speed. Air temperature and vapor pressure, on the other hand, exert a minimal reduction effect on ET0. A regression relation exists between screenhouse and open-field ET0 and pan-evaporation. The statistical Class-A pan-coefficient for the study area is 0.84.

Micro-variation in peach stem diameter and its relationship with soil water potential and meteorological factors

ZHAN Jing-Wu, WANG You-Ke, ZHANG Lu-Jun, ZHANG Ping, HE Jun-Qi

2009, 17(3): 489-494. doi: 10.3724/SP.J.1011.2009.00489

Abstract(1692) PDF(1510)

Abstract:
In well-irrigated and gradual-drought pot experiments, micro-variations in “Shinvhong” peach stem diameter were continuously monitored. Responses in maximum daily stem shrinkage (MDS), stem increase (DI), and stem diameter recovering time (RT) to soil water potential and meteorological factors were then analyzed and a suitable irrigation index established. The results show that when soil water potential decreases, RT and MDS increase while DI rapidly drops below zero. Meteorological factors have a notable impact on peach stem diameter. Factors including radiation and air relative humidity have the strongest impact on stem diameter. In fact continuous rainfall significantly affects DI and RT. DI is the most ideal irrigation indicator as it is very much influenced by soil water potential and less affected by meteorological factors. DI value of zero is probably the best irrigation threshold. MDS is strongly affected by meteorological factors and requires reference MDS under well-irrigated conditions. RT on the other hand is not significantly related with soil water potential. Therefore neither of these variables is suitable as irrigation index.

Effect of plant and light on CH₄ exchange in the soil-plant system of wheat fields

SUN Shan-Bin, LI Jun, LU Pei-Ling, YU Qiang, YAO Yu-Gang, SUN Yan-Li

2009, 17(3): 495-499. doi: 10.3724/SP.J.1011.2009.00495

Abstract(1519) PDF(1181)

Abstract:
Methane (CH₄) fluxes in wheat fields of the North China Plain were measured by closed chamber and GC techniques. The measured fluxes in the soil-plant systems through opaque chamber and transparent chamber were then compared. The results show obvious seasonal variations but insignificant diurnal variations in CH₄ flux in the system. Wheat cover induces larger seasonal flux variation in the soil-plant system. Wheat and light increase soil-plant CH₄ uptake. More importantly, however, transparent closed chamber proves the best CH₄ flux measurement method in the field experiment.

Dynamics of soil enzyme activity in the rhizosphere of desert halophyte

YI Liang-Peng, MA Jian, LI Yan

2009, 17(3): 500-505. doi: 10.3724/SP.J.1011.2009.00500

Abstract(1801) PDF(1363)

Abstract:
A rhizobag experiment was conducted in desert solonchak and cultivated gray desert soils to investigate nutrient content and soil enzyme activity in the rhizospheres of six desert halophytes. The results show significant increase in total N and decrease in total P in the rhizosphere in comparison with bulk soil. Available N and P have inverse dynamics in that while available N decreases, available P increases, except for Phragmites communis Trin. Available N deficit is highest while accumulated available P is lowest in Salsola nitraria Pall among the six halophytes. Analysis for sucrase, protease, urease, neutral phospherease, alkaline phosphcrease and catalase activity as well as its relationship with soil nutrient content shows inverse dynamics for sucrase, protease and catalase in both soil rhizospheres. In solonchak soils, the activity of the three soil enzymes in the rhizosphere is generally higher than in bulk soils while that in cultivated gray-desert soils are lower. In solonchak soils, the activity of alkaline phosphcrease, catalase and invertase is significantly related with soil nutrient content, which could be a strong indicator of soil nutrient status. The results suggest significant impact of halophyte on enzyme activity in desert solonchak.

Dynamics of nitrogen metabolism activity in rice root at the late development stage

NING Shu-Ju, DOU Hui-Juan, CHEN Xiao-Fei, LIN Wen-Xiong, WEI Dao-Zhi

2009, 17(3): 506-511. doi: 10.3724/SP.J.1011.2009.00506

Abstract(1855) PDF(1667)

Abstract:
Rice cultivars “Liangyoupeijiu”, “9311” and “Shanyou63” were used to investigate the activities of glutamine synthetase (GS), glutamic acid-pyruvic acid transaminase (GPT), glutamic acid oxaloacetate transaminase (GOT), glutamate dehydrogenase (GDH) and protease in rice root during the late development stage. Also the content of soluble protein and free amino acids in rice root, and that of sugar and free amino acids of root bleeding-sap of rice after blooming were analyzed. The results show that GPT and GDH activity peak precedes blooming while that of GS and GOT occurs after one and two weeks of blossom in “9311”. In “Liangyoupeijiu”, GPT, GDH and GOT activity peaks in the first week after blooming while that of GS occurs before blossom. In “Shanyou63”, the four enzymes reach their highest activity two weeks after blossom. The content of soluble protein and free amino acids in “9311” and “Liangyoupeijiu” peaks in the first week after blossom while that in “Shanyou63” delays to the second and third weeks. Peak of root bleeding-sap occurs in the second week after blossom in “Liangyoupeijiu”, which is one week earlier than in “9311” and “Shanyou63”. Peak time difference between bleeding sap and free amino acids in roots is one week, but the lag-time is different for the three cultivars — one week for “Liangyoupeijiu”, two weeks for “9311” and insignificant for “Shanyou63”. Bleeding-sap sugar content in “Shanyou63” is remarkably higher than in the other two cultivars (P<0.01), while the content of free amino acids in “9311” is significantly higher than in the other two cultivars (P<0.05). It is inferred from the results that nitrogen metabolism in “Liangyoupeijiu” peaks earlier, but at a lower value than in the other two cultivars. This indicates an earlier decline in root physiological activity at late development stage in “Liangyoupeijiu” than in the other two cultivars. Notable differences exist in the strength and peak time of metabolism among the three cultivars. Tissue metabolism and bleeding-sap peak occurs at different times and with different strength, and at varying time-lags among the cultivars.

Physiological effect of potassium chlorate on flower bud formation in Myrica rubra cv. Dongkui

LIU Jian-Fu, YUAN Hai-Chao, LI Song-Gang, JI Lu-Lu

2009, 17(3): 512-516. doi: 10.3724/SP.J.1011.2009.00512

Abstract(1529) PDF(1327)

Abstract:
We used six-year old Myrica rubra cv. Dongkui trees as experimental materials to study the effect of potassium chlorate on selected biological indices of M. rubra tree leaf during flower bud differentiation. The results indicate that MDA content and electrolyte leakage remarkably increase after spurting potassium chlorate, compared with the control. When potassium chlorate concentration is lower than 1 500 mg·L^-1, chlorophyll a and b, and total chlorophyll content obviously increase. SOD, POD and CAT activity is remarkably enhanced, resulting in a remarkable rise in net photosynthetic rate. Soluble protein content obviously increases while soluble sugar reduces during physiological differentiation. However, soluble protein content drops and soluble sugar remarkable rises during morphological differentiation. Soluble sugar to protein content ratio increases significantly, enhancing flower bud differentiation in M. rubra. When potassium chlorate concentration is higher than 1 500 mg·L^-1, chlorophyll a and b, and total chlorophyll as well as carrot contents drop, SOD, POD and CAT activity decreases, reducing leaf photosynthetic ability, soluble sugar content and soluble sugar to protein ratio. This suppresses flower bud differentiation in M. rubra. It can therefore be inferred from the study that 1 000 mg·L^-1 to 1 500 mg·L^-1 potassium chlorate remarkably enhances flower induction.

Temporal variation and spatial distribution of the root system of corn in a soil profile

LIU Jing-Miao, AN Shun-Qing, LIAO Rong-Wei, REN San-Xue, LIANG Hong

2009, 17(3): 517-521. doi: 10.3724/SP.J.1011.2009.00517

Abstract(3451) PDF(5612)

Abstract:
The development of the root system of corn in soil profile is an indispensable parameter for the estimation of corn growth. The distribution of the root system can be used to evaluate the influence of climate on vegetative growth. This constitutes a creative scientific management and development system of water-saving agriculture. In the Gucheng Agro-meteorological Field Experimental Station of Chinese Academy of Meteorological Sciences, root length, root areal reach, root depth and root dry-weight of “Tunyu 46” corn were observed using clod sampling method and installed underground surface glazing. Observation data on the spatial and temporal distribution characters of the root system in the soil profile were then analyzed. The results show that root dry-weight and root length decrease with increasing soil depth. In spin silk period, root length in the 40 cm, 80 cm, and 120 cm soil layer is respectively 51.5%, 76.2% and 90.5% of total root length. Root length to total root length ratio in various soil layers is similar for both spin silk and late milk maturity periods. Root thickness decreases in upper soil layer and increases in lower soil layer with increasing soil depth. In the late milk maturity period, root depth may reach 230 cm, and total combined root length can reach 8.288 km·m^-2. Clearly thus, root depth and the total root length of “Tunyu 46” are larger than those of other corn varieties. Root distribution characteristics show that the root system of “Tunyu 46” is a lot more developed and robust for defending drought. Based on data obtained from the installed glazing, root depth is much deeper than that observed far from the glazing.

Tiller redundancy in winter wheat in irrigated arid areas

HOU Hui-Zhi, HUANG Gao-Bao

2009, 17(3): 522-526. doi: 10.3724/SP.J.1011.2009.00522

Abstract(2015) PDF(1121)

Abstract:
Yield components of two different winter wheat varieties in the Hexi irrigated area of Gansu were analyzed through all, 1/3, 1/2 tiller and main-stem removal and the control (CK), labelled as A, B, C, D and E respectively. The results indicate that total biomass and effective tiller weight of the two winter wheat varieties under treatments B and D are higher than under CK. Compared with CK, though main-stem spike length, spike weight, per-spike grain number and grain weight are highest in treatment A, there is no remarkable difference in these variables among treatments. Tiller spike length, spike weight, per-spike grain number and grain weight in treatments B and D are higher than in CK, but those in treatments A and C are lower than in CK. We therefore conclude that at least 1/3 tiller is redundant for winter wheat cultivation in Hexi area of Gansu.

Influence of elevation on growth duration of maize (Zea mays L.)

CHEN Xue-Jun, CAO Guang-Cai, JIA Yin-Suo, WU Dong-Bing, CHEN Jing, YU Ya-Xiong, LI Wei, LI Jie

2009, 17(3): 527-532. doi: 10.3724/SP.J.1011.2009.00527

Abstract(1944) PDF(1312)

Abstract:
In order to determine the most suitable planting site and crop variety, an ecological experiment was conducted on the effect of elevation on maize growth during 2006 ~ 2007. The study utilized seven maize varieties in five experimental stations across Gansu Province, and five maize varieties in five experimental stations across Yunnan Province. The results show that at the same sowing time, jointing stage, heading stage and maturity stage of maize prolong with increasing elevation. In other words, the durations from sowing to jointing, jointing to heading and heading to maturity become longer with higher elevation. Growth period is therefore positively related with elevation at 0.01 significant level. But when elevation rises 100 m, maize growth becomes sluggish by 4 ~ 5 days. Maize plant height and ear leaf number reduce with rise in elevation.

Weed communities and distribution characteristics in the paddy fields of main rice growing regions of Hubei Province

CHANG Xiang-Qian, LI Ru-Hai, CHU Shi-Hai, ZHU Wen-Da, CHEN Qi-Zhi

2009, 17(3): 533-536. doi: 10.3724/SP.J.1011.2009.00533

Abstract(1972) PDF(1696)

Abstract:
Comprehensive weed infestation indices of existing weed populations from 25 sampling sites in three main rice growing regions, Jianghan Plain, Huanggang region, and Xiangfan-Suizhou region, of Hubei Province were determined by a seven-point scale through weed dominance visualization. 43 weed species of 23 families were collected. The comprehensive infestation index ranking of the dominant weed species is Echinochloa crusgalli, Paspalum paspaloides, Alternanthera philoxeroides, Monochoria vaginalis, Leptochloa chinensis, Ludwigia prostrate, Eclipta prostrate and Lemna minor. Of the weed species, the dominant weeds in Xiangfan- Suizhou, Jianghan and Huanggang regions are Echinochloa crusgalli, Alternanthera philoxeroides; Echinochloa crusgalli, Paspalum paspaloides; Echinochloa crusgalli, Monochoria vaginalis respectively. There is a strong similarity between weed community in the paddy fields of Jianghan Plain and Huanggang region, with a S?renson index of 0.774 1. Weed communities in the paddy fields in the two regions are less similar to that in Xiangfan-Suizhou region. Overall, weed community richness in the paddy fields of Hubei Province is low. This is probably due to long-term utilization of herbicides in the province.

Breeding effects of different batches goose in the coupled crop-livestock system

GUAN Fa-Chun, LIANG Zhneng-Wei

2009, 17(3): 537-540. doi: 10.3724/SP.J.1011.2009.00537

Abstract(1568) PDF(1305)

Abstract:
In order to determine the growth dynamics and contribution ratio of different feeding fields for goose, two batches of goose raised on coupled crop-livestock production system in the agro-livestock ecotone on the Songnen Plain were compared. The results show significant changes in the monthly dynamics of goose grazing space with a staged evidence of spatial utilization of the feeding space. The tendency is that birds graze in farmland in June ~ August and move to grassland in September ~ October. The rate of average weight gain in the first batch is faster than that in the second. Feeding field contribution ratio of the two batches is different — highest for croplands in the first batch of goose while highest for grasslands in the second batch of goose. Contribution ratio of the different feeding fields and average weight gain rate in goose reflect the efficiency and benefit of the coupled agro-system. This is not only in close relation with demand and supply of goose feed, but is also closely related with environmental factors surrounding one month-old goose population. Further research on both the internal performing rhythm and external influencing factors of coupled crop-livestock system in the ecotone of the Songnen Plain should be conducted.

Comparison of overwintered bionomics of Chilo suppressalis larvae from paddy-rice field with those from water-oat field in North China

HAN Yong-Qiang, HAO Li-Xia, HOU Mao-Lin

2009, 17(3): 541-544. doi: 10.3724/SP.J.1011.2009.00541

Abstract(1228) PDF(1162)

Abstract:
Bionomics of Chilo suppressalis larvae overwintering in paddy-rice and water-oat fields were investigated in Beijing in early-winter (middle November) and after-winter (early March). The results show that overwintering larvae are 4th instar or older, and the 6th instar ratio in water-oat fields is 17.5% higher than that in paddy-rice fields in early-winter. Old larvae account for a higher percent in after-winter period than in early-winter. Female to male larvae ratios are respectively 1︰2.0 and 1︰1.7 in early-winter and after-winter periods in paddy-rice fields, and 1︰1.4 and 1︰1.2 in water-oat fields. Larvae duration is longer in early-winter than after-winter, and not significantly different between in paddy-rice and water-oat fields in one period. However, larvae from water-oat fields take 14.0% more time before pupation than that from paddy-rice fields in early-winter, while larvae and pupa from water-oat fields are significantly heavier than those from paddy-rice fields. Mortality rate of larvae collected in early-winter is greater than 65%. Fungi infection is the primary mortality factor in water-oat fields (i.e. over 90% total mortality), while parasitic wasp and bacteria infection constitute the primary mortality factors in paddy-rice fields (i.e. respectively over 50% and 25% total mortality).Apanteles chilonis and Eriborus terebrans are the two dominant parasitic wasps.

Species and distribution characteristics of entomogenous fungi in Shanxi Province

WANG Hong-Min, WANG Shu-Guang, ZHANG Xian-Hong, HAO Chi

2009, 17(3): 545-548. doi: 10.3724/SP.J.1011.2009.00545

Abstract(1490) PDF(1359)

Abstract:
Investigation on entomogenous fungi and their geographical distribution in Shanxi Province was conducted for the period 1996 ~ 2005. A number of field data collection, isolation, culturing and identification was performed. The study reveals that Shanxi Province is rich in entomogenous fungi diversity. About 72 species of 17 genera of fungi are believed exist in the province. Among the fungi collection, 63 species are collected from four national nature reserves in the province, 12 from six major forest areas and another 22 species from the area around Taiyuan. This respectively represents 64.9%, 12.4% and 22.7% of the species collection. Most of the species come from the three major nature reserves of Pangquangou, Manghe and Lishan. The investigation also indicates that Aspergillus Micheli ex Fries, Penicillium Link ex Fries, Paecilomyces Bainier and Fusarium Link ex Fries are the dominant groups of entomogenous fungi. They account for 59.7% of the species collection.

Response of spiffy bushclover (Lespedeza formosa) to simulated moderate drought stress in two growth substrates

BAI Ming-E, TANG Jian-Jun, HONG Li-Xing, DING Wei-Hua, ZHU Tang-Jun, CHEN Xin

2009, 17(3): 549-553. doi: 10.3724/SP.J.1011.2009.00549

Abstract(1895) PDF(1499)

Abstract:
Application of high-stress tolerant tree species is a key technique for the restoration of degraded soils. Hence a drought-stress experiment was conducted to determine drought tolerance of spiffy bushclover (Lespedeza formosa) in two growth substrates (nutrient-rich and nutrient-deficient) under greenhouse conditions. The results show that leaf saturation deficiency, chlorophyll content, plant height, and root and shoot biomass of spiffy bushclover under drought stress significantly decrease compared with conventional irrigation conditions. On the other hand, proline content, soluble sugar content and malondialdehyde (MDA) in functional leaves of spiffy bushclover significantly increase under drought-stress. Plants in nutrient-rich substrate have higher tolerance to simulated drought than those in nutrient-deficient substrate. It is therefore concluded that spiffy bushclover could be a drought-tolerant species suitable for vegetation restoration on dry eco-sites, and nutrient-rich substrates enhance spiffy bushclover performance and drought tolerance.

Effect of soil water on protective enzyme activity and membrane lipid peroxidation in pea

YAN Zhi-Li, NIU Jun-Yi, XI Ling-Ling, ZHOU Hai-Yan, JIANG Juan, LIU Jian-Hua

2009, 17(3): 554-559. doi: 10.3724/SP.J.1011.2009.00554

Abstract(1489) PDF(1211)

Abstract:
A pot experiment was conducted to investigate the effect of soil water on protective enzymes of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), and also on membrane lipid peroxidation including malonaldehyde (MDA) and plasma membrane permeability (RC) in pea (Pisum sativum Linn.) leaf during flowering and pod-bearing stages under drought stress and water recovery conditions. Antioxidant ability of pea during flowering and pod-bearing stages was also analyzed. The results indicate that SOD and CAT activity is not significantly influenced by 5-day drought stress with only obvious time lag, but significantly decreases under 10-day drought stress condition. Leaf MDA content increases significantly under 10-day high drought stress. POD activity and leaf RC increase under drought stress. Water recovery has a considerable compensation effect on CAT and POD activity, but also leads to over-compensation effect on SOD activity. Meanwhile MAD content and RC level decrease notably. Pea has strong oxidation resistance within 10 days of drought stress and water recovery. The resistance capacity decreases only under 10-day severe drought stress and water recovery.

Effect of water stress on chlorophyll fluorescence in leaves of tea plant (Camellia sinensis)

GUO Chun-Fang, SUN Yun, TANG Yu-Hai, ZHANG Mu-Qing

2009, 17(3): 560-564. doi: 10.3724/SP.J.1011.2009.00560

Abstract(1454) PDF(1552)

Abstract:
The effects of water stress on the chlorophyll fluorescence parameters in the leaves of “Tieguanyin” and “Fudingdabaicha” tea cultivars were investigated. The results show that under water stress, the minimal fluorescence (Fo) of tea plants increases significantly, while the maximal fluorescence (Fm), variable fluorescence (Fv), light energy transformation efficiency of PSⅡ (Fv/Fm) and activity potential of PSⅡ (Fv/Fo) decrease markedly, suggesting that PSⅡ reaction center is destroyed by water stress. Photochemical reaction rate (P_rate), fluorescence increment time (T_1/2) and electron transport rate (ETR) decrease, leading to increased thermal dissipation rate (D_rate), non-photochemical quenching (qN) and relative limitation of photosynthesis (L_PFD), but obviously decreased photochemical quenching (qP) and actual photochemical efficiency of PSⅡ (Yield). The tea cultivar “Tieguanyin” has stronger stress tolerance and higher PSⅡ photochemical efficiency than “Fudingdabaicha” .

Effect of high-temperature stress on physiological and biochemical indices of four Lysimachia plants

XU Gui-Fang, ZHANG Zhao-Yang

2009, 17(3): 565-569. doi: 10.3724/SP.J.1011.2009.00565

Abstract(1728) PDF(1547)

Abstract:
In order to investigate the physiological characteristics of Lysimachia plants in high temperatures, a pot seedling experiment in artificial climatic chamber was conducted using four Lysimachia species. The effect of high-temperature stress on plasma relative permeability, protective enzyme activity and leaf osmoregulatory molecules in plants were analyzed. The study shows that with the high-temperature stress strengthening, the membrane damages and leaf cell membrane permeability increases. SOD and POD activities increase under the moderately high-temperature stress, while decline under extremely high-temperature stress. Total chlorophyll content, proline content and leaf soluble protein increase under high-temperature stress, though the trends differ for different species. Analysis of physiological and biochemical characters suggests that high-temperature resistance ability of L. alfredii and L. christinae var huaye is high and that of L. nummularia ‘Aurea’ and L. congestiflora is low.

Effect of cerium on water metabolism in soybean seedling under UV-B radiation stress

ZHANG Jun-Wei, ZHOU Qing

2009, 17(3): 570-573. doi: 10.3724/SP.J.1011.2009.00570

Abstract(1412) PDF(1059)

Abstract:
To develop further insight into the effect of rare-earth on water metabolism in plants under UV-B radiation stress, the effect of Ce(Ш) on stomatal density, stomatal conductance (Gs), abscisic acid (ABA) content, hydrogen peroxide (H₂O₂) content, and catalase (CAT) activity in soybean (Glycine max) seedling leaf exposed to ultraviolet-B radiation (UV-B, 280 ~ 320 nm) was analyzed in hydroponics culture under laboratory conditions. Static experimental results show that 20 mg·L^-1 CeCl₃ increases stomatal density of paraxial leaf back surface compared with the control, whereas the reverse effect occurs in soybean seedlings exposed to high UV-B radiation (0.45 W·m^-2). Ce(Ш) plus UV-B treatment retards decrease in stomatal density. On the other hand, dynamic experimental results show that 20 mg·L^-1 Ce(Ш) increases Gs compared with the control. UV-B radiation induces a decrease in Gs. Also soybean seedling Gs under Ce(Ш) plus UV-B treatment is higher than in UV-B treatment alone. This shows that Ce(Ш) retards decrease in soybean seedling Gs under UV-B treatment and induces a good recovery at the end of the experiment. In comparison with the control, UV-B radiation induces ABA and H₂O₂ accumulation while increasing CAT activity. However, Ce(Ш) reduces the above-mentioned accumulations while increasing CAT activity in soybean seedling leaf under UV-B radiation stress compared with UV-B treatment alone. The experimental results reveal that Ce(Ш) reduces damage from UV-B radiation stress on water metabolism in soybean seedling.

Characteristics of substance and energy in rice-duck-azolla integrated farming system

ZHEN Ruo-Hong, WANG Qiang-Sheng, ZHOU Jian-Tao, ZHENG Jian-Chu, HE Jia-Jun, BIAN Xin-Min

2009, 17(3): 574-579. doi: 10.3724/SP.J.1011.2009.00574

Abstract(1318) PDF(1251)

Abstract:
This article studied the characteristics of substance and energy in rice-duck-azolla integrated farming (RDA) system. RDA system increases food-chain complexity and system stability because ducks and azolla are incorporated into rice paddy systems. Light utilization efficiency is highest in RDA, with respectively 18.52% and 23.08% higher than in rice-duck integrated farming (RD) and conventional farming (CK) systems. Energy circulation index in RDA is 0.096, significantly higher than in RD and CK. NPK flux is highest in RDA, implying that cycling intensity and recycled farmland nutrients are higher in RDA. RDA depends less on fertilizer and is therefore more friendly to the environment.

Using emergy to analysis agro-ecosystem sustainability in the edge-regions of Qinghai-Tibet Plateau— A case study of Tibetan and Qiang Autonomous Perfecture of Aba, Sichuan Province

WEI Fen-Zi, YUE Min

2009, 17(3): 580-587. doi: 10.3724/SP.J.1011.2009.00580

Abstract(1487) PDF(1112)

Abstract:
Quantitative analysis and evaluation of the agro-ecosystem of Aba, Sichuan Province, were conducted on the basis of emergy theory. Based on the results, there is an increase in total emergy input from 1.126 × 10²² to 1.661 × 10²² sej·a^-1, with an observed increase in total emergy output from 5.002 × 10²⁰ to 1.383 × 10²² sej·a^-1 for 1952 ~ 2005. Ecological function potential drops from 54.08% to 37.02% and the basic population capacity increases from 199 400 to 315 100. Emergy self-support ratio drops from 74.58% to 54.13%, while emergy investment ratio increases from 34.0% to 85.0%. Emergy density increases from 1.34 × 10¹¹ to 1.97 × 10¹¹ sej·m^-2 and emergy/money ratio decreases from 4.93 × 10¹⁴ to 1.81 × 10¹³ sej·$^-1. There is an increase in environment load ratio and net energy yield ratio from 0.85 to 1.70 and from 0.18 to 1.82 respectively. Sustainable development index increases from 0.20 to 1.07. The results therefore indicate a continuous increase in agro-ecosystem production efficiency in Aba. Eco-tourism plays an important role in the development of the system. However, an unsustainability risk of the system exists due to insufficient input of industry-assisted emergy and over-consumption of natural resources. From the discussions above, it is important that sustainable development agro-ecosystem should be promoted in Aba.

Analysis of ecological footprint and capacity of Hebei Province for the year 2006

SUN Yan-Qin, LIU Cun-Qi

2009, 17(3): 588-592. doi: 10.3724/SP.J.1011.2009.00588

Abstract(1681) PDF(1494)

Abstract:
By using ecological footprint model and data on Hebei Province for 2006, the ecological footprint, production and ecological capacity of the province were calculated. From the study, per-capita ecological capacity, ecological footprint, production footprint, ecological deficit and ecological footprint intensity of the province are estimated to be 0.468 3 ghm², 2.189 7 ghm², 3.436 3 ghm², 1.721 4 ghm², 4.675 8 respectively. Ecological footprint diversity indexes on the basis of ecological footprint and ecological capacity for Hebei Province are respectively 0.837 4 and 0.988 0. Also social development indexes based on ecological footprint and ecological capacity for the study area are 1.833 8 and 0.462 7 respectively. Ecological footprint for 104 yuan GDP is 1.290 9 ghm². Ecological trade deficit and ecological overshot in the region are respectively -1.246 6 ghm² and 2.794 3 ghm². The findings suggest that the ecological and socio-economic systems of Hebei Province are under ecological overshot and deficit, meaning that current development strategies in the province are unsustainable. Inner industrial structures must be adjusted and new energy consumption mechanisms developed for the realization of ecological sustainability and healthy economy.

Analysis of assets and debts of agro-ecosystems in northwest China— A case study of the oasis agro-ecosystem of Liangzhou District, Gansu Province

XIE Peng, LIN Hai-Ming, HUANG Gao-Bao, CHAI Qiang

2009, 17(3): 593-598. doi: 10.3724/SP.J.1011.2009.00593

Abstract(1323) PDF(1031)

Abstract:
The dynamics and magnitude of assets and debts of oasis agro-ecosystems in Liangzhou District, Gansu Province were analyzed for the period of 1949~2005. The analysis explored sustainable development capacity and predicted future oasis agro- ecosystem development in Northwest China. The results show a rapid decline in the environmental assets of the agro-ecosystem from 1949 to 1970, dropping on the average from 14.14 to 4.93, which is 65.13% reduction. There is also a slow increment to 33.33 from 1970 to 2005. A steady negative growth exists in environmental debt from -0.91 to -56.67, increasing 62.27 times from 1949 to 2005. Net environmental assets exhibit a decreasing/increasing trend for the period under study. Environmental assets are strategic, gradually driving weakening asset surplus from 1949 to 1970, and dropping to zero in the 1970. Since 1970, debts have become dominant in the oasis agro-ecosystem, leading to asset deficit that has gradually increased, especially in the late 1980s. However, the situation begins to improve after 2000. The asset/debt table in 2005 shows that among 30 source indexes of livelihood, development, environment, society and intelligence supporting systems of sustainable development ability, 10 are in the asset column, 17 in the debt column, with a net asset of -23.34 for Liangzhou agro-ecosystem. The study shows that economic development in Liangzhou District is far from sustainable, however, environmental asset storage of the agro-ecosystem is lately improving. This implies that economic development in the region is transforming from a non-sustainable to a sustainable mode.

Establishment of market-oriented compensation system for returning farmland to forestland

MA Li-Mei, FAN Sheng-Yue, ZHANG Hui

2009, 17(3): 599-604. doi: 10.3724/SP.J.1011.2009.00599

Abstract(1511) PDF(1097)

Abstract:
Returning farmland to forestland or grassland has emerged as a major ecological construction project in China in recent years. The project has already registered substantial achievements since 1999. But the defects of the system have simultaneously put the central government at crucial crossroad. The engineering operation of the system has several obvious issues to address. In response to these issues, market competition mechanism via market-oriented ecological purchasing systems plays a crucial role in the project implementation. This effectively adjusts and completes the existing ecological compensation system through indirect government intervention. The design detail, building-up and fixed-price pattern of the market-oriented ecological purchasing system should therefore be simultaneously planned.

Ecological defects and countermeasures of Eucalyptus plantation in Fujian Province

PAN Hui, HUANG Shi-De, ZHANG Jin-Wen, WANG Guang-Hua, ZHU Hong-Ru

2009, 17(3): 605-609. doi: 10.3724/SP.J.1011.2009.00605

Abstract(2893) PDF(2063)

Abstract:
Based on the rapid trend of development of Eucalyptus plantations in Fujian Province in recent years, ecological problems of Eucalyptus plantation were investigated. The results of the study, in combination with long-term investigation on Eucalyptus plantation at our field research station, show that ecological defects in the region are not merely due to the biology characteristic of Eucalyptus but are rather driven by undesirable cultural system and management practices. There is therefore an urgent need to draft out a set of feasible cultural systems for improving ecological stabilization of Eucalyptus plantations. Such systems should include choosing suitable tree species, optimizing stand and tree species structure; disseminating methods of controlled burning cutting- blank and limiting soil preparation practices. Restricting residuum logging, scientific fertilization, adopting sound management density and rotation felling are equally very important.

Ecological significance of enhanced UV-B radiation in secondary metabolism

PENG Qi, ZHOU Qing

2009, 17(3): 610-615. doi: 10.3724/SP.J.1011.2009.00610

Abstract(1433) PDF(2356)

Abstract:
Stratospheric ozone depletion increases solar UV-B radiation (280~320 nm) reaching the earth surface, significantly affecting secondary metabolism in plants. The relationship between secondary metabolite and anti-ultraviolet radiation, insect inhibition, fungal infection prevention and herbivore feeding, litter decomposition and allelopathy is a complicated phenomenon. This relationship affects species composition, inter-species relationship, biodiversity and productivity change, material circulation, geochemical cycle, energy flow isokinetic and ecological balance of the eco-system. The effect of enhanced UV-B radiation on phytocoenosis and ecological systems are summarized in the study, the specific emphasis is played on the ecological significance of enhanced UV-B radiation on secondary metabolism. Furthermore, the study establishes the trend of future research and development in managing UV-B radiation emission.

Effect of methyl iodide fumigation on soil urease activity

ZHAO Yun, WANG Qiu-Xia, GUO Mei-Xia, SONG Zhao-Xin, CAO Ao-Cheng

2009, 17(3): 616-618. doi: 10.3724/SP.J.1011.2009.00616

Abstract(1365) PDF(1131)

Abstract:

2009 Vol. 17, No. 3