中国生态农业学报(中英文)

Biochar research advances regarding soil improvement and crop response

WANG Dian, ZHANG Xiang, JIANG Cun-Cang, PENG Shu-Ang

2012, 20(8): 963-967. doi: 10.3724/SP.J.1011.2012.00963

Abstract(2080) PDF(2369)

Abstract:
Biochar is produced by heating crop residues and other organic substances under limited oxygen conditions. Because biochar is rich in nutrients and highly alkaline and stable, it has been reported to effectively reduce soil acidity, retain soil nutrients, promote nutrient uptake and enhance crop yield. This paper reviewed progress in biochar research, which (domestic or international) is at infancy stage. Because of the different methods of biochar research and various biomass carbon resources for different crops, great controversies have existed about the different roles of biochar. At present, biochar research has mainly focused on surface phenomena. As the study of such mechanism was still inadequate, researchers were required to make further explorations in this field. This review also discussed some strategies and areas for future biochar research.

Research progress on phthalate esters (PAEs) organicpollutants in the environment

LIU Qing, YANG Hong-Jun, SHI Yan-Xi, SHU Long

2012, 20(8): 968-975. doi: 10.3724/SP.J.1011.2012.00968

Abstract(2416) PDF(5030)

Abstract:
Phthalate esters (PAEs) are widely used as plasticizers, serving as important additives to increase flexibility of polymers and to make them ideal for use as plasticizers. A variety of possible chemical structures of PAEs induces a wide range of physicochemical properties and enhances environmental partitioning behavior for this class of compounds. As organic pollutants, PAEs can intensely accumulate in biotic organisms and poses immense security problems to the environment and human life. PAEs have therefore gained tremendous attention due to the threat they pose. This paper presented a comprehensive and critical review on research progress regarding PAEs in the environment, distribution in the environment, analysis and detection methods, migration and transformation behaviors, bioaccumulations, and abiotic and biotic degradations. A more consistent trend was that PAEs in the environment were mainly from synthetic sources. PAEs were appreciably absorbable by organic matter in soils and sediments, aerosol particles or some suspended matter in surface water. PAEs were also absorbable by vegetation with certain residues in vegetative parts. Abiotic and biotic degradations were the two degradation methods of PAEs in the environment, but the main mode was biotic degradation. This paper also pointed out the limitations in current studies and future research prospects on PAEs. Recommendations for further research initiatives such as environmental behavior, health risk assessment, treatment and abatement technology, and substitute products development were put forward.

Effects of biochar on organic carbon content and fractions of gray desert soil

MA Li, LV Ning, YE Jun, RU Si-Bo, LI Guo-Feng, HOU Zhen-An

2012, 20(8): 976-981. doi: 10.3724/SP.J.1011.2012.00976

Abstract(1825) PDF(1246)

Abstract:
Soil organic carbon is critical for soil fertility and crop yield. Biochar (BC) is a carbon-rich organic material derived from incomplete pyrolysis of biomass and can constitute a significant fraction of soil carbon due to its prolonged lifespan in soils. The study investigated the influence of biochar on wheat growth and soil organic carbon in grey desert soils under greenhouse experiment. The objective was to learn how this soil amendment improved crop growth and increased soil carbon storage. Biochar was produced from dried cotton stalks via pyrolysis in oxygen-limited conditions. Three qualities of biochar produced at 450 ℃, 600 ℃ and 750 ℃ (referred as BC450, BC600 and BC750) were used as the soil organic amendment in the study. The experiment was that of 3×3 factorial design with three qualities of biochar (BC450, BC600 and BC750) and three application rates (5 g·kg^-1, 10 g·kg^-1 and 20 g·kg^-1 of soil weight) plus an un-amended soil set as the control (CK). Wheat was planted for two consecutive growth seasons in 2009. The first-season of wheat was May 8 to July 15 and the second was August 8 to October 15. The results showed that dry matter weight of wheat under added BC treatments were significantly higher than that under CK. There were no significant differences among the three types and three application rates of biochar in terms of the first-season wheat dry matter weight. However, the second-season wheat dry matter weight was significantly affected by biochar qualities, application rates and the interaction of them. The highest wheat dry matter weight was under BC750 with an application rate of 20 g·kg^-1. Soil total organic carbon increased with increasing biochar pyrolysis temperature and application rate. Soil total organic carbon under BC450, BC600 and BC750 was 2.11, 3.32 and 4.19 times of CK, respectively. Soil readily oxidizable carbon content was significantly higher under biochar treatments than the control. Water-soluble organic carbon was significantly higher under biochar treatments at 5 g·kg^-1 and 10 g·kg^-1 application rates than the control. However, there was no significant difference between 20 g·kg^-1 biochar treatment and the control. Microbial biomass carbon increased significantly under biochar treatment, except for BC750 biochar at 5 g·kg^-1 application rate. Readily oxidizable carbon and microbial biomass carbon contents of soil changed in the following order of BC450 > BC600 > BC750. However, soil water-soluble organic carbon content was not affected by biochar pyrolysis temperature. The order of influence of different biochar application rates on readily oxidizable soil carbon was 10 g·kg^-1≈20 g·kg^-1 > 5 g·kg^-1, and that of water-soluble organic carbon was 5 g·kg^-1≈10 g·kg^-1 > 20g·kg^-1. For soil microbial quotient, BC450 and BC600 at 5 g·kg^-1 application rate were higher than CK. Also BC450 at 10 g·kg^-1 and 20 g·kg^-1 application rates were not significantly different from CK. Other biochar treatments were as well lower than CK. These results suggested that application of biochar as soil organic amendment was an efficient way of increasing soil carbon reserve, changing soil organic carbon fraction and promoting soil productivity.

Effects of nitrogen application rate on dry matter accumulation, nitrogenefficiency, and potassium and sodium uptake of sweet potato (Ipomoea batatas) in coastal North Jiangsu Province

NING Yun-Wang, CAO Bing-Ge, MA Hong-Bo, WANG Ji-Dong, ZHANG Hui, XU Xian-Ju, ZHANG Yong-Chun

2012, 20(8): 982-987. doi: 10.3724/SP.J.1011.2012.00982

Abstract(1559) PDF(1189)

Abstract:
Sweet potato (Ipomoea batatas) is a high energy crop with great potentials in the coastal areas in China. In order to determine optimum nitrogen (N) application rate (NAR) in sweet potato production, a field experiment was conducted in coastal North Jiangsu Province. Survival rate (SR), commodity rate (CR), dry weight vine-tuber ratio (V/T), dry matter accumulation (DMA), N accumulation (NAV), N use efficiency (NUE), N harvest index (NHI), and potassium (K) and sodium (Na) uptakes of sweet potato were investigated under six N levels (N0~N5). The N levels were 0 kg(N)·hm^-2(N0), 60 kg(N)·hm^-2 (N1), 120 kg(N)·hm^-2 (N2), 180 kg(N)·hm^-2 (N3), 240 kg(N)·hm^-2 (N4), and 300 kg(N)·hm^-2 (N5), respectively. The results were summarized as follows: (1) A sig-nificant positive correlation was noted between NAR and aboveground DMA or NAV at P < 0.01, but no significant correlation ex-isted between NAR and root NAV at P > 0.05. (2). Compared with N0, N1 treatment had no significant effects on sweet potato V/T, SR, NUE and NHI. (3) Sweet potato CR, root and tuber DMA as well as theoretical yield (TY=NAV×NUE×NHI) were highest under N1 treatment. When sweet potato NARs were 60~300 kg(N)·hm^-2 , significant positive correlation existed between NAR and V/T at P < 0.01. However, significant negative correlation was noted among SR, CR, NUE, NHI, root and tuber DMA of sweet potato at P < 0.01. (4) There was significant positive correlation between K and Na uptake at P < 0.01; both of which increased with increasing NARs. K and Na contents of aboveground tissues of sweet potato under N1 treatment were significantly higher than those under other treatments. However, K/Na ratio for the whole plant was not different among treatments. The study suggested that the optimum NAR in sweet potato fields in coastal North Jiangsu Province was 60 kg(N)·hm^-2.

Effect of different organic manures on oil flax dry matteraccumulation, distribution and yield

YAN Zhi-Li, GUO Li-Zhuo, FANG Zi-Sen, YANG Jian-Chun, GAO Jun-Shan, LIU Ji-Zu, YANG Ji-Zhong, NIU Jun-Yi

2012, 20(8): 988-995. doi: 10.3724/SP.J.1011.2012.00988

Abstract(1624) PDF(1312)

Abstract:
To realize oil flax (Linum usitatissimum Linn) high yield and good quality, field experiments were conducted in Baiyin and Lanzhou Cities of Gansu Province and Ordos City of Inner Mongolia Autonomous Region. The study compared the effects of the applications of four different fertilizers on oil flax dry matter accumulation and distribution and yield. The four fertilizers included farmyard manure (T3), oil flax residue (T4), and "Qingtiaobu" (T5) and "Woliheng" (T6) bio-fertilizers. Treatments without fertilizer (T1) and with chemical fertilizer (T2) were used as controls. The results showed similar trends in oil flax dry matter accumulation under all the fertilizer treatments in three different experiment sites with the order of T4 > T2 > T3 > T6 > T5 > T1. Fitted logistic equations of oil flax dry matter accumulation in all the three sites were significant at P < 0.01. The maximum rate of dry matter accumulation generally occurred at squaring stage, or at young fruit stage when planting date was delayed. Days for dry matter accumulation increasing with time in straight line and maximum accumulation rate in the three sites were in the order of T3 > T2 > T4 > T5 > T6 > T1 and T4 > T2 > T3 > T6 > T5 > T1, respectively. Dry matter distribution ratios of flowers and fruits at ripping stage under different organic fertilizer applications were higher than that under the controls. Pod number per plant, seed number per pod and thousand-grain weight of T4 were significantly (P < 0.01) higher than those of the controls. Pod number per plant, seed number per pod and thousand-grain weight of T3 were higher than those of T2, but the differences were insignificant across the three experi-mental sites. Both T3 and T4 yields increased by 22.85%~45.40% and 62.83%~88.13% over treatments without fertilizer. Also yields of T5 and T6 increased by 15.14%~18.10% and 17.65%~21.01% over treatments without fertilizer. Yield of T4 signifi-cantly increased by 9.58%~39.49% over the treatment with chemical fertilizer. Yields of T5 and T6 significantly decreased by 14.63%~20.52% and 12.77%~18.57% over treatments with chemical fertilizer. Though yield of T3 decreased by 1.50%~8.91% over treatments with chemical fertilizer, the difference was not significant. Oil residue and farmyard manure were therefore the recommended fertilizers for enhanced development of organic production of oil flax.

Effects of combined application of different nitrogen sources and magnesium fertilizers on cabbage yield, quality and nutrient uptake

DING Yu-Chuan, JIAO Xiao-Yan, NIE Du, LI Li-Jun, HUANG Ming-Jing

2012, 20(8): 996-1002. doi: 10.3724/SP.J.1011.2012.00996

Abstract(1501) PDF(980)

Abstract:
Vegetable crops have preferences for nitrate-nitrogen (N). Nitrate accumulation in vegetable crops is closely related with the form of N and application rate of N fertilizer, especially under over fertilization of N. The purpose of this research was to investigate the effects of combined application of different N sources and magnesium (Mg) fertilizers on yield, quality and nutrient uptake of cabbage (Brassica oleracea L.) under field conditions. The experiment was conducted in a randomized complete block design (RCBD) with three replicates of each treatment. Four N sources (no N, sole nitrate-N, sole ammonium-N, and mixed nitrate/ammonium-N) and four rates of magnesium sulfate fertilizer (0, 75 kg·hm^-2, 150 kg·hm^-2 and 300 kg·hm^-2) were used in the study. Results showed that under the same N conditions, combined application of different N sources and Mg fertilizers had significant effects on yield, quality and nutrient uptake of cabbage. The highest cabbage yield was obtained under combined application of sole nitrate-N and medium rate (150 kg·hm^-2) of Mg fertilizer. Cabbage yield under treatment of sole nitrate-N and medium rate Mg fertilizer increased by 56.9%, 14.7% and 5.2%, respectively, compared with those under no fertilizer, sole ammonium-N, and mixed nitrate/ammonium-N applications with medium rate of Mg fertilizer. N resources had significant influence on cabbage yield. Sole nitrate-N treatment increased cabbage yield by 13.0% over sole ammonium-N treatment. No significant yield difference was noted between sole nitrate-N and mixed nitrate/ammonium-N treatments. Compared with treatments without Mg fertilizer, 75 kg·hm^-2 Mg fertilizer increased cabbage yield by 9.3%. Nevertheless, no significant increase was noted with further increase in Mg fertilizer rate. The highest cabbage nitrate content was about 2 759.0 mg·kg^-1, obtained under combined application of sole nitrate-N with high rate (300 kg·hm^-2) of Mg fertilizer. Compared with no fertilizer treatment, cabbage nitrate content under sole nitrate-N with high Mg fertilizer rate increased by 101.4%, 82.3% and 14.1%, respectively, over those under no fertilizer, sole ammonium-N and mixed nitrate/ammonium-N treatments with high Mg fertilizer rate. While cabbage nitrate content was not influenced by low and medium Mg fertilizer rates, significant increase (11.2%) was noted in nitrate content at high Mg fertilizer rate compared with no fertilizer. Cabbage contents of vitamin C, reducing sugar, total amino acids significantly increased with increasing proportion of nitrate-N. Uptakes of P, K and Ca significantly increased with increasing proportion of nitrate-N. Moreover, uptakes of P, K and Mg also increased with increasing Mg fertilizer rate. Analysis revealed that interactions among different N sources and Mg had significant effects on cabbage vitamin C content and cabbage N, P, K, Ca and Mg uptake. This research indicated that mixed nitrate/ammonium-N application with proper Mg application rates not only enhanced cabbage yield and vitamin C, reducing sugar and total amino acids contents, but also reduced nitrate content and improved nutritional quality of cabbage.

Assessment of current conditions of household fertilizationof apples in Weibei Plateau

ZHAO Zuo-Ping, TONG Yan-An, LIU Fen, WANG Xiao-Ying, ZENG Yan-Juan

2012, 20(8): 1003-1009. doi: 10.3724/SP.J.1011.2012.01003

Abstract(1317) PDF(1486)

Abstract:
To evaluate the level of apple plantation management and fertilization status, 300 apple-farmer households were investigated for selected attributed including apple yield, fertilization and other management techniques in the Weibei Plateau of Shaanxi Province. The results showed that the yield and fertilization rate of apple were very different among regions. The average amount of used nitrogen fertilizer was 671.71 kg·hm^-2, that of phosphate fertilizer was 338.21 kg·hm^-2 and then that of potassium was 240.70 kg·hm ^-2. While chemical N application in 78.3% of the investigated orchards was higher than the recommended, chemical P2O5 application in only 22.2% of the investigated orchards was rational. Also chemical K₂O application in 51.2% of the investigated orchards was lower than the recommended. The proportion of organic fertilizer in total nutrient declined significantly, from 51% in 1994 to 5.54% at present. While nitrogen fertilizer was excessive in some orchards, some orchards received no fertilizer application; especially potassium fertilizer and organic manure. Based on the results of the experiment and expert experience, the suitable fertilization amounts were suggested. If 25 000~45 000 kg·hm^-2 apple yield was to be realized, about 240~360 kg·hm ^-2 N, 220~340 kg·hm^-2 P₂O₅, 160~240 kg·hm ^-2 K₂O and 40 000~60 000 kg·hm 2 organic manure were recommended. Furthermore, the method and time of fertilization were found unsuitable and the traditional way of fertilization was not changed. Over 70% of the fertilization was done as base fertilizer. It was probably a good way to reduce N fertilizer use and to improve fertilizer utilization ratio. Application of more potassium fertilizer and organic manure and combination of spring fertilization with suitable irrigation were critical for apple production. This achieved integrated management of nutrients and improved nutrient use efficiency.

Marginal effect of soybean and peanut intercropped withmaize in upland red soils

ZHANG Xiang-Qian, HUANG Guo-Qin, BIAN Xin-Min, ZHAO Qi-Guo

2012, 20(8): 1010-1017. doi: 10.3724/SP.J.1011.2012.01010

Abstract(1527) PDF(1115)

Abstract:
To understand the marginal effect of leguminous crops in intercropping systems of maize, chlorophyll content, leaf area index, root dry weight, root nodule, agronomic traits and yield of border-row soybean and peanut were determined under low nitrogen (50 kg·hm²) fertilized soybean-maize and peanut-maize intercropping systems. The field experiment was carried out in the Upland Red Soil Experimental Station of Jiangxi Agricultural University for the period from Jul. 28, 2011 to Nov. 20, 2011. The results showed that the chlorophyll content of the first and second border-rows of intercropped soybean and peanut was higher than that of the mono-crop system at different growth stages with/without nitrogen fertilization. However, no obvious differences were noted in chlorophyll content between the third border-row of intercropped and mono-cropped soybean and peanut. While leaf area index of the first and second border-rows of intercropped soybean and peanut increased at different growth stages, no obvious change was noted in the third border-row, compared with the mono-cropped soybean and peanut. Also the effect of nitrogen fertilization under the mono-cropped was greater than that of the intercropping. Root dry weight of the first and second border-rows of intercropped soybean increased by 14.7% and 2.8% and those of intercropped peanut increased by 16.5% and 3.1%, respectively, compared with mono-cropped soybean and peanut under no nitrogen fertilization. Root dry weight of the first and second border-rows of intercropped soybean increased by 11.3% and 1.3% and those of intercropped peanut increased by 13.5% and 4.6%, respectively, compared with mono-cropped soybean and peanut under nitrogen fertilization. The third border-row of intercropped systems showed no obvious difference from mono-cropped. Nitrogen fertilization under mono-cropping showed greater effect than intercropping. Intercropping also increased per-plant root nodule number and weight of the first and second border-rows of intercropped soybean and peanut at maturity stage. It, however, showed no obvious effect on the third border-row and 50 kg·hm^-2 nitrogen fertilization decreased root nodule number and weight. Nitrogen fertilization and intercropping improved agronomic traits of soybean and peanut, with the most significant marginal effect of the first border-row. The economic and biological yields per plant and yields per row of the first and second border-rows of intercropped soybean and peanut were higher than those of mono-cropping system with/without nitrogen fertilization. The first border-row presented the highest value, while the values of the third border-row were not obviously different from those of the mono-cropping system. Furthermore, the effects of nitrogen fertilization on agronomic traits and yield of soybean and peanut were greater than those of intercropping system. The study therefore showed that marginal advantages of intercropping was the first border-row > the second border-row > the third border-row ≈ mono-cropped system. The effect of nitrogen fertilization was greater than intercropping.

Effects of biological tillage on physicochemical properties and soil enzyme activity and growth and quality of Brassica oleracea var. italica

LI Shuang-Xi, ZHENG Xian-Qing, YUAN Da-Wei, ZHANG Juan-Qin, HE Qi-Yong, LV Wei-Guang, TAO Xiao-Bin

2012, 20(8): 1018-1023. doi: 10.3724/SP.J.1011.2012.01018

Abstract(1194) PDF(1204)

Abstract:
Field plot experiments were conducted to investigate the effect of biological tillage (inoculating earthworm) on soil physicochemical properties, enzyme activity and growth and quality of Brassica oleracea var. italica. Three treatments [conventional tillage (CK), no tillage (T1) and biological tillage (T2)] were set up for the experiment. The results showed that biological tillage increased soil nutrient content and soil moisture compared with CK, especially in the 5~20 cm soil layer. Also compared with CK, the contents of soil organic matter, total nitrogen, available phosphorous, and moisture under biological tillage treatment improved by 58.33%, 68.93%, 67.06% and 16.19%, respectively. Similarly, enzyme activities of soil catalase, urease and saccharase under biological tillage were significantly different from those under CK (P < 0.05). Plant height, leaf extent, leaf length and leaf width of B. oleracea were also significantly different from those of CK (P < 0.05). There was no significant difference in chlorophyll content among the three treatments. Biological tillage enhanced net photosynthetic rate of B. oleracea. The quality of B. oleracea advanced greatly, Vc content under T2 was 1.2 times that of CK. Gluconsinolates content of B. oleracea was as well higher than that of T1 and CK by 1.05 mol·g^-1 and 3.29 mol·g^-1 (P < 0.05), respectively. No significant difference was noted in soluble sugar content among the treatments. Increased earthworm (biological tillage) activity was contributed to improved soil physicochemical properties and enzyme activities in agro-ecosystems, which was critical for improving soil fertilization.

Influence of grazing disturbance on stoichiometric characteristics of alpine Rhododendron shrublands underground soil nutrient pool

WEI Wei, CAO Wen-Xia, QI Juan, ZHANG De-Gang, SHI Shang-Li

2012, 20(8): 1024-1029. doi: 10.3724/SP.J.1011.2012.01024

Abstract(1332) PDF(1158)

Abstract:
Alpine range is sensitive to global climate change and artificial disturbances and generally adapts to changes in external environment by adjustments in chemical elements. Research on belowground ecosystems is critical for ecological restoration. A combination of field and lab experiments was conducted to study the nutrients characteristics of soils, roots of alpine shrublands in Qilian Mountains under different grazing disturbances. The dynamics of root system phytocoenosis in alpine regions were also analyzed. The results showed that underground biomass of the plant community decreased with increasing soil depth. About 60%~70% of root biomass was concentrated in the 0~10 cm soil layer. Also with increasing grazing intensity, living roots penetrated deeper into the soil. Total root biomass along with carbon, nitrogen and phosphorus contents decreased with increasing grazing intensity. Compared with lightly grazed areas, C, N and P contents in heavily grazed areas decreased by 26%, 17% and 27%, respectively. Per unit mass surface living roots and carbon were highest in lightly grazed areas, nitrogen highest in medium grazed areas and phosphorus highest in heavily grazed areas. Variations in dead root N and P contents were inversely correlated to those in living root N and P contents. With increasing grazing intensity, soil organic carbon, total nitrogen, and available N and P increased. However, the content of total phosphorus remained relatively stable even though surface total phosphorus content decreased. Under non-grazing treatment, root biomass increased, C/N and C/P ratios increased both in surface soils and roots, and N/P ratio decreased, compared with grazing treatments. This implied that roots were vital elements for both soil carbon accumulation and nutrient cycle. Non-grazing in vegetation growth seasons facilitated plant recovery and better growth and high plant nutrient efficiency. Non-grazing during vegetation growth seasons was an effective way of promoting recovery of fragile alpine shrub for high ecological functions and economic values.

Effect of sowing date on agronomic, physiologic and yieldindicators of wheat in North Henan Province

ZHANG Huan-Jun, YU Hong-Yan, XIANG Jian, DING Wei-Xin

2012, 20(8): 1030-1036. doi: 10.3724/SP.J.1011.2012].01030

Abstract(1295) PDF(1407)

Abstract:
To understand inter-annual variability in grain yield, a pot experiment was conducted to evaluate the effect of sowing date on agronomic, physiologic and yield indicators of wheat. The four sowing dates were October 5 (T1), 10 (T2), 15 (T3) and 20 (T4). Agronomic indicators of the numbers of productive spike and grains per spike, and the 1000-grain weight were measured after wheat harvest. Also physiologic indicators of root activity (RA), acid phosphatase (APA) and nitrate reductase (NRA) activities were measured during wheat growth season. Results indicated that sowing date had significant influence on grain yield and wheat yield was highest for the October 10 (T2) sowing date. Wheat absorptive capacities in nitrogen and phosphorus in T2 treatment were much higher than in other treatments. Productive spikes and grains per spike in T2 were 38.00 tiller·pot 1 and 37.67 grain·spike 1, respectively, also significantly higher than those in other treatments. Productive spikes and grains per spike were positively correlated with wheat yield. While no differences in chlorophyll contents were noted among treatments at tillering stage, it was significantly higher in T2 than in T3 and T4 treatments at jointing and flowering stages. Nitrate reductase activity (NRA) increased with wheat growth in T1 and T2, but remained relatively stable in T3 and T4 treatments during the entire growth period. The activity of nitrate reductase was up to 57.12 g·g^-1(FW)·h^-1 at flowering stage in T2 treatment, significantly higher than those in other treatments. Nitrate content decreased with increasing wheat growth in the treatments. It was highest in T2 at jointing stages, and no significant differences noted among treatments at flowering stage. Acid phosphatase activity (ARP) was about 0.28 mg·g^-1(FW)·h^-1 in all treatments at tillering and jointing stages. It was up to 0.34 mg·g^-1(FW)·h^-1 in T2 at flowering stage, which was significantly higher than in other treatments. In the study, wheat root activity (RA) decreased with delay in sowing date. Analysis showed significant correlation between grain yield and numbers of productive spikes or gains per spike. Also wheat yield was significantly correlated with APA and NRA at jointing stage, and with aboveground biomass and NRA at the flowering stage. The findings of the study suggested that sowing date influenced wheat yield mainly through changing APA and NRA. Also soil N and P absorption varied with sowing date, which in turn caused variations in wheat yield.

Effect of interval sowing on agronomic traits and thermo-toleranceof japonica rice from Northeast China

YU Jiang-Hui, ZHAO Sen, ZHOU Hao, MENG Qiu-Cheng, JIANG Jian-Xiong, XIAO Guo-Ying

2012, 20(8): 1037-1042. doi: 10.3724/SP.J.1011.2012.01037

Abstract(1351) PDF(1085)

Abstract:
The agronomic traits including plant height, panicle length, seed set, 1000-grain weight, panicles per plant, grains per panicle and theoretic yield per plant of 5 thermo-tolerant japonica rice cultivars ("Dongdao 2", "Dongnong 03-33", "Dongnong 415-1", "Hejiang 195" and "Jijing 3") from Northeast China were evaluated and the relationships between nature air temperature and seed set were analyzed by use of interval sowing populations (Mar. 20, Mar. 30, Apr. 9, Apr. 19, Apr. 29, May 9, May 19 and May 29 in 2011) at Changsha, and then the thermo-tolerance at the heading stage of them was summarized. Results showed that when sowing date was postponed, the days to flower became short gradually. There were wide variations in panicles per plant, grains per panicle and theoretic yield per plant. Meanwhile the variations in plant height, panicle length, seed set and 1000-grain weight were small among different sowing dates. A negative correlation was noted between daily mean and maximum temperature and seed set. Even though the seed set of "Hejiang 195" was affected least by air temperature, the seed set of "Dongdao 2", "Dongnong 03-33" and "Dongnong 415-1" correlated with air temperature significant at the 5% level, while that of "Jijing 3" significant at the 1% level. Within a certain range of temperature, the regression curve for seed set and air temperature was cone-shaped. Furthermore, the effects of daily maximum and mean temperatures on seed set of rice were consistent. Among the interval sowings that coincided with high temperatures at the heading stage, the seed set varied in the range of 64.9%~75.1%, beside that of "Dongnong 03-33" sowed on May 29, and "Jijing 3" sowed on May 19, whose seed sets were 58.7% and 52.5%, respectively. These cultivars exhibited more reliable thermo-tolerance among the tested rice cultivars. Based on the analysis of agronomic characters of interval sowing and the relationship between nature air temperature and seed set, it was recommended to plant "Dongdao 2" and "Hejiang 195" as early season rice in Hunan Province.

Growth characteristics of alligator weed (Alternanthera philoxeroides) inrice ecosystems and effects on rice growth and development

LIU Yu-Fang, PENG Mei-Fang, ZENG Qiang-Guo, SU Wen-Jie, WANG Cheng-Chao, LIU Wen-Hai, WAN Fang-Hao

2012, 20(8): 1043-1047. doi: 10.3724/SP.J.1011.2012.01043

Abstract(1292) PDF(1081)

Abstract:
To understand the invading capability of alligator weed (Alternanthera philoxeroide) in cultivated rice fields and rice resistance to A. philoxeroide invasion, the growth characteristics of A. philoxeroide and effects on rice development at early invasion were studied. A paddy field invasion simulation was conducted through transplanting propagators of A. philoxeroide into cultivated rice fields after seedling transplant. The results showed that A. philoxeroide growth weakened in the first cultivation season of rice after field transplanting. The numbers of clones and erect caulis of A. philoxeroide decreased slightly from early tillering to late tillering and also increased slightly from late tillering to mature stage of rice (all insignificant). Although weed height increased significantly, weed stem grew small and soft with weak tops growth. A. philoxeroide weed leaves were generally small, weak and curly and produced few new buds in rice fields. No significant effects were noted regarding rice growth parameters such as number of tillers, effective tillering per cluster and plant height when only few A. philoxeroides propagators were transplanted into rice fields. A. philoxeroide near rice field margins and in rice field levees hardly grew or spread into main rice fields. Although only weed clone number, erect caulis and plant height increased significantly, weed vegetation cover grew thick. These findings suggested that both cultivated lands and rice fields controlled growth and reproduction of A. philoxeroides. It was also proposed to keep rice fields under cultivation to prevent weed invasion.

Potassium utilization in EdHP1 (H⁺-pyrophosphatase) transgenic wheat

RUAN Li, ZHANG Jia-Bao, XIN Xiu-Li, CHENG Xian-Guo

2012, 20(8): 1048-1053. doi: 10.3724/SP.J.1011.2012.01048

Abstract(1223) PDF(1049)

Abstract:
With intensive land farming, soil potassium deficiency has become increasingly serious, limiting sustainable agricultural development. In this study, the differences between EdHP1 (H⁺-pyrophosphatase) transgenic and wild wheat were investigated in terms of potassium absorption and utilization, rhizosphere soil potassium dynamic and soil enzyme activities. The research aimed to determine the potentials of transgenic technologies in promoting wheat potassium absorption and utilization. The results showed that available K in rhizosphere of transgenic wheat was significantly lower than that of wild wheat at different K-levels. Available K in rhizosphere of transgenic wheat were 8.30% (30 d), 15.02% (60 d) and 12.53% (75 d) below those of wild wheat for K1-level (KCl application rate of 186 kg·hm^-2). For transgenic wheat high potassium absorption, available K is transported from non-rhizosphere to rhizosphere soil. Under K0 (no KCl), K1 and K2 (KCl application rate of 805 kg·hm^-2) treatments, biomass K use efficiencies (KUI-B) were 22.39%, 136.21% and 14.03%, respectively. Also while shoot K contents were 225.97%, 18.77% and 17.28%, root cation exchange capacities (CEC) were 55.19%, 33.16% and 30.44%, respectively. Rhizosphere soil catalase and urease activities of transgenic wheat were significantly higher than those of wild wheat at different K-levels. Thus transgenic technology improved root CEC and created good rhizosphere environment for efficient wheat potassium absorption and utilization.

Effect of soil organic matter on the contents of availableand water-extracted phosphorus

TAO Shi-Feng, XU Xiao-Feng, KOU Tai-Ji

2012, 20(8): 1054-1058. doi: 10.3724/SP.J.1011.2012.01054

Abstract(1581) PDF(2963)

Abstract:
A total of 40 soil samples of 4 soil types were collected in cultivated farmlands in the outskirts of Luoyang and analyzed using conventional methods for the effects of soil organic matter content on the concentrations of available phosphorus, total phosphorus and water-extracted phosphorus. Based on soil organic matter content less/greater than 16.0 g·kg^-1, the soil samples were divided into two groups, and the relationships between available and total phosphorus, and water-extracted and available phosphorus in the two groups estimated. The results showed that the slope of linear correlation between available and total phosphorus was higher in soil sample group with >16.0 g·kg^-1 organic matter content than the group with <16.0 g·kg^-1 organic matter content. Also the slope of linear correlation between water-extracted and available phosphorus was lower in the >16.0 g·kg^-1 organic matter group than in the <16.0 g·kg^-1 organic matter group. This trend was shown in both the Olsen and Mehlich-3 extraction methods. The study showed that under low soil phosphorus, high content of soil organic matter meant less soil available phosphorus. This also resulted in high water-extracted phosphorus concentration. It in turn meant that in soils with high organic matter content and low phosphorus, phosphorus recycle was much faster. When soil phosphorus content increased, available phosphorus concentration increased more rapidly in soil samples with high soil organic matter. Meanwhile, water-extracted phosphorus increase was relatively slow. The study throw further light on the need and strategies of reducing leaching loss of phosphorus.

Response of anatomy and hydraulic characteristics of xylem stem ofPopulus euphratica Oliv. to drought stress

XU Qian

2012, 20(8) doi: 10.3724/SP.J.1011.2012.01059

Abstract(2589) PDF(5830)

Abstract:
Populus euphratica Oliv. is a precious woody plant in arid regions with vital ecological functions such as high tolerance to salinity/alkalinity, high drought resistance, wind-break/sand-fixation, etc. Because of human socio-economic activities and the resulting development of water resources in recent years, a large number of P. euphratica decayed. Current studies on P. euphratica have focused on changes in physiological and biochemical characteristics, changes in dominant P. euphratica community characteristics, vitro morphogenesis development and histological trend observations. However, there have been little studies on the anatomy and hydraulic characteristics of xylem stems under drought stress. Analysis of changes in the anatomy and hydraulic characteristics of P. euphratica stem xylem under drought stress was significant for interpreting its resistance mechanism. This water control experiment analyzed the response of the anatomy and hydraulic characteristics of P. euphratica stem xylem to different degrees of drought stress. Results showed that with increasing drought stress, the xylem vessel density significantly decreased (P < 0.01). Also xylem vessel diameter, wall thickness and wall mechanical strength increased significantly (P < 0.01). The large the vessels diameter, the more water transported. Also thicker and harder vessel walls ensured secure water relay. Perforation and pit diameters also significantly increased (P < 0.05) with increasing drought stress, resulting in more efficient axial and radial water relay. However, no observable changes were noted in vessel micro-morphology. There were two types of vessel ― pitted vessel and spiral vessel. Most of the pits were bordered pits with alternate arrangement. Spiral thickening was noted at end walls of vessel. All perforations were of the single type, probably due to common natural growth and long-term evolution. For hydraulic characteristics, conductivity (Ks) and native embolism level (PLC) significant increased (P < 0.05) with increasing drought stress. To effectively adapt to arid environments, it was concluded that changes in anatomy and hydraulic characteristics of P. euphratica stem xylem were active growth processes. To a certain extent, these activities compensated for the negative effects of drought stress on P. euphratica.

Effects of cutting aquatic plants on nitrogen and phosphorusinterception in ecological ditches

ZHANG Shu-Nan, XIAO Run-Lin, YU Hong-Bing, LIU Feng

2012, 20(8): 1066-1071. doi: 10.3724/SP.J.1011.2012.01066

Abstract(1598) PDF(1535)

Abstract:
In this study, Canna glauca, Hydrocotyle vulgaris, Sparganium stoloniferum, Myriophyllum spicatum and Juncus effusus aquatic plants were planted in an ecological ditch. The effects of plant cutting management on nitrogen (N) and phosphorus (P) interception in ecological ditches were then analyzed by N and P content comparisons and removal rates in water samples. The results showed that the amounts of total N and P removed by cutting aquatic plants in September and November were 11.889 kg and 1.099 kg, respectively, in the 300 m2 ecological ditch. Total N uptake by different aquatic plants was in the order of C. glauca (7.686 kg) > M. spicatum (1.501 kg) > H. vulgaris (1.128 kg) > J. effusus (0.974 kg) > S. stoloniferum (0.601 kg). The order for total P was C. glauca (0.433 kg) > M. spicatum (0.233 kg) > S. stoloniferum (0.191 kg) > H. vulgaris (0.134 kg) > J. effusus (0.109 kg). Cutting plants also improved N and P removal efficiency in ditch sediments, except for S. stoloniferum. Compared to non-cutting areas, cutting areas showed increased sediment total N nutrient removal rates with M. spicatum (20.73%) > H. vulgaris (20.00%) > J. ef-fusus (16.05%) > C. glauca (4.86%) > S. stoloniferum ( 9.72%). That for total P was J. effusus (20.69%) > H. vulgaris (16.67%) > C. glauca (4.55%) > M. spicatum (0.00%) > S. stoloniferum ( 16.00%). N and P removal rates in water also increased under cutting treatment. Thus cutting aquatic plants not only removed nutrients from ditch systems, but also increased N and P interception in water and ditch sediments.

Effect of reclaimed municipal wastewater on ryegrass growthand soil phosphorus conversion

LI Zhong-Yang, FAN Xiang-Yang, QI Xue-Bin, QIAO Dong-Mei, LI Ping, ZHAO Zhi-Juan

2012, 20(8): 1072-1076. doi: 10.3724/SP.J.1011.2012.01072

Abstract(1300) PDF(976)

Abstract:
Ryegrass was irrigated with reclaimed municipal wastewater (RW), 1∶1 clean water and reclaimed municipal wastewater (CW+RW) and clean water (CW) as the control in the pot experiment in a greenhouse to study the effects of reclaimed municipal wastewater on ryegrass growth, conversion characteristics of soil phosphorus and the implications for agricultural production in China. The findings suggested that in comparison with the control, reclaimed municipal wastewater significantly increased aboveground and root biomass of ryegrass. While CW+RW increased aboveground and root biomass by 18.92% and 6.42%, RW increased these parameters by 26.79% and 10.55%, respectively. CW+RW and RW increased P concentration in aboveground ryegrass by 8.48% and 10.93%, respectively. Reclaimed municipal wastewater irrigation apparently reduced total soil P concentration. Olsen-P concentration was significantly increased, respectively, by 29.15% and 43.80% under CW+RW and RW treatments. CW+RW and RW also increased active organic phosphorus concentration by 50.30% and 81.57%, respectively. They, however, increased moderately active inorganic phosphorus by 7.66% and 13.68%, respectively. Ca₂-P concentration was enhanced under CW+RW and RW treatments, increasing from 12.90 mg·kg^-1 of the control to 16.42 mg·kg^-1 and 15.49 mg·kg^-1 with increment of 27.29% and 19.38%, respectively. CW+RW and RW also increased Ca8-P concentration by 19.94% and 16.03%, respectively. Reclaimed municipal wastewater irrigation increased soil P activity by decreasing soil pH and significantly increasing soil organic matter content. Reclaimed municipal wastewater irrigation was definitely improved soil phosphorus utilization efficiency.

Cu and glyphosate toxicity to earthworm (Eisenia fetida)

ZHOU Chui-Fan, WANG Yu-Jun, YU Yuan-Chun, YU Xiao-Peng, BAI Yu-Jie, ZHOU Dong-Mei

2012, 20(8): 1077-1082. doi: 10.3724/SP.J.1011.2012.01077

Abstract(1705) PDF(1609)

Abstract:
Interactions of pollutions are among current research focus in environmental sciences. Fungicides contained copper (Cu) and herbicide glyphosate (GPS) are widely used in orchards and other agricultural ecosystems. Co-existence of Cu and GPS could result in combined pollution of soil environment. GPS affects metal behaviors in water and soil systems because its functional groups such as amine, carboxylate and phosphonate react with metal ions to form metal complexes. A laboratory experiment was therefore conducted to investigate the interactions of GPS and Cu with respect to sub-acute toxicity to soil invertebrate earthworms. Earthworms were exposed to spiked soil (70% garden mould and 30% dairy manure) for 35 d with different concentrations of Cu and GPS (technical-grade glyphosate acid). Deionized water was the blank control, Cu concentrations were 25 mg·kg^-1, 50 mg·kg^-1, 100 mg·kg^-1, 200 mg·kg^-1 and 400 mg·kg^-1 and GPS concentrations were 25 mg·kg^-1, 25 mg·kg^-1, 100 mg·kg^-1, 200 mg·kg^-1 and 500 mg·kg^-1 by soil dry weight in a single toxicity test. Simultaneously, two Cu levels of 25 mg·kg^-1 and 200 mg·kg^-1 were mixed by adding 0 mg·kg^-1, 25 mg·kg^-1, 50 mg·kg^-1, 100 mg·kg^-1 and 200 mg·kg^-1 of GPS in a complementary test. The purpose of the study was to address the possible inductions of earthworm (Eisenia fetida) exposure to single Cu and GPS and the corresponding interactions. The relative growth rate of earthworm biomass and Cu uptake were then measured. Results showed that the relative growth rate of earthworm biomass was significantly inhibited by high Cu concentration (α=0.01, r²=0.570). Furthermore, earthworm Cu content significantly increased with increasing soil Cu concentration (α=0.01, r² =0.905). GPS had no significant effect on the relative growth rate of earthworm biomass. The complementation test data showed that GPS significantly decreased earthworm Cu burden when soil Cu concentration was 200 mg·kg^-1. Higher acute toxicity was noted for Cu than for GPS. To a certain degree, GPS decreased toxicity. Thus GPS was recommended in controlling soil toxicity and bioavailability of soil heavy metals in conditions where both GPS and heavy metals co-exist.

Analysis of carbon source metabolism functions of cadmium-tolerantbacteria separated from rice (Oryza satiua) rhizosphere

ZHOU Li-Ying, LIN Su-Lan, LI Yi, LIN Shu-Ting, LIU Jie, XIAO Qing-Tie, YE Ren-Jie, LIN Wen-Xiong, LIN Rui-Yu

2012, 20(8): 1083-1087. doi: 10.3724/SP.J.1011.2012.01083

Abstract(1371) PDF(1447)

Abstract:
To understand metabolic abilities of carbon sources in three cadmium-tolerant bacteria (strain A, strain B and strain C) isolated from rice rhizosphere soils, basic characteristics of bacteria strains were determined by physiological and biochemical reactions and metabolic functions of carbon sources analyzed via the BIOLOG ECO plate method. The main principle was based on the fact that color-reduction reaction showed differences in carbon source utilization. The physiological and biochemical characteristics showed that all three bacteria strains behaved as Gram-negative with born flagellum. Strain C was identified as Pseudomonas aeruginosa, while strains A and B both belonged to different Pseudomonas species. The conclusions on physiological and biochemical characteristics were the same as in previous molecular identifications. BIOLOG ECO analysis showed that average well color development (AWCD) nearly approached the maximum after culturing the strains for 72 hours. Significant differences were noted in AWCD among cultured strains for 24 hours, dominated by amino acid utilization efficiency. Among the thirty-one single carbon sources used, higher utilization rates were noted in nine compounds. The compounds included N-Acetyl-D- glucosamine, L-Arginine, L-Asparagine, Itaconic acid, Putrescicine, 4-Hydroxy benzoic acid, Pyruvic acid methyl ester, Tween 40 and Tween 80. Also significant differences were detected among the three bacteria strains regarding utilization rates of L-Arginine, Itaconic acid and Pyruvic acid methyl ester. On the basis of carbon source utilization, more information was gathered on strain functions. Thus this study expanded our knowledge on needed carbon sources for cadmium-tolerant strain growth. The study also taught us optimization strategy of cultured media which was beneficial for future research work. Furthermore, it provided precious microorganism resources for constructing corresponding bacteria gene engineering.

Response of dryland spring wheat yield to elevated CO₂ concentration and temperature by APSIM model

LI Guang, LI Yue, HUANG Gao-Bao, LUO Zhu-Zhu, WANG Qi, LIU Qiang, YAN Zhen-Gang, ZHAO You-Yi

2012, 20(8): 1088-1095. doi: 10.3724/SP.J.1011.2012.01088

Abstract(1758) PDF(1480)

Abstract:
Global warming has become the most complicated issue facing agriculture production in the world and has received much attention in recent years. In order to determine the effect of global warming on spring wheat grain yield, field experimental results in the semiarid Dingxi region were used in APSIM model simulation and analysis. Spring wheat yield response to elevated CO₂　concentration and temperature was researched by simulating wheat yield under regular climatic conditions. The used APSIM model parameters were firstly modified and then verified based on field data. Spring wheat grain yield was stimulated by the APSIM model for a unitized design of 7 levels of temperature and CO₂ concentration. Regression equations and path analyses were also used to analyze the response of spring wheat grain yield to the changes in temperature and CO₂ concentration. The results showed that average increase in spring wheat grain yield was 4.9%, with a maximum increase of 14.6% when CO₂ concentration increased by 100 mol·mol^-1 at constant temperature. A quadratic parabola relationship was noted between spring wheat grain yield and CO₂ concentration, which indicated an increasing tendency. Spring wheat grain yield increment reduced with further increases in CO₂ concentration. Average drop in spring wheat grain yield was 6.1%, with a maximum drop of 14.2% when temperature increased by 1 ℃ at constant CO₂ concentration. Also a quadratic parabola relationship was noted between spring wheat grain yield and temperature, which suggested a declining tendency. While synergy effects of temperature and CO₂ concentration on spring wheat grain yield were positive, although negative temperature effects on grain yield were more obvious than positive CO₂ concentration effects. The study concluded that global warming with increased temperature and CO₂ concentration negatively affected dryland spring wheat grain yield in semiarid China.

Establishment and comparison of pedotransfer functions of soil moisture constant in the Three-River Headwaters Region of Qinghai Province

YI Xiang-Sheng, LI Guo-Sheng, YIN Yan-Yu

2012, 20(8): 1096-1104. doi: 10.3724/SP.J.1011.2012.01096

Abstract(1495) PDF(1009)

Abstract:
Soil moisture constants such as saturated water content and field water capacity are important hydraulic parameters in soil science. However, they are frequently lacking in routine soil surveys because direct measurements are time-consuming and labor intensive. As such, it was necessary to find indirect, cheap and rapid ways of acquiring soil moisture constants from other more easily available soil physical and chemical properties. In this study, pedotransfer functions were established by using the methods of regression, BP neural network and Rosetta model to predict saturated soil water content, capillary water-holding capacity and field water capacity from soil organic matter, texture and bulk density in the Three-River Headwaters Region of Qinghai Province. The general performance of pedotransfer functions was evaluated based on mean error, root mean squared error and determination coefficient between observed and predicted values. Vital results obtained were grouped mainly into three aspects as follows: (1) Mean error and root mean squared error of pedotransfer functions derived from regression method for the three soil moisture constants were small with big determination coefficients, showing good prediction. Specifically, mean error and root mean squared error of field water capacity derived from regression method were below 3.397%, with determination coefficient above 0.868. (2) Mean error and root mean squared error of pedotransfer functions for the three soil moisture constants obtained by BP neural network method were below 4.685% with determination coefficients above 0.857. Moreover, observed and predicted values of the three soil moisture constants were close to the 1︰1 line. It therefore generally suggested that the estimation of the three soil moisture constants by the BP neural network method was good. (3) As for pedotransfer functions derived from Rosetta model, mean error and root mean squared error of the three soil moisture constants were larger and with lower determination coefficients than the other two methods. This showed that Rosetta model performed relatively poor in estimating soil moisture constants in the study area. In general, pedotransfer functions of saturated soil water content and capillary water-holding capacity established by BP neural network method were the best. Furthermore, regression method was best for estimating field water capacity and Rosetta model was worse than the other two methods. This research not only provided the scientific basis for studying soil hydraulic parameters in the Three-River Headwaters Region in Qinghai Province, but was also critical for estimating soil water at region scales.

Quantitative analysis of farmer attitude towards water-saving plantingstructure adjustment: A case study of Heihe River middle reaches

WANG Juan, WU Pu-Te, WANG Yu-Bao, ZHAO Xi-Ning, SONG Jian-Feng, HUANG Jun

2012, 20(8): 1105-1112. doi: 10.3724/SP.J.1011.2012.01105

Abstract(1445) PDF(1155)

Abstract:
To ensure smooth implementation of water-saving planting structure adjustment, countermeasures were proposed by analyzing farmer attitude toward it. It was important for increasing crop water use efficiency, ensuring food security and agricultural development in water deficient districts. Based on survey data (by questionnaire and household interviews) of 200 farmers in 3 irri-gation districts in the middle reaches of Heihe River Basin, the Enter and Backward conditional methods of Logistic Regression were used to analyze the factors affecting farmer attitude towards crop planning structure adjustment. The results indicated that education, ratio of labor force, arable land area, commercialization degree, government participation and water-saving consciousness were posi-tively related with planting structure adjustment adoption. Also farmer age, previous season crop number, commercialization degree and risk consciousness were negatively related with planting structure adjustment adoption. Based on above analysis, key factors of supportive ratios of planting structure adjustment were sequenced in order of importance as: age > government participation > wa-ter-saving consciousness > commercialization degree > education > arable land area. Among these factors, age and government partici-pation were most critical, with significant levels of 0.002 and 0.044, respectively. Also a probability equation between five key factors and supportive ratios was developed. The regression results showed that the goodness of fit between model and observed values was 78%, suggesting a good regression relation. Finally, several countermeasures were put forward to boost implementation of wa-ter-saving planting structure adjustment with model-simulated ones. They were reinforced propaganda trainings and investments in sci-ence and technology, strengthening economic compensations and farmer benefits, and emphasizing government guidance.

2012 Vol. 20, No. 8