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Measurement, spatial spillover and influencing factors of agricultural carbon emissions efficiency in China
WU Haoyue, HUANG Hanjiao, HE Yu, CHEN Wenkuan
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Effects of tillage and straw returning method on the distribution of carbon and nitrogen in soil aggregates
ZHANG Yuming, HU Chunsheng, CHEN Suying, WANG Yuying, LI Xiaoxin, DONG Wenxu, LIU Xiuping, PEI Lin, ZHANG Hui
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Relationship between policy incentives, ecological cognition, and organic fertilizer application by farmers: Based on a moderated mediation model
SANG Xiance, LUO Xiaofeng, HUANG Yanzhong, TANG Lin
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Spatio-temporal evolution of carbon stocks in the Yellow River Basin based on InVEST and CA-Markov models
YANG Jie, XIE Baopeng, ZHANG Degang
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Effects of straw returning and fertilization on soil bacterial and fungal community structures and diversities in rice-wheat rotation soil
ZHANG Hanlin, BAI Naling, ZHENG Xianqing, LI Shuangxi, ZHANG Juanqin, ZHANG Haiyun, ZHOU Sheng, SUN Huifeng, LYU Weiguang
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2015 Vol. 23, No. 2
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2015, 23(2): 127-140.
doi: 10.13930/j.cnki.cjea.140734
Abstract:
With the completion of the Three Gorges Project, water impoundment operations have been smoothly for some years now. The Three Gorges Project has also had a broad and far-reaching impact on the ecological environment, with tremendous social and economic benefits. This paper analyzed the progress of research on the effects of the Three Gorges Reservoir (TGR) on the ambient ecological environment using domestic and foreign research publications in recent 20 years. Firstly, the progress of research on the characteristics of land use change in the TGR area was analyzed. Then changes in environmental factors (e.g., reservoir-related climate change, change in soil and water environment and change in biodiversity) were determined. The study also summarized the effects of environmental quality and ecosystem services in the TGR area. Finally, the study put forward the existing problems and shortcomings of current research works and proposed the prospects of future research. It was recommended to pay more attention to the dynamics of the effects of reservoir project on the ecological environment in the TGR area. There was also need to establish a long-term observation database, integrate macroscopic with microscopic research and carry out a comprehensive evaluation of the ecological environment in the TGR area.
With the completion of the Three Gorges Project, water impoundment operations have been smoothly for some years now. The Three Gorges Project has also had a broad and far-reaching impact on the ecological environment, with tremendous social and economic benefits. This paper analyzed the progress of research on the effects of the Three Gorges Reservoir (TGR) on the ambient ecological environment using domestic and foreign research publications in recent 20 years. Firstly, the progress of research on the characteristics of land use change in the TGR area was analyzed. Then changes in environmental factors (e.g., reservoir-related climate change, change in soil and water environment and change in biodiversity) were determined. The study also summarized the effects of environmental quality and ecosystem services in the TGR area. Finally, the study put forward the existing problems and shortcomings of current research works and proposed the prospects of future research. It was recommended to pay more attention to the dynamics of the effects of reservoir project on the ecological environment in the TGR area. There was also need to establish a long-term observation database, integrate macroscopic with microscopic research and carry out a comprehensive evaluation of the ecological environment in the TGR area.
2015, 23(2): 141-149.
doi: 10.13930/j.cnki.cjea.140740
Abstract:
Maize/soybean and maize/sweet potato relay strip intercropping systems are the two main intercropping systems in Southwest China. In two main maize production areas in Sichuan Province, differences in photosynthetic characteristics of maize under maize/soybean and maize/sweet potato relay strip intercropping systems were investigated based on long-term experiment (2008-2010). Also the data for 2011 was used to investigated the effects of nitrogen application rates on maize photosynthetic characteristics with the split-plot design experiment of different nitrogen application rates [0 kg(N) hm-2 (N0), 90 kg(N) hm-2 (N90), 180 kg(N) hm-2 (N180), 270 kg(N) hm-2 (N270) and 360 (N360) kg(N) hm-2] in maize/soybean and maize/sweet potato relay strip intercropping systems. Differences in photosynthetic characteristics in maize were determined based on analysis of leaf area index, relative content of chlorophyll, nitrogen content in ear leaf, photosynthetic rate and chlorophyll fluorescence parameters. Results showed that different planting patterns and nitrogen managements had fine adjustment effects on photosynthetic characteristics of maize. Compared with the traditional relay strip intercropping pattern ― maize/sweep potato relay intercropping system, maize/soybean relay intercropping system significantly slowed down the decreasing rates of leaf area per plant and the relative content of chlorophyll from filling stage to maturity stage, increased the activity of PSⅡ in ear-leaf and photochemical efficiency. Consequently, under maize/soybean relay intercropping, maize photosynthetic rate increased, and biomass per plant at maturity stage was higher by 10.49 g over that under maize/sweet potato relay intercropping. After strip crop rotation, the differences in all the indexes of photosynthetic characteristics since tasseling stage between the two cropping patterns were significant. Under maize/soybean relay strip intercropping, leaf area per plant, net photosynthetic rate, and ear-leaf Fv/Fm and ФPSⅡ were higher after flowering stage respectively by 941 cm2, 4.81 ?mol·m-2·s-1, 0.017 and 0.020 than those under maize/sweet potato system. From filling to maturity stages, the decreasing rates of all the indexes of maize/soybean relay intercropping were obviously lower than those of maize/sweet potato relay intercropping. Maize biomass per plant at maturity stage of maize/soybean relay intercropping was higher by 26.83 g than that of maize/sweet potato relay intercropping. Maize leaf area per plant and chlorophyll fluorescence parameters increased under treatment N180 for maize/soybean relay intercropping system, and under treatment N270 for maize/sweet potato relay intercropping system, with both treatments having increased photosynthetic rate and biomass accumulation. Excessive application of nitrogen (270-360 kg·hm-2) deceased chlorophyll content, leaf Fv/Fm and ФPSⅡ and photosynthetic rate in both intercropping systems.
Maize/soybean and maize/sweet potato relay strip intercropping systems are the two main intercropping systems in Southwest China. In two main maize production areas in Sichuan Province, differences in photosynthetic characteristics of maize under maize/soybean and maize/sweet potato relay strip intercropping systems were investigated based on long-term experiment (2008-2010). Also the data for 2011 was used to investigated the effects of nitrogen application rates on maize photosynthetic characteristics with the split-plot design experiment of different nitrogen application rates [0 kg(N) hm-2 (N0), 90 kg(N) hm-2 (N90), 180 kg(N) hm-2 (N180), 270 kg(N) hm-2 (N270) and 360 (N360) kg(N) hm-2] in maize/soybean and maize/sweet potato relay strip intercropping systems. Differences in photosynthetic characteristics in maize were determined based on analysis of leaf area index, relative content of chlorophyll, nitrogen content in ear leaf, photosynthetic rate and chlorophyll fluorescence parameters. Results showed that different planting patterns and nitrogen managements had fine adjustment effects on photosynthetic characteristics of maize. Compared with the traditional relay strip intercropping pattern ― maize/sweep potato relay intercropping system, maize/soybean relay intercropping system significantly slowed down the decreasing rates of leaf area per plant and the relative content of chlorophyll from filling stage to maturity stage, increased the activity of PSⅡ in ear-leaf and photochemical efficiency. Consequently, under maize/soybean relay intercropping, maize photosynthetic rate increased, and biomass per plant at maturity stage was higher by 10.49 g over that under maize/sweet potato relay intercropping. After strip crop rotation, the differences in all the indexes of photosynthetic characteristics since tasseling stage between the two cropping patterns were significant. Under maize/soybean relay strip intercropping, leaf area per plant, net photosynthetic rate, and ear-leaf Fv/Fm and ФPSⅡ were higher after flowering stage respectively by 941 cm2, 4.81 ?mol·m-2·s-1, 0.017 and 0.020 than those under maize/sweet potato system. From filling to maturity stages, the decreasing rates of all the indexes of maize/soybean relay intercropping were obviously lower than those of maize/sweet potato relay intercropping. Maize biomass per plant at maturity stage of maize/soybean relay intercropping was higher by 26.83 g than that of maize/sweet potato relay intercropping. Maize leaf area per plant and chlorophyll fluorescence parameters increased under treatment N180 for maize/soybean relay intercropping system, and under treatment N270 for maize/sweet potato relay intercropping system, with both treatments having increased photosynthetic rate and biomass accumulation. Excessive application of nitrogen (270-360 kg·hm-2) deceased chlorophyll content, leaf Fv/Fm and ФPSⅡ and photosynthetic rate in both intercropping systems.
2015, 23(2): 150-158.
doi: 10.13930/j.cnki.cjea.140934
Abstract:
Rational management measures involving crop selection, tillage, crop rotation, fertilization, etc. are important for prevention of contamination and protection of soil and water resources. A number of field studies conducted under subsurface drainage conditions with various management practices have focused on reducing N loss through runoff. Also several models have been developed to evaluate the effects of the management measures on N loss through runoff. Models such as SWAT, DNDC and RZWQM were developed to simulate physical, chemical and biological responses of root-zone soil system to various agricultural management practices. Most of these models have been extensively tested under various soil, climate and agricultural management conditions. They have been used to assess the effects of agricultural practices on crop production or crop rotation systems and the related water and nitrate transport processes. In this study, the Root Zone Water Quality Model (RZWQM) was used to simulate water and nitrate nitrogen accumulations in the soil profile, nitrate nitrogen leaching and ammonia volatilization and yield of winter wheat/summer maize rotation systems in the North China Plain. The objective of the study was to explore the feasibility of predicting optimum nitrogen fertilization process using the RZWQM. A rotation trial of winter wheat and summer maize was conducted on Dahe Experiment Station of Hebei Academy of Agricultural and Forestry Sciences. Four nitrogen fertilizer rates [575 kg·hm-2 (N3), 400 kg·hm-2 (N2), 215 kg·hm-2 (N1), and 0 kg·hm-2 (N0)] were set for the winter wheat/summer maize rotation system. While data for maize was used to calibrate the RZWQM, data for wheat was used to validate the model. The results showed the deviations in the model calibration and validation were acceptable. The Root Mean Square Error (RMSE) of soil water content was as low as 0.019 cm3 cm-3 and the Mean Relative Error (MRE) was 15.98%. RMSE and MRE for accumulated soil nitrate were 4.580 mg kg-2 and 52.63%, respectively. There were significant linear correlations between nitrogen use and nitrate leaching as well as ammonia volatilization in winter wheat/summer maize rotation systems. In summary, the RZWQM effectively simulated the transport processes of water and nitrogen in the soil profile in the North China Plain. Thus the study provided a convenient and reliable method of prediction and estimation of transport processes of water and fertilizer in root-zone soil. Irrespectively, there was the need for further research on extended RZWQM model application and robust calibration of critical parameters to increase the model simulation efficiency.
Rational management measures involving crop selection, tillage, crop rotation, fertilization, etc. are important for prevention of contamination and protection of soil and water resources. A number of field studies conducted under subsurface drainage conditions with various management practices have focused on reducing N loss through runoff. Also several models have been developed to evaluate the effects of the management measures on N loss through runoff. Models such as SWAT, DNDC and RZWQM were developed to simulate physical, chemical and biological responses of root-zone soil system to various agricultural management practices. Most of these models have been extensively tested under various soil, climate and agricultural management conditions. They have been used to assess the effects of agricultural practices on crop production or crop rotation systems and the related water and nitrate transport processes. In this study, the Root Zone Water Quality Model (RZWQM) was used to simulate water and nitrate nitrogen accumulations in the soil profile, nitrate nitrogen leaching and ammonia volatilization and yield of winter wheat/summer maize rotation systems in the North China Plain. The objective of the study was to explore the feasibility of predicting optimum nitrogen fertilization process using the RZWQM. A rotation trial of winter wheat and summer maize was conducted on Dahe Experiment Station of Hebei Academy of Agricultural and Forestry Sciences. Four nitrogen fertilizer rates [575 kg·hm-2 (N3), 400 kg·hm-2 (N2), 215 kg·hm-2 (N1), and 0 kg·hm-2 (N0)] were set for the winter wheat/summer maize rotation system. While data for maize was used to calibrate the RZWQM, data for wheat was used to validate the model. The results showed the deviations in the model calibration and validation were acceptable. The Root Mean Square Error (RMSE) of soil water content was as low as 0.019 cm3 cm-3 and the Mean Relative Error (MRE) was 15.98%. RMSE and MRE for accumulated soil nitrate were 4.580 mg kg-2 and 52.63%, respectively. There were significant linear correlations between nitrogen use and nitrate leaching as well as ammonia volatilization in winter wheat/summer maize rotation systems. In summary, the RZWQM effectively simulated the transport processes of water and nitrogen in the soil profile in the North China Plain. Thus the study provided a convenient and reliable method of prediction and estimation of transport processes of water and fertilizer in root-zone soil. Irrespectively, there was the need for further research on extended RZWQM model application and robust calibration of critical parameters to increase the model simulation efficiency.
2015, 23(2): 159-166.
doi: 10.13930/j.cnki.cjea.140908
Abstract:
Although straw mulch is widely used to improve soil water and heat in farmlands, the comprehensive effects of application of straw mulch depend on environmental conditions such as soil and climate. In subtropical China, productivity of sloping red soil farmlands is limited by severe rain-induced erosion in the wet spring-summer period and frequent seasonal droughts in the dry summer-autumn period. There were possible hydrological connections between soil erosion and drought. At present, it has remained unclear how temporal variations in soil hydraulic properties due to local soil and water loss affect soil water storage in wet and dry seasons. In addition, little attention has been paid to comparison of the different effects of straw mulch on soil water storage in the two seasons. However, related knowledge is important to increase water use in local fields. The objectives of this study were to explore the role of straw mulch on preserving soil water in the wet and dry seasons in sloping red soil farmlands. To this end, a field experiment was performed in Xianning City of Hubei Province with red soils (Ultisols) originating from Quaternary red clays. In an experimental field of low hill with 8° slope, two treatments, including rice straw mulch over surface soil (SW) and no mulch (CK, control), were used to analyze the effects of straw mulch on variations in soil water retention, water availability, water supply, hydraulic conductivity, water content and water storage. Results showed that SW improved soil water retention and water availability, with increases in field water capacity, wilting coefficient and available water holding capacity of respectively 6.0%, 7.3% and 4.4% over CK. SW also greatly lowered the decline in saturated hydraulic conductivity of the surface layer of the red soil, especially under intense rainfall events. After 102.8 mm of rainfall event, mean soil saturated hydraulic conductivity under SW was on average 2.7 times that under CK. After straw mulch, water supply and unsaturated hydraulic conductivity of the soil increased when soil water suction was low, and decreased as soil water suction was high. Compared with CK, SW had a smaller rise in soil water storage in high-intensity precipitation events and less decline in soil water storage during no rain periods. In general, there was more soil water storage under SW than CK. Straw mulch increased soil water storage in wet and dry seasons respectively by increasing field infiltration and reducing evapotranspiration. Under SW, soil water storage increased only in limited volume in the rainy season and water preservation capability was less than that in the dry season. It was concluded that the ways, features and capabilities of soil water preservation by straw mulch were different for the wet season and dry season in sloping red soil farmlands in subtropical China.
Although straw mulch is widely used to improve soil water and heat in farmlands, the comprehensive effects of application of straw mulch depend on environmental conditions such as soil and climate. In subtropical China, productivity of sloping red soil farmlands is limited by severe rain-induced erosion in the wet spring-summer period and frequent seasonal droughts in the dry summer-autumn period. There were possible hydrological connections between soil erosion and drought. At present, it has remained unclear how temporal variations in soil hydraulic properties due to local soil and water loss affect soil water storage in wet and dry seasons. In addition, little attention has been paid to comparison of the different effects of straw mulch on soil water storage in the two seasons. However, related knowledge is important to increase water use in local fields. The objectives of this study were to explore the role of straw mulch on preserving soil water in the wet and dry seasons in sloping red soil farmlands. To this end, a field experiment was performed in Xianning City of Hubei Province with red soils (Ultisols) originating from Quaternary red clays. In an experimental field of low hill with 8° slope, two treatments, including rice straw mulch over surface soil (SW) and no mulch (CK, control), were used to analyze the effects of straw mulch on variations in soil water retention, water availability, water supply, hydraulic conductivity, water content and water storage. Results showed that SW improved soil water retention and water availability, with increases in field water capacity, wilting coefficient and available water holding capacity of respectively 6.0%, 7.3% and 4.4% over CK. SW also greatly lowered the decline in saturated hydraulic conductivity of the surface layer of the red soil, especially under intense rainfall events. After 102.8 mm of rainfall event, mean soil saturated hydraulic conductivity under SW was on average 2.7 times that under CK. After straw mulch, water supply and unsaturated hydraulic conductivity of the soil increased when soil water suction was low, and decreased as soil water suction was high. Compared with CK, SW had a smaller rise in soil water storage in high-intensity precipitation events and less decline in soil water storage during no rain periods. In general, there was more soil water storage under SW than CK. Straw mulch increased soil water storage in wet and dry seasons respectively by increasing field infiltration and reducing evapotranspiration. Under SW, soil water storage increased only in limited volume in the rainy season and water preservation capability was less than that in the dry season. It was concluded that the ways, features and capabilities of soil water preservation by straw mulch were different for the wet season and dry season in sloping red soil farmlands in subtropical China.
Effect of global warming on climate feasibility index and available field days of flue-cured tobacco
2015, 23(2): 167-173.
doi: 10.13930/j.cnki.cjea.141062
Abstract:
In order to study the effects of global warming on the adaptability of flue-cured tobacco and available field days in Bijie tobacco-growing region, climate date for 1971?2010 in Bijie tobacco-growing region were used to analyze the trend and characteristics of climate change in the last 40 years. The analysis determined climate feasibility index (CFI) of flue-cured tobacco, the relationship between available field days and temperature and the trends of change in these factors. The results showed that average annual temperature in Bijie tobacco-growing region steadily increased at 0.38 ℃ 10a-1. The average annual rainfall in the last 40 years in Bijie tobacco-growing region was 1 047.78 mm, with 527.03 mm during tobacco growing period. Average annual sunshine duration in Bijie tobacco-growing region in the last 40 years was 1 318.20 h, with 632.70 h during tobacco-growing period. Sunshine duration gradually decreased during 1971-2010 in Bijie tobacco-growing region due to global warming. CFI increased gradually from 1970 to 2010, with a average annual CFI of 0.62. The start of period with average daily temperature ≥13 ℃ occurred early by about 30 d (average of 7.5 d 10a-1) during the 40 years. Then the end day of period with average daily temperature ≥18 ℃ (which is the harvest stage of flue-cured tobacco) delayed by about 27 d (average of 6.75 d 10a-1) after 40 years of global warming. The trend in flue-cured tobacco available field days in the last 40 years steadily increased by 58 d (an increase of 14.5 d 10a-1) with increasing annual average temperature. Although global warming reduced rainfall and shortened the sunshine duration in Bijie tobacco-growing region, CFI of flue-cured tobacco increased. This was conducive for the proper growth of flue-cured tobacco due to increasing available field days in the Bijie tobacco-growing region.
In order to study the effects of global warming on the adaptability of flue-cured tobacco and available field days in Bijie tobacco-growing region, climate date for 1971?2010 in Bijie tobacco-growing region were used to analyze the trend and characteristics of climate change in the last 40 years. The analysis determined climate feasibility index (CFI) of flue-cured tobacco, the relationship between available field days and temperature and the trends of change in these factors. The results showed that average annual temperature in Bijie tobacco-growing region steadily increased at 0.38 ℃ 10a-1. The average annual rainfall in the last 40 years in Bijie tobacco-growing region was 1 047.78 mm, with 527.03 mm during tobacco growing period. Average annual sunshine duration in Bijie tobacco-growing region in the last 40 years was 1 318.20 h, with 632.70 h during tobacco-growing period. Sunshine duration gradually decreased during 1971-2010 in Bijie tobacco-growing region due to global warming. CFI increased gradually from 1970 to 2010, with a average annual CFI of 0.62. The start of period with average daily temperature ≥13 ℃ occurred early by about 30 d (average of 7.5 d 10a-1) during the 40 years. Then the end day of period with average daily temperature ≥18 ℃ (which is the harvest stage of flue-cured tobacco) delayed by about 27 d (average of 6.75 d 10a-1) after 40 years of global warming. The trend in flue-cured tobacco available field days in the last 40 years steadily increased by 58 d (an increase of 14.5 d 10a-1) with increasing annual average temperature. Although global warming reduced rainfall and shortened the sunshine duration in Bijie tobacco-growing region, CFI of flue-cured tobacco increased. This was conducive for the proper growth of flue-cured tobacco due to increasing available field days in the Bijie tobacco-growing region.
2015, 23(2): 174-182.
doi: 10.13930/j.cnki.cjea.140874
Abstract:
Rainfed agriculture is a critical production mode in arid and semiarid regions, which accounts for 30% of the earth's surface. Spring wheat is one of the main crops in the semiarid region of the Loess Plateau in China. It is therefore important to investigate the photosynthetic characteristics of spring wheat (Triticum aestivum L.) in the semiarid region of the Loess Plateau. Previous studies have mainly focused on the responses of photosynthesis to environmental factors, with few researches on photosynthetic limitations under natural conditions in the semiarid regions of Northwest China. Exploration of photosynthetic limitations of flag leaves of spring wheat under natural conditions could contribute to current understanding of the principles of stomatal regulation in semiarid regions. It can also provide a theoretical basis for water use efficiency at the leaf-scale. In order to investigate stomatal and non-stomatal limitations of photosynthetic rates of flag leaves of spring wheat at different growth stages under natural conditions in semiarid areas, a field experiment was conducted in 2012 during the heading and filling stages of spring wheat. Physiological char-acteristics such as photosynthetic rate (Pn), stomatal conductance (gs) and intercellular CO2 concentration (Ci) were measured by the LI-6400 portable photosynthesis analyzer. Then environmental factors such as photosynthetically active radiation (PAR), vapor pres-sure deficit (VPD), air temperature (Ta) and air relative humidity (RH) were simultaneously recorded. The study firstly analyzed di-urnal variations in environmental factors and photosynthetic characteristics of flag leaves of spring wheat. Analyzed next was the response of photosynthetic characteristics to environmental factors, finally followed by discussion on stomatal and non-stomatal limitations at heading and filling growth stages. Results showed that PAR, Ta, and VPD had unimodal type of diurnal curve at both growth stages, while RH had uni-trough type of diurnal curve. The peak values of PAR and VPD occurred at about 11:00 am, with forenoon values obviously larger than afternoon ones. The peak value of Ta and RH occurred at about 15:00 pm. PAR and VPD were markedly larger at filling stage than at heading stage. The Pn tracked a unimodal type of diurnal curve at heading and bimodal type at filling stage with similar peak values of about 18.5 ?mol(CO2)·m-2·s-1. gs followed a diurnal curve that was similar to that of Pn. Ci decreased in the forenoon and slowly increased in the afternoon. This was attributed not only to photosynthetic consumption and stomatal conductance limitation, but also to mesophyll conductance limitation. Pn and gs were highly correlated at both growth stages, with correlation coefficients (R2) of 0.916 and 0.945, respectively. gs generally limited Pn at both heading and filling stages, with stomatal limitation indexes of 0.64 and 0.63, respectively. At heading stage, gs was highly sensitive to VPD. For this reason, there was obvious stomatal limitation in the afternoon due to induced water deficit by high transpiration rate. At filling stage, midday de-pression was mainly caused by stomatal closure due to strong radiation and high VPD. Besides this, there was somewhat non-stomatal limitation during midday depression. Due to declining sensitivity of gs to VPD and midday depression strategy, stomatal limitation decreased from heading stage to filling stage. This contributed to higher Pn of flag leaves of spring wheat in semiarid regions and thereby guaranteed good harvest.
Rainfed agriculture is a critical production mode in arid and semiarid regions, which accounts for 30% of the earth's surface. Spring wheat is one of the main crops in the semiarid region of the Loess Plateau in China. It is therefore important to investigate the photosynthetic characteristics of spring wheat (Triticum aestivum L.) in the semiarid region of the Loess Plateau. Previous studies have mainly focused on the responses of photosynthesis to environmental factors, with few researches on photosynthetic limitations under natural conditions in the semiarid regions of Northwest China. Exploration of photosynthetic limitations of flag leaves of spring wheat under natural conditions could contribute to current understanding of the principles of stomatal regulation in semiarid regions. It can also provide a theoretical basis for water use efficiency at the leaf-scale. In order to investigate stomatal and non-stomatal limitations of photosynthetic rates of flag leaves of spring wheat at different growth stages under natural conditions in semiarid areas, a field experiment was conducted in 2012 during the heading and filling stages of spring wheat. Physiological char-acteristics such as photosynthetic rate (Pn), stomatal conductance (gs) and intercellular CO2 concentration (Ci) were measured by the LI-6400 portable photosynthesis analyzer. Then environmental factors such as photosynthetically active radiation (PAR), vapor pres-sure deficit (VPD), air temperature (Ta) and air relative humidity (RH) were simultaneously recorded. The study firstly analyzed di-urnal variations in environmental factors and photosynthetic characteristics of flag leaves of spring wheat. Analyzed next was the response of photosynthetic characteristics to environmental factors, finally followed by discussion on stomatal and non-stomatal limitations at heading and filling growth stages. Results showed that PAR, Ta, and VPD had unimodal type of diurnal curve at both growth stages, while RH had uni-trough type of diurnal curve. The peak values of PAR and VPD occurred at about 11:00 am, with forenoon values obviously larger than afternoon ones. The peak value of Ta and RH occurred at about 15:00 pm. PAR and VPD were markedly larger at filling stage than at heading stage. The Pn tracked a unimodal type of diurnal curve at heading and bimodal type at filling stage with similar peak values of about 18.5 ?mol(CO2)·m-2·s-1. gs followed a diurnal curve that was similar to that of Pn. Ci decreased in the forenoon and slowly increased in the afternoon. This was attributed not only to photosynthetic consumption and stomatal conductance limitation, but also to mesophyll conductance limitation. Pn and gs were highly correlated at both growth stages, with correlation coefficients (R2) of 0.916 and 0.945, respectively. gs generally limited Pn at both heading and filling stages, with stomatal limitation indexes of 0.64 and 0.63, respectively. At heading stage, gs was highly sensitive to VPD. For this reason, there was obvious stomatal limitation in the afternoon due to induced water deficit by high transpiration rate. At filling stage, midday de-pression was mainly caused by stomatal closure due to strong radiation and high VPD. Besides this, there was somewhat non-stomatal limitation during midday depression. Due to declining sensitivity of gs to VPD and midday depression strategy, stomatal limitation decreased from heading stage to filling stage. This contributed to higher Pn of flag leaves of spring wheat in semiarid regions and thereby guaranteed good harvest.
2015, 23(2): 183-190.
doi: 10.13930/j.cnki.cjea.140650
Abstract:
To construct a model of maize morphogenesis during physiological development, the processes of growth and orders of stem, leaves and ears were measured on the basis of the physiological development time (PDT). The model parameters were determined from genetic traits and the minimum, maximum and critical nitrogen contents used to determine the impact of nitrogen on the model performance. The model was tested on 'Jinshan27', 'Xianyu335', 'Weike702' and 'Zhengdan958' maize varieties. The experiment results showed that the internode potential length increased gradually with increasing number of maize internode up till the maximum at eight internodes, and then gradually decreased; while the internode potential thinkness was the largest for the first internode. Therefore the potential genetic parameters were determined at the potential length of the eighth internode, and the potential thinkness of the 1st internode, which was used to calculate the potential lengths and thicknesses of the other internodes. The experiment results indicated the peak values of leaf length and width at the 13th leaf. Therefore, the potential length and width of the 13th leaf were used to determine the potential genetic parameters of leaf. The ear and tassel length and thinkness were also simulated on the basis of PDT under the impacts of nitrogen application. The results under different varieties and test sites showed that the absolute prediction errors ranges of the internode length, internode thickness, leaf length, leaf width, ear length, ear width, tassel length and tassel width were respectively 0- 2.5 cm, 0.001- 0.397 cm, 0- 2.6 cm, 0- 1.5 cm, 0.1- 1.4 cm, 0- 0.255 cm, 0.1- 2.1 cm and 0.001- 0.158 cm. The corresponding root mean square errors (RMSE) were respectively 0.2- 0.8 cm, 0.050- 0.156 cm, 0.5- 1.1 cm, 0.1- 0.5 cm, 0.4- 0.7 cm, 0.070- 0.141 cm, 0.5- 0.9 cm and 0.050- 0.066 cm. The model prediction was satisfactory, with moisture significantly influencing maize organ morphogenesis. Due to the substandard test conditions, the model moisture factor was not established. The next stage of the model should focus on the coupling of the morphogenesis of water and nitrogen in maize organs. The model should also be tested for much more variety and wider geographical scope.
To construct a model of maize morphogenesis during physiological development, the processes of growth and orders of stem, leaves and ears were measured on the basis of the physiological development time (PDT). The model parameters were determined from genetic traits and the minimum, maximum and critical nitrogen contents used to determine the impact of nitrogen on the model performance. The model was tested on 'Jinshan27', 'Xianyu335', 'Weike702' and 'Zhengdan958' maize varieties. The experiment results showed that the internode potential length increased gradually with increasing number of maize internode up till the maximum at eight internodes, and then gradually decreased; while the internode potential thinkness was the largest for the first internode. Therefore the potential genetic parameters were determined at the potential length of the eighth internode, and the potential thinkness of the 1st internode, which was used to calculate the potential lengths and thicknesses of the other internodes. The experiment results indicated the peak values of leaf length and width at the 13th leaf. Therefore, the potential length and width of the 13th leaf were used to determine the potential genetic parameters of leaf. The ear and tassel length and thinkness were also simulated on the basis of PDT under the impacts of nitrogen application. The results under different varieties and test sites showed that the absolute prediction errors ranges of the internode length, internode thickness, leaf length, leaf width, ear length, ear width, tassel length and tassel width were respectively 0- 2.5 cm, 0.001- 0.397 cm, 0- 2.6 cm, 0- 1.5 cm, 0.1- 1.4 cm, 0- 0.255 cm, 0.1- 2.1 cm and 0.001- 0.158 cm. The corresponding root mean square errors (RMSE) were respectively 0.2- 0.8 cm, 0.050- 0.156 cm, 0.5- 1.1 cm, 0.1- 0.5 cm, 0.4- 0.7 cm, 0.070- 0.141 cm, 0.5- 0.9 cm and 0.050- 0.066 cm. The model prediction was satisfactory, with moisture significantly influencing maize organ morphogenesis. Due to the substandard test conditions, the model moisture factor was not established. The next stage of the model should focus on the coupling of the morphogenesis of water and nitrogen in maize organs. The model should also be tested for much more variety and wider geographical scope.
2015, 23(2): 191-198.
doi: 10.13930/j.cnki.cjea.140873
Abstract:
Due to periodic wet and dry processes, water-level fluctuation zone of the reservoir area is typically ecologically fragile. It is therefore important for protection of the eco-environments of reservoir areas to control soil and water loss in such specifically fragile zones. Mulberry forest plots were selected in the water-level fluctuation zone of the Three Gorges Reservoir in September 2012 at four altitudes (165 m, 170 m, 175 m and 180 m), with no flooding at the 180 m altitude. Soil physio-chemical characteristics, anti-erodibility and the driving factors of mulberry forest lands at different altitudes were studied. The aim of the study was to explore soil anti-erodibility effect of mulberry forests at different altitudes. The study further provides scientific basis for controlling soil and water loss in the reservoir area. Results suggested that soil anti-erodibility indexes for the 0-20 cm soil layer of mulberry forest lands at different altitudes were greatly different, and were in the order of 180 m (38.22%) > 170 m (23.09%) > 165 m (18.4%) > 175 m (10.5%). Soil anti-erodibility index was greater for unsubmerged area than submerged areas. For the same altitude, soil anti- erodibility index of the 0 10 cm layer was higher than that of the 10 20 cm layer. Fifteen indicators of soil anti-erodibility were optimized to 3 principal components ― F1, F2 and F3. The comprehensive evaluation model of soil anti-erodibility index was F = 0.655F1 + 0.236F2 + 0.109F3. Based on the comprehensive model evaluation, soil anti-erodibility was ranked as 180 m > 170 m > 165 m > 175 m. Correlation analysis showed that soil anti-erodibility index had significant positive correlation (P < 0.01) with soil clay content and greater-than 0.25 mm water stable aggregate content, with respectively correlation coefficients of 0.878 and 0.732. A significant positive correlation was observed between soil anti-erodibility index and organic matter content, with a correlation coefficient of 0.689. There was no significant correlation between soil anti-erodibility index and sand or silt content. It was concluded that soil clay, greater-than 0.25 mm water stable aggregate and organic matter were the key factors influencing soil anti-erodibility in the water-level fluctuation zone of the Three Gorges Reservoir area.
Due to periodic wet and dry processes, water-level fluctuation zone of the reservoir area is typically ecologically fragile. It is therefore important for protection of the eco-environments of reservoir areas to control soil and water loss in such specifically fragile zones. Mulberry forest plots were selected in the water-level fluctuation zone of the Three Gorges Reservoir in September 2012 at four altitudes (165 m, 170 m, 175 m and 180 m), with no flooding at the 180 m altitude. Soil physio-chemical characteristics, anti-erodibility and the driving factors of mulberry forest lands at different altitudes were studied. The aim of the study was to explore soil anti-erodibility effect of mulberry forests at different altitudes. The study further provides scientific basis for controlling soil and water loss in the reservoir area. Results suggested that soil anti-erodibility indexes for the 0-20 cm soil layer of mulberry forest lands at different altitudes were greatly different, and were in the order of 180 m (38.22%) > 170 m (23.09%) > 165 m (18.4%) > 175 m (10.5%). Soil anti-erodibility index was greater for unsubmerged area than submerged areas. For the same altitude, soil anti- erodibility index of the 0 10 cm layer was higher than that of the 10 20 cm layer. Fifteen indicators of soil anti-erodibility were optimized to 3 principal components ― F1, F2 and F3. The comprehensive evaluation model of soil anti-erodibility index was F = 0.655F1 + 0.236F2 + 0.109F3. Based on the comprehensive model evaluation, soil anti-erodibility was ranked as 180 m > 170 m > 165 m > 175 m. Correlation analysis showed that soil anti-erodibility index had significant positive correlation (P < 0.01) with soil clay content and greater-than 0.25 mm water stable aggregate content, with respectively correlation coefficients of 0.878 and 0.732. A significant positive correlation was observed between soil anti-erodibility index and organic matter content, with a correlation coefficient of 0.689. There was no significant correlation between soil anti-erodibility index and sand or silt content. It was concluded that soil clay, greater-than 0.25 mm water stable aggregate and organic matter were the key factors influencing soil anti-erodibility in the water-level fluctuation zone of the Three Gorges Reservoir area.
2015, 23(2): 199-206.
doi: 10.13930/j.cnki.cjea.140968
Abstract:
Nutrient loss during the processing of livestock and poultry manure is significantly different under different modes of manure disposal, subsequently influencing nutrient utilization in farmlands. Separation of solids from liquids before anaerobic fermentation of liquids is currently the main mode of treatment of poultry manure in China. Studies on the configurations of pig farm and croplands under solid and liquid waste disposal modes following the separation and the subsequent anaerobic fermentation of liquid manure is greatly important to reduce pollution by livestock excrement and promote sustainable development of animal husbandry. The purpose of this study was to determine the optimal farmland area needed for large-scale pig farm, and to provide the scientific basis and reference for establishing a sustainable agro-ecological mode of crops and animals. Based on the proportions of pig population and pig nitrogen and phosphorus discharge data for different types of swine, the rate of nutrient loss during waste treatment, and then nutrient demands by different crops, the areas of farmlands for waste consumption and the carrying capacities of farmlands with different planting patterns were estimated under typical anaerobic fermentation of liquids following the separation of solids from liquids of waste in a farm with 10 000 pigs. In order to avoid environmental pollution, the optimal farmland area needed for a large-scale pig farm was determined based on calculated maximum farmland areas from crop nitrogen and phosphorus requirement. The results showed that under anaerobic fermentation of liquid after solid-liquid separation of waste, the configuration of a 10000-pig farm needed an area of at least 12.4-13.7 hm2 of grain/oil cropland, 14.2-17.9 hm2 solanaceous vegetable field or 16.4-51.3 hm2 orchard/seedling field for safe disposal of biogas slurry. One hectare of grain/oil cropland, solanaceous vegetable field or orchard/seedling field was enough for the disposal of liquid waste produced respectively by 730-803 heads, 559-704 heads or 195-609 heads of pig. For entirely safe disposal of manure fertilizer and biogas slurry, a 10000-pig farm needed at least an area of 299.3-312.9 hm2 grain/oil cropland, 145.1-179.0 hm2 solanaceous vegetable field or 553.1-1 343.8 hm2 orchard/seedling field. Accordingly, one hectare of grain/oil cropland, solanaceous vegetable field and orchard/seedling field was enough for the disposal of manure fertilizer and biogas slurry produced respectively by 32-33 heads, 56-59 heads and 7-18 heads of pigs. The above results suggested that waste use patterns and crop types of ambient farmlands should be rationally determined according to breeding quantity of pig farm and its surrounding farmland area.
Nutrient loss during the processing of livestock and poultry manure is significantly different under different modes of manure disposal, subsequently influencing nutrient utilization in farmlands. Separation of solids from liquids before anaerobic fermentation of liquids is currently the main mode of treatment of poultry manure in China. Studies on the configurations of pig farm and croplands under solid and liquid waste disposal modes following the separation and the subsequent anaerobic fermentation of liquid manure is greatly important to reduce pollution by livestock excrement and promote sustainable development of animal husbandry. The purpose of this study was to determine the optimal farmland area needed for large-scale pig farm, and to provide the scientific basis and reference for establishing a sustainable agro-ecological mode of crops and animals. Based on the proportions of pig population and pig nitrogen and phosphorus discharge data for different types of swine, the rate of nutrient loss during waste treatment, and then nutrient demands by different crops, the areas of farmlands for waste consumption and the carrying capacities of farmlands with different planting patterns were estimated under typical anaerobic fermentation of liquids following the separation of solids from liquids of waste in a farm with 10 000 pigs. In order to avoid environmental pollution, the optimal farmland area needed for a large-scale pig farm was determined based on calculated maximum farmland areas from crop nitrogen and phosphorus requirement. The results showed that under anaerobic fermentation of liquid after solid-liquid separation of waste, the configuration of a 10000-pig farm needed an area of at least 12.4-13.7 hm2 of grain/oil cropland, 14.2-17.9 hm2 solanaceous vegetable field or 16.4-51.3 hm2 orchard/seedling field for safe disposal of biogas slurry. One hectare of grain/oil cropland, solanaceous vegetable field or orchard/seedling field was enough for the disposal of liquid waste produced respectively by 730-803 heads, 559-704 heads or 195-609 heads of pig. For entirely safe disposal of manure fertilizer and biogas slurry, a 10000-pig farm needed at least an area of 299.3-312.9 hm2 grain/oil cropland, 145.1-179.0 hm2 solanaceous vegetable field or 553.1-1 343.8 hm2 orchard/seedling field. Accordingly, one hectare of grain/oil cropland, solanaceous vegetable field and orchard/seedling field was enough for the disposal of manure fertilizer and biogas slurry produced respectively by 32-33 heads, 56-59 heads and 7-18 heads of pigs. The above results suggested that waste use patterns and crop types of ambient farmlands should be rationally determined according to breeding quantity of pig farm and its surrounding farmland area.
2015, 23(2): 207-214.
doi: 10.13930/j.cnki.cjea.141070
Abstract:
Biochar application has become a promising technology for remediation of soil heavy metal pollution due to potential beneficial effects on contaminated soils. Previous studies have largely dealt with the properties of biochar, the improvement of soil fertility as well as the process of remediation of heavy metal polluted soils. Rice husk biochar has also been reported to be used in the solidification of Cd and Pb in solid wastes and the adsorption of Cd in waste waters. However, little has been documented on the changes in forms of soil Cd, Cd content in vegetables and soil nutrient availability after the application of rice husk biochar in Cd contaminated soil. Thus two successive lettuces (Lactuca sativa L.) crops were planted in a pot experiment with Cd of 4.564 mg(CdSO4)·kg -1(air-dried soil) to explore the effects of different doses of rice husk biochar on lettuce shoot and root Cd concentration, soil nutrient and Cd forms. Biochar dosage levels used in the study were 5 g kg-1, 10 g kg-1, 15 g kg-1, 20 g kg-1 and 25 g kg-1, with none application of rice husk biochar as the control. The results showed that compared with the control, rice husk biochar reduced Cd concentration in the shoots and roots of the two lettuce crops. 25 g kg 1 rice husk biochar showed the best effects, respectively decreased Cd concentration by 19.6% and 45.8% in shoots, and by 36.8% and 28.0% in roots, for two crops. At this dose, soil pH and soil available P, available K and organic matter contents increased by a maximum of 4.0%, 19.6%, 44.0% and 48.5%, respectively. Also soil alkali-hydrolyzable N content significantly decreased by 19.7%. Rice husk biochar also changed the forms and availability of soil Cd. With increasing dose of rice husk biochar, the concentrations of ammonium acetate extractable Cd and weak acid soluble Cd in the soil decreased by 17.9% and 10.4%, while oxidisable Cd concentration decreased with a residual Cd concentration increase of 17.6%. It was apparent that enhancement of soil pH, reduction of soil available Cd content and increase in residual Cd content were the main processes by which rice husk biochar reduced Cd content in lettuce. Therefore rice husk biochar could be used as an effective element for soil amendment that inhibit Cd uptake by vegetables in Cd contaminated soil.
Biochar application has become a promising technology for remediation of soil heavy metal pollution due to potential beneficial effects on contaminated soils. Previous studies have largely dealt with the properties of biochar, the improvement of soil fertility as well as the process of remediation of heavy metal polluted soils. Rice husk biochar has also been reported to be used in the solidification of Cd and Pb in solid wastes and the adsorption of Cd in waste waters. However, little has been documented on the changes in forms of soil Cd, Cd content in vegetables and soil nutrient availability after the application of rice husk biochar in Cd contaminated soil. Thus two successive lettuces (Lactuca sativa L.) crops were planted in a pot experiment with Cd of 4.564 mg(CdSO4)·kg -1(air-dried soil) to explore the effects of different doses of rice husk biochar on lettuce shoot and root Cd concentration, soil nutrient and Cd forms. Biochar dosage levels used in the study were 5 g kg-1, 10 g kg-1, 15 g kg-1, 20 g kg-1 and 25 g kg-1, with none application of rice husk biochar as the control. The results showed that compared with the control, rice husk biochar reduced Cd concentration in the shoots and roots of the two lettuce crops. 25 g kg 1 rice husk biochar showed the best effects, respectively decreased Cd concentration by 19.6% and 45.8% in shoots, and by 36.8% and 28.0% in roots, for two crops. At this dose, soil pH and soil available P, available K and organic matter contents increased by a maximum of 4.0%, 19.6%, 44.0% and 48.5%, respectively. Also soil alkali-hydrolyzable N content significantly decreased by 19.7%. Rice husk biochar also changed the forms and availability of soil Cd. With increasing dose of rice husk biochar, the concentrations of ammonium acetate extractable Cd and weak acid soluble Cd in the soil decreased by 17.9% and 10.4%, while oxidisable Cd concentration decreased with a residual Cd concentration increase of 17.6%. It was apparent that enhancement of soil pH, reduction of soil available Cd content and increase in residual Cd content were the main processes by which rice husk biochar reduced Cd content in lettuce. Therefore rice husk biochar could be used as an effective element for soil amendment that inhibit Cd uptake by vegetables in Cd contaminated soil.
2015, 23(2): 215-224.
doi: 10.13930/j.cnki.cjea.140941
Abstract:
Potato root exudates were collected from two treatments (CK: potato rotation with other crops; CP5: continuous potato cropping for five years) under field conditions to explore the possible obstacle mechanisms of continuous cropping of potato. The root exudates were collected at three growth stages - seedling, squaring and florescence stages. The chemical composition of the root exudates were determined by the GC-MS method and the autotoxicity of the exudates to potato plants tested in a pot experiment. The results showed that the main components of potato root exudates in both CK and CP5 treatments included glucides, organic acids, amines, alcohols, esters and pyrimidines, with glucides and organic acids as the dominant components. Also while the chemical composition of root exudates of CP5 was much more complex than that of CK, the content of organic acids in CP5 was significantly higher than in CK. The compound, dibutyl phthalate (DP), existed only in root exudates of CP5, with relative contents of 0.16%, 0.21% and 0.24% respectively at seedling, squaring and florescence stages. Root exudates of CP5 also was tested positive for the compound palmitic acid (PA), with relative contents of 0.34%, 1.12% and 0.47% respectively at seedling, squaring and florescence stages. Although PA was detected in CK treatment, it only appeared at squaring and florescence stages in respective concentration of 0.56% and 0.24%. Biological analyses showed that PA and DP significantly inhibited potato growth. The inhibiting effect of PA or DP of 1 mmol·L-1 was far exceeded that of 0.5 mmol·L-1 concentration. Continuous potato cropping changed the composition of potato root exudates, and PA and DP were autotoxins of potato root exudates, though with no superimposition effects. Potato root secreted much more root exudates at squaring stage, which period was suitable for collection of potato root exudates.
Potato root exudates were collected from two treatments (CK: potato rotation with other crops; CP5: continuous potato cropping for five years) under field conditions to explore the possible obstacle mechanisms of continuous cropping of potato. The root exudates were collected at three growth stages - seedling, squaring and florescence stages. The chemical composition of the root exudates were determined by the GC-MS method and the autotoxicity of the exudates to potato plants tested in a pot experiment. The results showed that the main components of potato root exudates in both CK and CP5 treatments included glucides, organic acids, amines, alcohols, esters and pyrimidines, with glucides and organic acids as the dominant components. Also while the chemical composition of root exudates of CP5 was much more complex than that of CK, the content of organic acids in CP5 was significantly higher than in CK. The compound, dibutyl phthalate (DP), existed only in root exudates of CP5, with relative contents of 0.16%, 0.21% and 0.24% respectively at seedling, squaring and florescence stages. Root exudates of CP5 also was tested positive for the compound palmitic acid (PA), with relative contents of 0.34%, 1.12% and 0.47% respectively at seedling, squaring and florescence stages. Although PA was detected in CK treatment, it only appeared at squaring and florescence stages in respective concentration of 0.56% and 0.24%. Biological analyses showed that PA and DP significantly inhibited potato growth. The inhibiting effect of PA or DP of 1 mmol·L-1 was far exceeded that of 0.5 mmol·L-1 concentration. Continuous potato cropping changed the composition of potato root exudates, and PA and DP were autotoxins of potato root exudates, though with no superimposition effects. Potato root secreted much more root exudates at squaring stage, which period was suitable for collection of potato root exudates.
2015, 23(2): 225-232.
doi: 10.13930/j.cnki.cjea.140755
Abstract:
Because of its high nutritive value and extensive use, potato has become a critical crop in the southern mountain areas of Ningxia, China. However, the expansion of cultivated land areas under potato has made not only crop rotation difficult, but as has also worsened the obstacles of potato continuous cropping in recent years. In order to alleviate and eventually resolve the obstacles of potato continuous cropping, rhizosphere soils were sampled under the following potato treatments after 2 years, 7 years and 11 years of continuous cropping in the southern mountain areas of Ningxia, China. Terminal restriction fragment length polymorphism (T-RFLP) was used to study the genetic diversity of soil microorganisms, to explore the dynamics of main soil microbial groups in rhizosphere soils and to find the possible reasons for the obstacles of potato continuous cropping in the region. The results showed that some specific T-RFs fragments changed or disappeared in rhizosphere soil samples under different periods of continuous cropping, though higher polymorphism of T-RFLP of bacteria and fungi in rhizosphere soils of continuously cropped potato was observed. While the Shannon-Wienen, Simpson and Sorenson indexes of bacterial dropped, those of fungus increased with increasing years of continuous cropping. Analysis of soil microorganism biota revealed that Firmicute, Bacilli and Clostridia were the highest proportion of total bacteria communities in potato rhizosphere soils. Continuous cropping significantly changed structures of soil bacteria and fungi communities. While the proportions of Bacilli and Sphingobacteria decreased or even disappeared with increasing cropping years, β-proteobacteria and Deinococci proportions increased. The proportion of Dothideomycete and Capnodiales of fungi community in rhizosphere soils dropped whereas that of Sordariomycete and Hypocreales grew. The results suggested that potato continuous cropping limited the population of beneficial microbes such as Bacillus, while boosting that of pathogenic bacteria such as Ralstonia in the rhizosphere soils. In conclusion, soil microbial diversity in rhizosphere soils under different periods of continuous cropping was obviously influenced. The fall of the diversity of bacteria community gave way to the rise of fungi community under continuous cropping, causing imbalance in microbial community and soil micro-ecological/environmental deterioration. The obstacle of continuous cropping possibly resulted from complex interaction of multiple soil factors in rhizosphere soils. There was therefore the need for continuous field research to help comprehensively determine the mechanism of continuous cropping obstacle.
Because of its high nutritive value and extensive use, potato has become a critical crop in the southern mountain areas of Ningxia, China. However, the expansion of cultivated land areas under potato has made not only crop rotation difficult, but as has also worsened the obstacles of potato continuous cropping in recent years. In order to alleviate and eventually resolve the obstacles of potato continuous cropping, rhizosphere soils were sampled under the following potato treatments after 2 years, 7 years and 11 years of continuous cropping in the southern mountain areas of Ningxia, China. Terminal restriction fragment length polymorphism (T-RFLP) was used to study the genetic diversity of soil microorganisms, to explore the dynamics of main soil microbial groups in rhizosphere soils and to find the possible reasons for the obstacles of potato continuous cropping in the region. The results showed that some specific T-RFs fragments changed or disappeared in rhizosphere soil samples under different periods of continuous cropping, though higher polymorphism of T-RFLP of bacteria and fungi in rhizosphere soils of continuously cropped potato was observed. While the Shannon-Wienen, Simpson and Sorenson indexes of bacterial dropped, those of fungus increased with increasing years of continuous cropping. Analysis of soil microorganism biota revealed that Firmicute, Bacilli and Clostridia were the highest proportion of total bacteria communities in potato rhizosphere soils. Continuous cropping significantly changed structures of soil bacteria and fungi communities. While the proportions of Bacilli and Sphingobacteria decreased or even disappeared with increasing cropping years, β-proteobacteria and Deinococci proportions increased. The proportion of Dothideomycete and Capnodiales of fungi community in rhizosphere soils dropped whereas that of Sordariomycete and Hypocreales grew. The results suggested that potato continuous cropping limited the population of beneficial microbes such as Bacillus, while boosting that of pathogenic bacteria such as Ralstonia in the rhizosphere soils. In conclusion, soil microbial diversity in rhizosphere soils under different periods of continuous cropping was obviously influenced. The fall of the diversity of bacteria community gave way to the rise of fungi community under continuous cropping, causing imbalance in microbial community and soil micro-ecological/environmental deterioration. The obstacle of continuous cropping possibly resulted from complex interaction of multiple soil factors in rhizosphere soils. There was therefore the need for continuous field research to help comprehensively determine the mechanism of continuous cropping obstacle.
QIU Qiujin,
XIE Huiling,
LI Yuanping,
WANG Wei,
CHEN Shan,
XIAO Qingtie,
ZHENG Xinyu,
LIN Ruiyu,
LIN Wenxiong
2015, 23(2): 233-238.
doi: 10.13930/j.cnki.cjea.140853
Abstract:
In order to illustrate the mechanism of wheat allelopathy, two strong allelopathic wheat accessions ('115/Qinghai' and '92L89') and one weak allelopathic accession ('Kang10103') were used in a set of hydroponic culture experiments. Roots of Alopecurus aequalis were treated with 0%, 0.2%, 1.0% and 5.0% (v/v) water-based extracts of root tissues of different wheat accessions to determine physiological responses of A. aequalis root to the wheat root extracts. The results showed that extracts significantly inhibited the growth of A. aequalis, with root fresh weight decreasing with increasing extract concentration. Also strong allelopathic accessions had higher inhibitory rates than weak accession. No differences existed among the 3 accessions when extract concentration reached 5.0%. After exposure to extracts, A. aequalis root vigor declined at inhibitory rates of 52.0% 59.6%, 46.5% 55.0% and 27.2% 44.7% respectively for '115/Qinghai', '92L89' and 'Kang10103'. Also no differences were noted between the two strong allelopathic accessions. The contents of soluble protein and methane dicarboxylic aldehyde (MDA) as well as the activities of super-oxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of A. aequalis roots increased significantly after treated with wheat root extracts. The order of the activities of SOD and POD was '115/Qinghai' > '92L89' ≈ 'Kang10103'. The activity of CAT changed significantly with changing concentrations of the extracts, and not with different wheat varieties. The contents of MDA in roots of A. aequalis treated with '115/Qinghai', '92L89' and 'Kang10103' root tissues extracts were respectively 10.9-25.5 times, 5.9-24.2 times and 1.2-6.8 times that of the control. Lipid peroxidation was activated and anti-oxidative flavonoids and phenols were induced in the roots by wheat allelopathy. Thus decreasing root vigor, enhancing protective enzyme activities and synthesizing anti-oxidative substances were promising physiological responses of roots of A. aequalis exposed to wheat allelopathy.
In order to illustrate the mechanism of wheat allelopathy, two strong allelopathic wheat accessions ('115/Qinghai' and '92L89') and one weak allelopathic accession ('Kang10103') were used in a set of hydroponic culture experiments. Roots of Alopecurus aequalis were treated with 0%, 0.2%, 1.0% and 5.0% (v/v) water-based extracts of root tissues of different wheat accessions to determine physiological responses of A. aequalis root to the wheat root extracts. The results showed that extracts significantly inhibited the growth of A. aequalis, with root fresh weight decreasing with increasing extract concentration. Also strong allelopathic accessions had higher inhibitory rates than weak accession. No differences existed among the 3 accessions when extract concentration reached 5.0%. After exposure to extracts, A. aequalis root vigor declined at inhibitory rates of 52.0% 59.6%, 46.5% 55.0% and 27.2% 44.7% respectively for '115/Qinghai', '92L89' and 'Kang10103'. Also no differences were noted between the two strong allelopathic accessions. The contents of soluble protein and methane dicarboxylic aldehyde (MDA) as well as the activities of super-oxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of A. aequalis roots increased significantly after treated with wheat root extracts. The order of the activities of SOD and POD was '115/Qinghai' > '92L89' ≈ 'Kang10103'. The activity of CAT changed significantly with changing concentrations of the extracts, and not with different wheat varieties. The contents of MDA in roots of A. aequalis treated with '115/Qinghai', '92L89' and 'Kang10103' root tissues extracts were respectively 10.9-25.5 times, 5.9-24.2 times and 1.2-6.8 times that of the control. Lipid peroxidation was activated and anti-oxidative flavonoids and phenols were induced in the roots by wheat allelopathy. Thus decreasing root vigor, enhancing protective enzyme activities and synthesizing anti-oxidative substances were promising physiological responses of roots of A. aequalis exposed to wheat allelopathy.
2015, 23(2): 239-245.
doi: 10.13930/j.cnki.cjea.140957
Abstract:
Evaluation of farmlands is a local-based process that requires local farmers to combine substantial indigenous farming knowledge. Local farmers are the creators, users and maintainers of their farmlands for long periods of time. This case study mapped, recorded and assessed the farmland evaluation system of local farmlands formed in the early 1980s in Shaping Village, Hequ County. An integrated geospatial methodology from geography and anthropology was used in the case study to record the process of evaluation of farmland and its influencing factors, upon which the farmland evaluation system was built. The results showed that: 1) Farmlands in Shaping Village evaluated by 18 indigenous farmers in 1982 were ranked into 6 grades. The proportions of the areas of the first 4 grades to the total area of farmlands were 1.32%, 7.81%, 19.14% and 17.43%, respectively. These 4 grades of farmlands had sound soil quality and were mainly used for growing food and cash crops. The last 2 grades of farmlands had inferior soil quality and were used for arbor forests, shrubs and grass, with area proportions relative to total area of 9.28% and 48.77%, respectively. 2) Fourteen factors were taken in account by farmers during evaluation of farmlands, including natural, social and economic factors; 3) The weights of these factors were decided with Analytic Hierarchy Process (AHP) based on scored values by local farmers. The order of weight of these factors was: yield per unit area ≥ soil fertility ≥ soil texture ≥ land use type ≥ distance ≥ slope gradient ≥ water retention and supply ≥ slope aspect ≥ slope position ≥ soil depth ≥ road accessibility ≥ country road ≥ field area ≥ soil erosion degree. Among these factors, yield per unit area, soil fertility, soil texture and land use type were the main factors. 4) Base on transformation from "local" description into "scientific" expression, the main characters of different grades of farmland according to the local farmers' evaluation were consistent with the results of AHP. The results suggested that local farmers in particular regions had accumulated abundant knowledge on the use and management of farmlands, which was logical and rational. The farmland evaluation developed by local farmers was more reliable than the short-term appraisal by experts, which was directly applicable in the evaluation of farmlands at village level. Therefore indigenous evaluation of farmlands was a better method that was in line with local natural, social and economic conditions of villages. The study concluded by recommending that future communications between local and scientific knowledge should be enhanced in evaluating farmlands so as to build more locally-adjusted and applicable farmland-sustainable management systems.
Evaluation of farmlands is a local-based process that requires local farmers to combine substantial indigenous farming knowledge. Local farmers are the creators, users and maintainers of their farmlands for long periods of time. This case study mapped, recorded and assessed the farmland evaluation system of local farmlands formed in the early 1980s in Shaping Village, Hequ County. An integrated geospatial methodology from geography and anthropology was used in the case study to record the process of evaluation of farmland and its influencing factors, upon which the farmland evaluation system was built. The results showed that: 1) Farmlands in Shaping Village evaluated by 18 indigenous farmers in 1982 were ranked into 6 grades. The proportions of the areas of the first 4 grades to the total area of farmlands were 1.32%, 7.81%, 19.14% and 17.43%, respectively. These 4 grades of farmlands had sound soil quality and were mainly used for growing food and cash crops. The last 2 grades of farmlands had inferior soil quality and were used for arbor forests, shrubs and grass, with area proportions relative to total area of 9.28% and 48.77%, respectively. 2) Fourteen factors were taken in account by farmers during evaluation of farmlands, including natural, social and economic factors; 3) The weights of these factors were decided with Analytic Hierarchy Process (AHP) based on scored values by local farmers. The order of weight of these factors was: yield per unit area ≥ soil fertility ≥ soil texture ≥ land use type ≥ distance ≥ slope gradient ≥ water retention and supply ≥ slope aspect ≥ slope position ≥ soil depth ≥ road accessibility ≥ country road ≥ field area ≥ soil erosion degree. Among these factors, yield per unit area, soil fertility, soil texture and land use type were the main factors. 4) Base on transformation from "local" description into "scientific" expression, the main characters of different grades of farmland according to the local farmers' evaluation were consistent with the results of AHP. The results suggested that local farmers in particular regions had accumulated abundant knowledge on the use and management of farmlands, which was logical and rational. The farmland evaluation developed by local farmers was more reliable than the short-term appraisal by experts, which was directly applicable in the evaluation of farmlands at village level. Therefore indigenous evaluation of farmlands was a better method that was in line with local natural, social and economic conditions of villages. The study concluded by recommending that future communications between local and scientific knowledge should be enhanced in evaluating farmlands so as to build more locally-adjusted and applicable farmland-sustainable management systems.
2015, 23(2): 246-256.
doi: 10.13930/j.cnki.cjea.141003
Abstract:
Xinjiang Production and Construction Corps (XPCC) is in the transition zone of the Xinjiang oasis and desert. In the diverse natural environment, agriculture is the main stay in XPCC and the intensity of agriculture in XPCC is higher than in other areas of Xinjiang. Land use/cover types in XPCC have changed markedly with socio-economic development. The Eighth Division of XPCC was investigated in this study. Aided by field verification, the changes in land use/cover in the study region were determined in RS and GIS environments. The study used Landsat TM satellite imagery for 2000 and 2005 in combination with environment first satellite CCD imagery for 2010 to explore the dynamics of land use/cover and landscape patterns. The changes were analyzed for vegetation cover degree for different land use/cover types using MODIS data for 2000, 2005 and 2010. The results showed that: 1) the study area mainly composed of cultivated land, brush land and grassland, accounting for 88.9% of the study area. The changes in land use/cover in the region were mainly driven by natural and human factors. The areas of grassland and brush land decreased respectively from 2 603.2 km2 and 1 166.2 km2 in 2000 to 1 677.3 km2 and 933.8 km2 in 2010. On the contrary, the areas of cultivated land and urban land increased respectively from 2 892.8 km2 and 209.2 km2 in 2000 to 4 038.3 km2 and 259.1 km2 in 2010. Grassland and brush land were mainly converted into cultivated land and cultivated land converted into urban land. The overall state of land use/cover change in the study area was in unbalanced. 2) An increasing simplification was noted in the characteristics of the landscape in the study area. Land use/cover change had changed regional landscape pattern in the region. Landscape pattern analysis showed obvious increasing dominance with decreasing landscape diversity and evenness. While patchy fragmentation decreased, biodiversity appeared to shift in a single direction. 3) The order of vegetation cover degree for different land use/cover types was forest land > cultivated land > grassland > brush land > desert land. Vegetation cover degrees of forest land, brush land, grassland and cultivated land increased respectively by 6.7%, 38.2%, 15.6% and 12.3% from 2000 to 2010. While the areas of land under high vegetation increased, that under low vegetation decreased. 4) Rainfall was the key factor influencing vegetation change in the arid oasis. The findings of this study provided the scientific basis for the protection and management of the ecological environment and planning reasonable production modes in the XPCC region.
Xinjiang Production and Construction Corps (XPCC) is in the transition zone of the Xinjiang oasis and desert. In the diverse natural environment, agriculture is the main stay in XPCC and the intensity of agriculture in XPCC is higher than in other areas of Xinjiang. Land use/cover types in XPCC have changed markedly with socio-economic development. The Eighth Division of XPCC was investigated in this study. Aided by field verification, the changes in land use/cover in the study region were determined in RS and GIS environments. The study used Landsat TM satellite imagery for 2000 and 2005 in combination with environment first satellite CCD imagery for 2010 to explore the dynamics of land use/cover and landscape patterns. The changes were analyzed for vegetation cover degree for different land use/cover types using MODIS data for 2000, 2005 and 2010. The results showed that: 1) the study area mainly composed of cultivated land, brush land and grassland, accounting for 88.9% of the study area. The changes in land use/cover in the region were mainly driven by natural and human factors. The areas of grassland and brush land decreased respectively from 2 603.2 km2 and 1 166.2 km2 in 2000 to 1 677.3 km2 and 933.8 km2 in 2010. On the contrary, the areas of cultivated land and urban land increased respectively from 2 892.8 km2 and 209.2 km2 in 2000 to 4 038.3 km2 and 259.1 km2 in 2010. Grassland and brush land were mainly converted into cultivated land and cultivated land converted into urban land. The overall state of land use/cover change in the study area was in unbalanced. 2) An increasing simplification was noted in the characteristics of the landscape in the study area. Land use/cover change had changed regional landscape pattern in the region. Landscape pattern analysis showed obvious increasing dominance with decreasing landscape diversity and evenness. While patchy fragmentation decreased, biodiversity appeared to shift in a single direction. 3) The order of vegetation cover degree for different land use/cover types was forest land > cultivated land > grassland > brush land > desert land. Vegetation cover degrees of forest land, brush land, grassland and cultivated land increased respectively by 6.7%, 38.2%, 15.6% and 12.3% from 2000 to 2010. While the areas of land under high vegetation increased, that under low vegetation decreased. 4) Rainfall was the key factor influencing vegetation change in the arid oasis. The findings of this study provided the scientific basis for the protection and management of the ecological environment and planning reasonable production modes in the XPCC region.
Editor-in-chief：LIU Changming
Competent Authorities：Chinese Academy of Sciences
Sponsored by：Institute of Genetics and Developmental Biology, Chinese Academy of Sciences; China Ecological Economics Society
Organizer：Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences
ISSN 2096-6237
CN 13-1432/S
- Chinese core periodicals
- Core Chinese Sci-Tech Periodicals
- China's Top Science and Technology Periodicals
- Covered by Chinese Science Citation Database (CSCD)
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