中国生态农业学报(中英文)

Tracing groundwater nitrogen source in Huai River Basin agro-ecosystem

LIAO Man, MA Teng, ZHENG Qianlin, LIU Yanjun, LUO Fei

2019, 27(5): 665-676. doi: 10.13930/j.cnki.cjea.180763

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Abstract:
Nitrogen pollution in groundwater systems in Huai River Basin has drawn a lot of attention. In order to trace the source of nitrogen pollution in groundwater, 2002-2017 agricultural statistics data for 35 cities in the Huai River Basin agro-ecosystem were collected. A nitrogen balance model was set up based on nitrogen input and output in Huai River Basin, and it was used to calculate nitrogen surplus and intensity in the basin. Nitrogen input included input from fertilizers, humans & animal excreta, atmospheric deposition, biological fixation, seed nitrogen and straw nitrogen. Nitrogen output included crop harvest, denitrification and ammonia volatilization output. Also, combined nitrogen surplus and leaching coefficient, the nitrogen leaching model was built to quantitatively estimate the amount of nitrogen leaching into groundwater bodies from agro-ecosystem in Huai River Basin. The results showed that average nitrogen input in Huai River Basin agro-ecosystem was up to 10 050 100 t·a^-1 for the 2002-2017, fertilizer input was the largest source of this amount nitrogen input and it accounted for 52.76%. Average nitrogen output was up to 7 064 300 t·a^-1 for the period 2002-2017, crop harvest was the largest amount output of this amount nitrogen and it accounted for 87.29%. Nitrogen surplus and nitrogen source intensity decreased gradually with time for the period from 2002 to 2017. Nitrogen source intensity result was the same with previous studies, which ensured the accuracy of the results. At the regional aspects, the city in Henan Province had the highest nitrogen source intensity, while the cities in Shandong and Anhui Provinces had the lowest nitrogen source intensity. The amount of nitrogen that leached into the groundwater in Huai River Basin agro-ecosystem was 2.622×10⁵-4.171×10⁵ t·a^-1, with the highest amount in 2006. The average nitrogen amount in groundwater was 3.141×10⁵ t·a^-1 for the period from 2002 to 2017, which caused a large pollution load in the water environment. F statistic and ρ value tests in SPSS 21.0 gave the relationship between the actual nitrate concentration in groundwater and the estimation nitrogen amount leaching into the groundwater. Finally, the estimated and observed values passed significance test, with a correlation coefficient of 0.517, which confirmed the accuracy of the model. Nitrogen input as chemical fertilizer input and nitrogen output as crop harvest were respectively the main input and output factors in the study area. The most serious pollution was in 2006. The study provided important data needed to solve non-point agricultural pollution with important practical implications for the prevention and control of nitrogen pollution in groundwater.

Impact of surface acidification of manure on ammonia emission in animal housing

LIU Juan, BAI Zhaohai, CAO Yubo, ZHANG Nannan, ZHAO Zhanqing, MA Lin

2019, 27(5): 677-685. doi: 10.13930/j.cnki.cjea.181086

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Abstract:
Ammonia is a key substance in the formation of haze precursors, and livestock pen is one of the main sources of ammonia emission. Here, we selected fresh cow and sow manure to evaluate the impacts of surface acidification on ammonia emission under simulated livestock pen conditions with different acids of different concentrations. Acid solution was sprayed on the surface of the manure to acidify the manure surface. Ammonia emission was measured using the dynamic boric acid trap method. Our results revealed that when lactic acid was diluted to 0.012 mol·L^-1 and 0.006 mol·L^-1 and applied on the surface of manure at the rate of 0.31 mL·cm^-2, ammonia emission from sow manure reduced respectively by 43% (P < 0.05) and 32% (P=0.07) in 24 h, compared with the control treatment. Ammonia emission reduced by 74% (P < 0.01) and 61% (P < 0.05) respectively for 0.017 mol·L^-1 and 0.009 mol·L^-1 of diluted phosphoric acids. Ammonia emission of sow manure reduced by 64% (P < 0.01) within 72 h treatment of 0.017 mol·L^-1 phosphoric acid. Using the same treatment method as before, surface acidification of cow manure reduced ammonia emission by 80% compared with control treatment. The frequency of acid addition to manure surface had no significant impact on ammonia emission mitigation when manure was not refreshed. Surface acidification lowered manure pH, but with no significant impact on the whole manure. Overall, surface acidification reduced ammonia emission in animal pens. The reduction efficiency depended not only on the type and concentration of acid, but also on the type of manure. Surface acidification of manure was a cost-effective ammonia abatement technique. This study also supported the increasing understanding of manure acidification technology aimed at reducing ammonia emission from animal pens.

Available phosphorus status and critical threshold for leaching in greenhouse soils influenced by different fertilizer sources

NIU Junfang, FENG Junxia, ZHANG Xiying

2019, 27(5): 686-693. doi: 10.13930/j.cnki.cjea.180909

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Abstract:
It is significant to study soil phosphorus (P) leaching resulted from excessive inputs of manure or chemical fertilizer in greenhouse soils. Soil P movement not only depends on content but also on forms of P supplied by fertilizers. Therefore, research on soil P status influenced by manure and chemical fertilizers is important for scientific fertilization and preventing non-point source pollution. In this paper, laboratory soil incubation experiment was conducted to investigate soil available P (Olsen-P) and calcium chloride extracts P (CaCl₂-P) contents influenced by manure and inorganic P sources at different rates[0, 50, 100, 150, 300, 600 mg(P)·kg^-1(dry soil)] in three soils with different planting years in Raoyang County, Hebei Province. The three soils included soil next to the greenhouse without planting vegetables (control), plastic greenhouse soil with 30 years of planting vegetables (plastic greenhouse soil) and solar greenhouse soil with 4 years of planting vegetables (solar greenhouse soil). The main purpose was to study the effects on available P content in greenhouse soils and determine the threshold of P leaching under manure and inorganic fertilizers application by mathematical stimulation. The results showed that both organic and inorganic P input increased soil Olsen-P and CaCl₂-P contents significantly in three soils. For the control soil with low Olsen-P content, inorganic fertilizer improved Olsen-P content more greatly compared to manure when the fertilizer rate was more than 50 mg(P)·kg^-1(dry soil). But for the plastic greenhouse soils, only under higher P input[300 and 600 mg(P)·kg^-1(dry soil)], inorganic fertilizer showed more significantly Olsen-P-increasing effect than manure. And there was no significant difference between inorganic and organic fertilizers at low P supply. In general, soil CaCl₂-P content was higher under inorganic fertilizer treatments than organic fertilizer treatments in three types of soil, especially under high P input rate[>300 mg(P)·kg^-1(dry soil)]. Two segment linear regression analyses results showed that the critical soil P leaching thresholds under organic and inorganic P addition in greenhouse soils were 87.8 mg·kg^-1 and 198.7 mg·kg^-1, respectively. With the increase of soil Olsen-P, the increment rate of soil CaCl₂-P with inorganic P addition was twice as much as that with organic P addition. Therefore, in the high P greenhouse soils in Hebei Province, the input of inorganic P fertilizer should be reduced. All P input from manure and inorganic fertilizers should be prohibited in greenhouses soil with Olsen-P content exceeding 198.7 mg·kg^-1. In vegetable greenhouses with soil Olsen-P below 198.7 mg·kg^-1, manure replacement of inorganic fertilizer should be intensified.

Evaluation of regional ecological carrying capacity coupling with landscape pattern and ecosystem services

LIU Shiliang, WU Xue, ZHU Jiali, ZHANG Hui, JIA Kejing, ZHAO Shuang

2019, 27(5): 694-704. doi: 10.13930/j.cnki.cjea.180910

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Abstract:
The main basis of landscape development and planning is the evaluation of regional ecological carrying capacity. The results of this evaluation can reflect the extent to which ecological carrying capacity can remain unaffected by continuous development and planning activities of humans. Nowadays, among the existing methods for assessing ecological carrying capacity, the method based on ecosystem services value is relatively mature and widely used. However, the assessment of ecosystem services value is based on the classification of ecological land types in the region; therefore, it is difficult to apply where the land use status lacks extensibility and resilience. To fill this gap, this study coupled landscape pattern and vegetation change parameters with the ecosystem service provision capacity through a comprehensive index system with 3 criteria and 11 indicators. The landscape pattern determined the size, shape, and connectivity of various ecological patches, which in turn affected the abundance, distribution, and population viability and anti-interference ability of the landscape. Thus, landscape pattern indexes could be used to identify regional ecological protection priorities under urbanization, further improving regional environmental quality and resource utilization efficiency. The vegetation change index could spatially describe changes in breadth and depth of vegetation cover in regions, which were the result of the interaction between nature and human activities. This study applied the assessment model to Shijiazhuang City, measuring its comprehensive ecological carrying capacity at the grid, township and district scale. The results showed that the spatial distribution of the ecological carrying capacity of Shijiazhuang based on the grid analysis was relatively high in the western mountainous area and low in the east plain. Regarding the indicator layer, the distribution of ecosystem service provision capacity was relatively consistent with the comprehensive ecological carrying capacity distribution, whereas the landscape metrics presented a mosaic distribution pattern and the vegetation change index represented a circle layer distribution pattern. Meanwhile, the spatial heterogeneity of the first-level indicators was more significant. The further regional analysis results focusing on the administrative scales of districts and townships showed that the indicator distribution on smaller scale was more heterogeneous, and evaluation results in some regions were inconsistent with those assessed at higher administrative level. Therefore, local decision-makers should adjust more targeted management objectives and actions according to the jurisdiction. In general, through horizontal analysis in space and vertical contrast on scales, western Shijiazhuang City should focus on integrating the forest ecosystem conservation into urban development and construction; the eastern districts and townships should coordinate between the ecological environment and economic development, and improve the ecosystem service capacity through the optimization of ecological space patterns, thereby improving the comprehensive carrying capacity of national land space.

Nitrogen, phosphorus and potassium cycling and sustainability of rice yield in a winter crop-double cropping rice rotation system

ZHANG Fan

2019, 27(5): 705-716. doi: 10.13930/j.cnki.cjea.180767

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Abstract:
The study of nitrogen (N), phosphorus (P), and potassium (K) nutrient cycling and yield sustainability in agricultural ecosystems is fundamental for achieving optimal nutrient management and sustainable agricultural development. A long-term experiment of a winter crop-double cropping rice rotation system initiated in 2004 on a red paddy soil in Hunan Province, consisting of five treatments, including fallow-double cropping rice (CK), potato-double cropping rice, ryegrass-double cropping rice, milk vetch-double cropping rice, and rape-double cropping rice with three replicates of all the treatments. The sustainability and stability of double cropping rice yields were analyzed, and N, P, and K cycling and balance were calculated based on an Input-Output analysis method. The results indicated:1) the sustainable yield index (SYI) and yield stability (CV) of early rice in the ryegrass-double cropping rice rotation system were 0.81 and 0.09, respectively. Winter ryegrass in the paddy field promoted the stability and sustainability of early rice yield. The SYI and CV of late rice in the rape-double cropping rice rotation system were 0.82 and 0.07, respectively. Winter rape in the paddy field improved of yield stability and sustainability of late rice. 2) Long-term winter crop-double cropping rice rotation did not significantly affect rice yield and the N, P, and K contents of brown rice (P>0.05). 3) Under the current input level of N, P, K in the annual rotation of winter crop and double cropping rice, the ryegrass-double cropping rice rotation, milk vetch-double cropping rice rotation, rape-double cropping rice rotation, and potato-double cropping rice rotation systems had serious K deficiency; the K deficit was 375.70, 279.98, 363.71, and 93.74 kg(K)·hm^-2, respectively. Ryegrass-double cropping rice rotation, milk vetch-double cropping rice rotation, and rape-double cropping rice rotation systems had serious K deficiency in the winter crop planting season, the K deficit was 240.07, 89.57, and 140.08 kg(K)·hm^-2, respectively. However, the potato-double cropping rice rotation system had a K surplus of 255.21 kg(K)·hm^-2 in the potato planting season; simultaneously, both the ryegrass-double cropping rice rotation and milk vetch-double cropping rice rotation systems had a N deficit in the winter crop planting season of 59.47 and 89.17 kg(N)·hm^-2, respectively. Both the rape-double cropping rice rotation and potato-double cropping rice rotation systems had serious K deficiency in the late rice planting season of 45.93 and 124.33 kg(K)·hm^-2, respectively. Nutrient cycling of winter crop-double cropping rice rotation systems was a nutrient cycle driven by winter crops and external N, P, and K fertilizers. Based on the results, the winter crops should be scientifically managed, with the input of N, P, and K in the three seasons.

Effects of nitrogen forms on decomposition and nutrient release of rapeseed straw

LI Xiaowei, HAN Shang, LEI Zhimeng, WU Ji, SHI Zuliang, SUN Zhixiang, LI Min, WANG Hui, TANG Shan, CHENG Wenlong, ZHU Lin

2019, 27(5): 717-725. doi: 10.13930/j.cnki.cjea.180810

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Excess rape straw causes unreasonable straw processing, such as burning, resulting in resource waste and serious environmental pollution. Returning straw to the soil is an effective way to improve this situation. Previous studies have found that nitrogen can regulate the soil microbial carbon-nitrogen ratio to promote straw decomposition. At present, much research has focused on the effects of nitrogen rate on straw decomposition, whereas the effects of different forms of nitrogen have rarely been proposed. In this experiment, rape straw was returned to soil for 120 days with different forms of nitrogen:urea (PU), urea ammonium nitrate (UAN), and lime nitrogen (CaCN₂), at a 90 kg·hm^-2 application rate in nylon net bags. The effects of different forms of nitrogen on the decomposition and nutrient release of rape straw were studied. The straw weight and carbon, nitrogen, phosphorus, and potassium contents of straw residues were investigated at 5, 10, 30, 60, 90, and 120 d after straw mixtures were buried into soil to explore characteristics of straw decomposition and nutrient release with the application of different nitrogen forms. The aim of the study was to optimize straw incorporation into soil to improve straw utilization efficiency. The results showed that the decomposition of rape straw was fast in the early stage (0-30 d) and slow in the later stage (30-120 d). At 120 d, the cumulative decomposition rate of rape straw was 46.08%-52.34%. The release rates of carbon, nitrogen, phosphorus and potassium were 44.25%-51.52%, 51.19%-54.87%, 52.82%-58.45%, and 96.61%-97.46%, respectively. The addition of nitrogen significantly promoted the decomposition of rape straw. At 120 d, the cumulative decomposition rate of nitrogen treatments increased by 10.80%-13.59% than that of the control treatment. Different forms of nitrogen have different effects on straw decomposition and release rates of carbon, nitrogen, phosphorus and potassium. Among them, the PU treatment decomposition process was divided into two stages, rapid decomposition (0-30 d) and slow decomposition (30-120 d); at 30 d, the decomposition rate of rape straw reached 40.39%. After 30 d, the decomposition rate gradually became stable and reached 51.06% at 120 d. The UAN treatment decomposition process was divided into three stages, rapid decomposition (0-30 d), slowing decomposition (30-60 d), and slow decomposition (30-120 d); the decomposition rate reached 40.67% at 30 d. The decomposition rate increased by 7.54% from 30 to 60 d, and it was 51.63% at 120 d. The decomposition effect of the CaCN₂ treatment was mainly manifested after 60 d. At 60 d, the decomposition rate of rape straw reached 44.37%, and was 52.34% at 120 d. Overall, the effect of UAN was more significant. Compared with no nitrogen treatment, the cumulative decomposition rate of straw in the UAN treatment increased by 12.04%; the cumulative release rates of carbon, nitrogen, phosphorus increased by 9.33%, 7.19%, and 6.97%, respectively. The effect of each treatment on the potassium release rate of straw was not significant. Therefore, this study provided the basis for enhancing rape straw decomposition to promote straw resource utilization.

Applicability of Partial Root-zone Irrigation model to simulate evapotranspiration and transpiration in drip irrigation jujube orchards in southern Xinjiang

ZHENG Ming, ZHAO Jinghua, MA Yingjie, HONG Ming

2019, 27(5): 726-737. doi: 10.13930/j.cnki.cjea.180984

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Abstract:
Constructing a model suitable for simulating evapotranspiration and evapotranspiration components of mature jujube orchard under drip irrigation in southern Xinjiang and understanding their soil evaporation characteristics would be beneficial for growers. Based on the Shuttleworth-Wallace model and the evapotranspiration estimation model of sparse vegetation under local wet irrigation, a Partial Root-zone Irrigation model of drip irrigation for the jujube orchard was constructed. The evapotranspiration data were measured by eddy correlation methods in the jujube orchard in 2017, and the coefficients of the Shuttleworth-Wallace model and the Partial Root-zone Irrigation model of drip irrigation for jujube orchard were fitted and evaluated; the effects of the model parameters on evapotranspiration were observed by increasing and decreasing the model parameters by 10%, and the accuracy of the formulas for calculating the parameters of each model was verified. Evapotranspiration was then measured using the eddy correlation method and transpiration was measured using the liquid flow method to obtain accurate values. The reliability of the two models used to simulate evapotranspiration and transpiration in jujube orchard in 2018 were evaluated. The models were suitable for calculating evapotranspiration and evapotranspiration components in the drip irrigation jujube orchard of southern Xinjiang in 2018, as well as simulating the soil evaporation characteristics. Model coefficients of the Shuttleworth-Wallace model and Partial Root-zone Irrigation model for the drip irrigation jujube orchard were accurately fitted according to the criteria for evaluating the simulation results of the model. The results of the two models for simulating evapotranspiration were excellent for the jujube orchard in 2018, and the accuracy of the two models were the same. The results of the Partial Root-zone Irrigation model for drip irrigation jujube orchard were also good, with a difference of 15.73 mm between the model and actual measured value. It was not advisable to simulate transpiration by using the Shuttleworth-Wallace model. Therefore, the Partial Root-zone Irrigation model for drip irrigation was selected to simulate soil evaporation in the jujube orchard, and the results showed that soil evaporation accounted for 19.74% of the evapotranspiration. Thus, the Partial Root-zone Irrigation model for the drip irrigation jujube orchards can be used to accurately estimate the evapotranspiration and evapotranspiration components of the orchards.

Comparison of mineral elements between fruit and vegetative branch leaves of the Chinese winter jujube during the fruit development stage

WANG Yao, DONG Linshui, SONG Aiyun, LIU Jingtao, LU Zhaohua, PENG Ling, ZHANG Mengli

2019, 27(5): 738-746. doi: 10.13930/j.cnki.cjea.181098

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To provide a theoretical rational fertilization basis for improving the quality of Chinese winter jujube, we studied the contents of N, P, K, Ca, Mg, and Na in its fruit and vegetative branch leaves at different fruit development stages (initial-bloom, full-bloom, after-flowering, hardcore, and mature stages) and analyzed N/P, K/Na, Ca/Na, and Mg/Na ratios. The results indicated that from the initial-bloom to mature stage, the N and P contents showed a downward trend, and K content increased gradually during the fruit development stage of Chinese winter jujube; however, the Ca and Mg contents in leaves increased initially and then decreased. The Na content in leaves showed a slight change, but increased suddenly in the mature stage. In the above stages of fruit development, the K content in fruit branch leaves was higher than that in vegetative branch leaves, whereas the N, P, Ca, Mg, and Na contents in fruit branch leaves showed the opposite trend. Variance analysis showed that there was a significant difference (P < 0.05) in Ca and Mg contents between the fruit and vegetative branch leaves during full-bloom and after-flowering stages. The N content was significantly different only during the full-bloom stage. There was no significant difference in K and Na contents between the two types of leaves during the fruit development stage. The analysis of element content ratio in the leaves showed that N/P increased gradually from the full-bloom to mature stage, with values > 16, indicating that the growth of Chinese winter jujube leaves was mainly restricted by P content during these stages. The analysis also showed that K/Na, Ca/Na, and Mg/Na in fruit development stages changed similarly with the K, Ca, and Mg contents, respectively. The correlation analysis showed that N/P was mainly determined by the P content, Ca/Na was determined by Ca and Na contents, and Mg/Na was determined by Mg and Na contents, whereas K/Na in vegetative branch leaves was mainly determined by Na content. In summary, the full-bloom to after-flowering stage (June-July) was a relatively stable period of mineral elements in Chinese winter jujube, which could be used as a suitable period for the nutritional diagnosis of this species. Simultaneously, Ca and Mg fertilizers should be appropriately applied to the fruit branch leaves during this period to ensure the fruit quality and yield of Chinese winter jujube.

Physiological adversity resistance of sea rice to salinity stress

WANG Xuming, ZHAO Xiaxia, CHEN Jingyang, XU Jianghuan, ZHOU Bolin, WANG Panpan, MO Su, MO Junjie, XIE Ping, ZHOU Hongkai

2019, 27(5): 747-756. doi: 10.13930/j.cnki.cjea.180656

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The sea rice varieties 'FL478' 'JX99' 'Pokkali' and salt-sensitive variety 'IR29' were used to determine malondialdehyde content, cell membrane permeability, soluble sugar and proline in rice leaf. We also investigated the activities of Δ1-pyrroline-5-carboxylic acid synthetase (P5CS), ornithine-δ-aminotransferase (δ-OAT) and superoxide dismutase (SOD) under 0 g·kg^-1, 1 g·kg^-1, 2 g·kg^-1, 3 g·kg^-1, 4 g·kg^-1 and 5 g·kg^-1 of soil salt treatments at booting stage of potted rice under rainproof greenhouse conditions. This aim of the study was to investigate the relationship between osmotic regulators, stress resistance enzymes and salt tolerance of sea rice under salinity stress. The study also provided theoretical basis for the exploration of salt tolerance genes and breeding sea rice varieties with salt tolerance. The results were as follows:1) salinity stress inhibited the synthesis and accumulation of chlorophyll in rice. Then chlorophyll content in rice leaf decreased with increasing salt stress concentration, and was significantly higher than that of salt-sensitive rice. 2) The response of soluble sugars of sea rice and salt-sensitive rice to salinity stress had significantly differences. The rise in soluble sugars of sea rice was less than that of salt-sensitive rice under 0-3 g·kg^-1 soil salt content, but the content of soluble sugars of sea rice was significantly higher than that of salt-sensitive rice under 4-5 g·kg^-1 soil salt content. 3) Malondialdehyde contents of sea rice and salt-sensitive varieties increased with increasing salt stress, resulting in increased cell membrane permeability. However, malondialdehyde content of sea rice was significantly lower than that of salt-sensitive rice. This implied that leaf membrane damage of sea rice was significantly less than that of salt-sensitive rice. 4) Proline content and P5CS, δ-OAT and SOD activities of rice leaf increased initially and then decreased with increasing salt stress. Proline content and P5CS, δ-OAT and SOD activities of sea rice and salt-sensitive rice were maximum under 3 g·kg^-1 and 2 g·kg^-1 salt content, respectively. However, proline content and P5CS, δ-OAT and SOD activities of sea rice were significantly higher than those of salt-sensitive rice. 5) Simple and partial correlations of soluble sugar, proline and P5CS were significantly positive under salinity stress. Salt tolerance characteristics of sea rice were considered as physiological salt tolerance. Proline synthetase P5CS and δ-OAT of sea rice were both activated by salinity stress. The activity of two pathways of proline synthesis (ornithine synthase and glutamate synthase pathways) were simultaneously increased, which promoted rapid and high accumulation of free proline in sea rice. Rapid accumulation of free proline also activated SOD activity, which effectively destroyed the accumulation of intracellular reactive oxygen species. Soluble sugar and proline synergistically alleviated osmotic stress and sea rice showed a strong salt tolerance.

Effect of exogenous ethylene on physiological metabolism of Zea mays seedlings under cadmium stress

LIU Juan, ZHAO Huanrui, LIU Yonghua, WANG Jinghui

2019, 27(5): 757-765. doi: 10.13930/j.cnki.cjea.180915

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There has been increasing heavy metals[especially cadmium (Cd)] pollution in farmlands in China. Studies have identified the crucial role of exogenous ethylene in the reversal of Cd stress in plants such as Arabidopsis thaliana mustard. However, few studies have been done on maize (Zea mays), which is the second largest staple crop in China. To investigate the potential process by which exogenous ethylene alleviates Cd stress in maize, hydroponic experiments were conducted. The experiments included a treatment that served as a blank control and others that were Cd and (NH₄)₂SO₄ treatments. Changes in physiological indexes of maize seedling leaf along with subcellular distribution of Cd in leaves and roots of the plant were determined under Cd treatment, exogenous ethylene treatment and exogenous sulphur treatment. The results suggested that H₂O₂ and malondialdehyde (MDA) contents of maize seedling leaf decreased under exogenous ethylene and exogenous (NH₄)₂SO₄ treatments, comparing with Cd treatment alone. Also, the rate of net photosynthesis was promoted by 1.23 times and 1.22 times respectively under exogenous ethylene and exogenous (NH₄)₂SO₄ treatments. The activity of antioxidant enzymes[superoxide diamutase (SOD), catalase (CAT)] significantly decreased, while the contents of antioxidants[ascorbic acid (AsA) and glutathione (GSH)] significantly increased under exogenous ethylene or exogenous (NH₄)₂SO₄ treatments with Cd stress. The results suggested that exogenous ethylene reduced Cd-induced oxidative stress and the degree of lipid peroxidation by enhancing non-enzymatic antioxidant reaction. However, it did not affect enzymatic antioxidant reaction, but then promoted photosynthetic processes. Compared with Cd treatment alone, the activities of ATP sulfurylase and glutathione reductase (GR), and the contents of cysteine and GSH in maize seedlings increased respectively by 54.43%, 27.93%, 50.77%, and 49.85% with exogenous ethylene treatment. However, there was no significant change in non-protein thio (NPT) and phytochelatins (PCs) contents. The results showed that ethylene potentiated GSH biosynthesis to resist Cd conditions. To show this that was the case, a GSH biosynthetic inhibitor-buthionine sulfoximine (BSO) - was applied on maize seedlings under Cd and exogenous ethylene conditions. Compared with Cd plus exogenous ethylene treatment, BSO significantly decreased GSH content, increased H₂O₂ content and reduced net photosynthesis rate. Furthermore, Cd content in roots significantly increased while it decreased in leaves after treatment with exogenous ethylene under Cd stress. Further analysis showed that Cd content in cell wall and vacuole of roots was enhanced with exogenous ethylene treatment. Totally, exogenous ethylene reversal of the effect of Cd stress on maize was a complex process involving the promotion of GSH and AsA contents and Cd distribution in roots. On the one hand, exogenous ethylene treatment enhanced non-enzymatic antioxidant capacity by increasing the contents of GSH and AsA, and not by improving the activities of antioxidant enzymes nor chelating NPT and PC in maize leaf. On the other hand, translocation of Cd from maize root to leaf was reduced by enhancing Cd sequestration in cell walls and vacuoles of maize root. The results provided the fundamental information for the application of ethylene in the reversal of heavy metal stress.

Effect of Penicillium griseofulvum on control of Orobanche aegyptiaca and microorganisms in rhizosphere soils of tomato

CHEN Jie, MA Yongqing, GUO Zhenguo, XUE Quanhong

2019, 27(5): 766-773. doi: 10.13930/j.cnki.cjea.180903

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Root parasitic weed Orobanche aegyptiaca adversely affects yield and quality of tomato (Solanum lycopersicum). The means of effective control is still the focus in O. aegyptiaca research. Fungus is one of the biocontrol agents of Orobanche spp.. However, few studies have been done on the use of non-pathogentic fungi to control Orobanche spp. weed. In this study, the effects of cell-free culture filtrate of Penicillium griseofulvum, a non-pathogentic fungus strain of O. aegyptiaca, on O. aegyptiaca seed germination and germ tube growth were investigated in a petri-dish experiment. In addition, a pot experiment was conducted to explore the effect of powdered P. griseofulvum inoculum on weedy O. aegyptiaca control. The effects of P. griseofulvum inoculum on the growth of host tomato plants and the change in microflora in rhizosphere soils of tomato plants were also investigated. Results showed that:1) in the petri-dish experiment, cell-free culture filtrate of P. griseofulvum significantly inhibited both O. aegyptiaca seed germination and germ tube growth. When O. aegyptiaca seeds and tomato seedlings were co-cultured for 6 days, O. aegyptiaca seed germination was completely inhibited (100.0%) in treatments with P. griseofulvum cell-free culture filtrate. After co-culturing for 6 days, O. aegyptiaca seed germination rates reduced by 80.26%, 70.26%, 68.10% and 47.51%, respectively in treatments with volume ratios of P. griseofulvum cell-free culture filtrate and Hogland nutrient solution ratios of 1:2, 1:4, 1:6 and 1:8. The lengths of O. aegyptiaca germ tubes significantly reduced by 100.00%, 68.84% and 19.24%, respectively when treated by undiluted, 10-fold diluted and 100-fold diluted P. griseofulvum cell-free culture filtrate. 2) In the pot experiment, P. griseofulvum inoculum inhibited the emergence of O. aegyptiaca tubercles and the growth of individual O. aegyptiaca tubercle, but simultaneously increased tomato fruit yield. The number of epigeal O. aegyptiaca tubercles, epigeal rate of O. aegyptiaca tubercles and dry weight of individual O. aegyptiaca tubercles all significantly reduced after the application of powdered P. griseofulvum inoculum at 1.0 g·kg^-1 for 130 days respectively by 76.19%, 85.30% and 28.48% than the control. After the application of P. griseofulvum inoculum for 130 days, tomato fruit yield was 346.8 g per plant (51.57%) more than the control (228.8 g). In addition, P. griseofulvum also adjusted microflora structure in rhizosphere soils of tomato plants. The application of P. griseofulvum inoculum reduced fungi population (excluding CF3) and significantly increased population ratio of bacteria to fungi in rhizosphere soils of tomato plants by 75.60% and 117.57%, respectively, compared with the control. On average, application of P. griseofulvum inoculant reduced fungi population (excluding P. griseofulvum) and increased actinomycetes population in rhizosphere soils of tomato plants respectively by 42.81% and 84.15% over the control. In conclusion, P. griseofulvum had the ability to control O. aegyptiaca infection of tomato plant with fungus as suitable biological agent to control O. aegyptiaca.

Evolution of grassland ecological footprints based on variable structures of farming-pasturing interlocked areas

GAO Yining, ZHAO Mengli, WANG Hongliang, HAO Jinmin, XIONG Mei, ZHAO Tianqi

2019, 27(5): 774-784. doi: 10.13930/j.cnki.cjea.180900

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Abstract:
Siziwang Banner is a typical agri-pastoral ecotone of Inner Mongolia, where animal husbandry is the foundation supporting economic development. The grassland resources have a profound influence on the livestock industry. The time scale studied in this paper spans nearly 30 years, and during this period, the grassland resources of Siziwang Banner were degraded by human economic activities on a large scale. With the increasing awareness of environmental protection, the national and local governments have adopted a series of ecological measures, through projects such as returning farmland to grasslands, and the comprehensive management of grasslands to help improve their ecology. The transformation from grassland degradation to improving ecological, to a certain extent, reflects that regional economic construction is no longer purely at the expense of the environment but is gradually adopting a sustainable development approach. Coordination between economic construction and ecological protection should be emphasized. In order to study grassland ecology and economic development, a feasible ecological evaluation model is needed. The ecological footprint model has been widely used in China, but grassland ecological footprints are rarely found in agro-pastoral interlaced areas. The ecological footprint of the grassland and the time series of GDP per capita from 1987 to 2016 were used to analyze the grassland consumption and economic growth in Siziwang Banner, by using the Bai-Perron structural mutation co-integration test. The results of this co-integration test, which did not consider structural mutation, showed that it was not suitable for Siziwang Banner under a variety of grassland ecological protection policies. Besides, a co-integration test of structural mutation could reflect the economy of the agricultural and pastoral ecotone over a long period. The structural changes reflected the dynamic equilibrium between grassland consumption and economic growth and presented a one-way causality from grassland consumption to economic growth. The evolution of the grassland ecological footprint could be divided into three stages:a low-degree coordination stage (1987-2002), a policy-driven stage (2002-2009), and a rapid development stage (2009-2016). In the different stages, the absolute value of short-term fluctuations of the grasslands ecological footprint tended to be flat, but the long-term equilibrium coefficients gradually increased. The results showed that the ecological protection policy was helpful for improving the utilization efficiency of grassland resources. We found that the dependence of economic growth on grassland consumption gradually decreased, and the mode of economic growth at the expense of resources changed under the policies of ecological protection over the past 20 years. Sustainable methods for both economic development and ecological protection were advancing. Our results were not only beneficial to coordinate the development of regional economies and the utilization of grassland resources, but could also be used as reference for the future scientific planning of grassland ecological protection in the ecotones of agriculture and animal husbandry.

Development of a "production-ecology-life" coupling tea garden in a mountain area

LIU Penghu, WANG Yixiang, HUANG Ying, LUO Xuhui, GAO Chengfang, WENG Boqi

2019, 27(5): 785-792. doi: 10.13930/j.cnki.cjea.180817

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Abstract:
Based on a survey of several rural tea gardens in Fujian Province, the new coupling ecosystem of production, ecology, and life in mountain areas, referred to as "production-ecology-life" coupling tea gardens, was suggested according to the rural revitalization strategy and green development requirements for the mountain tea industry. This model was based on the timing-space-structured rational layout of tea garden functional elements, including production, ecology and life, and the coupling of mountain ecological processes. It promoted the complementarity and superposition of tea garden subsystems through ordered links and mutual promotion of related elements, and improved resource utilization and labor productivity in mountain tea gardens. In this paper, we discussed the construction of a comprehensive development and management system for the "production-ecology-life" coupling tea garden in a mountain area from six subsystems, including ecological restoration and soil fertility improvement; soil and water conservation and dimensional interplanting/breeding; water conservation and tea garden landscape; green environment and tea travel-life; scientific reclamation and water and fertilizer regulation; and diverse development and leisure health. Finally, eight countermeasures for green management and sustainable development of the "production-ecology-life" coupling tea garden in mountain areas were suggested, including policy guidance and scientific planning; project driving and integration demonstration; encouragement of innovation and reward subsidy; diversified development and promotion of efficiency; green management and brand cultivation; coordinating the "production-ecology-life" relationship and improving the coordination mechanism; improving the occasion and optimizing positive action; and strengthening management and promoting industrial integration. These measures provided a reference for transforming and enhancing the green tea industry in the future.

Decoupling and predictive analysis of greenhouse gas emission from animal husbandry in China

WANG Huan, QIAO Juan

2019, 27(5): 793-802. doi: 10.13930/j.cnki.cjea.180826

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Abstract:
With increasing greenhouse gas emission, China has committed to cap carbon dioxide emissions by 2030. As animal husbandry has become an important part of the emission reduction effort, it is necessary to analyze the current situation and trend in greenhouse gas emission due to animal husbandry in the country. Based on the 2000-2014 provincial panel data and the Guidelines on Provincial Greenhouse Gas Emission Inventories, we estimated greenhouse gas emission due to animal husbandry and then used the Tapio decoupling model to analyze the relationship between greenhouse gas emission and the economic development due to animal husbandry. Furthermore, LMDI model was used to decompose the driving factors, and the greenhouse gas emissions target of animal husbandry in 2020 under different scenarios were also analyzed. The results suggested that greenhouse gas emission from animal husbandry decreased from 377.852 4 million tons in 2000 to 358.157 6 million tons in 2014, representing a drop of 5.21%. Emission reduction from non-dairy cattle was significant. However, it was still above the 50% threshold — 181.805 4 million tons. Emissions from sheep, pigs and cattle were respectively 70.725 6 million tons, 62.026 9 million tons and 43.599 7 million tons, all of which still increased. The decoupling effect of greenhouse gas emission from animal husbandry was ideal. The whole country was under weak decoupling that underwent three stages of fluctuation — relative stability — increase. The decoupling condition for each province was good, among which 15 provinces had strong decoupling, 15 provinces had weak decoupling and 1 province had receding decoupling. The comprehensive effect tracked an inverted U-curve at the national level, which was quite different for the provinces. The efficiency of production was the main contributor to the national and provincial emission reductions, while the effect of economic development was the most important driving factor of emission. The difference in comprehensive effect mainly came from the difference in industrial structure and labor. In 2020, greenhouse gas emission from animal husbandry far exceeded planned target. The predicted range of greenhouse gas emission from animal husbandry was from 335.630 8 to 400.677 1 million tons. Then the predicted endpoint values were respectively 12.84% and 34.71% more than the target, which great increased the pressure of emission reduction. In this case, only the lowest decoupling elasticity and the fastest economic growth rate had the least greenhouse gas emission gap. Greenhouse gas emission reduction was an inevitable requirement for sustainable development in the world. Although the decoupling effect of greenhouse gas emission from animal husbandry in China was obvious under the effect of several factors, emission reduction was still an arduous task, requiring the formulation of practical measures to promote it. Therefore, this work suggested that China needed to adjust its industrial structure and import livestock products instead of promoting domestic production. There was the need to implement differential governance of decoupling in different regions and improving farming efficiency. Also, clear animal husbandry emission reduction objectives and task assignments to provinces were required.

Evaluation and improvement of agricultural land resource utilization efficiency:A case study of Jiangxi Province

HUANG Heping, WANG Zhipeng

2019, 27(5): 803-814. doi: 10.13930/j.cnki.cjea.180992

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Abstract:
Land resources are material carriers for human reproduction, the basis of socioeconomic and cultural development, and the foundation for the survival and development of all things worldwide. Scientific evaluation of the spatial-temporal evolution characteristics of agricultural land use efficiency is necessary for alleviating negative impacts due to interactions between humans and land and for ensuring food security. The utilization efficiency of land resources has been the focus of academic attention and research. It is of great significance to assess the reasons for the loss of land efficiency and to find ways to improve it for sustainable agricultural development. In this study, the VRS-DEA (Variable Scale Reward-Date Envelopment Analysis) model and Malmquist index were used to analyze the spatial-temporal characteristics of agricultural land resource utilization efficiency in Jiangxi Province from 1990 to 2016. And the ecological value of agricultural land resources was incorporated into an input-output index system to quantitatively analyze the causes of its efficiency loss, and suggest effective ways to improve the agricultural land resource utilization efficiency in Jiangxi Province. The results of the research showed that:1) The overall utilization efficiency of agricultural land resources was relatively high in Jiangxi Province. From 1990 to 2016, the utilization efficiency first decreased and then increased, with an average efficiency of 0.889. 2) Regarding efficiency decomposition, the comprehensive technical efficiency was the combination of pure technical and scale efficiencies; however, the scale efficiency impact was stronger than that of pure technical efficiency; therefore, the inefficiency of scale was an important reason for the inefficiency of comprehensive technology. 3) With regard to spatial pattern evolution, there were significant differences in the trajectories of efficiency variations among regions, and the trend of non-equilibrium development was more prominent. Over the years, the efficient and relatively efficient areas of DEA were mainly distributed in the cities of north-central Jiangxi, showing "large aggregation-small dispersion" characteristics with obvious trapezoidal layers. 4) The total factor productivity (TFP) of agricultural land resource utilization generally increased in Jiangxi Province. The contribution of technological progress was the largest, and the growth of total factor productivity was a result of the "monorail-driven" mode of technological progress. The main factors restricting the growth of TFP of agricultural land resource utilization were the low pure technical efficiency and scale efficiency. 5) The lack of output value of crop production was the main reason for loss of efficiency. The redundant input of pesticides, fertilizers, and planting practitioners were the secondary causes. The reasons for the loss of agricultural land use efficiency in different cities were different, and the input and output factors had great potential for improvement. 6) Regarding the efficiency improvement path, optimizing the allocation of resources, standardizing the use of pesticides and chemical fertilizers, gradually transferring surplus rural labor, and improving the level of mechanization and scale of land production were key to improving the efficiency of land resource utilization. The research results could provide a reference for further understanding the overall utilization situation of agricultural land resources, identifying existing problems, and optimizing the development path in Jiangxi Province. This research provided a scientific basis to formulate efficient utilization and management decisions of agricultural land resources in the future.

2019 Vol. 27, No. 5