2019 Vol. 27, No. 12

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Crop Cultivation and Physiological Ecology
Effect of drought stress on maize phenology and yield components and its sim-ulation
MI Na, ZHANG Yushu, CAI Fu, JI Ruipeng, FANG Yuan, ZHANG Shujie, CHEN Nina
2019, 27(12): 1779-1788. doi: 10.13930/j.cnki.cjea.190390
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Drought is one of the main limiting factors for maize production in Northeast China, and drought stress is particularly severe during the seeding and flowering stages of the crop. The occurrence of drought around anthesis affects the temporal separation of male (anthesis) and female (silking) floral maturity (referred to as the anthesis-silking interval, ASI), which leads to a reduction in maize kernel numbers. To examine the effect of drought stress during the "yield critical period" on maize phenology, yield and yield components as well as to assess the modeling results of phenology and yield simulated by a crop growth model under drought stress, a field experiment was conducted. Sowing was performed on different dates at 10-day intervals beginning from April 20 over a 5-year period (2011-2015). Observation data of maize yield and yield components, particularly phonology and yield data in the drought years of 2014 and 2015 were used to analyze the effect of drought stress on maize phenology and yield components. The results of simulation using the CERES-Maize model were assessed in this study. Further improvements for the CERES-Maize model under drought conditions were proposed. The findings revealed that drought during the yield critical period delayed silking much greater than anthesis. More than 90% of the plants reached the anthesis stage, whereas only 45%-88% of the plants reached the silking stage. Drought in 2014 and 2015 reduced the kernel numbers of maize by 32% and maize yield by 33%-78%. Grain yield was significantly (P < 0.001) and positively correlated with the number of kernels per ear. The CERES-Maize model showed good performance (normalized root mean square error (NRMSE) of yield simulation was 6.5% for 2012 and 10.8% for 2013) in the normal years, whereas its performance during the drought years was unsatisfactory (NRMSE of yield simulation was 21.6% for 2014 and 76.5% for 2015), which was attributed partly to the neglect of the longer ASI, failure to reach silking, or delayed phenology, causing a decrease in yield. Above all, drought stress during the yield critical period affected maize phonology (anthesis to silking stage) to some extent, affecting kernel number and grain yield. Thus, it is necessary to study the modeling of maize yield under drought stress based on ASI and silking dynamics by coupling the plant biomass framework.
Variations and effects of climate in growth period of Lycium barbarum L. in Ningxia
LI Xiangfang, LI Dongliang, DUAN Xiaofeng, LIU Yao
2019, 27(12): 1789-1798. doi: 10.13930/j.cnki.cjea.190477
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In order to clarify the characteristics of climate change (1961-2017) in the growing season of Lycium barbarum and its impact on L. barbarum growth in Ningxia, and to provide corresponding data for effective utilization of climatic resources and scientific theoretical basis for the production and decision-making department of L. barbarum, the characteristics of climate change during the growth period of L. barbarum and its effects in Ningxia were analyzed by Mann-Kendall mutation detection, climatic tendency rate and correlation test, based on the observations of 17 meteorological stations in Ningxia from 1961 to 2017. Results showed that warming and drying were the main characteristics of climate change during the growth period of L. barbarum in Ningxia. Over the past 57 years, the average temperature, ≥ 10℃ accumulated temperature and sunshine hours during the growing period of L. barbarum in Ningxia increased due to climate warming, and the linear trend passed 0.001 significance level test. Average temperature changed abruptly around 1990, and increased by 0.7℃ during 1991-2017 compared with 1961-1990. ≥ 10℃ accumulated temperature had the maximum increase rate in 1990s, and abruptly changed in 2003. After that, annual ≥ 10℃ accumulated temperature increased by 370.6℃. Annual sunshine hours increased by 93.9 h in 2005 compared with before 2005. Precipitation showed a weak decreasing trend in 1961-2017. Effects of climate change on the growth of L. barbarum had more advantages than disadvantages. With the increase of air temperature and the rapid rise of air temperature in spring, the germination period of L. barbarum shifted to an earlier date, the total growth period was prolonged, and the yield per unit area was increased, which was beneficial to agricultural production. The decrease of precipitation during fruit ripening and picking period reduced the occurrence of anthracnose and improved the quality of L. barbarum. Furthermore, there was a significant positive correlation between the accumulated temperature from the date of passing 5℃ to the germination stage of L. barbarum, the ≥ 10℃ accumulated temperature and the yield of L. barbarum in Zhongning. Meanwhile, climate warming increased soil moisture evaporation in winter, which lead to an increasing trend on incidence of pests and diseases of L. barbarum. It needs a further research on how to make full use of favorable climatic resources, to avoid or alleviate the adverse effects of climate change on L. barbarum production.
Effects of kernel size and sowing depth on maize root growth in the middle Sichuan hilly area
ZHOU Fang, CHENG Qiubo, JIN Rong, DU Lunjing, LI Xiaolong, CHEN Xiang, LIU Binxiang, YUAN Jichao, KONG Fanlei
2019, 27(12): 1799-1811. doi: 10.13930/j.cnki.cjea.190307
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Poorly executed mechanized seeding and frequent occurrence of seasonal drought in the hilly areas in middle Sichuan compresses the growth of maize. Using the main cultivar for this region, 'Zhenghong505', and adopting a split zone design with field and pot experiments, the effects of different kernel sizes and sowing depths on the growth and distribution of roots at the seeding and ear stages of maize were studied to provide a theoretical basis for mechanized precision sowing and drought-resistant cultivation of maize in this region. The results were as follows:1) Larger kernels and an appropriate shallow sowing depth (2-6 cm) can both significantly increase the germination rate. Compared with deep sowing (10 cm), the germination rate under shallow sowing (2 cm) increased by 6.5%. 2) The length, surface area, volume, and dry weight of roots arising from large kernels were significantly greater than those from small kernels. Although the differences in root growth gradually reduced with the growth process, the length, surface area, volume, and dry weight of the roots were still 28.6%, 25.0%, 22.4%, and 11.4% higher, respectively, than for small kernels at the silking stage. 3) At the 3-leaf stage, the root length, surface area, volume, and dry weight of roots arising from kernels planted at 2 cm and 6 cm were significantly higher than for those sowed at 10 cm depth, and these parameters for roots from kernels planted at 10 cm surpassed those for kernels planted at 2 cm by the 5-7-leaf stage. The length, surface area, volume, and dry weight of the roots arising from kernels planted at 10 cm at the silking stage were significantly higher (17.1%, 11.9%, 14.0%, and 10.4%, respectively) than those at the 2 cm sowing depth, and the roots in the 10-20 cm soil layer contributed to an increase in yield. 4) Kernel size had little effect on root distribution, but a sowing depth of 10 cm increased the root distribution rate in soil layers below 10 cm. 5) Yields from large and medium kernels were significantly higher (9.1% and 7.3%, respectively) than those from small kernels. Deep sowing effectively increased yields by 11.8% at 6 cm depth and 26.3% at 10 cm sowing depth compared with sowing at 2 cm. Large kernels were conducive to the establishment of well-developed roots, whereas sowing at an appropriate depth was conducive to the growth and downward distribution of roots in the middle and late stages, thereby increasing their water absorption capacity and drought resistance, ultimately achieving the increase in yield. Therefore, when planting maize, large and medium kernels should be selected and sown deeper appropriately.
Impact of ozone stress on thermodynamic characteristic values of rice starch and the differences between superior and inferior grains
ZHANG Yanliu, MU Hairong, SHAO Zaisheng, JING Liquan, WANG Yulong, YANG Lianxin, WANG Yunxia
2019, 27(12): 1812-1822. doi: 10.13930/j.cnki.cjea.190329
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As a strong oxidant, ozone pollution not only threatens human health but also negatively affects plant life. Elevated concentrations of ground-level ozone reduces rice yield and tends to deteriorate grain quality traits, including appearance, nutritional value and taste. However, the effect of ozone stress on the thermodynamic characteristics (DSC) of rice starch in respect of growth season, variety, and grain position on a panicle is not well-known. In this study, a glasshouse-type gas fumigation platform was used to examine how ozone stress affected the DSC of rice grains located at different positions on a panicle. Plants of eight rice varieties were exposed to ozone fumigation from the plant tilling stage until plant maturity. Two levels of ozone concentration, 100 nL·L-1 and 9 nL·L-1 were applied to rice plants as ozone stress treatment and control, respectively. At harvest, according to their positions on a panicle, rice grains were separated into three groups:superior grains, inferior grains, and medium grains, according to their position in a panicle-upper part, lower part and middle part of panicle. The DSC values of rice starch from the different groups were measured. The study showed that ozone stress significantly reduced the enthalpy value of brown rice by 4.15% compared with the control, but it had no significant effect on the gelatinization starting temperature, the peak gelatinization temperature, the gelatinization termination temperature, and the peak width and peak height of the DSC curve. In 2017, the enthalpy value, gelatinization peak temperature, gelatinization starting temperature, and peak height of brown rice were significantly higher than the values in 2016. However, the opposite trend was observed for the peak width of the DSC curve. There were significant differences among rice varieties in respect of the DSC characteristic values of rice starch. All the DSC values of grains at different positions on a panicle were in the order of upper part > middle part > lower part, and the differences were statistically significant, apart from the case of the gelatinization starting temperature. Results of ANOVA revealed significant ozone by year interactions for enthalpy value, gelatinization peak temperature, and gelatinization termination temperature, and significant ozone by variety interactions for gelatinization peak temperature, gelatinization termination temperature, and peak width and peak height of the DSC curve. Meanwhile, ANOVA revealed significant ozone by grain position interactions only for the peak width of DSC curve. The findings demonstrated that the DSC thermodynamic parameters of rice grains varied with the growing season, the varieties tested, and the grain position on a panicle. Ozone fumigation during the rice growing season reduced the enthalpy value of grains at different positions on a panicle, which indicated ozone-stressed rice grains are prone to gelatinization.
Relationships of Zanthoxylum bungeanum yield with topography and soil fertility in Jiulongpo area
YANG Shixi, LYU Guangbin, HUANG Yun, XIANG Huahui, WANG Zhengyin
2019, 27(12): 1823-1832. doi: 10.13930/j.cnki.cjea.190127
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The relationships of soil nutrient conditions and topography with production in Jiulongpo Zanthoxylum bungeanum planting areas was studied through a field investigation-based research and lab analysis to provide a theoretical basis for scientific and effective fertilization practices. The characteristics of altitude and slope, and soil pH, organic matter content, macro- and micro-elements content, cation exchange capacity (CEC) and exchange acidity as well as Z. bungeanum yeild in low-, medium and high-yield areas of Z. bungeanum were investigated. The results showed that Z. bungeanum was generally planted at altitudes between 200 and 500 meters in Jiulongpo, and the altitude of the high-yield area was approximately 300 meters. The slope from low-to high-yield areas appeared to be slight increase but not obvious. The soil was acidic, with a pH < 6.5; and soil fertility was high, with large differences in nutrient factors. CEC and available phosphorus, calcium, magnesium, iron, manganese, copper, and zinc were abundant at 27.2 cmol(+)·kg-1, 35.2 mg·kg-1, 3 289.8 mg·kg-1, 271.8 mg·kg-1, 48.6 mg·kg-1, 62.1 mg·kg-1, 1.5 mg·kg-1, and 4.5 mg·kg-1, respectively. Organic matter and available nitrogen, potassium and exchange acid were at a moderate levels of 19.1 mg·kg-1, 114.9 mg·kg-1, 107.0 mg·kg-1 and 8.1 cmol(+)·kg-1, respectively. The content of water-soluble boron was a relatively low 0.28 mg·kg-1. Z. bungeanum yield exhibited a positive correlation with available calcium, CEC, pH, available manganese, and water-soluble boron. Available calcium, CEC, exchange acidity, and available copper, iron, and zinc were the main influencing factors on yield. An optimal linear regression equation of available calcium (X6) and yield (Y) was established based on stepwise regression analysis (Y=11.693 + 0.003X6). In conclusion, soil nutrient in Jiulongpo Z. bungeanum area was imbalanced seriously, more attention should be paid to balancing fertilization, increasing organic fertilizer, improving the physical and chemical properties of soil, and relieving soil acidification.
Analysis of water use efficiency and driving factors in the Beijing-Tianjin-Hebei Province Plain using the Copula method
LONG Xuezhi, LIU Suxia, MO Xingguo, CHEN Xuejuan
2019, 27(12): 1833-1845. doi: 10.13930/j.cnki.cjea.190340
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Agricultural irrigation accounts for>65% of water use in the Beijing-Tianjin-Hebei Province Plain. Improving the agricultural water use efficiency will help relieve the pressure on the water resources found in the Beijing-Tianjin-Hebei Plain and promote sustainable development. Based on water use efficiency (WUE), net primary productivity (NPP), and actual evapotranspiration (ETa) from 1980 to 2013 simulated by the VIP model, combined with the annual mean air temperature (Tmean), annual precipitation (Pre), and annual sunshine duration (Sun), the Copula method was used to create five groups of joint probability distributions:WUE and NPP, ETa, Tmean, Pre, and Sun. Conditional probability was calculated based on the hypothesis that WUE was greater than any particular value under low, medium, and high value ranges of each driving factor. The findings showed that the greater the values of NPP, ETa, and Sun, the more likely was WUE to be greater than any particular value. However, the lower the values of Tmean and Pre, the more likely was WUE to be greater than any particular value. The sensitivity of WUE to variation in the value of each driving factor was reflected by the difference of the conditional probability of WUE under high and low value ranges, suggesting that WUE was most sensitive to the variation in the value of NPP followed by those of Sun, ETa, Pre, and Tmean. Comparison of the conditional probabilities of WUE under the same value conditions of NPP, ETa, Tmean, Pre, and Sun showed that a lower NPP clearly suppressed WUE and that improvement in NPP guaranteed a higher value of WUE. Crop WUE is controlled simultaneously by photosynthesis and transpiration, which makes it difficult to ascertain the driving mechanism underlying WUE. Based on the joint probability distribution determined using the Copula method and conditional probability analysis, we concluded that improving NPP when water consumption is controlled may be a more effective strategy than reducing water consumption when grain yield is controlled to adopt in the Beijing-Tianjin-Hebei Province Plain.
Agricultural Resources and Environment
Application of native wildflower mixtures in agricultural landscapes
HU Wenhao, NA Shuhao, LI Xuedong, LI Xiang, YU Zhenrong, WANG Wenjing, DUAN Meichun
2019, 27(12): 1846-1856. doi: 10.13930/j.cnki.cjea.190262
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The use of native wildflower mixtures, a kind of landscape vegetation planting method that mainly selects native wildflowers and establishes communities via mixed sowing, has become a popular technical measure for agricultural landscape restoration in Europe, America, and elsewhere in recent years. Studies have reported that native wildflower mixtures can improve habitat quality and landscape structure, attract pollinators and natural enemies, and enhance pollination and pest control functions in agricultural landscapes. Moreover, researchers have found that the combination of native wildflowers is an important method for landscape construction. The design of native wildflower mixtures plays an important role in the establishment of planting; therefore, the selections of species, their proportion, and sowing method and layout are important issues that ought to be resolved in the design. Based on a summary of European and American experiences of designing of native wildflower mixtures and biodiversity monitoring, we observed that the nativization, diverse functions, and inclusion of key species play important roles in plant selection. Further, we discussed the detailed techniques for the design, such as the growth cycle, species and seeding quantity, seeding area, and spatial layout, to promote the localization of native wildflower development. Native wildflower mixtures are an important technology for achieving agricultural landscape restoration. In European and American countries, a series of relevant policies have been proposed to promote industrial development and farmers' subsidies. In European countries, numerous legislative and agricultural environmental protection policies have been established to provide farmers with various ecological subsidies to promote their complete participation in the process of local wildflower combination planting. However, in China, there is a lack of cases in which mature local wildflower combinations have been applied. Therefore, it is necessary to completely explore the germplasm resources and evaluate the ecological, cultivation, and landscape characteristics of native wildflower combinations in China to achieve native wildflower combinations. To this end, the present study proposes the realization of the design and promotion of rural wildflower combinations via multidisciplinary cooperation. The government, companies, research institutions, and farmers should all participate in the process of designing rural wildflower combinations and propose market-oriented ecological subsidy policies to promote the same. The application of native wildflower combinations in the field of agricultural landscape restoration could contribute to improving the agricultural ecology in China.
Spatiotemporal characteristics of cultivated soil fertility in the intensive agricultural region of North China: A case study of Quzhou County in Hebei Province
SUN Xiaobing, ZHANG Qingpu, KONG Xiangbin, WEN Liangyou, ZHAO Jing, LIU Fengjian
2019, 27(12): 1857-1869. doi: 10.13930/j.cnki.cjea.190397
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Fertility is a fundamental characteristic of soil, reflecting its ability to provide nutrients and an environment essential for plant growth. It is a comprehensive reflection of soil's physical, chemical, and biological properties. Scientifically and accurately evaluating the soil fertility in cultivated land and revealing the spatiotemporal characteristics of soil fertility are of great significance for guiding agricultural production and sustainable use of cultivated land resources. The present study focused on Quzhou County, a typical county in the region of intensive agriculture in North China. Based on the test data of soil sample points of cultivated land and data of cultivated land utilization, fuzzy comprehensive evaluation and geostatistical methods were used to evaluate the soil fertility of cultivated land to reveal the spatiotemporal evolution of cultivated land soil fertility. The results showed that soil organic matter, total nitrogen, available phosphorus, and available potassium of the cultivated land increased, whereas pH decreased, from 2000 to 2018, which were all affected by both structural and stochastic factors. The mean soil fertility index of cultivated land increased from 0.25 to 0.54 from 2000 to 2018, and the growth rate was 116.00%. The soil fertility of cultivated land changed from a lower level to a medium level, and the overall degrees of variation and spatial autocorrelation were at medium levels. The levels of soil fertility of cultivated land in 2000 and 2018 were mainly grades Ⅱ and Ⅲ, accounting for 83.92% and 50.43%, respectively, these lands were widely distributed in all towns except for Houcun and Yizhuang. The levels of cultivated land soil fertility of grades Ⅰ and Ⅱ decreased, whereas those of grades Ⅲ, Ⅳ, and Ⅴ increased from 2000 to 2018, and the Ⅱ degree transferred area and slightly increased area were the largest. The area of conversion from grade Ⅱ to grade Ⅲ was the largest, accounting for 59.49% of the total area, and the tendency for a slight increase in soil fertility of cultivated land was most common, accounting for 52.59% of the total area. However, the cultivated land areas of highest grade and with the highest increase were relatively small, constituting only 1.86% and 3.34%, respectively, of the total area. The results showed that, with the exception of pH, the nutrient features of cultivated soil increased in Quzhou County from 2000 to 2018, and the quality of cultivated land soil fertility changed from low to medium, which was affected by the natural background and manmade agricultural production activities. Therefore, the effective balance and coordination of soil nutrient content are helpful to improve soil fertility and sustainable use of land resources.
Resource utilization of invasive Spartina alterniflora: A review
XIE Baohua, LU Feng, HAN Guangxuan
2019, 27(12): 1870-1879. doi: 10.13930/j.cnki.cjea.190339
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In China, Spartina alterniflora, an invasive alien plant species, covers an area of approximately 54 600 hectares. The total dry matter of the aboveground part of S. alterniflora is 7.5×105~1.15×106 tons per year. The control and utilization of S. alterniflora have received increasing attention. A combined utilization and control approach could produce simultaneous economic and ecological benefits. Studies of the utilization of S. alterniflora in China tended to focus on the direct utilization of straw, including its use as fuel, feed, and raw material. These methods of utilization were generally low-value. Possible high-value utilization includes the medicinal value of S. alterniflora and its salt-tolerant genes. In all the studies, the largest proportion (43%) of straw was utilized as fuel, whereas the smallest proportion (approximately 8%) was utilized for other purposes, such as fertilizer and for its salt-tolerant genes. Previous studies have focused on utilization technologies, but they have not looked at S. alterniflora collection technology and market promotion. In the future, attention should be paid to every link of the industry chain of S. alterniflora utilization, and cooperation between research institutions and enterprises is essential for the synchronous development of industry, education, and research.
Research progress in the impact of land use on water nutrients
XU Erqi
2019, 27(12): 1880-1891. doi: 10.13930/j.cnki.cjea.190110
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Increasingly severe water pollution is a threat to human health and survival, and eutrophication is one of the main challenges faced by pollution governance. Because land use is closely related to water nutrients, quantifying the relationship would be an effective way to support the optimization of land use to improve water quality. Based on international and domestic researches, this study reviewed four methods, e.g., plot experiments, statistical analysis, empirical models, and mechanism models, for studying the effects of land use on water nutrients. The advantages and disadvantages of the application of each method were examined. Until now, studies have been conducted mainly to characterize the quantitative structures of land use. However, there is a limitation in the quantification of the intensity and spatial distribution of land use, and a model of the relationship between land use information and water nutrients is lacking. Research progress has found that multiple land use information was loosely studied from an individual or a partial perspective. This easily led to a significant difference in the explanatory power of land use on water nutrients in different case studies. Thus, research progress was particularly summarized on how three aspects of land use information (land use type, use intensity, and spatial distribution) influence water nutrients. The controversy and uncertainty about the scale effect of the quantitative relationship between land use and water eutrophication have been discussed. The main shortcomings of recent studies were concluded, which included the inadequate capability of approaches for correlating land use to water nutrients, unclear mechanism underlying multiple land use information related to water nutrients, and uncertainty about the abovementioned scale effect. To resolve these issues, this study proposed a breakthrough framework of comprehensive expression and quantification of multiple land use information space that was based on the ecohydrological processes affecting the export, migration, and transformation of water nutrients. Using this proposed multiple land use information space, future studies could focus on integrating process mechanism and empirical statistical methods, comprehensively quantifying multiple land use indicators related to eutrophication, and constructing multiscale structures of land use affecting water nutrients. This study can provide a guide for deep investigation of the relationship between land use and water nutrients.
Accumulation characteristics and health risks of heavy metals in vegetables in typical urbanized areas
ZHAO Hui, HE Bo, MENG Jing, ZHOU Yunqiao, SHI Bin, WANG Tieyu
2019, 27(12): 1892-1902. doi: 10.13930/j.cnki.cjea.190199
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Heavy metal pollution-related problems due to industrialization and urbanization are of great concern, and they pose severe threats and challenges to environmental quality, food safety, human health, and sustainable socioeconomic development. This study examined vegetables and soils in areas with intensive electroplating and dyeing industries. Vegetable and soil samples were collected, and single-factor pollution assessment and the Nemero comprehensive pollution index were used to evaluate the pollution levels of five heavy metals, i.e., Cd, Ni, Cr, As, and Pb, in vegetable samples. Further, the target hazard quotient method was used to assess health risk. Pollution by Cd was found in the vegetable soil in the study area. Enrichment and absorptive capacity of heavy metals in vegetable samples in the study area were in this order:Cd > Ni > Cr > As > Pb. Leafy vegetables had the highest Cd enrichment, whereas beans had the highest Ni enrichment. Single-factor pollution assessment revealed that the over-standard rate of heavy metals in the vegetable samples was in this order:Ni > Cr > Cd > Pb=As; moreover, the over-standard rates of Ni, Cr, and Cd were 10.53%, 2.63%, and 1.32%, respectively, and the content of Pb and As in the vegetable samples did not exceed the standard content. Nemero evaluation of the samples revealed that leafy vegetables had a mild level of pollution, beans had a moderate level of pollution, and melons were not contaminated by heavy metals. Health risk assessment revealed that the comprehensive target hazard quotient (TTHQ) of leafy vegetables and beans was>1 and that the long-term consumption of leafy vegetables and beans in the study area would adversely affect health. The TTHQ for adults and children was as follows:leafy vegetables > beans > melons. The health risks posed by the intake of heavy metals in food were higher for children than for adults. In general, the health risks posed by heavy metals in vegetables in the study area were within the acceptable range, but the health risks posed by Cd in leafy vegetables and Ni in beans need serious consideration.
Agricultural Ecologic Economics and Ecoagriculture
Carbon effect of modern tobacco agriculture: Based on tobacco cooperatives in Shaanxi Province
ZHANG Ruoyan, CHEN Ru, WANG Xiujuan, JIANG Zhide
2019, 27(12): 1903-1915. doi: 10.13930/j.cnki.cjea.190402
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Greenhouse gas emission from agriculture activities have an important impact on global warming. As the part of the agriculture system, tobacco agriculture has the obligation to address the climate change in the background of Ecological Civilization Construction and Rural Revitalization. To Explore the carbon effect of tobacco agriculture in Shaanxi Province and formulate effectively emission reduction policies to promote the low-carbon tobacco agriculture development, this paper constructed the comprehensive carbon effect accounting system of the tobacco agricultural, calculated the carbon emission, carbon sink, net carbon sink, and analyzed the carbon efficiency, carbon intensity and other comprehensive carbon effect indexes through all production processes of the 393 farmers who engaged in tobacco agriculture from tobacco professional cooperative in Shaanxi Province. The results showed that:for the total 641.17 hectare tobacco fields in the survey area, the total carbon emission was 3 276.27 t C, and the average carbon emission per hectare 5.11 t C, among which the agricultural energy consumption was the largest emission, and the percentage of total carbon emission was 68.21%. Next was the agricultural material inputs which accounted for 24.88% of the total carbon emissions. The agricultural waste disposal, the farmland management, and the farmland soil's nitrous oxide emission accounted for low proportion of carbon emission. The order of average carbon emission per hectare for each region from large to small was Baoji, Shangluo, Ankang and Hanzhong. The total carbon sink was 1 361.86 t C, the average per hectare of the carbon sink was 2.12 t C. Soil carbon sequestration caused by straw returning, no-tillage, and rational applying the chemical fertilizer and organic fertilization accounted for 81.12% of the total carbon sequestration. The average carbon sequestration per hectare in each region was ranked as Shangluo > Baoji > Hanzhong > Ankang. The total net carbon sink was -1 914.41 t C, and the net carbon sink per hectare was -2.99 t C. The total carbon emission of tobacco agriculture was greater than that of carbon sink, showing negative net carbon sink effect. Therefore, it is important to develop the low-carbon modern tobacco agriculture to promote low-carbon technological progress and explore the clean energy instead of coal in the bulk curing barn for flue-cured tobacco. In addition, by adopting measures such as adjusting management and operation mode, optimizing the input structure of farmers, improving the utilization efficiency of agricultural resources, improving tobacco agricultural technology and changing farming methods, Hanzhong Tobacco Professional Cooperative presented the optimal comprehensive carbon effects such as carbon efficiency, carbon intensity, carbon density, and maximize the net carbon sink per hectare.
Evaluation of ecological and economic benefits of pomelo orchards with different grass growing systems based on emergy analysis
LUO Xuhui, LU Xinkun, LIU Cenwei, ZHANG Lijun, CHEN En, Gordon W. Price, WENG Boqi
2019, 27(12): 1916-1924. doi: 10.13930/j.cnki.cjea.190458
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Honey pomelo[Citrus. grandis (L.) Osbeck. cv. Hongroumiyou] is the dominant crop in Pinghe County, Fujian Province; however, this historically fruit is facing production challenges. The practice of grass cultivation, rather than grass clearing, in the pomelo orchards is an important method to promote sustainable development in the honey pomelo industry. In order to clearly evaluate the effects of grass management pattern on the ecosystem, the economic and ecological benefits, two cultivation techniques, grass cultivation and grass clearing, were compared in orchards growing honey pomelo located in Qianlin Village, Wuzai Town, Pinghe County in 2017-2018. An emergy methodology was used to compare the two systems by calculating indices of emergy self-sufficiency ratio (ESR), emergy investment value (EIV), emergy yield ratio (EYR), environmental load ratio (ELR), efficient emergy yield ratio (EEYR), and emergy feedback rate (EFR). Results of the emergy indicators for orchards with grass cultivation or with grass clearing were:ESR, 0.003 for both; EIV, 339.291 and 295.763; EYR, 1.003 for both; ELR, 0.348 and 0.321; EEYR, 4.57 and 2.90-7E J·sej-1; and EFR, 0.002 and 0.000; respectively. Compared to grass clearing, grass cultivation had a lower total energy input of 9.21%, a smaller non-renewable natural resources input of 76.71%, and a higher EIV resulting from the rapid decrease of natural energy input and the relatively low cost of purchased emergy input. The grass cultivation pattern showed better economic vigor with an increase of the commercial emergy of 1.00+E sej·hm-2(versus 4.60+10E J·hm-2 for grass clearing). The ratio of labor emergy input to the total was 70.45%-72.90%. The main contributors to labor input were fruit picking, daily management, and water-soluble fertilizer spraying. Although labor for weeding increased under grass cultivation, with a value of 1.31+16E sej·hm-2, total labor energy input decreased by 3.30+16E sej·hm-2 and labor efficiency rose by 17.50% through improvements in daily management and labor savings on pesticide spraying, fertilizing, and organic fertilizer transport. The environmental loading ratio in the cultivated grass system rose, with a value of 0.027 because of purchasing resource savings on organic fertilizers and labor. This study demonstrated that honey pomelo production incorporating a cultivated grass regime had the potential to improve commercial fruit production, increase farmer incomes, and provide a more sustainable production system, and such a management pattern would benefit supply-side reform.
Effect of environmental regulations and village regulations on farmers' green production willingness: Taking the resource use of livestock and poultry waste of large-scale pig farmers as an example
XIA Jiaqi, HE Ke, ZHANG Junbiao
2019, 27(12): 1925-1936. doi: 10.13930/j.cnki.cjea.190407
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Abstract:
Pollution from pig breeding is a major contributor to agricultural pollution. However, existing environmental regulations have limited role, because it may not be well integrated into local informal system. This paper considers the environmental regulations to the farmers' willingness of green production and innovatively adds the village regulations, using large-scale pig farmers in Hubei Province as the research object as well as the structural equation model to study the influence of environmental regulations and village regulations on pig farmers' willingness to recycle livestock and poultry waste, and explore the mechanism of the influence of formal institutions and informal institutional factors on the willingness of large-scale pig farmers to use resources. The findings reveal that:1) environmental regulations have a significant positive effect on large-scale pig farmers' willingness; 2) village regulations have a significant positive effect on large-scale pig farmers' willingness; and 3) village regulations play an intermediary role in the impact of environmental regulations on large-scale pig farmers' willingness to use these resources. Restrictive environmental regulations have an indirect effect on the willingness of large-scale pig farmers to use these resources through normative village regulations, and guiding environmental regulations have an indirect effect on this willingness through cultural village regulations. Based on these findings, this study proposed the following policy implications. In the process of rural environmental governance, the government should improve the environmental regulations, standardize the village rules and regulations, and give full play to the advantages of both in practice, so as to make the environmental regulations "propriety" and the village rules and regulations "reasonable".

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