中国生态农业学报(中英文)

Agricultural land sharing/sparing and their potential effects on biodiversity

YANG Mei, LIU Zhangyong

2017, 25(6): 787-794. doi: 10.13930/j.cnki.cjea.160996

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Abstract:
Agricultural systems are complicated by both the efforts to produce food and protecting biodiversity. Intensive agriculture is the main reason for the decline in agro-biodiversity across the world. Land sparing and land sharing have been important land use strategies in maintaining a balance between food production and biodiversity conservation. The former advocates the improvement of farm environments and therefore expected to be a wildlife-friendly landscape. However, the latter proposes that the land should divide into two categories, one for intensive land utilization, the other one for biodiversity conservation. Thus a debate has risen as to which approach was better for biodiversity. In this review, we highlighted the benefits and limits of the two land use strategies and the effects of each on biodiversity. Furthermore, the factors were discussed, which guided the choice towards any of the land use strategies, including plant species sensitive to intensive farming, landscape-specific conditions, landscape scale/structure and socio-economic factors. On this basis, the resourceful application of the two land use approaches in future agriculture development was proposed. This included: 1) designing agricultural landscape structure suitable for local circumstances, e.g., yield potential and conservation of endemic species; 2) promoting sustainable agricultural intensification and enhancing the management of "spillover effects" to increase the recovery ability of the ecosystem; and 3) developing intermediate approaches or mixtures of land sharing and land sparing at different spatial scales, e.g., planting trees on farms in intensive agricultural areas.

Process analysis of land destruction and reclamation in coal mining areas using ecological risk assessment

SUN Qi, BAI Zhongke, CAO Yingui

2017, 25(6): 795-804. doi: 10.13930/j.cnki.cjea.170113

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With the development of coal mining and land reclamation, the landforms and environmental conditions in mining areas have been disturbed. It is necessary to take positive initiatives to prevent eco-risks during mining exploitations and construct a key ecological civilization and socio-economic development. This paper used Pingshuo Coal Mine in Shanxi Province as a case study to analyze and build an evaluation model of dynamic ecological risks in coal mining areas. Using 30 m×30 m grid units, the study evaluated, mapped and classified at unit grid scale ecological risks in the mining area. Based on the study, the ecological risk in the mining area varied with land destruction and reclamation processes. A model of the cumulative effect of land destruction was used to assess risk sources. Also remote-sensing images and field measured data were used to calculate the values of ecological vulnerability index in the region. Through index calculations, the ecological risk values for the mining area were determined for 2001 and 2010. Also through the combination of existing remote-sensing techniques with field measurements, the values were reasonably up-scaled for the entire area with a highly visualized evaluation results. Then the effects of potential risks were determined and optimized land use forms and mining technology identified using the dynamic changes in ecological risk. The results showed that with increasing coal production, the cumulative affecting area of land destruction increased by 7 095.17 hm² from 2001 to 2010. However, the cumulative effect decreased obviously for reclaimed dumps. With the continuous eastward open-pit mining, the effect of mining on the west region of the study area weakened. After 10 years of land reclamation and ecological reconstruction, ecological risks in reclaimed dumps declined and the ecosystem seemly stabilized. The medium and low risk area accounted for 0.02% of the disturbed area due to mining in 2001 and up to 16.77% in 2010. This implied that land reclamation reduced the effects of ecological risk in the region. The combined risk value for open-cast and underground mining was unstable, with a value of ecological risk as low as 0.45 or as high as 0.80. The risk of partial uneven subsidence and soil erosion clearly increased in frequency and intensity in the area. The study demonstrated that the analysis of ecological risk could reflect the processes of land destruction and reclamation via mining, changes in ecosystem structure and function, and the spatial heterogeneity in space-time fabric. Hence such analysis was a reference base for planning environment recovery and regional development. As a source of risk for the regional ecosystem, land reclamation in mining areas should focus on increasing the ecological functions of reclaimed areas.

Continuum removal method for monitoring Fulvia fulva morbidity using hyperspectral data

JIA Fangfang, HONG Quanchun, SONG Weiyi

2017, 25(6): 805-811. doi: 10.13930/j.cnki.cjea.161107

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Fulvia fulva is a major disease in tomato cultivation. Compared with traditional laboratory analysis method, hyperspectral remote-sensing technology can provide simple, cost effective and non-destructive information that can offer processing methods for diagnosing and quantifying plant health. However, there are many limitations (e.g., large volume of data, redundant information and complex spectral) in dealing with hyperspectral data. This paper aimed to clarify the spectrum characteristics of tomato leaf infected by F. fulva and estimate its morbidity degree to provide theoretic basis for large-scale monitoring of F. fulva using hyperspectral remote sensing. To this end, experiments were carried out in 2016 in with disease nursery of tomato F. fulva in Shangqiu. In the research, leaf spectral reflectance of tomato was acquired via ASD FieldSpec 3 spectrometer (350-2 500 nm). The continuum removal method was adopted to process the original spectrum reflectance of tomato leaf with different morbidity degrees of F. fulva. The bands sensitive to F. fulva morbidity degree were selected and an inversion model of morbidity degree established based on absorption parameters of the spectrum features. The results showed that spectral reflectance of healthy tomato plants was higher than that of disease plants in the wavelength range of 350-2 500 nm. Besides, the reflectance, spectral sensitivity and relative reflectance decreased with increasing F. fulva morbidity degree. The most sensitive wave bands for distinguishing F. fulva severity were located in the visible region (550-730 nm) and shortwave infrared region (1 860-2 260 nm). With increasing F. fulva morbidity degree, the absorption position (λ) of both visible spectrum and shortwave infrared spectrum moved to the short wavelength band, while the maximum absorption depth (D_c) and area (A) increased. Particularly, the morbidity degree had a very significant correlation with maximum absorption depth in visible band (D_c1), maximum absorption area in shortwave infrared band (A₂), maximum absorption depth in shortwave infrared band (D_c2), position of maximum absorption depth in visible band (λ₁) and position of maximum absorption depth in shortwave infrared band (λ₂). Consequently, a stepwise regression model for F. fulva morbidity degree was built based on the spectral absorption parameters. The model had good validation results, with determination coefficient (R²) of 0.81. The results of the study not only contributed to the estimation of F. fulva morbidity degree using hyperspectral remote-sensing data, but also had promising values of practical application in monitoring and preventing crop diseases.

Effect of partial replacement of inorganic N with organic manure on crop yield and soil nutrient balance in arable ecosystem in karst peak-cluster depression

FU Wei, LIU Kunping, CHEN Hongsong, CHEN Xiangbi, LIN Haifei, ZHANG Wei, WANG Kelin

2017, 25(6): 812-820. doi: 10.13930/j.cnki.cjea.161016

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Abstract:
Based on a long-term experiment on maize-soybean relay intercropping system in the karst peak-cluster depression in Guangxi, the effects of organic nitrogen (manure) in place of chemical nitrogen (fertilizer) on crop yield and soil nutrient balance were investigated. The experiment was started in 2006, and the data were collected in 2010-2014. Four treatments with four repetitions were designed in the study—including CK (no fertilizer), NPK (chemical fertilizer in maize at N 200 kg·hm^-2, P₂O₅ 90 kg·hm^-2, K₂O 120 kg·hm^-2; and in soybean at N 22.5 kg·hm^-2, P₂O₅ 60 kg·hm^-2, K₂O 67.5 kg·hm^-2), C7M3 (the total amounts of N, P and K were same as NPK treatment, in which 70% N was from chemical fertilizer and 30% N from organic cattle manure), and then C4M6 (60% N was from organic cattle manure and 40% N from chemical fertilizer, the amounts of P and K were the same as the treatment NPK). The results showed that: 1) compared with CK, treatments of NPK, C7M3 and C4M6 all increased soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP) and available potassium (AK). Furthermore, SOM content in C4M6 was significantly higher than that in NPK (P < 0.05). The contents of TN, AP and AK increased with increasing organic manure supplement. 2) The yields of maize and soybean in the fertilizer treatments were respectively 4.15-4.36 and 2.47-2.58 times higher than that in CK. Crop yield order in fertilizer treatments was C4M6 > NPK > C7M3, but there was no significant difference among treatments (P > 0.05). 3) For CK treatment, maize yield decreased by 5.45 g·m^-2·a^-1, while soybean yield increased by 1.50 g·m^-2·a^-1 during experimental period. The yields of both maize and soybean increased under long-term fertilization as the experiment went on. 4) In the experiment, K deficit was observed in organic manure treatments and CK during maize growth period, but N deficit appeared in all treatments during soybean growth period. In the maize-soybean relay intercropping system, K deficit of 7.9 kg·hm^-2·a^-1 was observed only in C4M6. P surplus was observed for all fertilizer treatments with surplus amounts of 81.2 kg(P)·hm^-2, 83.4 kg(P)·hm^-2 and 74.8 kg(P)·hm^-2 in NPK, C7M3 and C4M6 treatments, respectively. In summary, based on the characteristics of nutrient balance and crop yield, that partial replacement of chemical nitrogen fertilizer by cattle manure was reasonable. We recommend that farmers should "reduce N, maintain P and increase K" during maize growth period, but should "maintain N and reduce P and K" in soybean growth period in maize-soybean agricultural ecosystem in karst peak-cluster depression areas.

Regulation effects of irrigation and nitrogen fertilization on nutrient absorption, water/nitrogen use efficiency and yield of rape

GAO Na, ZHANG Yulong, LIU Yu, LIAO Changjian, WU Hanqing, ZHANG Yuling, ZOU Hongtao, YU Na

2017, 25(6): 821-828. doi: 10.13930/j.cnki.cjea.161009

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Excessive fertilizer and irrigation are often used in greenhouse cultivation in order to ensure adequate and profitable yield of vegetables. This has led to the pollution of agricultural environment that in turn hindered sustainable agricultural development. Reasonable application of irrigation and nitrogen is vital for enhancing nutrient use efficiency and controlling non-point source pollution. Using a stable isotope of ¹⁵N-traced urea, a pot experiment was conducted to evaluate the effects of different irrigation and nitrogen applications on nutrient absorption, water/nitrogen utilization and yield of rape. The study included three irrigation levels[W₁, 60%θ_f (field capacity); W₂, 75%θ_f; and W₃, 90%θ_f] and four nitrogen rates (N₀, 0 g·kg^-1; N₁, 0.1 g·kg^-1; N₂, 0.2 g·kg^-1; and N₃, 0.3 g·kg^-1). The contents and absorptions of nitrogen, phosphorus and potassium by different parts of rape plant were determined along with water and nitrogen use efficiencies. The results suggested that both irrigation level and nitrogen application rate had significant effects on contents of N, P, K in the leaves and roots of rape plants. Besides, leaf P content was significantly affected by the interaction of irrigation and nitrogen. The contents of N and K in the leaves were much higher than those in the roots. While the content of P in the whole rape plant and N in the roots increased, the content of K in the whole plant and N in the leaf decreased with increasing irrigation. N application increased plant N and K contents, but reduced P content. There were significant effects of irrigation level and nitrogen rate on N, P and K uptake and the interaction effects were also prominent for P and K absorption. Medium irrigation level and low nitrogen rate (W₂N₁) had the highest nutrient uptake. The yield of rape was significantly affected by irrigation level and nitrogen rate. Yield increased with increasing irrigation level and a significant parabolic relationship was observed between nitrogen rate and yield. The application rate of nitrogen and the interaction of irrigation and nitrogen had a significant effect on irrigation water use efficiency (IWUE). Also the response of yield in terms of IWUE increased with increasing nitrogen application. Both irrigation and nitrogen fertilizer had significant effects on the utilization of fertilizer ¹⁵N. Besides, a statistically significant interaction was noted between water and nitrogen in terms of nitrogen recovery rate. Fertilizer ¹⁵N recovery rate increased with increasing irrigation level. The rates of ¹⁵N residue and ¹⁵N loss were respectively lowest and highest under medium irrigation level. With increasing nitrogen does, fertilizer recovery rate gradually decreased and the loss rate increased. It was concluded that for comprehensive nutrient uptake, yield output, and water and nitrogen utilization, W₃N₁ and W₂N₁ treatments were the best.

Effect of combined application of controlled-release urea and conventional urea under reduced N rate on yield and N utilization efficiency of rice

HUANG Qiaoyi, TANG Shuanhu, ZHANG Fabao, ZHANG Mu, HUANG Xu, HUANG Jianfeng, LI Ping, FU Hongting

2017, 25(6): 829-838. doi: 10.13930/j.cnki.cjea.160836

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Abstract:
The effects of different blending rates of controlled-release urea (CRU) and conventional urea (CU) at different nitrogen (N) application rates on the growth, yield, N uptake and N use efficiency of rice were studied to provide a reference base for the application and dissemination of CRU in rice production. Field experiments of rice were carried out in Taishan City and Wengyuan County in Guangdong Province during the 2015 rice growing season. Ten treatments were set in the experiment—conventional fertilization with 4 split applications (CF), single basal application of 25% CRU plus 75% CU (25%CRU) and single basal application of 50% CRU plus 50% CU (50%CRU), respectively, under 100%, 80% and 60% of conventional N rate[195 kg(N)·hm^-2, 156 kg(N)·hm^-2 and 117 kg(N)·hm^-2], and no nitrogen fertilization (CK). Tiller number and leaf SPAD values were measured at vegetative stages of rice. Straw and grain yield were collected at maturity for N analysis. Then yield and yield components were recorded after harvest. The results showed that there was no difference in tiller number at vegetative growth stages under different N fertilization treatments, and that leaf SPAD increased with increasing N application rate. With increasing N application rate, rice grain yield increased initially and then decreased. Also the highest rice grain yield was obtained under 156 kg(N)·hm^-2 treatment. N uptake of rice increased with increasing N application. At the same N rate, no differences was noted in grain yield, N uptake of rice grain and rice straw among CF, 25%CRU and 50%CRU treatments. With increasing N application rate, N partial factor productivity and N harvest index decreased gradually. For the same N rate, agronomic N use efficiency, N physiology efficiency under 25%CRU and 50%CRU treatments were higher than that under CF treatment (P < 0.05), with average increases of 14.99%, 17.23% and 98.22%, 57.44%, respectively. N harvest indices under 25%CRU and 50%CRU treatments were averagely higher by 6.99% and 6.69%, respectively, than that under CF treatment at conventional application rate[195 kg(N)·hm^-2], especially in Taishan City. Soil available N under 60% conventional N rate[117 kg(N)·hm^-2 ] treatment after rice harvest was significantly lower than that under 100% and 80% conventional N rate treatments. In conclusion, rice grain yield and N use efficiency under 25%CRU at 80% conventional N rate in both experiment sites were superior over those under other treatments. Therefore, single basal application of 25%CRU plus 75%CU with N rate of 156 kg(N)hm^-2 increased rice yield and N use efficiency, and maintained soil N fertility in Guangdong. This was a potential beneficial and rational N application mode for the region.

Effect of tillage practice on carbon footprint of rainfed winter wheat

LI Ping, HAO Xingyu, ZONG Yuzheng, GU Runsheng, JIA Shaohui, DONG Qi, GUO Liping

2017, 25(6): 839-847. doi: 10.13930/j.cnki.cjea.160981

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Abstract:
It is crucial to mitigate greenhouse gas emissions from soil and to abate carbon emissions from the production of goods (e.g., fertilizers, seeds, etc.) and production processes (e.g., diesel consumption by machines) for sustainable agricultural production. In order to evaluate carbon footprint and carbon emission intensity of different tillage practices in rainfed field, a 15-year long-term experiment with three different tillage practices was conducted in Linfen, Shanxi Province, a typical semi-arid area in North China. The investigated tillage management practices were rotary tillage without straw incorporation (RT), straw incorporation and rotary tillage (SRT) and straw-mulch and no-tillage (SNT). Carbon footprint in the production life-cycle of different tillage practice of rainfed winter wheat was explored, in which N₂O emissions from field were measured using the static chamber-gas chromatography method and the other emissions calculated by analyzing emissions from the production of main goods and the associated processes during life-cycle period of winter wheat. The results showed that N₂O emissions under SNT and RT management practices were 19.2% and 18.9% lower than that under SRT practice, respectively. N₂O emissions mainly occurred during the period from booting to maturity and then the period of summer fallow when soil temperature and moisture were most appropriate. N₂O emissions derived directly from nitrogen fertilizer and carbon emissions from the processes of chemical fertilizer production explained the most share of carbon footprint in the life-cycle of rainfed winter wheat, accounting for 21.6% and 46.4% of the total carbon footprints, respectively. N₂O emissions and carbon emissions derived from nitrogen fertilizer production and diesel consumption, and direct emission for field accounted for over 90% of the carbon footprint of rainfed winter wheat system. Carbon footprint under SNT practice was the lowest among three treatments, it was respectively 7.9%-11.0% and 6.9%-8.3% lower than those under SRT and RT. SNT management practice had the lowest carbon footprint among three tillage practices. Thus, straw incorporation with no-tillage was the most appropriate practice for sustainable agricultural production aimed at low greenhouse gas emissions and low carbon consumption in the semi-arid area of North China.

Winter wheat grain protein content monitoring model driven by hyperspectral remote sensing images at different growth stages

HE Jia, LIU Bingfeng, LI Shimin, GUO Yan, WANG Laigang, ZHANG Yan, LI Jun

2017, 25(6): 865-875. doi: 10.13930/j.cnki.cjea.161066

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Hyperspectral remote sensing data have strong band continuity, high spectral resolution and rich spectrum information. It can rapidly and nondestructively acquire vegetation information and it is an reliable real-time technology applicable in the monitoring and management of crop growth. Grain protein content (GPC) is an important indicator for wheat quality. Early detection of GPC of wheat using hyperspectral remote sensing data can enhance effective decision-making to support the acquisition and processing of high quality wheat. The objectives of this study were to establish GPC estimation model based on winter wheat canopy hyperspectral reflectance at different growth stages with different rates of nitrogen or phosphorus applications. The overall goal was to improve forecast precision of GPC estimation model at different growth stages of winter wheat. Thus experiments were carried out in 2009-2014 at Northwest A & F University, Shaanxi Province. The treatments included different winter wheat varieties with various drought resistances under five nitrogen fertilizer application rates (0, 75, 150, 225 and 300 kg·hm^-2 pure nitrogen) and four phosphorus application rates (0, 60, 120 and 180 kg·hm^-2 P₂O₅). Plant nitrogen content (PNC) and canopy hyperspectral reflectance of different wheat cultivars were measured at jointing, booting, heading, filling and maturity stages. Also GPC was measured at maturity stage. The relationship among PNC, canopy hyperspectral reflectance and GPC was explored using correlation analysis, regression analysis, grey relation analysis or partial least squares. The GPC monitoring model was built according to the relation of "vegetation index based on canopy hyperspectral reflectance (Ⅵ)—PNC—GPC" with PNC as the linking point. The results showed a higher GPC prediction accuracy by GPC monitoring model based on PNC at jointing, booting, heading, grain-filling and maturity stages. The monitoring models of PNC at jointing, booting, heading, filling, maturity stages of winter wheat respectively based on modified chlorophyll absorption reflectance index (MCARI₁), normalized difference chlorophyll index (NDCI), modified normalized difference vegetation index (mNDⅥ), MCARI₁ and NDCI had better estimations of PNC, with determination coefficients (R²) of 0.826, 0.854, 0.867, 0.859 and 0.819, accordingly. When linked with PNC, by using the "Ⅵ—PNC—GP" method, the GPC monitoring models for the maturity stage consisted of combinations of Ⅵ and PNC at jointing, booting, heading, filling, maturity stages had the determination coefficients (R²) of 0.935, 0.972, 0.990, 0.979 and 0.936, respectively. Then validatation of the models with measured values was conducted to verify the reliability and applicability of the models. The results showed that the relative errors (RE) between the measured and predicted values for the five vegetation indices were 11.26%, 10.74%, 8.41%, 10.25% and 11.36%, respectively. Then the corresponding root mean square errors (RMSE) were 2.221 g·kg^-1, 1.825 g·kg^-1, 1.214 g·kg^-1, 1.767 g·kg^-1 and 2.137 g·kg^-1. It therefore suggested that MCARI₁, NDCI, mNDVI, MCARI₁ and NDCI vegetation indices were the most suitable model for monitoring winter wheat GPC at jointing, booting, heading, filling and maturity stages, respectively. There was higher prediction precision with different vegetation indices at different growth stages monitoring winter wheat GPC under different N and P rates. Furthermore, the monitoring model based on different vegetation indices at different growth stages had a higher prediction accuracy. This results provided technical support for GPC monitoring of winter wheat at different fertilization and different growth stages.

Biochemically-based model for photosynthetic parameter estimation using Bayesian method and its application in grapes in arid region

ZHU Zhonghua, HAN Tuo, LIU Jinquan, ZHU Gaofeng

2017, 25(6): 876-883. doi: 10.13930/j.cnki.cjea.160967

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The response of photosynthesis to CO₂ concentration can provide a number of important parameters related to environmental factors. Using white seedless grape as the tested material in this study, net photosynthetic rates of leaves were measured for different intercellular CO₂ concentrations during two typical growing seasons from June to September in 2014 and 2015. A widely used biochemical model (FvCB model) in the simulation of CO₂ and H₂O gas exchange at the leaf scale was parameterized using data obtained from situ leaf-scale observations. In order to obtain the photosynthetic parameters values, to explore seasonal variations in the photosynthetic parameters in different seasons and to discuss the feasibility and advantage of the Bayesian method in solving high dimensional and complex model parameters estimation, the Bayesian approach was used to estimate the parameters of the FvCB model. In order to generate the Bayesian posterior probability distribution, a version of the Markov Chain Monte Carlo (MCMC) technique was used. In contrast, the least square procedure was used in the application of the same set of observational data. The results showed that maximum ribulose 1.5-bisphosphate carboxylase/oxygenase (Rubisco) carboxylation rate (V_cmax), potential light-saturated electron transport rate (J_max) and the rate of use of triose-phosphates utilization (TPU) had evident seasonal variations which increased from June to August, and then decreased in September. The maximum values were observed in August (54.30 μmol·m^-2·s^-1, 88.45 μmol·m^-2·s^-1 and 6.56 μmol·m^-2·s^-1, respectively) and minimum values in September (34.66 μmol·m^-2·s^-1, 58.86 μmol·m^-2·s^-1 and 4.38 μmol·m^-2·s^-1, respectively). The trend in mesophyll conductance (g_m) was relatively stable in different months, with respective values of 5.16 μmol·m^-2·s^-1·Pa^-1, 5.29 μmol·m^-2·s^-1·Pa^-1, 5.39 μmol·m^-2·s^-1·Pa^-1, 5.41 μmol·m^-2·s^-1·Pa^-1 from June to September. In comparison with traditional least square method, the values of V_cmax estimated by the Bayesian method were relatively small and those of J_max, TPU and g_m had no obvious difference. Also because the estimated parameters by the Bayesian method were obtained after adequate consideration of prior information, each parameter was in biological sense obviously more meaning. As a consequence, it indicated that the Bayesian approach combined with Markov Chains and Monte Carlo (MCMC) sampling algorithm was an effective way of estimation of the parameters in the FvCB model. As the parameters in the FvCB model were different in different seasons, it was necessary to consider these variations in using the parameters in the FvCB model.

Evaluation of upland cotton yield stability and adaptability using GGE-biplot analysis: A case study of 'Ezamian 30' cotton cultivar in Yangtze River Valley

XU Naiyin, RONG Yihua, LI Jian, FU Yonghong, MEI Hancheng

2017, 25(6): 884-892. doi: 10.13930/j.cnki.cjea.161119

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Abstract:
The major challenge for a breeder is choosing genotypes with high yield and stability, which have always been the main objectives of crop yield breeding. However, the ever-existing genotype-by-environment interaction has also always impeded the progress in selecting new cultivars for a wide spectrum of the environment. Scientific and reasonable assessment of the stability and adaptability of varieties are conducive for improving the selection and utilization efficiency of crop breeding. In this study, the GGE-biplot^® software was used to explore and visualize yield ability, stability and adaptability of a newly registered cotton cultivar 'Ezamian 30' and other candidate lines in the same groups of national cotton trials during the period 2012-2013 in the Yangtze River Valley (YRV). Meanwhile, the "Pairwise Comparison view" of the GGE biplot was used for one-to-one comparison with the control cultivar 'Ezamian 10' for superiority of adaptability to the local conditions. The results showed that: 1) 'Ezamian 30' had a prominent high-yield and an excellent stability in the 2-year multi-environmental variety trials. 2) The integrated performance (i.e., ideal index) of 'Ezamian 30' in joint evaluation of high yield and stability was significantly superior to that of the control 'Ezamian 10' and other candidate lines in the trials. 3) The dominant suitable planting area of 'Ezamian 30' was widest among all candidate cultivars, which covered an overwhelming majority of the whole cotton planting region in YRV. 4) For one-to-one comparison, 'Ezamian 30' evidently had a beneficial planting advantage with higher yield potential than the control cultivar and other candidate lines in most of cotton growing area in YRV. This study demonstrated the effectiveness of GGE-biplot in the concurrently evaluating high yield/stability, suitable planting area delineation, etc. Furthermore, it showed the ideal characteristics of 'Ezamian 30' for high yield, stability and adaptability. Thus it provided not only theoretical guidelines for reasonable extension and utilization of 'Ezamian 30', but also set up a reference base for comprehensive evaluation of other varieties and/or crops.

Evaluation for shade tolerance of black soybean germplasms and their root structure response to shade stress at seedling stage

YANG Caiqiong, HU Baoyu, WU Haijun, QIN Wenting, ZHANG Xiaowen, LIU Weiguo, YANG Wenyu, LIU Jiang

2017, 25(6): 893-902. doi: 10.13930/j.cnki.cjea.161092

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Maize-soybean relay strip intercropping systems is an important planting mode in Southwest China. However, shade-tolerant germplasms of black soybean are scarce and the mechanism of shade tolerance of black soybean is still unclear, which significantly affects further promotion of the mode. The objective of this study was to establish a mathematical model to evaluate shade-tolerance ability of black soybean seedlings, screen shade-tolerance appraisal indicators and discuss the diverse responses of the root structures of different black soybean germplasms seedlings to shade stress. The study was also intended to lay the foundation for breeding varieties and for explaining the mechanism of shade tolerance of black soybean. Thus in the study, shade tolerance of 23 black soybean germplasms were evaluated in a pot culture experiment with normal light and shade treatments. The morphological characteristics (plant height, stem diameter, hypocotyl length, leaf dry weight, stem dry weight, main stem count, total root length, root surface area, total root volume, etc.) and physiological parameters were measured at the 3^rd trifoliolate leaf stage (V3). An evaluation mathematical model was established using multivariate statistical analysis. Additionally, based on the evaluation results, correlation analysis was conducted to determine differential responses of roots to shade stress. The 23 black soybean germplasms were divided into three groups, including tolerant, moderately tolerant and sensitive germplasms. A total of 5 evaluation indexes closely related to shade tolerance were screened out. The study showed that the response of root structure to shade stress varied with shade-tolerance ability of black soybean germplasms. Root parameters such as total root length, root surface area, total root volume and root dry weight all had a similar order, which was shade tolerant germplasms > moderate shade tolerant germplasms > sensitive germplasms. The results indicated that shade tolerant germplasms of black soybean had a stronger root system.

Histocyte distribution and cadmium forms in different rice cultivar seedlings with exogenous cadmium supply

FU Shuolan, WANG Changquan, LI Bing, XU Qiang, ZHANG Jingsheng, LI Meng, TANG Jie, HE Yuting, SHEN Jie, ZENG Jiexi, YAN Xun

2017, 25(6): 903-910. doi: 10.13930/j.cnki.cjea.161041

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Abstract:
A hydroponic experiment was conducted to study cadmium (Cd) accumulation characteristics in different rice genotypes — low Cd accumulation ('D83A/R527') and high Cd accumulation ('Fuyou838'). The subcellular distribution and chemical forms of Cd in the root and shoot of different rice genotypes were investigated after exposure to Cd concentrations of 5 μmol·L^-1, 10 μmol·L^-1 and 25 μmol·L^-1. The aim of the study was to explore subcellular distribution and chemical forms change of Cd in rice to provide reference for research on Cd absorption mechanisms of rice. The results showed that: 1) the concentrations of Cd in roots and shoots and the transfer rate in 'D83A/R527' were significantly lower than those in 'Fuyou838' (P < 0.05). 2) The contents of Cd in subcellular fractions of two rice cultivars were in the orders of soluble fraction (F3) > cell wall (F1) > organelle (F2) in roots, but cell wall (F1) > soluble fraction (F3) > organelle (F2) in shoots. The proportions of Cd in cell walls (36.76%-51.75%) in both roots and shoots of 'D83A/R527' were higher than those in 'Fuyou838' (31.29%-49.07%). 3) The order of contents of Cd chemical forms revealed by different processing methods was sodium chloride extraction state (F_NaCl-Cd) > acetic acid extractable state (F_HAc-Cd) > deionized water extraction (F_W-Cd) > ethanol extracted state (F_E-Cd) > HCl extractable state (F_HCl-Cd) in both cultivars. When Cd concentration increased, the proportions of F_E-Cd and F_W-Cd (active forms) from root of 'D83A/R527' declined gradually (24.75%-18.34%), but increased gradually in 'Fuyou838' (27.18%-28.68%). The percentages of F_HAC-Cd and F_HCl-Cd (inertia forms) in shoot of 'D83A/R527' (32.41%-38.98%) were higher than those in 'Fuyou838' (28.44%-31.22%). The proportions of F_NaCl-Cd in both root and shoot of 'D83A/R527' (32.71%-51.17%) were higher than those in 'Fuyou838' (32.14%-47.63%). In short, Cd accumulation in 'D83A/R527' was lower than that in 'Fuyou838'. Then cell wall mass fractions of both root and shoot systems were higher in 'D83A/R527' than that in 'Fuyou838'. Also there was lower accumulation of active forms of Cd and higher accumulation of inertia forms of Cd in 'D83A/R527' than that in 'Fuyou838'. Therefore, rice cultivar 'D83A/R527' had a better Cd fixation capacity than 'Fuyou838'.

Effect of different rates of slow/controlled release urea on nitrogen content in spring maize in loess highlands

SUN Xiao, JING Jianyuan, LYU Shenqiang, SHANG Haobo, LI Na, TIAN Xiaoxiao, LI Jia, WANG Lyu, WANG Linquan

2017, 25(6): 848-855. doi: 10.13930/j.cnki.cjea.161122

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Abstract:
A field experiment was conducted under plastic film mulching conditions in the highlands of the Loess Plateau area to study the effects of different rates of different types of slow and controlled release urea (via basal application at reduced rate) on grain yield, nitrogen use efficiency and nitrogen accumulation in spring maize. The aim of the study was to determine the optimum type and application rate of slow or controlled release urea via simplified and efficient fertilization techniques for spring maize production in the study area. Spring maize cultivar used in the study was Zea mays L. cv. 'Xianyu335'. The experiment consisted of nine treatments—no N use (N0), farmer conventional N fertilization[common urea with application rate of 225 kg(N)·hm^-2, N225], common urea N reduction (application rate of 180 kg(N)·hm^-2, N180], and N rate reduction with six kinds of slow or controlled release urea[application rate of 180 kg(N)·hm^-2], i.e., resin coated urea (RCU), controlled loss urea (CLU), sulfur coated urea (SCU), urea formaldehyde (UF), polypeptide urea (PU) and stabilized urea (SU). Plant and soil (0-20 cm layer) samples were collected at different growth stages for analysis of grain yield, plant N accumulation and soil inorganic N concentration. The application of N fertilizer increased grain yield of maize by 28%-65% relative to N0. Compared with N225, N180 decreased grain yield by 19.1%. The application of RCU, UF, PU and SU did not significantly reduce grain yield, while the application of SCU and CLU increased grain yield by 4.5% and 2.7%, respectively. Compared with N225, N180 reduced net income by 2 051 ￥·hm^-2. A total of six slow or controlled release urea (except for UF) increased plant N accumulation, but increased N use efficiency by 2.26%-12.69% and net income by 347-1 747 ￥·hm^-2. The highest N use efficiency and economic benefits were observed under SCU and CLU treatments. Greater N uptake and N use efficiency in slow or controlled release urea treatments partly resulted from greater N release during huge bellbottom stage to silking stage. Slow or controlled release urea (including CLU and SCU) via basal application at reduced amount (by 20%) maintained grain yield, improved N use efficiency and economic benefits, and saved labor cost. Therefore, it was recommended for used as an option for simplified and efficient fertilization in spring maize production in similar areas in the Loess Plateau.

Effect of tillage and fertilization on water use efficiency of maize in dryland conditions

WANG Hao, WANG Shulan, XU Zonggui, LI Jun

2017, 25(6): 856-864. doi: 10.13930/j.cnki.cjea.160990

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Abstract:
As crop production in rain-fed systems is highly dependent on natural rainfall, making full use of rainfall and increasing water use efficiency are the main modes of dryland farming. Spring maize is one of the main grain crops in Weibei drylands where the plowing induces greater soil water evaporation. Conventional tillage is conducive for high water use efficiency in dryland farming. A study on fertilization and tillage in a field experiment was conducted in Weibei highlands in 2013-2015 to determine the effects of tillage and fertilization on soil water consumption and water use efficiency of spring maize in Weibei drylands. A total of six treatments were processed in the experiment — conventional tillage with low fertilization (A1), no-tillage with high fertilization (A2), subsoiling with balanced fertilization (A3), conventional tillage without fertilization (B1), no-tillage without fertilization (B2) and subsoiling without fertilization (B3). Soil water moisture in the 0-200 cm layer during fallow period and maize growth stages was measured and also grain yield under different treatments measured. The results showed that: 1) conservation tillage significantly improved soil water storage during fallow period. Compared with B1, B2 and B3 treatments increased oil water storage by 23.39 mm and 27.73 mm, respectively. 2). Conservation tillage increased soil water storage during the growth stage. Compared with B1, B2 and B3 enhanced water storage in the 0-200 cm by 13.41 mm and 15.70 mm, respectively. Compared with A1, A2 and A3 improved soil water storage by 13.15 mm and 19.54 mm, respectively. During the experiment, balanced fertilization effectively improved average soil water storage for the whole growth period by 6.79 mm. 3) Conservation tillage combination with fertilization increased grain yield and water use efficiency. Compared with B1 treatment, B3 improved grain yield by 212-576 kg·hm^-2 and increased water use efficiency (WUE) by 0.83-2.21 kg·hm^-2·mm^-1 (P < 0.05). Also compared with A1, A3 treatment increased grain yield by 659-1 495 kg·hm^-2 and WUE by 0.65-3.82 kg×hm^-2·mm^-1 (P < 0.05). Balanced fertilization had the highest grain yield and WUE. Compared with low and high fertilization, balanced fertilization increased grain yield by 1 268-2 682 kg·hm^-2, and improved WUE by 0.08-4.45 kg×hm^-2·mm^-1 (P < 0.05). Correlation analysis showed a significant positive correlation between grain yield and soil water consumption during grain-filling stage. It was also noted that conservation tillage improved soil water storage in the early growth, increased soil water storage during tasseling-grain filling stage and promoted WUE at critical periods to increase grain yield. Thus, the combination of subsoiling with balanced fertilization was a suitable tillage system for enhancing grain yield and WUE in Weibei drylands.

Effect of agronomic measures on phosphorous loss via runoff in sloping croplands around Chaohu Lake

WANG Jing, WANG Yunqing, YE Yin, MENG Chaofeng, WANG Daozhong, GUO Xisheng, LYU Guo'an

2017, 25(6): 911-919. doi: 10.13930/j.cnki.cjea.160916

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Abstract:
Eutrophication has been recognized as one of the main global environmental problems in areas with intensive agricultural production where there is nutrient export from farmlands to surface water bodies. Phosphorous (P) via runoff from farmland has been found to be one of the main contributors to water-quality degradation in Chaohu Lake. Thus, source control of P loss from farmlands was critical in remediation of eutrophication in Chaohu Lake. In order to test the efficiency and efficacy of different agronomic measures on reducing runoff, sediment and P loss, a long-term field runoff experiment was carried out in a sloping cropland around Chaohu Lake. Four treatments of agronomic measure were applied — 1) conventional tillage (CK), 2) plant hedgerow of Hemerocallis citrina (PH), 3) plant hedgerow with straw mulching (PHS) and 4) contour ridge (CR). Runoff volume, soil loss, concentrations of TP (total phosphorus), PP (particulate phosphorus), DTP (dissolved total phosphorus), D-Ortho-P (dissolved orthophosphate phosphorus) and DOP (dissolved organic phosphorus) as well as P loss via runoff were determined. The results for 2014-2015 showed that PH, PHS and CR treatments significantly reduced soil and water loss in the order as follows: PHS > PH > CR (P < 0.05). Also the reduction in sediment was great than that in runoff. Compared with CK, agronomic measures of PH, PHS and CR decreased runoff, respectively, by 23.5%, 36.5% and 19.7%, and reduced sediment, respectively, by 29.5%, 45.2% and 26.3%, showing significant effect on soil and water conservation (P < 0.05). The concentration of TP in runoff under CK was 0.612-1.220 mg·L^-1, in which PP was the predominant form, accounting for 71.5%-81.7% of the TP. In DTP, D-Ortho-P was the main form, accounting for 87.4%-90.7%, while DOP remained in low concentration. It was found that the three agronomic measures (PH, PHS and CR) significantly reduced PP and TP concentrations in runoff (P < 0.05), concurrently increased the concentrations of DTP and D-Ortho-P, but had no obvious effect on DOP concentration (P > 0.05). Obviously, TP concentrations in the current study were higher than 0.4 mg·L^-1, exceeding Class V level of the national environmental quality standards for surface water (GB3838—2002). The results implied that P loss via runoff from farmlands in Chaohu Lake region posed pollution risk if allowed to drain directly into the lake. Besides, annual P runoff loss from sloping croplands under CK was 0.706 kg·hm^-2, the equivalent of 0.98% of applied P fertilizer in the experiment. Compared with CK, PH, PHS and CR reduced annual P loss respectively by 38.4%, 53.8% and 33.4%. Another finding in the study was that the reduction in runoff volume and that in PP concentration were mainly responsible for the decline in P loss. In conclusion therefore, PH, PHS and CR significantly reduced soil, water and P loss via runoff in sloping farmlands in Chaohu Lake region. Among the treatments, PHS was the most effective. The results of this study provided more insight into the need for strategies to reduce agricultural non-point source pollution in Chaohu Lake region and other similar regions.

Farmland potassium balance in China: A review

JI Hongjie, ZHANG Huaizhi, ZHANG Weili, TIAN Changyu

2017, 25(6): 920-930. doi: 10.13930/j.cnki.cjea.160944

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Abstract:
Soil potassium balance (KB) is an indicator for potassium input and output in croplands. It is also a simple method to judge the situation of soil potassium deficiency, which has been extensively used in soil nutrient condition evaluation and fertilizer recommendations for crops. In this paper, KB in croplands in China was reviewed on four fronts—calculation method, spatio-temporal variability analysis, crop type difference analysis and soil potassium content analysis. The studies showed an overall deficient KB in croplands in China. Regional variations in potassium deficiency were significant, with surplus farmland potassium in some areas that resulted in KB polarization. The difference in nutrient uptake among crops, the fertilizer volatility and agricultural market prices together determine the difference in KB among different crop types or even same crop in different years. Due to differences in the calculation parameters or regional planning, vast differences were noted in different reports (literatures) in terms of the amounts of total deficient potassium, deficient potassium per hectare and spatial variation in potassium deficiency. Thus although direct comparison of these results for different studies was apparently inappropriate, such comparison should be done after comprehensive analysis of related index systems. Irrespectively, in temporal variations, the effects of different planting on KB in croplands and soil potassium accumulation were basically identical. In essence, the current state of soil nutrient pool was the result of long-term accumulation of regional cropping systems (including rotation) and fertilization behaviors, which in turn determined future trend in the development of soil nutrient pool. In order to control soil potassium polarization and to ensure a stable promotion of soil potassium pool in China, it was recommended to focus future research on areas such as the optimization of nitrogen and potassium application amounts, KB in annual crop rotation systems, seasonal differentiation of potassium fertilization in accordance with soil application and crop adsorption characteristics.

Effect of climate change on growth and yield of winter wheat in Henan Province

CHENG Lin, LI Tongxiao, LIU Ronghua

2017, 25(6): 931-940. doi: 10.13930/j.cnki.cjea.161054

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Abstract:
Winter wheat is one of the main grain crops in China. The growth, development and yield formation processes of winter wheat are affected to various degrees by climate change. Henan Province is the main cultivation base of winter wheat. Thus, the intensive analysis of the impacts of climate change on different growth periods of winter wheat is critical for scientific study of the positive and negative effects of climate change. Based on the formation processes of winter wheat yield variables, the whole growth stage was divided into 3 main growth periods, planting to greening, greening to heading and heading to maturity. Daily meteorological data (for the period of 1961-2014) on winter wheat development periods and grain yield (in 1981-2014) in 30 agro-meteorological observation stations in Henan Province were used to analyze the characteristics of the main growth periods and the effect of climate change on yield. Through mathematical statistics, the meteorological variables were used to analyze the trend in climatic change, its effect on the development periods of wheat and its contribution rate to grain yield during the main growth periods. Using DSSAT-CERES Wheat crop model, the effect of climate change at different growth periods on wheat yield was simulated. The results showed that the distinct characteristics of effect of climate change in study area was the significant (P < 0.05) reduction in sunshine hours, which was at the rate of 40.09 h·(10a)^-1 during planting-greening period. There was also a large increase in average maximum and minimum air temperatures, respectively at the rates of 0.484 ℃·(10a)^-1 and 0.591 ℃·(10a)^-1 during greening-heading period. With increasing daily minimum temperature before heading, panicle differentiation in winter wheat terminated earlier by 2.9 days per decade. Climate change before greening had a continuous effect on the development progresses, with negative correlation between meteorological factors and sustained days from planting to heading and then planting to maturity. The results of two different analytical methods indicated that there was no significant effect of climate change during planting to greening stage on yield in Henan Province. In a certain scope, climate change even had positive effects on grain yield. The average contribution rate of climate change to winter yield variables was 0.758 during planting to greening turning stage. At representative stations, climate change during greening to heading resulted in reductions in kernel density and kernel number, respectively, by 2.74% and 3.94%, followed by 2.46% and 1.87% reductions during heading to maturity. The significant decrease in kernel number due to climate change during greening to heading was the primary reason for the yield reduction. Intensified climate change was harmful to both high and stable yields. Climate change during the periods from planting to greening, greening to heading and heading to maturity led to average yield variations in the representative stations by-1.6%, -6.3% and-4.8%, respectively. Under climate change, the key meteorological variables that influenced yield was daily maximum air temperature during planting-greening and heading-maturity periods, and daily minimum air temperature during greening-heading stage.

Multi-model ensemble for simulation of the impact of climate change on maize yield

ZHANG Yi, ZHAO Yanxia

2017, 25(6): 941-948. doi: 10.13930/j.cnki.cjea.161152

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Abstract:
Climate projections through process-based statistical crop models are important in studying the impacts of climate change on agricultural production. However, extensive assessments have generally relied on single climate with single crop models which have shown large discrepancies in predicted crop yields and estimations uncertainty hardly assessed. The proper understanding of uncertainties associated with such models is essential for effective use of projected results in devising adaptation strategies. Assessing crop yield response to future climate conditions based on an ensemble of possible outcomes from multiple climate projections and crop models could be more reliable than using a single model outcome. To estimate uncertainties associated with the study of the impacts of climate change on crop yield, we used 8 climate projections by GCMs under RCP4.5 in the CMIP5 (which represented the uncertainties in the projected climate change) and a statistical process-based crop model (which represented the uncertainties in the different structures or different formulations of physiological processes of crop models). Historical data of crop and meteorological data during 1981-2009 from agro-meteorological stations of China Meteorological Administration in Hailun, Changling and Benxi in Northeast China were used to establish and evaluate statistical and process-based APSIM (Agricultural Production Systems sIMulator) models, respectively. Then the two crop models were linked with 8 climate projections to evaluate the impact of climate change on maize yield during 2010-2039 and 2040-2069, using 1976-2005 as the baseline period. In total, 2 crop models under 8 climate projections for a period of 30 years (a total of 480 simulations) were generated for both the baseline and two future climate periods. The results showed that APSIM model well simulated the growth and yield of maize. The root mean square error (RMSE) for the growth progress (flowering and maturity) simulation was 3-4 days and that for the yield simulation was 0.6-0.8 t·hm^-2. The established statistical model suggested that temperature during emergence (mid May) had a positive effect on maize yield. However, the increase of temperature and rainfall, and lack of solar radiation during flowering and grain-filling periods (mid July to early September) had negative impact on increase of maize yield. Compared with 1976-2005, the resulting probability distributions indicated that due to climate change, maize yield in 2010-2039 decreased on average by 3.8% (Hailun)-7.4% (Benxi), at a probability of 64% (Changling)-73% (Benxi). During 2040-2069, maize yield increased by 6.4% (Hailun)-10.5% (Benxi), at a probability of 74% (Hailun)-83% (Benxi). The simulated yield decrease by the APSIM model was 6.6% (Hailun)-8.9% (Benxi) during 2010-2039 and 9.7% (Hailun)-13.7% (Benxi) during 2040-2069. These were higher relative to those simulated by the statistical model, which were 0.9% (Hailun)-6.0% (Benxi) during 2010-2039 and then 2.0% (Changling)-7.3% (Benxi) during 2040-2069.

2017 Vol. 25, No. 6