中国生态农业学报(中英文)

Yield improvement and greenhouse effect of different intercropping systems based on life cycle assessment

GENG Chuanxiong, REN Jiabing, MA Xinling, LONG Guangqiang, LU Yao, TANG Li

2020, 28(2): 159-167. doi: 10.13930/j.cnki.cjea.190704

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Abstract:
Global warming has become the most pressing problem affecting the ecological environment, and the greenhouse gases (N₂O, CH₄, and CO₂) produced due to agricultural practices are one of the factors that cannot be neglected. Establishing different planting models and production management measures, reducing energy consumption and greenhouse gas emissions in the farmland ecosystems, and achieving high yields and efficiency in an environment friendly manner are important safety strategies for sustainable agricultural development. In this study, the effects of intercropping systems on greenhouse gas emission and yields were explored in the farm ecosystems for the wheat/faba bean and corn/potato intercropping systems. Two years of research using the life cycle assessment (LCA) method has produced data that compare the differences in crop yield, global warming potential, and energy consumption in the intercropping and monocropping systems. The wheat/faba bean intercropping and wheat monocropping system as well as the corn/potato intercropping and maize monocropping systems were used as research objectives and a production unit of 1 000 kg was evaluated as the functional unit. The agricultural capital system, life cycle resource consumption, and greenhouse gas emission inventory for agricultural resources systems and farming systems under different planting models were established; and monocropping and intercropping environmental impact assessments was conducted. The results showed that compared to the yield of monocropped wheat, the yield of intercropped wheat increased by 18.04% and 39.94%, respectively, in 2014 and 2015. Besides, the global warming potential of intercropped wheat decreased by 15.28% and 28.53%, while the energy consumption decreased by 15.29% and 28.53%, respectively, in 2014 and 2015. Furthermore, compared with monocropped maize, the yield of intercropped maize increased by 2.65% and 23.16%, whereas the global warming potential of intercropped maize decreased by 2.61% and 19.05%, respectively, in 2014 and 2015. In addition, energy consumption decreased by 2.61% and 18.83%, respectively, in 2014 and 2015. Compared with monocropping, reasonable intercropping significantly increased the crop yield while reducing greenhouse gas emissions and energy consumption. This aided in protecting the environment while reducing energy consumption, and achieving a high yield and efficiency of crops at a lower environmental cost.

Ecological suitability zoning of Coffea arabica L. in Yunnan Province

ZHANG Mingda, WANG Ruifang, LI Yi, HU Xueqiong, LI Meng, ZHANG Maosong, DUAN Changchun

2020, 28(2): 168-178. doi: 10.13930/j.cnki.cjea.190509

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Abstract:
Arabica coffee (Coffea arabica L.) is the most important commodity of plateau characteristic agriculture and for targeted poverty alleviation in Yunnan. Research on the ecological suitability of planting is conducive for optimizing the layout and expanding the scale. There are no reports on the suitability of C. arabica using GIS in China. Using ArcGIS, in this study, we established a refined spatial distribution model of climate, soil, and terrain factors and screened out three levels and 11 ecological suitability evaluation indexes using the analytic hierarchy process (AHP) to optimize the layout and expand the scale for planting C. arabica. The results showed the following:1) Climate is a key factor affecting ecological suitability, followed by terrain factor; soil factor was the least influential factor. 2) The minimum temperature of the coldest month, rainfall during February-March, and elevation had a significant effect on ecological suitability, which should be focused on while planning planting. 3) The most suitable and suitable areas for C. arabica cultivation were mainly distributed southwest and southeast of Yunnan, accounting for 18.8% and 15.0% of the land area in Yunnan; sub-suitable areas accounted for 21.0% of the land area. 4) Pu'er City comprised a high proportion of suitable areas, and large-scale planting can be carried out in central and southern regions of Pu'er City. 5) The key counties in Lincang, Dehong, and Baoshan should make rational use of ecological advantages of the Hengduan Mountains to strengthen appropriate regional planning and layout of coffee cultivation. 6) Xishuangbanna, Wenshan, and Honghe had a high proportion of highly suitable areas, and therefore, it is necessary to strengthen the planning layout and planting scale, and make full use of the ecological advantages and potential. 7) Dali and Nujiang, as well as other valley hotspots in Yunnan, are also suitable for C. arabica cultivation, but attention should be paid to prevent the effects of disasters such as low temperature and drought. There is still a large proportion of developmental potential areas for C. arabica cultivation, which offers a foundation for improving yield and quality and enhancing the international competitiveness of C. arabica in Yunnan. By combining field investigation findings, our results indicate that ecological suitability and zoning analyses are accurate, which can be extended to the development of characteristic agriculture industry in the plateau, and provide a scientific basis for the optimization of site selection planning and scientific ecological layout.

Evolution of drought and flood trend in the growth period of spring maize in Northeast China in the past 60 years

REN Zongyue, LIU Xiaojing, LIU Jiafu, CHEN Peng

2020, 28(2): 179-190. doi: 10.13930/j.cnki.cjea.190684

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Abstract:
The evolution of regional drought and flood trend provides a theoretical basis for understanding crop response to climate change, decision making on disaster prevention and reduction, and ensuring China's food security. Here, the northeast region of China was used as the research area, which was divided into 14 parts based on the growth characteristics of spring maize. The daily meteorological data from 78 stations in the study area from 1958 to 2017 were used to calculate the crop water surplus deficit index (CWSDI') of spring maize during the growing period. The CWSDI' values were divided into eight drought and flood levels. The results revealed the temporal and spatial trend of drought and flood during the growth period of spring maize in the northeast region using Mann-Kendall trend test, mutation test, and geographic information system spatial analysis technology. During the growth period of spring maize, CWSDI' generally increased in the three growth stages of sowing-heading period and decreased in the heading-maturation stage, and the decreasing trend was the most significant in the milk-maturation stage, but without any obvious regional difference. The frequency of drought in the growth period of spring maize in the research area was considerably higher than that of flood. The drought situation had gradually worsened since the 1990s, but the flood situation showed no obvious change. The jointing-heading and milk-maturation stages were the least and most affected stages by drought and flood, respectively. The frequency of drought and flood in each growth stage of spring maize was as follows:extreme drought > light drought > other drought and flood levels. The frequency of moderate drought and heavy drought in the western part of Liaoning was higher than that in other areas. Extreme drought mostly occurred in the western part of the study site, whereas light flood mostly occurred in Heilongjiang. Moderate flood and heavy flood rarely occurred in the study site. In the future, efforts should be made to prevent drought and flood in the early and late growth stages of spring maize. Furthermore, more attention should be paid to the western part of the study site owing to the more severe drought situation in order to achieve timely and effective irrigation. The results will provide a basis for the prediction of agricultural drought and flood disasters and optimization of water resource allocation on a regional scale.

Application of agricultural drought index based on Run Theory for the assessment of yield loss in spring maize owing to drought in Liaoning Province

TAN Fangying, HE Liang, LYU Houquan, SONG Yingbo, CHENG Lu, HOU Yingyu

2020, 28(2): 191-199. doi: 10.13930/j.cnki.cjea.190675

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Abstract:
Drought is one of the main factors restricting agricultural development and food security in China. Identifying agricultural drought accurately and assessing the impact of drought on crop yield in detail is the core of drought research. The results of this research can provide a theoretical basis for drought disaster prevention and mitigation. The water deficit anomaly index of spring maize across the entire growth period was calculated based on daily weather data from 52 meteorological stations in Liaoning Province from 1961 to 2015, and a new drought index for spring maize over the entire growth period was constructed by using Run Theory. Drought yield loss assessment models at the county or city scales were further constructed based on the drought index and yield loss rate from 1981 to 2015. Finally, key prevention areas for spring maize drought in Liaoning Province were identified. The drought index for spring maize in Liaoning Province exhibited a decreasing distribution from west to east. The likelihood of severe drought events was higher and the interannual variability of spring maize yield was largest in western Liaoning. The rate of yield loss of spring maize had a significant positive linear correlation with the drought index in more than 80% of the counties in the spring maize main producing area, except for most parts of eastern Liaoning and some counties in central Liaoning. Moreover, significant spatial differences were observed in the yield loss of spring maize. With the same drought index, the region with the largest yield loss rate of Liaoning Province was Chaoyang, followed by the southern and northern parts of Liaoning; the Liaodong Bay and the central plain had the lowest yield loss rate. However, in Fengcheng City and Donggang City, where spring maize growth was not restricted by precipitation, the yield of corn was higher in the years with less precipitation. The results of the present study indicated that the government should pay more attention to drought-sensitive zones such as the Chaoyang District, and northern and southern Liaoning west, and north of the Qianshan Mountains. To increase and stabilize spring maize yield in the above areas, it is necessary to increase drought-tolerant varieties, develop water-saving irrigation, and improve water use efficiency. Most counties in eastern Liaoning and some counties in central Liaoning with abundant rainfall or good irrigation conditions can increase spring maize production by improving planting and management methods. Additional attention should be paid to the prevention of damage caused by floods and cold, especially in Fengcheng and Donggang.

Effect of climate, genotype, and water management on winter wheat yield and water use efficiency in Hebei Plain

SUN Rui, DONG Xinliang, ZHAO Changlong, SU Han, WANG Jintao, LIU Xiaojing, SUN Hongyong

2020, 28(2): 200-210. doi: 10.13930/j.cnki.cjea.190671

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Abstract:
Winter wheat is the main crop in the North China Plain, and its growth is affected by weather, varieties, and management measures. Many scholars have conducted extensive research on the mechanism of winter wheat growth, but most of these studies focused on a single factor. Moreover, research was mostly conducted at the regional scale, with few studies being conducted in areas at the same latitude. To investigate the effects of weather, genotype, and water management interaction on winter wheat yield and water use efficiency (WUE), field experiments were conducted at four typical experimental sites (Hengshui, Nanpi, Luancheng and Nandagang) in the Hebei Plain in the 38° north latitude zone from 2018 to 2019. Three winter wheat varieties 'KN2009', 'GY2018' and 'SL02-1' and two water management levels-irrigation and rain-fed treatments-were used at all four sites. The soil water content was measured at 20 cm intervals in the 1.6 m soil profile before sowing and after harvest. Grain yield and yield components were also measured. Weather factors were collected from a nearby weather station 200-500 m from the experimental sites. Under irrigation conditions, grain yield was 6 316.7 kg·hm^-2, 5 204.1 kg·hm^-2, 4 356.5 kg·hm^-2, and 2 597.7 kg·hm^-2, respectively; WUE was 1.62 kg·m^-3, 1.72 kg·m^-3, 1.36 kg·m^-3, and 1.08 kg·m^-3, respectively; irrigation water use efficiency (IWUE) was 1.62 kg·m^-3, 3.20 kg·m^-3, 2.19 kg·m^-3, and 1.02 kg·m^-3, respectively, at Hengshui, Nanpi, Luancheng and Nandagang sites. Under rain-fed conditions, grain yield at Nanpi, Luancheng, Hengshui and Nandagang was 2 644.4 kg·hm^-2, 2 602.8 kg·hm^-2, 2 422.3 kg·hm^-2, and 1 784.3 kg·hm^-2, respectively; WUE was 1.13 kg·m^-3, 1.10 kg·m^-3, 1.18 kg·m^-3, and 1.01 kg·m^-3, respectively. Grain yield differed significantly among the four sites, while no significant difference was noted among varieties. With regard to WUE, trends differed between the irrigation and rain-fed treatments. The WUE of different sites under irrigation conditions differed significantly, while there were no significant differences among varieties. The WUE of different sites under rain-fed conditions did not differ significantly, while WUE differed to some extent among varieties. Statistical analysis of results for grain yield and yield components revealed that the number of spikes was the most important factor affecting yield, while the effects of grain number per spike and 1000-grain weight on yield were inconsistent with different sites, varieties, and water conditions. Multivariate analysis of variance revealed that the interaction of weather factors and water management had a highly significant effect on yield and WUE (P < 0.01), while weather factors, genotype, and water management had a significant effect on WUE (P < 0.05). Thus, the effects of climate conditions and management measures on winter wheat yield, water consumption, and WUE were significantly greater than those of variety, and water factor was the influential factor on yield and WUE. Based on comprehensive yield, water consumption, and WUE analysis, Nanpi had relatively high grain yield with low water consumption and relatively high WUE. Wheat varieties with strong tillering ability were potentially suitable for planting in this region.

Difference in water consumption and yield among different drought-resistant wheat cultivars

REN Jie, SUN Min, REN Aixia, LIN Wen, XUE Jianfu, TONG Jin, WANG Wenxiang, GAO Zhiqiang

2020, 28(2): 211-220. doi: 10.13930/j.cnki.cjea.190515

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Drought is the main factor that restricts wheat yield in the arid land of the Loess Plateau. Selecting suitable wheat cultivars is important to improve wheat yield in this area. To identify differences among 10 drought-resistant dryland wheat cultivars for cultivation in the dryland of eastern Loess Plateau based on annual precipitation range, a field experiment was conducted in Wenxi County, Yuncheng City, Shanxi Province from 2012 to 2017. A few studies have been conducted taking into account drought resistance and annual precipitation range into consideration. In this study, the 10 selected wheat cultivars were screened for drought resistance. Then, the study period was classified as dry year and median year, based on the annual precipitation, and wheat varieties were classified as strong and weak drought-resistant cultivars. We compared differences in water use efficiency, dry matter accumulation, yield, and yield components among the cultivars for five consecutive years, and analyzed the relationships between yield, dry matter accumulation and water consumption. Furthermore, the effect of water saving on the yield of wheat cultivars was determined. The results showed that the strong drought-resistant cultivars were JM92, YH20410, YH22-33, YH618, YH719, and C6697; whereas the weak drought-resistant cultivars were LH6, LH9, LH11, and LH13. In the dry year, average water consumption of the strong drought-resistant cultivars was higher than that of the weak drought-resistant cultivars. When water consumption was increased by 1 mm, the yield of wheat increased by 29.6 kg·hm^-2, and the main factors affecting the yield of the strong drought-resistant cultivars were spike number and grain number per spike. Moreover, dry matter accumulation in the vegetative organs increased by 50.8 kg·hm^-2. Therefore, the water use efficiency of the strong drought-resistant cultivars, especially JM92 and YH20410, was higher than that of the weak drought-resistant cultivars. In addition, water saving per unit grain production of the strong drought-resistant cultivars was 13.61% higher than that of the weak drought-resistant cultivars. The yield increment of 1 mm soil water consumption was increased by 15.74% higher of the strong drought-resistant cultivars compared with that of the weak drought-resistant cultivars. Water consumption of six cultivars with strong drought resistance was generally higher in the median year, and both yield and water use efficiency of JM92 and YH20410 were relatively higher. Therefore, our results indicate that JM92 and YH20410 perform better in both dry year and median year.

Study on the input and demand of crop nutrients and the potential of fertilizer reduction in Anhui Province

GENG Wei, YUAN Manman, WU Gang, WANG Jiabao, SUN Yixiang

2020, 28(2): 221-235. doi: 10.13930/j.cnki.cjea.190537

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The use of organic-inorganic integrated farmland nutrient management model is an effective approach to develop sustainable agriculture in China. As nutrient demand and supply in agricultural production in various regions are undefined, it is crucial to study the relationships among organic fertilizer nutrient resources, fertilizer nutrient input, and crop nutrient demand to promote the rational distribution and application of nutrient resources. By using previously published methods and statistical analysis, here, we evaluated the nutrient composition of organic fertilizers (including straw, manure, green manure, and cake fertilizer). We aimed to clarify the current situation of organic and inorganic nutrient inputs for agricultural production in 16 cities in Anhui Province from 2010 to 2016, and evaluate differences and relationships among organic and inorganic nutrients and crop nutrient demand according to the local structure of agricultural planting. Finally, we explored the potential for fertilizer reduction in Anhui Province. The annual average amount of organic fertilizer in Anhui Province from 2010 to 2016 was 2.877 million tons, and that of N, P₂O₅, and K₂O was 1.044 9, 0.396 0, and 1.436 1 million tons, respectively, which could meet the nutrient demand for crops. However, the utilization rate of N, P₂O₅, and K₂O in organic fertilizer in the current season was as low as 21.44%, 19.91%, and 52.61%, respectively. Therefore, the actual return amount of organic fertilizer only accounted for 20.74% (N), 25.38% (P₂O₅), and 63.61% (K₂O) of the crop nutrient demand, and only 11.87% (N), 10.27% (P₂O₅), and 51.35% (K₂O) of the total nutrient input of farmland. The actual nutrient input (including organic fertilizer and chemical fertilizer) in the province was 1.75 (N), 2.47 (P₂O₅), and 1.24 (K₂O) times of the crop nutrient demand. The application of N in seven cities and the application of P₂O₅ in 13 cities were more than two times of the crop demand; there was a high risk of environmental pollution in these cities. By controlling the nutrient input, the reduction potential of fertilizer in Anhui Province was 35.12%, and that of N, P₂O₅, and K₂O was 21.28%, 23.97%, and 78.61%, respectively. By improving the utilization rate of organic fertilizer and developing winter green fertilizer, Anhui Province can achieve the maximum reduction in fertilizer application. This study provides reference data for zero growth of fertilizer and green sustainable development of agriculture and animal husbandry in Anhui Province.

Effects of N application on nitrogen and potassium nutrition and stripe rust of wheat in an intercropping system

ZHU Jinhui, GUO Zengpeng, DONG Kun, DONG Yan

2020, 28(2): 236-244. doi: 10.13930/j.cnki.cjea.190473

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In order to provide a theoretical basis for rational fertilization to achieve disease control and yield increase of wheat, the effects of nitrogen (N) application levels and intercropping on the absorption and distribution of N and potassium (K) and the occurrence of stripe rust of wheat were studied. A field experiment with three N application rates-0 kg(N)·hm^-2 (N0), 90 kg(N)·hm^-2 (N1), 180 kg(N)·hm^-2 (N2)-and two planting patterns (wheat monocropping, and wheat and faba bean intercropping) were set up in Anning and Eshan, Yunnan Province to study the effect of N application rate and intercropping with faba bean on the content and distribution of N and K, and the incidence and disease index of wheat stripe rust. The results showed that wheat yeld was considerably increased by N application, especially in intercropping. Compared with monocropping, intercropping significantly increased wheat yield averagely by 31.9% (Anning) and 18.0% (Eshan). The yield advantage of wheat-faba bean intercropping was obvious and the land equivalent ratio (LER) was 1.20-1.37 (Anning) and 1.16-1.27 (Eshan) at the N0-N2 levels. However, the yield-increasing effect of intercropping was decreased with increase in the N application rate. N application not only increased the yield, but also aggravated the damage of wheat stripe rust, and therefore, the incidence and disease index were increased by 2.4%-30.0% and 5.6%-38.5% in Anning, and 6.4%-22.4% and 5.3%-43.2% in Eshan, respectively. Intercropping with faba bean presented a better control effect on wheat stripe rust than monocropping. The incidence and disease index of wheat stripe rust were reduced by 9.6%-22.0% and 23.7%-33.7% (Anning) and 29.5%-36.5% and 29.3%-39.6% (Eshan), respectively. The N content was increased by N application, which mainly accumulated in the leaves, accounting for 41.3%-47.4% (Anning) and 35.9%-44.1% (Eshan) of total N absorption. However, the N content was considerably reduced by 17.8%-21.8% (Anning) and 16.2%-16.9% (Eshan), whereas the K content was significantly increased by 22.6%-23.0% (Anning) and 16.2%-18.3% (Eshan), and thus the N/K ratio in the leaves was significantly reduced under intercropping system, compared with that under monocropping system. The correlation analysis showed that the incidence and disease index of wheat stripe rust were positively correlated with the plant N content and leaf N/K ratio, and negatively correlated with the K content. The N content in wheat plants and the N/K ratio in the leaves were increased by N application and thus, the occurrence of wheat stripe rust was aggravated. On the contrary, intercropping enhanced wheat resistance to stripe rust by increasing K content and reducing plant N content and N/K ratio in the leaves, and balancing N and K nutrients in wheat plants.

Effects of indigenous arbuscular mycorrhizal fungi and nitrogen forms on plant nitrogen utilization and the influencing factors in a pepper-common bean intercropping system

LIU Yuanyuan, ZHAO Qianxu, DENG Xi, WANG Bao, ZHANG Naiming, ZONG Qingfu, XIA Yunsheng

2020, 28(2): 245-254. doi: 10.13930/j.cnki.cjea.190575

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In recent years, continuous cropping of peppers and unreasonable application of high-residue nitrogen (N) fertilizer have been the main factors preventing high yields and high-quality cultivation of peppers. A study of indigenous arbuscular mycorrhizal fungi (AMF) and intercropping to enhance the utilization of different forms of N by vegetables, combined with the feedback effect of soil hypha density, available N nutrients, and enzymes may provide a basis for efficient utilization of N in protected culturing soil and reduced soil N residues. A pot experiment with different planting options (pepper-common bean intercropping, pepper monocropping, and common bean monocropping), different AMF treatments[no AMF (NM), and indigenous AMF inoculation] and different forms of N treatments[no N, inorganic N (ammonium bicarbonate, 120 mg·kg^-1, ION), and organic N (glutamine, 120 mg·kg^-1, ON)] was conducted to reveal the effects of indigenous AMF, N form, and pepper-common bean intercropping on mycorrhizal colonization, soil enzyme activity, and N utilization by plants under greenhouse conditions. The results showed that, compared with NM treatment, inoculation of indigenous AMF significantly increased plant biomass and N uptake of peppers and common beans, except in the case of common bean monocropping-ON treatment, and decreased the contents of NH₄⁺-N and NO₃^--N in rhizosphere soil. Whether inoculated with AMF or not, N application increased plant biomass and N uptake of peppers and common beans, with the order of ON > ION, except common bean monocropping-AMF treatment. In comparison with monocropping-ON-AMF treatment, intercropping-ON-AMF treatment increased the N uptake of peppers and common beans significantly by 39.9% and 93.0%, respectively. Intercropping and inoculating with indigenous AMF increased protease, urease, and nitrate reductase activities and organic matter content in rhizosphere soils to different extents. Correlation analysis showed that N uptake in peppers and common beans was significantly positively correlated with mycorrhizal colonization percentage, while soil NH₄⁺-N and NO₃^--N contents were significantly negatively correlated with mycorrhizal colonization percentage. In addition, the activities of soil protease, urease, and nitrate reductase were positively correlated with N uptake of peppers and common beans. Our results indicated that pepper-common bean intercropping combined with inoculation by indigenous AMF and application of an appropriate quantity of organic N significantly promoted pepper and common bean growth and N utilization in protected cultures.

Effects of interaction between elevated atmospheric CO₂ concentration and nitrogen fertilizer on photosynthetic characteristic and yield of maize

NIU Xiaoguang, YANG Rongquan, LI Ming, DUAN Bihua, DIAO Tiantian, MA Fen, GUO Liping

2020, 28(2): 255-264. doi: 10.13930/j.cnki.cjea.190677

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Since the industrial revolution, the concentration of atmospheric CO₂ has increased from 280 μmol·mol^-1 to 400 μmol·mol^-1. Nitrogen is a necessary element for many important enzyme-mediated processes in plant growth and is the primary nutrient needed for plant growth. Among different C₄ crops grown worldwide, including China, maize is the most widely planted crop. Clear answers regarding the effect of elevated atmospheric CO₂ concentration (eCO₂) on corn growth and the interaction between eCO₂ and nitrogen fertilizers (N) are yet not to be attained. Studying the impact of eCO₂ on maize growth under different nitrogen supply conditions is important to assess the role of climate change in the C₄ crop growth. A Free Air CO₂ Enrichment (FACE) facility was used in this experiment. The FACE facility has six octagon loops for eCO₂, (550±15) μmol·mol^-1, and six additional octagon loops for ambient CO₂ concentration of (400±15) μmol·mol^-1 (aCO₂); three of which are eCO₂ experimental loops and the other three are aCO₂ experimental loops applied with conventional nitrogen fertilizer, 180 kg(N)·hm^-2 (CN). The rest are low nitrogen, 72 kg(N)·hm^-2 (LN), application treatments. Twelve experimental loops were arranged randomly in the maize field, with the plants spacing of 25 cm and a rows spacing of 60 cm. Results showed that under eCO₂, the chlorophyll concentration of maize seedling leaves increased significantly by 9.5%, and the net photosynthetic rate increased by 9.0% at the tasseling stage. During the maize growth period, eCO₂ significantly enhanced the intercellular CO₂ concentration by 34.8%-48.5% and 40.0%-49.4% under low nitrogen and conventional nitrogen application conditions, respectively. In addition, the stomatal conductance decreased by 21.6% and 22.1% at the 12-leaf and the tasseling stages, respectively. As a consequence of decreased stomatal conductance, the efficiency of water consumption in maize leaves increased by 12.9%, 9.8%, and 18.8% at the 12-leaf stage, tasseling stage and filling stage, respectively. eCO₂ also decreased Non-Photochemical Quenching (NPQ), and increased PSⅡ effective photochemical quantum yield (F_v'/F_m') value. At the same nitrogen fertilizer (N) level, eCO₂ had no significant effect on the maize yield. Secondly, the interaction of eCO₂ and a reasonable increase of N application rate promoted the chlorophyll content, net photosynthetic rate, and F_v'/F_m' of maize functional leaves. For instance, the chlorophyll content of functional leaves for CN-eCO₂ against LN-aCO₂ increased by 17.3% and 10.7%, respectively, at the 12-leaf and tasseling stages. The combination of eCO₂ and a reasonable increase in the N application achieved the maximized maize yield, indicating the promotional effect of N application under the eCO₂ conditions. Appropriate application of nitrogen fertilizer has the potential to promote the growth and development of maize crop under eCO₂ conditions in future.

Effects of water stress at different growth stages on leaf physiological changes and fruit development of grape in greenhouse

NIU Zuirong, ZHAO Xia, ZHANG Rui, WANG Wangtian, WEN Wen

2020, 28(2): 265-271. doi: 10.13930/j.cnki.cjea.190734

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Gansu Hexi Corridor is one of the main grape producing areas in China. In recent years, the greenhouse cultivation improved the price of table grape and farmers income. However, as a high water demand economic crop, grape has been affected by drought in Hexi Corridor. The key to solve the contradiction between grape planting and shortage of water resources is to promote the water-saving and efficient production mode of grape cultivation. In order to explore the efficient water management mode and water-saving production of table grape in greenhouse, the experiment was conducted in a 6-year-old vineyard with water stress (the soil moisture was controlled at 55% to 75% of field water holding capacity) at budburst stage (its duration was 14 d), shoot elongation stage (its duration was 20 d), flowering-fruit bearing stage (its duration was 11 d), fruit enlargement stage (its duration was 72 d), and coloring maturity stage (its duration was 97 d), respectively; while the other stages was at full irrigation (the soil moisture content was up to 75%-100% of field water holding capacity). And the full-irrigation during the whole growth period of grape was set as the contral treatment (CK). The activity of superoxide dismutase (SOD), contents of malondialdehyde (MDA) and proline (Pro), as well as fruit diameter, hardness of fruit, single fruit weight and yield were observed, which were used for study the response mechanism of grape leaf physiology and fruit yield to water stress. The results showed that the SOD activity and Pro content of grape leaves were significantly reduced by water stress at fruit enlargement stage and coloring maturity stage. The MDA content of grape leaves was also significantly increased by water stress during the above two long growing stages, which had a negative effect on grape leaves. The water stresses at budburst stage, shoot elongation and flowering-fruit bearing stages had no significant effects on SOD activity and Pro content of grape leaves, significantly impacted MDA content of grape leaves. The yield under water stress at fruit enlargement stage was 14 830 kg·hm^-2, which decreased by more than 20% compared with CK, and treatments of water stress at budburst stage and shoot elongation stage. Therefore, the water stress during fruit expansion stage in greenhouse significantly decreased SOD activity and osmoregulation substances contents, increased MDA content, and led to yield decrease of grape. In Gansu Hexi Corridor, it was not suitable to apply water stress at fruit expansion stage for greenhouse grape. The water stress in the early growth period had no significant effect on the physiology of grape leaves and fruit.

Effects of ridge-furrow rainwater harvesting with biochar-soil crust mulching on ridge runoff, soil hydrothermal properties, and sainfoin yield

ZHANG Dengkui, WANG Qi, ZHOU Xujiao, WANG Xiaoyun, ZHAO Xiaole, ZHAO Wucheng, LEI Jun

2020, 28(2): 272-285. doi: 10.13930/j.cnki.cjea.190707

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Abstract:
Ridge-furrow rainwater harvesting (RFRH) with mulch offers farmers a means to address drought, water loss, and soil erosion in arid and semiarid regions. The purpose of this study was to determine a suitable biochar type and optimum ridge width for sainfoin (Onobrychis viciaefolia Scop.) production using the RFRH system with biochar application in the semi-arid regions in China. A field experiment with a completely random block design was conducted during the 2017 sainfoin growing season to (1) estimate runoff coefficient of the RFRH system with three ridge widths (30, 45, and 60 cm) and the same narrow width (60 cm), and mulched with three materials (soil crust, maize straw biochar-soil crust, and cow dung biochar-soil crust) and (2) assess the effects of three ridge widths and three mulching materials on soil water storage, topsoil temperature, as well as fodder yield and water use efficiency (WUE) of the RFRH system planted with sainfoin, and a traditional flat planting (FP) system was used as the control. The results showed that the predicted runoff coefficient for ridge-furrow planting with the ridges mulched with manually compacted soil crust, maize straw biochar-soil crust, and cow dung biochar-soil crust (MCS, MSB, and CMB, respectively) was 29.7%, 26.2%, and 25.1%, respectively, whereas the threshold rainfall to produce runoff was 4.2, 4.6, and 5.1 mm, respectively. The runoff coefficient of ridge, soil water storage, and soil temperature increased with increase in ridge width using the same mulching materials. The RFRH system, especially MSB and CMB treatments, increased soil water storage of the root layer and ridge topsoil (0-25 cm) temperature, and decreased the rate of change of furrow top soil (0-25 cm) temperature. Compared with that of FP, the mean soil water storage (0-200 cm) increased by 25.1, 24.7, and 19.4 mm, on an average, under MCS, MSB, and CMB throughout the sainfoin growth period, respectively; whereas the topsoil temperature increased by 1.4℃, 2.0℃, and 2.0℃, respectively, on an average. For the same mulching material, soil water storage and topsoil temperature increased with increase in ridge width. MCS significantly decreased the actual fodder yield of sainfoin, but MSB and CMB significantly increased the actual fodder yield. Compared with that under FP treatment, the actual fodder yield under MCS with 30, 45, and 60 cm ridge width decreased by 6.5%, 12.1%, and 13.8%, respectively. Whereas, the actual fodder yield under MSB with 30, 45, and 60 cm ridge width increased by 19.7%, 24.4%, and 22.5%, and that under CMB increased by 8.0%, 8.9%, and 6.8%, respectively. MSB and CMB significantly increased WUE of sainfoin. Compared with FP, MSB and CMB increased WUE by 6.8-9.7 and 4.4-4.8 kg·hm^-2·mm^-1, respectively. The ridge width had no significant effect on the actual fodder yield and WUE with the same mulching materials. When the ridge width (furrow width was 60 cm) was 49 cm for MSB and 41 cm for CMB, the forage yield reached the maximum. The actual fodder yield and WUE of sainfoin under MSB were significantly higher than those under CMB, which were significantly higher than those under MCS. In summary, RFRH with biochar-soil crust mulching has beneficial effects on soil water storage and yield of sainfoin in the region, especially ridges with maize straw biochar-soil crust mulching.

Effects of drip irrigation uniformity and amount on soil moisture and tomato yield in solar greenhouse

LIANG Bohui, NIU Wenquan, GUO Lili, WANG Yule, WANG Jingwei

2020, 28(2): 286-295. doi: 10.13930/j.cnki.cjea.190543

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Abstract:
Drip irrigation is an important factor associated with the water and fertilizer integration technology. The uniformity of drip irrigation is an important performance index to measure its quality. Therefore, choosing the appropriate drip uniformity can achieve the dual targets of cost effectiveness as well as high crop yield. A field experiment was carried out from October 2016 to April 2017 in the Yangling Agricultural Hi-tech Industries Demonstration Zone, Shaanxi Province, China. Experimental treatments applied in the split plot design included:three irrigation quantities in Zone A (190 mm, 220 mm, and 250 mm), and three drip irrigation uniformities in Zone B (65%, 75%, and 85%). In the early stages of planting test, no crop experiment was set up in the same area with only the drip irrigation belt laid, and the experimental treatments were also applied in a split plot divided into main treatment (Zone 1) and sub-treatment (Zone 2). The Zone 1 was treated with three irrigation quantities-5 mm, 10 mm, and 15 mm; and in Zone 2, the same there drip irrigation uniformities to Zone B were set. The results showed that when the irrigation uniformity was between 65% and 85%, the mean soil moisture uniformity during entire growth period was higher than the highest drip irrigation uniformity (85%) approximately. The influence of drip irrigation uniformity on the uniformity coefficient of soil moisture was enormous. There was a significantly linear relationship (P < 0.05) with determination coefficient of 0.918 between the mean soil moisture uniformity and the three factors i.e., irrigation quantity, irrigation uniformity, and initial soil water content. When the initial soil moisture was approximately 60% of the field capacity, and the irrigation amount was less than 15 mm, the interaction between the drip irrigation uniformity and the irrigation amount was linear (P < 0.05) and significantly related to the soil moisture uniformity. In other cases, there was no significant association. The irrigation amount had significant effect on tomoto, the irrigation uniformity and their interaction had no significant effect on tomato yield. Taking into account the yield and use efficiency of irrigation, the combination of irrigation amount of 220 mm and drip irrigation uniformity of 75% was the optimal one. Considering the economics and reliability of the system, the method involving small amount of multiple irrigation should be chosen. This was also suggested for the reduction in the standard of drip irrigation uniformity in the Northwest China.

Quantitative analysis of SO₄^2- in saline soil under areas disturbed and undisturbed by human using BP Neural Network

TIAN Anhong, FU Chengbiao, XIONG Heigang, ZHAO Junsan

2020, 28(2): 296-304. doi: 10.13930/j.cnki.cjea.190700

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Abstract:
SO₄^2- is one of the main ions in saline soil, but the inversion of SO₄^2- ion in soils under different levels of human disturbance has rarely been reported. Moreover, the relationship between soil hyperspectral and soil elements is nonlinear, and the traditional linear partial least squares model (PLSR) has limited inversion accuracy for soil elements. In order to quantitatively analyzed soil SO₄^2- content in saline soil, this study selected the saline soils in areas undisturbed and human-disturbed in Changji Hui Autonomous Prefecture of Xinjiang, to predict SO₄^2- contents based on soil hyperspectral by using BP Neural Network. The original (R) and logarithmic transformed (LogR) hyperspectral were subjected as 0-order, first-order and second-order differential preprocessing, respectively. The hyperspectral reflectivity corresponding to the sensitive band was taken as the input variable of the nonlinear BP neural network model, and the hidden node, learning rate and maximum number of iterations of BP were set as 300, 0.01, and 1 000. The training function was trainscg. The SO₄^2- contents of saline soil in undisturbed area (Area A) and human-disturbed area (Area B) were determined by using the scatter plot of measured and predicted SO₄^2- contents, the fitting effect map, and the BP training process. The prediction accuracy was tested by comparison with PLSR results. The simulation showed that the BP prediction accuracy after the second-order differentiation in the Area A was better than the first-order differential, while it was opposite for the Area B. The inversion accuracy of LogR spectral transformation was better than R for both Area A and Area B. The relative prediction performance (RPD), determination coefficient (R²), root mean square error (RMSE) and iteration number of the optimal BP model were 3.309, 0.906, 0.253 and 8 times in the Area A; and 2.234, 0.844, 0.786 and 45 times in the Area B. It indicated that BP predictive ability was strong for SO₄^2- content in Area A and Area B. However, for the first- and second-order differentials of spectral in the Area A and Area B, the RPD values of the PLSR were 1.4-1.8, and the prediction performance was normal; in the 0-order differential of the Area B, the RPD of PLSR were all less than 1.0, which could not predict SO₄^2- content. Therefore, the BP model can perform effectively quantitative analysis of SO₄^2- in different undisturbed or human-disturbed regions.

Spatial and temporal precipitation patterns using the CMOPRH CRT product over the Taihang Mountains

YU Linfei, LI Huilong, YANG Yonghui, SHI Shangzhong

2020, 28(2): 305-316. doi: 10.13930/j.cnki.cjea.190746

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Abstract:
In order to effectively use precipitation over the Taihang Mountains, and to perform water resource management and ecological construction scientifically, we used satellite precipitation data to explore the spatio-temporal precipitation pattern and precipitation trend over the Taihang Mountains from 1998 to 2017. In general, the complex terrain and sparse meteorological stations lead to limited precipitation measurement in mountainous areas especially in high-altitude regions. Satellite-based precipitation measurement is an effective supplement for measuring precipitation information in such regions. The CMOPRH CRT product is recognized worldwide. A previous study had proved the applicability of CMORPH CRT over the Taihang Mountains owing to the lower root mean square error and relative bias in this region, which indicated that this product had applicability over the Taihang Mountains. Therefore, in this study, we adopted the method of time series analysis and trend analysis to explore the spatial and temporal patterns of precipitation and precipitation trend over the Taihang Mountains based on the data obtained using the CMORPH CRT product from 1998 to 2017. Meanwhile, the ground observations of 18 rain gauges were used to validate the precipitation trend measured using the CMOPRH CRT product over the Taihang Mountains with "Pixel to Point" extraction method via ArcGIS. The results showed that there was no significant variation trend in the annual and seasonal precipitation from 1998 to 2017 over the Taihang Mountains. Higher precipitation occurred in the southern and eastern regions of the Taihang Mountains than in the northern and western regions. On a monthly scale, the precipitation in July accounted for the highest rate of annual precipitation, 7.2%-32.4% of the total annual precipitation, followed by August and June. There was a decrease trend in the south and northwest regions of the Taihang Mountains, and decreased by 2-6 mm·a^-1 on an average. The increasing precipitation trend appeared in the western and northern regions of the Taihang Mountains, and the annual precipitation increased by more than 8 mm. The greatest difference in precipitation trend was found in July on a spatial scale with a variation range of -8.6 to 8 mm·a^-1. We used actual data obtained using rain gauges to validate the precipitation trend measured using CMORPH CRT. Two sets of data showed a strong significant correlation at the annual scale. On the seasonal scale, the precipitation trend in winter (dry season) and summer (wet season) had a strong significant correlation with the precipitation trend measured using rain gauges, but the precipitation trend in spring and autumn did not show a significant correlation with the precipitation measured using rain gauges. We extracted the pixel values according to the spatial pattern of precipitation trend from 1998 to 2017 over the Taihang Mountains, and further divided them into six different precipitation trend (PT) ranges (PT ≤ -5 mm·a^-1, -5 mm·a^-1 < PT ≤ 0 mm·a^-1, 0 mm·a^-1 < PT ≤ 5 mm·a^-1, 5 mm·a^-1 < PT ≤ 10 mm·a^-1, 10 mm·a^-1 < PT ≤ 15 mm·a^-1, and PT ≥ 15 mm·a^-1) depending on the actual precipitation trend over study areas. There was a significant increase in precipitation from 1998 to 2017 in the PT > 5 mm·a^-1 area.

2020 Vol. 28, No. 2