中国生态农业学报(中英文)

Agroecology transition and suitable pathway for eco-agricultural development in China

LUO Shiming

2017, 25(1): 1-7. doi: 10.13930/j.cnki.cjea.160838

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After slash and burn, small subsistence agriculture and then industrial agriculture, agriculture is now entering an ecological stage. The turning point of agro-ecological transition in different countries has often occurred at the period when per capita average GDP range reached 10 thousand to 30 thousand USD. Diversified tactics, routes and terms have been chosen by different countries for agro-ecological transition according to their specific social backgrounds, which was worthy of studying and learning in China. The level of social economic development in China is approaching or reaching the turning point for agro-ecological transition. The central government has proposed a series of important policies that redefined development goal, renewed guiding principles, redesigned development patterns and proposed new technical and management measures for agriculture since 2015. Eco-agriculture has been widely accepted by the public in China today. It was therefore important to clarify the concept of eco-agriculture in relation to other concepts for a unified effort toward agro-ecological transformation. After analysis of the advantages and challenges faced by China, the strategy and tactic for agro-ecological transition in China were proposed in this study.

From eco-agriculture to eco-civilization construction: In memory of Prof. Ma Shijun's 100 years birthday and the 36^th anniversary of eco-engineering theory publication

SUN Hongliang, QI Ye

2017, 25(1): 8-12. doi: 10.13930/j.cnki.cjea.161065

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In 1979, Prof. Ma Shijun proposed the eco-engineering principles of "integration, co-ordination, circulation, regeneration and revitalization". Specially, he pointed out that eco-engineering was a production-technology system by which co-existence of species and revitalization of matters were applied with the best possible methods of systematic engineering and multi-level circulation. In 1987, Prof. Ma Shijun further stated that agriculture built upon principles of eco-engineering was eco-agriculture itself. This paper substantiated the precision and foresight of Prof. Ma Shijun's theory with several successful models of eco-engineering, which were integration model of shelterbelt forest and farmland in oasis of desert region of Northwest China, mutualistic symbiosis model of rice-fish system, large scale circular economy model of livestock "breeding in the west and raising in the east" in northeast agro-pastoral transition zone of Inner Mongolia, and ecosystem component equilibrium model of high quality forage grass cultivation in low-yield farmland in Huanghuaihai grain-producing area. It also explained why eco-agriculture is an important part of modern eco-eco-civilization. Eco-agriculture consists of a series of eco-engineering projects based on the relevant ecological principles. This paper ended with several recommendations for speedy development of eco-agriculture in China.

Problems and countermeasures of sustainable development of agricultural ecosystem in Southern China

HUANG Guoqin

2017, 25(1): 13-18. doi: 10.13930/j.cnki.cjea.160658

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The agricultural ecosystem in South China plays an important role in the whole agricultural ecosystem in China. Southern agricultural ecosystem has some features, such as, complex structure, diverse function, high efficient production, precious value and huge development and utilization potential. At present, there is a series of problems in southern agriculture ecological system-arable land abandonment, soil fertility decline, soil pollution, frequent natural disasters, low efficiency and lack of stamina, which seriously restrict the sustainable development of southern agricultural ecological system. In order to achieve the sustainable development of agricultural ecosystem in South China, the following measures should be adopt:(1) implementation of intensive land use; (2) carrying out of environmental remediation; (3) implementation of fallow rotation; (4) combination of land use and protection; (5) optimization of agricultural ecosystem structure and (6) deepening of rural reform.

Research advance in the mechanism and agronomic regulation of high-efficient use of nitrogen in cereal-legume intercropping

CHAI Qiang, HU Falong, CHEN Guiping

2017, 25(1): 19-26. doi: 10.13930/j.cnki.cjea.160603

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Chemical fertilizer use is very common in agriculture for sustainable food production and food security. However, the excessive use of N fertilizer has often caused severe environmental and ecological problems. The existing issues regarding the over use of N fertilizers include groundwater pollution, greenhouse effect, biodiversity loss, etc. Cereal-legume intercropping is a yield-stable, high-efficient and sustainable cropping system compared to any monoculture. A favorable model of cereal-legume intercropping allows two distinct crops with different biological characteristics and nitrogen demand to grow together in the same field. With consideration of reasonable regulation of the differences between two crops, improvements can be achieved by taking advantage of biological N₂ fixation to reduce the use of chemical fertilizers and increase crop productivity. It is presently a hot research area to address issues on N transfer, alleviation of inhibitory effect on nodulation and N₂ fixation, and temporal-special distribution of N in cereal-legume intercropping systems. Addressing these topics will improve N₂ fixation in legume crops and reduce the heavy dependence of crop production on chemical fertilizers.Furthermore, clarifying the underlying mechanisms of the three issues will greatly enhance high-efficient use of N by the two distinct crops. Crop variety, N fertilizer management, special layout and planting density are the vital regulation measures of the interrelations between cereals and legumes. The optimization of the above measures will improve synergistic effect of competition and recovery, and enhance coordination of nitrogen use in cereal-legume intercropping systems, and thereby promote biological potential on high-efficient use of N. This paper summarized research advances in the major mechanisms of high-efficient use of N and the relevant regulatory factors in cereal-legume intercropping systems. The summary of the paper was based on the results of previous studies and the approaches of sustainable agricultural development. The objective was to provide scientific and theoretical basis for establishing a simple, high-yield, efficient and N-saving model for cereal-legume intercropping systems.

Using allelopathy and trap crops to eliminate soil bank of broomrape seed

MA Yongqing

2017, 25(1): 27-35. doi: 10.13930/j.cnki.cjea.160806

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Allelopathy should satisfy the following four factors:1) donor plants release allelochemicals that affect recipient plants continuously and quantitatively; 2) allelochemicals are isolated and identified from donor plants and affect accompanying plants in natural ecosystems, whether indoors or in fields; 3) donor plants produce and release allelochemicals in sufficient concentrations under natural conditions to adjacent recipient plants; and 4) allelochemicals released to recipient plants with enough biological activity to affect plants physiological and biochemical processes, which effect must exclude competition, animal abuse, pathogenic infection and the physical environment. Broomrapes (Orobanche spp.) are root holoparasites belonging to the genus Orobanche that lack chlorophyll and depend entirely on hosts for nutrients. Although the world of broomrape includes some 100 species, sunflower broomrape (O. cumana) and Egyptian broomrape (O. aegyptiace) are the most common species and have the widest distribution in China. Sunflower broomrape is mainly distributed in the northern regions of Shaanxi, Hebei, Xinjiang, Shanxi, Inner Mongolia and also in Northeast China. Egyptian broomrape is mainly distributed in Xinjiang and causes heavy and direct damage to tomatoes and potatoes. Broomrape seeds are light (3-6 μg) and small, and each broomrape plant can produce a huge quantity of tiny dust-like seeds which can survive in the soil for as long as 15-20 years. Broomrape seeds have special germination requirements-seeds should be kept in a warm and moist environment for 1-2 weeks and then exposed to germination stimulants. Under natural conditions, the germination stimulants are from host or the non-host plant root exudates. Once attached to a root, the parasite taps water and assimilates nutrients from host vessels. Efficient and economic control of broomrape is extremely difficult because infestation occurs primarily underground. The most effective way is to decrease soil bank of broomrape seeds. Trap crops are non-host plants whose roots exude chemical stimulants required for broomrape seed germination, but do not allow the attachment and development of the parasitic weed. In the absence of hosts, the seeds would germinate and not survive as the necessary conditions for live attachment to the host plant are not available; a process commonly referred to as "suicidal germination". This paper introduced advanced researches on the use of allelopathy and trap crops (wheat, corn, cotton, soybean, etc.) to eliminate soil bank of broomrape seeds.

Effect of plant allelochemicals on seed germination and its ecological significance

CHEN Feng, MENG Yongjie, SHUAI Haiwei, LUO Xiaofeng, ZHOU Wenguan, LIU Jianwei, YANG Wenyu, SHU Kai

2017, 25(1): 36-46. doi: 10.13930/j.cnki.cjea.160632

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As a form of plant interaction, allelopathy plays a critical role in agriculture and forestry production, including biological invasion, continuous cropping obstacle and weed suppression. Consequently, it is important to guide production if we take advantage of plant allelopathy in crop production. Seed germination is a key stage of a plant and the regulatory mechanism of this physiological process by allelopathy has been paid more and more attention. Numerous studies demonstrated that allelochemicals could promote or inhibit seed germination of different plant species, which had an important influence on the plant growth and development, the composition and distribution of plant communities and the balance within the ecosystem. In this review, the effect of allelochemicals on seed germination and its ecological significance were summarized. On the one hand, the physiological and biochemical mechanisms underlying the inhibition effect of allelochemicals on seed germination were summarized. For example, allelochemicals restrained seed germination through inhibition of radicle and hypocotyl elongation. Allelochemicals also hindered seed germination by damaging subcellular structures, disturbed the synthesis and metabolism of both phytohormones and reactive oxygen species (ROS). Furthermore, allelochemicals delayed seed germination by mediating metabolism of protein, oil and starch, which provide energy during seed germination. On the other hand, we discussed the ecological significance of allelochemicals to seed germination from two perspectives, weeds control of farmland and ecosystem stabilization. Here, we summarized the effects of allelochemicals on weed suppression in natural settings, autotoxicity in agriculture and forestry, and biological invasion caused by allelopathy. Finally, based on current research progresses, future research directions in the field of allelopathy and autotoxicity were proposed and discussed.

Climate suitability regionalization for Taiwan green jujube introduction and expansion in Fujian Province using GIS

LI Lichun, CHEN Fuzi, WANG Jiayi, CHEN Hui, LIN Jing, LI Lirong

2017, 25(1): 47-54. doi: 10.13930/j.cnki.cjea.160641

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In order to reasonably utilize climatic resources and optimize Taiwan green jujube plantation layout in Fujian Province, regionalization of the suitability of climate for the introduction and expansion of Taiwan green jujube in Fujian was conducted using GIS platform. Based on local meteorological conditions, lifecycle and production management characteristics of Taiwan green jujube in Fujian, an indicator system for the regionalization of the suitability of climate was constructed. The indicator variables included the annual cumulative temperature≥10℃, mean annual temperature, extreme minimum annual temperature (with climate suitability guarantee of 90%), annual precipitation and annual sunshine hours from 67 meteorological stations in Fujian Province during 1971-2011. The climate suitability index was summed up after standardization disposal of the performances of the five indicators and weighing by expert evaluation and AHP methods.Finally, the regionalization of the suitability of climate for the introduction and expansion of Taiwan green jujube in Fujian Province was done in GIS environment using the small grid reckoning models of the five indicators, combined with equation of the climatic suitability index. The climatic suitability index was divided into three grades, including suitable, sub-suitable and unsuitable, by natural break method combined with field investigation and repeated test. The reliability of the results of the regionalization of the suitability of climate for the cultivation of Taiwan green jujube in the province was confirmed by related research and the existing state of Taiwan green jujube plantations in Fujian. The results showed:1) coastal areas south to Quanzhou City and several other counties inland of Zhangzhou (Zhangpu County, Yunxiao County, Zhao'an County and Dongshan County) were suitable for Taiwan green jujube cultivation. Heat conditions in the areas were abundant, with annual cumulative temperature≥10℃ of >7 000℃, which prevented frost damage to Taiwan green jujube in the areas. As a result, Taiwan green jujube cultivation in the above areas could ensure high quality and yields. 2) Coastal areas in the central Fujian Province and some towns in Yongding County and Shanghang County in the south of Longyan area were the sub-suitable regions for Taiwan green jujube cultivation, because of lower extreme annual minimum temperature (with climate suitability guarantee of 90%) in the areas (0-4℃). It was possible that Taiwan green jujube cultivation in the areas could be hampered by low temperature or frost damage. Therefore, it was need to take defensive measures to avoid low temperature or frost damage. 3) The other regions/counties were unsuitable. The general climatic conditions in the areas were not fit for the growth of Taiwan green jujube, thus cultivation had no obvious economic benefits. Recent research studies and state of cultivation of Taiwan green jujube in Fujian confirmed the reliability of the regionalization analysis. The results offered a critical reference base for the introduction, expansion and adjustment of cultivation structure of Taiwan green jujube in Fujian Province.

MODIS-based spatio-temporal distribution of wildfire in Inner Mongolia

JIA Xu, GAO Yong, QI Hugejin, WEI Baocheng, CUI Xiangxin, MENG Zhongju, TANG Guodong

2017, 25(1): 127-135. doi: 10.13930/j.cnki.cjea.160577

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data for the period 2002-2014. Through the integration of precipitation data, the impact of precipitation on the characteristics of annual variations in wildfire was investigated. The results showed that: 1) the spatial distribution of fire spots gradually decreased from northeast to southwest and the high density areas were mainly distributed in the border region between China and Mongolia, the forest-grassland belt and typical arable zones. 2) The largest wildfire area in Inner Mongolia was in 2003, followed by 2006, and the smallest was in 2010. Analysis showed that the interannual change of burning area was closely linked to fire high-risk monthly precipitation anomaly. The happening of fire showed seasonal variations, which autumn and spring was high-incidence season, especially the months of March, April, May and September. The fire-burned areas in Xing'anling mountainous and hilly region, Hulunbuir plateau and hilly region, and Xilingol Plateau accounted for 90% of the total burned areas in the seven ecological zones of Inner Mongolia, with area ratios of 52%, 28% and 10%, respectively. 3) The fire-burned areas ranked from large to small was in the sequence of pasture land, agriculture land, woodland and other land use types in the study area. Fire spots were mainly distributed in meadow steppe and typical steppe zones. A large proportion of the fire enhanced recovery of old pastures overtaken by invasive species and secondary growth. This form of pasture management in Inner Mongolia was an important cause of wildfires in pasture lands. The practice of burning straw every spring and autumn also intensified the distribution of fire in typical arable lands, especially in the Nenjiangxian Plain, Hetao Plain and Songnen Plain. The fire-burned area in Xing'anling mountainous and hilly region and Hulunbuir plateau and hilly region had the same variation trend. The results were critically helpful in understanding the spatial and temporal patterns of wildfire and provided scientific basis for wildfire monitoring and alert system. Keywords: Wildfire; Spatial and temporal distribution; MODIS; Inner Mongolia; Ecological zone; Land use type

Effect of elevated[CO₂] on growth and attack of Asian corn borers (Ostrinia furnacalis) in foxtail millet (Setaria italica)

LIU Zijuan, LI Ping, ZONG Yuzheng, DONG Qi, HAO Xingyu

2017, 25(1): 55-60. doi: 10.13930/j.cnki.cjea.160687

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Since industrial revolution, global atmospheric carbon dioxide (CO₂) concentration ([CO₂]) has risen from 280 μmol·mol^-1 to the current level of about 392 μmol·mol^-1. Foxtail millet (Setaria italica) is one of the most important C₄ crops in the semiarid regions of North China, yet there is lack of sufficient information on how the crop responds to climate change in China. Here, we studied the effects of elevated atmospheric[CO₂] on foxtail millet in order to understand the changes in foxtail millet production under future CO₂ concentrations along with the response of C₄ crops to climate change. An open top chamber (OTC) system was used to test the effect of elevated[CO₂] on foxtail millet. One OTC was used as the control chamber, which maintained the ambient[CO₂]. In another OTC, elevated[CO₂] (ambient[CO₂]+200 μmol·mol^-1) was constantly maintained from crop emergence to harvest. Foxtail millet was sown in 40 cm×60 cm pots (28 cm depth). Ten plants were grown in each pot and 10 pots were put in every OTC. Leaf photosynthesis was measured using a portable gas exchange system. Chlorophyll fluorescence parameter was assessed using a miniaturized pulse-amplitude modulated fluorescence analyzer with a leaf clip holder. The changes in morphological parameters, biomass, yield and damage of Asian corn borer (Ostrinia furnacalis) in response to elevated[CO₂] were also determined. The results showed that elevated[CO₂] increased the net photosynthesis rate (P_n), stomatal conductance (g_s), transpiration rate (T_r) and water use efficiency (WUE) of foxtail millet by 38.73%, 27.53%, 6.93% and 40.56%, respectively. The maximal photochemical quantum yield (F_v/F_m) and non-photochemical quenching coefficient (NPQ) of foxtail millet leaf photosystem Ⅱ significantly decreased under elevated[CO₂]. Photosystem Ⅱ quantum yield (Φ_PSII) and apparent electron transfer rate (ETR) increased, but the change in photochemical quenching destruction coefficient (qP) was not significant. Elevated[CO₂] increased foxtail millet plant height, stem diameter and spikelet number by 3.41%, 13.28% and 13.11%, respectively. Elevated[CO₂] did not significantly affect leaf mass, stem mass, thousand-seed weight or the number of grain per plant at harvest, but the mass of panicle and aboveground per m² significantly decreased by 12.8% and 7.44%, respectively. Furthermore, Asian corn borer damage aggravated at filling-stage and harvest under elevated[CO₂]. However, yield did not significantly change under elevated[CO₂]. In conclusion, elevated atmospheric[CO₂] promoted the growth and development of foxtail millet, but increased the risk of insect damage.

Effect of integrated rice-crayfish farming system on soil physico-chemical properties in waterlogged paddy soils

SI Guohan, PENG Chenglin, XU Xiangyu, XU Dabing, YUAN Jiafu, LI Jinhua

2017, 25(1): 61-68. doi: 10.13930/j.cnki.cjea.160661

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Integrated rice-crayfish system is a complex ecological system based on waterlogged paddy field cultivation characterized with crayfish fed by rice straw. Using rice monoculture system as the control, a 10-year (2005-2015) field experiment was conducted to study the effects of integrated rice-crayfish system on rice yield and soil physico-chemical properties at soil depths of 0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm. The economic benefit of integrated rice-crayfish system was evaluated using the input-output method. The results indicated that long-term integrated rice-crayfish system significantly reduced soil compaction at the 15-30 cm layer. The soil compaction in 15 cm, 20 cm, 25 cm and 30 cm soil was lower in integrated rice-crayfish system than in rice monoculture system by 20.9%, 29.9%, 24.8% and 14.7%, respectively. Long-term integrated rice-crayfish system increased soil water-stable aggregates (>0.25 mm) content, aggregate mean weight diameter (MWD) and geometric mean diameter (GMD) in the 0-40 cm layer, but decreased aggregate fractal dimension (D) in the 0-20 cm layer. Compared with rice monoculture system, long-term integrated rice-crayfish system significantly increased the contents of soil organic carbon, total K and available N in the 0-40 cm layer, then total N in the 0-30 cm layer, total P and available P in the 0-10 cm layer and available K in the 20-40 cm layer. The total amount of reducing matter in the 0-10 cm soil layer of the long-term integrated rice-crayfish system was lower than that in the monoculture rice system, but it was higher in the 20-30 cm soil layer. Rice yield in integrated rice-crayfish system significantly increased by 9.5% than that in the monoculture rice system. The output, profit and ratio of output to input in integrated rice-crayfish system were higher than those in the monoculture rice system by 46 818.0 ￥·hm^-2, 40 188.0 ￥·hm^-2 and 100.0%, respectively. It was therefore clear that integrated rice-crayfish system improved soil structure, enhanced soil nutrient and increased rice yield and economic benefit. However, it also increased the risk of soil gleying in the 10 cm depth.

Effect of wheat straw return to soil with zero-tillage on maize yield in irrigated oases

GUO Yao, CHAI Qiang, YIN Wen, FENG Fuxue, ZHAO Cai, YU Aizhong

2017, 25(1): 69-77. doi: 10.13930/j.cnki.cjea.160639

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Yield capability is a key factor for crop growth and yield formation. The response of yield capability of crops to straw return to soils usually has been important in establishing highly efficient cropping systems and optimizing cultivation practices. A field experiment was carried out in a typically irrigated oasis region in 2009-2012 to determine the effects of yield capability of maize with different treatments of wheat straw return to soil and different tillage operations. The tillage operations included (i) no tillage with straw standing (NTSS), where no tillage was combined with 25 cm length wheat straw standing in the field after wheat harvesting in the previous fall; (ii) no tillage with straw covering (NTS), where no tillage was combined with 25 cm length wheat straw chopped and evenly spread on the soil surface at wheat harvest in the previous fall; (iii) tillage with straw incorporation (TIS), where 25 cm length wheat straw was incorporated into the soil through conventional deep tillage (30 cm) at wheat harvest in the previous fall; and (iv) conventional tillage (as control), where conventional deep (30 cm) plow was done with wheat straw removed from the field. The results showed that compared with the control, wheat straw return treatments reduced leaf area index (LAI) and leaf area duration (LAD) of maize before the large bell mouth stage. However, it increased LAI and LAD of maize after silking, which effectively delayed senescence. No tillage with straw standing and straw covering (NTSS and NTS) had the best effects on senescence delay among all treatments. Mean leaf area index (MLAI) increased by 12.8% under NTSS, 19.1% under NTS and 7.0% under TIS. Similarly, total LAD increased by 12.9% under NTSS, 18.6% under NTS and 6.8% under TIS. Specifically, the increase in MLAI and LAD under NTSS and NTS treatments was the highest. No tillage with straw retention improved mean net assimilation rate (MNAR) of maize growth season, which was 10.7% greater under NTSS treatment than under the control. But NAR of maize increased before silking, and decreased after silking under treatments of no tillage with straw retention, compared with the control. Straw return treatments had higher grain yield than the control, which increased by 13.0% under NTSS, 15.6% under NTS and 7.9% under TIS, with NTS had the best effect on grain yield increase. There was a high significant positive correlation between grain yield and MLAI, ear number (EN) and kernel number per ear (KNE), a significant positive correlation between grain yield and harvest index (HI), but no correlation between grain yield and MNAR. Increased MLAI, EN, KNE and HI were the main reasons for high grain yield of maize under wheat straw return conditions. No tillage with 25 cm length straw mulching over the soil surface (NTS) was the most suitable straw return strategy for optimal yield capability. Based on the results therefore, no-tillage with 25 cm length straw return to soil was recommended as the most feasible cultural method to optimize yield capability of maize ration with wheat in irrigated oasis regions.

Effect of eggplant-banana rotation with bioorganic fertilizer treatment on soil microflora in banana continuous cropping orchard

HONG Shan, JU Hongling, RUAN Yunze, LU Ming, WANG Beibei, ZHAO Yan, DENG Yan, YIN Liyan

2017, 25(1): 78-85. doi: 10.13930/j.cnki.cjea.160609

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Banana Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense race 4, has been reported to be the most limiting factor in Cavendish-banana production worldwide since 1996. With the development of banana industry and regularization of produce in recent years, continuous banana cropping has become a common farming system. Furthermore, Cavendish-banana production comprises of about 90% of banana growing areas in south China, of which more than 200 000 hm2 banana orchards have suffered the disease. Among the management control of Fusarium wilt, rational crop rotation in combination with bio-organic fertilizer has been an effective and stable means of prevention of the disease. In this study, eggplant-banana rotation system was used to investigate the effect of cultivating eggplants combining bio-organic fertilizer on soil microflora in banana continuous cropping orchard with serious Fusarium wilt diseases using the plate count method and denaturing gradient gel electrophoresis (PCR-DGGE) technique. The chemical properties of the soil were also analyzed in the experiment. Results showed that the effects of application of bio-organic fertilizer on the number of culturable F. oxysporum, fungi and bacteria for both continuous cropping system and rotation with eggplant system of banana were not extremely significant compared with those of organic fertilizer treatment. However, compared with continuous cropping banana, rotation with eggplant of banana significantly reduced the number of culturable F. oxysporum, the number of culturable F. oxysporum decreased from 10⁴ cfu·g^-1 to 10³ cfu·g^-1 in dry soils. Despite no observed significant differences in soil physico-chemical properties between bio-organic fertilizer and organic fertilizer treatments of the eggplant-banana rotation system, soil pH, organic matter and available N, P and K contents increased under bio-organic fertilizer treatment. The ratio of bacteria to fungi (B/F) in eggplant-banana rotation system was significantly higher in bio-organic fertilizer than that in organic fertilizer treatment. Based on DGGE results, soil bacterial structure was obviously altered after eggplant-banana rotation with bioorganic fertilizer treatment for a year, and then soil bacterial richness, stability and diversity index increased compared with the control (continuous cropping of banana). The effect of eggplant-banana rotation system under bio-organic fertilizer treatment was good, and had a diversity index (Shannon-Wiener) of 3.22, while the control treatment with organic fertilizer had a diversity index of 2.89. In conclusion, the rotation of eggplant with banana could effectively improve soil microflora, and plus bio-organic fertilizer application even had a better effect.

Effect of irrigation method on in-out migration of Nilaparvata lugens (Stål) and Cyrtorrhinus livdipennis (Reute) of high-quality late rice field: A case study of Yiyang, Hunan Province

LI Chao, LIU Yang, CHEN Kailin, HE Yang, YANG Jian, TANG Wenguang, ZHOU Xueqi, ZHANG Yuzhu

2017, 25(1): 86-94. doi: 10.13930/j.cnki.cjea.160549

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Cyrtorrhinus livdipennis (Reute) is one of natural enemies of Nilaparvata lugens (Stål), which more importantly has a clear accompanying migration pattern. The study of the effects of irrigation method on the in-and-out migration of N. lugens and C. livdipennis of high-quality late rice field could provide theoretical and technical support for an integrated control of N. lugens and reduce the use of chemical pesticides in cultivation. This experiment designed two isolation (semi-isolation and fully-isolation) modes to study the effects of deficit irrigation, wet irrigation, intermittent irrigation and long-term irrigation on immigration of N. lugens and C. livdipennis in high-quality late rice fields in 2014-2015. The results showed a significant difference on immigration and emigration of N. lugens and C. livdipennis in high-quality late rice fields between two years. There was no N. lugens and C. livdipennis immigration under all irrigation treatments in 2015 due to low temperatures and frequent rainfalls during mid to late growth stages of late rice. However, with higher temperatures in 2014, there was a significant migration. Based on the state of immigration, N. lugens immigration was lowest under deficit irrigation, which occurred early with a large base number, and was only 0.6% of that of intermittent irrigation. The intermittent irrigation had the largest number of immigration. Immigration rate (immigration number divided by increase in immigration number) of N. lugens under intermittent irrigation was 19.4, 1.4 and 3.4 times that of deficit, wet and long-term irrigation, respectively. The time of C. livdipennis immigration under deficit irrigation and wet irrigation was 8 days earlier than that under the other methods of irrigation. Based on the state of emigration, the time of N. lugens emigration under long-term irrigation was 11 days earlier than the other modes of irrigation. The largest number of N. lugens emigration under intermittent irrigation was 1.4, 1.1 and 5.8 times that of deficit, wet and long-term irrigation, respectively. The emigration rate (emigration number divided by decrease in emigration number) under wet irrigation was 1.3, 1.1 and 1.8 times that of deficit, intermittent and long-term irrigation, respectively. The number of C. livdipennis emigration in deficit irrigation increased by 102.9%, 127.2% and 1709.1% compared with wet, intermittent and long-term irrigation whereas emigration rate increased by 7.0%, 83.4% and 49.7%, respectively. Therefore, deficit irrigation reduced immigration of N. lugens, but increased the population of N. lugens before immigration compared with other irrigation methods. It simultaneously promoted emigration of enemy C. livdipennis, which increased the risk of N. lugens outbreak and control difficulty of N. lugens. Long-term irrigation effectively prevented N. lugens from immigration and enemy C. livdipennis from emigration. Wet and intermittent irrigation simultaneously promoted N. lugens emigration, while intermittent irrigation significantly reduced emigration of enemy C. livdipennis (P < 0.05).

Alleviation mechanism of intercropping with wheat for faba bean autotoxicity under benzoic acid stress

CHEN Ling, DONG Kun, YANG Zhixian, DONG Yan, TANG Li, ZHENG Yi

2017, 25(1): 95-103. doi: 10.13930/j.cnki.cjea.160541

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Abstract:
Continuous cropping of faba bean causes serious growth obstacle, and benzoic acid is one of the main autotoxins in faba bean continuous cropping. Faba bean-wheat intercropping is a general planting pattern in Southwest China. To investigate the effect of benzoic acid on faba bean seedling growth and Fusarium wilt occurrence, and to explore the effect and alleviation mechanism of intercropping with wheat on faba bean autotoxicity, a hydroponic experiment of faba bean-wheat intercropping with benzoic acid application was conducted in the greenhouse of Yunnan Agricultural University. Four benzoic acid rates were set, which were C₀ (0 mg·L^-1), C₁ (50 mg·L^-1), C₂ (100 mg·L^-1) and C₃ (200 mg·L^-1), with two planting patterns, faba bean monocropping and faba bean and wheat intercropping. The growth, enzymes activities and occurrence of faba bean Fusarium wilt were investigated. The results showed that in comparison with C₀ treatment, seedling growth was inhibited with increasing benzoic acid concentration. Benzoic acid increased the incidence and disease index of monocropped faba bean Fusarium wilt, significantly increased root and leaf MDA contents, and decreased the activities of antioxidant enzyme (POD and CAT) and pathogenesis-related proteins (β-1, 3-glacanase and chitinase) with increasing application rates. Comparison with monocropped faba bean, intercropped faba bean increased shoot dry weight by 17.0%-47.1%, reduced disease incidence and disease index by 11.1%-25.0% and 20.0%-42.1%, respectively, under benzoic acid application. Furthermore, the peroxidase (POD) activity increased by 12.9%-16.9% in root and by 9.3%-24.9% in leaf; and the catalase (CAT) activity increased by 10.3%-54.0% in root and by 6.6%-20.5% in leaf under intercropped condition. Compared with monocropping of faba bean, intercropping with wheat increased faba bean β-1, 3-glacanase and chitinase activities in root by 4.7%-13.1% and 6.7%-15.8%, while decreased malondialdehyde (MDA) contents in both root and leaf significantly by 19.5%-25.4% and 20.5%-29.9%, respectively, with benzoic acid application. Under C₂ (100 mg·L^-1) treatment of benzoic acid stress, faba bean-wheat intercropping system showed the best effect of improving pathogenesis-related proteins and antioxidative enzymes activity. Intercropping of faba bean-wheat significantly increased physiological resistance to Fusarium oxysporum f. fabae and significantly decreased the incidence of Fusarium wilt. Therefore, it alleviated the damage of Fusarium wilt caused by benzoic acid, and promoted growth of faba bean. Thus, intercropping with wheat was an effective method to alleviate faba bean autotoxicity caused by benzoic acid. The results also provided an experimental evidence for developing an ecologicaleconomic and effective approach to control soil-borne diseases caused by continuous crop cultivation.

Variation in soil water in Shapotou Area under straight-tube root irrigation

MA Zhenyong, DU Hulin, LIU Rongguo, YAN Zizhu, LIU Ligang, LIU Chao, NIU Jinshuai

2017, 25(1): 104-117. doi: 10.13930/j.cnki.cjea.160596

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Abstract:
In order to improve water use efficiency of afforestation drive in Shapotou Area, straight-tube root irrigation test was carried out on biennial sand-fixation Haloxy lonammodendron in Shapotou Nature Reserve Area in Zhongwei, Ningxia. The test aimed to study the variation rules of soil moisture in the 0-100 cm soil profile under straight-tube root irrigation. The aqueduct length of straight-tube root irrigation was 40 cm and water seepage micro-porous were distributed at 30-40 cm end section of the aqueduct. Soil water content was measured by the TDR soil moisture recorder at a time interval of 1 h. Based on the recorded data, the variations in soil water under straight-tube root irrigation was analyzed. The results showed that:1) for the period of root irrigation, the Logistic curve well described the variations in soil water content with irrigation time. After the stop of irrigation, however, the variation in soil water content degeneration was best described by power function model. 2) The maximum soil water infiltration rates of different layers were in the ranked sequence of 60 cm > 40 cm > 80 cm > 100 cm > 20 cm. The shortest time needed to reach the maximum infiltration rate was in the 40 cm soil layer (with an average time of 1.22 h) and the longest time was in the 100 cm soil layer (with an average time of 4.57 h). The average maximum infiltration rate of 1 m soil profile was 1.65%·h^-1 and the average time needed to reach the maximum infiltration rate of 1 m soil profile was 2.16 h. 3) Based on the fitted curves, it was suggested that the optimum straight-tube root irrigation cycle of H. lonammodendron forest in Shapotou was approximately 4 d and each single irrigation time was 6-10 h. 4) After stopping irrigating for 2 h, the rate of recession of soil moisture increased with increasing soil depth. Also after stopping irrigation for 48 h, the rate of degeneration of soil water content in all soil layers was almost zero. During the growing period of H. lonammodendron, the rate of degeneration of soil water in the 1 m soil layer reached the maximum of 2.20%·h^-1 during grain-filling period and reached the minimum of 1.31%·h^-1 during aestivation period. 5) The straight-tube root irrigation had the minimal effect on soil water content in the 20 cm soil layer, but the biggest influence on the 60 cm soil layer. During irrigation, the constant value line of soil water content centered on the 60 cm deep line which radially distributed into the surface and deep soil layers. After irrigation, average soil water contents in the 20 cm and 60 cm soil layers were significantly different (P < 0.05) from those of the other layers. The research showed that the law of soil water infiltration in straight-tube root irrigation followed the Logistic curve, the regression rule followed the power function curve, and the straight-tube root irrigation had the minimum impact on soil water in the 20 cm layer and had the maximum impact on soil water in the 60 cm layer. The irrigation cycle of straight-tube root irrigation for H. lonammodendron in Shapotou Area was approximately 4 days and the recommended single irrigation time was 6-10 h.

Soil water content retrieval based on Sentinel-1A and Landsat 8 image for Bei'an-Heihe Expressway

ZENG Xujing, XING Yanqiu, SHAN Wei, ZHANG Yi, WANG Changqing

2017, 25(1): 118-126. doi: 10.13930/j.cnki.cjea.160657

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Abstract:
Soil water content is one of the basic parameters that affect hydrological variability and climate change. It has important practical significance and scientific value for climate change, water resources and estimation of crop yield to study the distribution of soil water content. To probe new ways of soil water content retrieval in complex vegetation coverage area, this study analyzed soil water contents of complex surfaces with various degrees of vegetation cover along Bei'an-Heihe Expressway using images from Sentinel-1A dual-polarization Synthetic Aperture Radar (SAR) for 21 June 2015. Also Landsat 8 images were integrated as assisted optical image for the same satellite transit time. Then the results of the inversion of soil water content under different land use types and polarization combinations were discussed. Backscattering coefficients of different polarization modes were extracted using the water cloud model. Support vector regression algorithm was used to estimate surface soil water content based on the soil inversion parameters. The applicability of different polarizations in the retrieval of soil water content on complex surface was also discussed. The results showed that VH polarization retrieval accuracy was 52.11%, while combined VH polarization with normalized difference vegetation index (NDIV) retrieval accuracy was only 53.6%. This was not satisfactory for the vegetation zone. VV polarization and dual polarization ratio of VV/VH images were very sensitive to bare land and low vegetation cover land, for which retrieval accuracies were respectively 75.4% and 59.5%. These methods were, however, not applicable in areas with moderate or high vegetation cover. The results of VH polarization inversion for arable lands soil water content was 9.37% lower than the measured value. Also the inversion value of VV polarization for areas with low bush was 10.45% lower than the measured value. The inversion results for dual polarization ratio of VV/VH in shrub and arable lands were not as good as the inversion results for single polarization. For the various combinations, the inversion with the highest precision model was that for the combination of VV with NDVI. In summary, the combination of VV and auxiliary variable NDVI comprehensively reflected soil water content in complex surface environments. The goodness of fit (R²) of VV polarization combined with NDVI was 84% and the calculated root mean squared error was 2.07. In comparison with VV polarization, the retrieval accuracy improved by 8.8% and the calculated root mean square error decreased by 2.704. The combination of VV polarization with NDIV had more advantages for the inversion of soil water content for the regions with middle vegetation cover. The application of combined VV polarization with NDIV increased the potential and effectiveness of Sentinel-1A c-band synthetic aperture radar in areal study of soil water content.

Coordinated development and its' spatio-temporal evolution of rural population, land and economy system in Sichuan Province

MA Li, TANG Hong, YIN Qi, YANG Qin, ZHANG Zhan

2017, 25(1): 136-146. doi: 10.13930/j.cnki.cjea.160595

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Abstract:
It is important for sustainable development of rural economic-social system to explore interaction degree among people's life standard, land use degree and economic development level. This paper used a comprehensive evaluation index system of "population, land and economy" to calculate the development indexes of rural population, land use and economic development. The coupling degree and coordinated development degree of population, land and economy system were also assessed. The coordinated development of rural population, land and economy system was categorized into five types-serious inharmonious and decline (SIHD), mild inharmonious and decline (MIHD), barely coordinated transition (BCT), well-coordinated development (WCD) and highly coordinated development (HCD). Using quantitative analysis and GIS platform, this paper analyzed the characteristics and problems of spatial and temporal variations of coordinated development among rural population, land and economy under accelerated urbanization in Sichuan Province, and then further explores the way for sustainable development of the rural socio-economy. The result showed that in 2014, BCT and WCD were predominated types in Sichuan rural population, land and economy system with obvious regional differences, as some regions had excellent coordination development level while some others were still undergoing SIHD. In terms of time span, there was a wide range of change in coordinated development of rural population, land and economy system during the period 2000-2014. The number of MIHD region and BCT region reduced, while BCT region which occupied 61.90% of the total region in 2000, and fell to 33.34% in 2014. Also WCD region increased gradually from 14.29% in 2000 to 52.38% in 2014, while HCD and SIHD remained relatively stable, showing an overall development momentum. In more recent years, reform of rural land policy positively influenced land and improved land use efficiency. The integration of urban and rural construction was conducive for promoting the development of rural economy, promoting increased rural land development index and economic development index. With regard to spatial characteristics, regions with HCD were mainly located in plain and hilly regions. On the contrary, there was low degree of coordination in regions with poor natural geographical conditions such as mountains and plateaus. Specifically in central plain areas, northeastern hilly regions and southern hilly regions of Sichuan, the degree of coordinated development was high compared with regions with low degree of coordinated development in Panxi area and northwest plateau region; which was basically consistent with the actual situation in Sichuan. In conclusion, influenced by geomorphic characteristics, resource endowment, geographical location, etc., the development levels of rural population, land and economy, and the degree of coordinated development of these three factors (rural population, land and economy) were quite different in terms of the various prefectures or counties in Sichuan. Thus strategies such as setting agricultural development goals and priorities and promoting sustainable development of rural socio-economy should be done based on the regional development characteristics and deficiencies.

2017 Vol. 25, No. 1