中国生态农业学报(中英文)

Effects of short-term global warming and precipitation reduction on the quantity and spectral characteristics of soil DOM in Cunninghamia lanceolata plantation

LI Huan, YANG Yusheng, SI Youtao, LIU Zhu

2017, 25(7): 949-957. doi: 10.13930/j.cnki.cjea.170070

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Abstract:
As a small but reactive soil organic matter (SOM) pool, dissolved organic matter (DOM) is considered to be a sensitive indicator of the dynamic of SOM and an important component of terrestrial biogeochemical cycle.The quality and quan tity of DOM are crucial in the dynamics of C, N and other nutrients in forest soils because these attributes are closely related to carbon accumulation in soil and nutrient availability to microorganisms and plants.Global warming has been widely recognized and has induced drastic changes in global precipitation patterns.Because temperature and precipitation are the two most important environmental drivers regulating forest SOM cycle, it is critical that we have a solid understanding of the response of soil DOM to such climatic changes.In this study, we conducted a short-term experiment in a Cunninghamia lanceolata plantation in subtropical China that stimulated soil warming and precipitation decline.The objective of the study was to address the effects of the two factors (temperature and precipitation) on the quantity and composition of DOM.The experimental design was a randomized complete block factorial design, with warming and precipitation as fixed factors.The four treatments (each replicated three time) were set up in the experiment included no warming and natural precipitation (CT), warming and natural precipitation (W), no warming and reduced precipitation (P), warming with reduced precipitation (WP).We found that:1) W treatment increased the quantity of labile soil dissolved organic carbon (DOC), but decreased the aromaticity and humification degree of DOM.The 0-10 cm soil layer contained more alkanes and little esters, while the 10-20 cm soil layer had more carbohydrates.2) P treatment resulted in a smaller soil water content, which limited DOC production.In the 0-10 cm soil layer, soil DOM was apparently less humified and less condensed, with much alkanes present.However, in the 10-20 cm soil layer, aromaticity and humification degree were enhanced, while the quantity of carbohydrates decreased.In addition, precipitation decline also improved the quantity of DON.3) The combination of warming climate and declining precipitation increased the concentrations of DOC and DON, and reduced the aromaticity index and humification degree.The 0-10 cm soil layer had relatively more carbohydrates than the 10-20 cm soil layer.4) In the 0-10 cm soil layer, warming climate was the only factor that significantly influenced the quantity and quality of DOM.With increasing soil depth, precipitation decline became the second significant factor influencing soil DOM structure.Our results provided a deeper insight into the dynamic changes of soil DOM under global warming and declining precipitation, which was helpful in more accurately predicting soil C and N cycle in response to future global climate change.

Impact of water/fertilizer management on methane emission in paddy fields and on global warming potential

XIE Liyong, XU Jing, GUO Liping, XU Yuxiu, SUN Xue, ZHAO Hongliang, GUO Fei, ZHAO Xun

2017, 25(7): 958-967. doi: 10.13930/j.cnki.cjea.160921

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Methane (CH₄) is a key greenhouse gas, second only to CO₂ in term of contribution to global warming.Paddy field, as an important source of CH₄ emission, has significant implications for global warming and climate change.In order to understand the main factors of CH₄ emission in paddy fields and its impact on global warming, this study calculated potential global warming and sought measures to mitigate CH₄ emission in paddy fields.To do so, we collected data on CH₄ emission in paddy fields in China using literatures published before 2015(including journals and doctoral and master dissertations) and documented in CNKI net, ScienceDirect and SpringLink.Then daily CH₄ emission, global warming potential (GWP) and associated factors influencing CH₄ emission in paddy fields in China were analyzed using regression and factorial analyses.The results showed that daily emission of CH₄ in paddy field and GWP due to CH₄ emission increased with increasing soil organic matter (SOM).The order of daily CH₄ emission from paddy field was:late paddy field of double cropping rice > early paddy field of double cropping rice > single cropping paddy field > late paddy field of rice-wheat rotation.GWP due to CH₄ emission in late paddy field was more than that in early paddy field for double cropping rice.The order of daily CH₄ emission from paddy fields with different fertilizer managements was:ST (straw turnover) > NO (chemical nitrogen fertilizer with organic manure) > NF (chemical nitrogen fertilizer)≈ BI (biochar).Water management significantly affected CH₄ emission from paddy fields with the order of continuous flooding (CF) > field drying (FDF) > flooding-drying alternation (FD) > control irrigation (CI).Proper water management also significantly reduced GWP due to CH₄ emission.The order of GWP due to CH₄ emission in early paddy fields, late paddy fields and single cropping rice paddy fields was also as follows:CF > FDF > FD > CI.The results suggested that CH₄ emission was influenced by many factors, including soil SOM content, water and fertilizer management, and basic soil conditions.However, agricultural management activities (e.g., water and fertilizer management, fertilizer amount, fertilizer type) played a major role in CH₄ emission in agricultural lands.This was influenced by soil nutrient conditions (soil SOM content and C:N ratio), climatic conditions (crop growth period, temperature and precipitation during growth period), management practices (fertilizer and water management), rotation system, and other factors.For a more accurate inventory of greenhouse gas emission and proposal of effective mitigation policies, it was critical to use appropriate prac-tices suitable to specific climatic, soil and cropping conditions, combined with rational nitrogen fertilizer application rate and water management.

Effect of nitrapyrin on functional diversity of soil microbial community in drip-fertigated cotton field

LIU Tao, LIANG Yongchao, CHU Guixin

2017, 25(7): 968-974. doi: 10.13930/j.cnki.cjea.161159

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As one of the nitrification inhibitors (NIs), nitrapyrin (2-chloro-6-(trichloromethyl)-pyridine) exhibits some effective influences on controlling nitrification, reducing nitrogen leaching and nitrification-denitrification losses, increasing crop nitrogen uptake.However, information is still scant regarding the effect of nitrapyrin on the functional diversity of soil microbial community under drip irrigation condition in arid area.In view of this, a field trial (of randomized block design) was conducted to evaluate the impact of repeated supply of nitrapyrin with urea via fertigation on the functional diversity of soil microbial community in a drip-fertigated cotton field.Three treatments were established:CK[0 kg (N)·hm^-2], Urea[225 kg (N)·hm^-2]and Urea+nitrapyrin[225 kg (N)·hm^-2+2.25 kg (nitrapyrin)·hm^-2], each treatment was replicated three times.Biolog-ECO technology was used to explore carbon metabolism and community functional diversity of soil microbial.The results showed that the application of urea and urea plus nitrapyrin significantly increased metabolic capacity of 31 carbon sources (AWCD) and intensity of carbon metabolism (S) of soil microbial community compared with CK (P < 0.05), it also increased the diversity and richness of soil microbial community[Shannon index (H'), Simpson index (D), McIntosh index (U) and Richness index (R)]and improved the utilization of six types of carbon sources used by soil microbial community to some extent.Urea+nitrapyrin treatment increased AWCD, S, H', D, U and R of soil microbial community respectively by 13.83%, 9.33%, 1.29%, 1.34%, 11.26% and 11.79%(P > 0.05), it decreased Pielou evenness index (J)(P > 0.05) compared with Urea treatment.Principal component analysis and cluster analysis indicated that the application of urea and urea plus nitrapyrin significantly influenced the functional diversity of soil microbial community.However, there was no significant difference between Urea and Urea+nitrapyrin treatments.Furthermore, the addition of nitrapyrin increased the utilization of polymers, phenolic acids, carboxylic acids, amino acids and amines by soil microbial community, but decreased the utilization of carbohydrates compare with Urea treatment (P > 0.05).The results demonstrated that the repeated supply of nitrapyrin with urea via fertigation regulated soil micro-ecological environment, increased soil microbial metabolism and functional diversity of community.It inhibited the reduction of soil microbial activity due to long-term application of inorganic nitrogen fertilizers in drip-fertigated cotton fields in arid areas.

Comparison of gas exchange characteristics between two invasive plants and a co-occurring native plant in Liaoning Province

WEI Zishang, CHEN Xinwei, YANG Dianlin, HUANGFU Chaohe

2017, 25(7): 975-982. doi: 10.13930/j.cnki.cjea.161190

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Biological invasion is one of the century's most serious environmental problems.A comparative study of invaders and co-occurring natives is an effective approach to gaining insights into the invasiveness of exotic plants.Ambrosia artemisiifolia L.and A.trifida L.are two aggressive North American annual weeds in China, whereas A.trifida occurs mainly in Northeast China.They usually invade cultivated fields and reduce crop productivity, causing significant ecological and socio-economic impacts in introduced areas.Besides its economic impact on crop yield, A.artemisiifolia also represents a major health problem since its pollen is a strong allergen and one of the main causes of hay fever.To explore the traits contributing to invasiveness of A.artemisiifolia and A.trifida and to test the relationship between plasticity of these traits and invasiveness, we conducted a comparative study of two invasive species and their co-occurring native Asteraceae plant, Aster tataricus, in tataricus in terms of gas exchange and efficiencies in resource utilization.We tested the hypothesis that A.artemisiifolia and A.trifida had growth-related ecophysiological advantages over the natives in its non-native range, which resulted in its rapid growth and enhanced its invasiveness.Photosynthesis, specific leaf area (SLA), and the efficiency of resource use (light, phosphorus, and nitrogen) were examined in field.Leaf construction cost (CC) is considered as a quantifiable measure of energy demand for biomass production and is related to energy use efficiency as it includes component of both morphological and physiological traits.The results showed that the light saturation point (LSP) of A.artemisiifolia, A.trifida were significantly higher than that of the native species A.tataricus.The order of P_nmax was that A.artemisiifolia > A.trifida > A.tataricus, and this parameter of two invasive species were significantly higher than that of A.tataricus by 151.28%, 82.80%, respectively.The specific leaf area (SLA), leaf N content per unit mass (N_mass), leaf P content per unit mass (P_mass), photosynthetic energy use efficiency (PEUE), photosynthetic nitrogen use efficiency (PNUE) of two invasive plants were significantly higher than those of the native, but the difference of leaf construction cost per unit mass (CC_mass) between the three plant species was not significant.In summary, the two Asteraceae invasive plant species has higher gas exchange characteristics and leaf traits as compared with co-family non-invasive plant species, and their photosynthetic characteristics and leaf characteristics were closely linked.The two Asteraceae invasive plant species had higher photosynthetic characteristics and energy use parameters, including P_nmax, PNUE, PEUE, water use efficiency (WUE), leading to more effectively resources capturing and utilization efficiency, which may be one of the reasons for successful invasion of these Asteraceae invasive plants in the studied area.

Landscape connectivity and network construction of riparian vegetation in typical reach of the middle and lower reaches of Yellow River

ZHAO Qinghe, MA Lijiao, LIU Qian, DING Shengyan, LU Xunling, CAO Zihao, ZHANG Yifan

2017, 25(7): 983-992. doi: 10.13930/j.cnki.cjea.161125

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Riparian ecosystems form the linkages and exchange zones of matter, energy and information between aquatic and terrestrial ecosystems.The characteristics of such zones significantly influence integrated landscape ecosystem functions from land to riparian regions.Riparian vegetation as an important component of riparian ecosystem, is the basis of the formation and maintenance of riparian buffer zone ecosystem services.However, riparian vegetation has now been widely recognized as fragile and sensitive system requiring conservation as it undergoes strong disturbances and great alteration by anthropogenic activities globally.Conservation activities have largely focused on the restoration or creation of natural areas to facilitate the movement of organisms.This is often based on reliable measurement of landscape connectivity and patch importance.In this study, a typical riparian buffer zone in the middle and lower reaches of Yellow River was analyzed for landscape connectivity and importance of riparian vegetation in 2003, 2009 and 2015 using remote sensing, landscape connectivity indexes, patch importance evaluation and corridor-network analysis.Also the study constructed a riparian vegetation corridor-network in order to provide support for maintaining biodiversity in riparian buffer zones in the middle and lower reaches of Yellow River.The results indicated that landscape connectivity of riparian vegetation increased both from 2003 to 2015 and with increasing threshold distance.Thus the number of links (NL) and the number of the largest component (NLC) of vegetation patches increased from 2003 to 2015 and they increased with increasing threshold distance.However, the number of components decreased from 2003 to 2015 and with increasing threshold distance.The integral index of connectivity (IIC) and the probability of connectivity (PC) increased with increasing threshold distance.Under different threshold distances, the importance value increased with increasing patch area.Thus with increasing threshold distance, the importance value of small patches (0-5 hm²) increased gradually, that of middle patches (5-10 hm²) initially increased and then decreased, while those of large patches ( > 10 hm²) decreased gradually.When the threshold distance was more than 1 000 m, the importance values of small, middle and large patches became stable, indicating that 1 000 m was the optimal threshold distance for the analysis of landscape connectivity in the study area.Ultimately, the corridor-network analysis proved to be important reference for the construction of riparian vegetation corridor-network. It sim-ultaneously considered important ecological nodes, ditches and road corridors in the study area as the established vegetation network system had high corridor node number, network closure and connection degree.In addition, riparian vegetation corridor-network construction should not only prioritize the connection between large patches, but also emphasize the stepping-stone role of small and middle patches between the large patches.

Functions and countermeasures of biodiversity conservation in agricultural landscapes:A review

SUN Yufang, LI Xiang, ZHANG Hongbin, CHEN Baoxiong, LI Yaokui, LIU Yunhui, YU Zhenrong

2017, 25(7): 993-1001. doi: 10.13930/j.cnki.cjea.160960

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Studies have shown that intensive agricultural production and homogenization of agricultural landscape have led to a decline in biodiversity across agricultural landscapes.This phenomenon has resulted in the loss of ecosystem services such as biodiversity conservation, natural pollination, pest regulation, erosion control and sustainable agricultural development.In this paper, the researches and practices of biodiversity in agricultural landscapes and the related ecosystem services were reviewed.We discussed the role of agricultural landscape in biodiversity conservation, pollination service, regulation service, soil and water conservation and other aspects of ecological service functions and conservation.We summarized the practical measures taken in Europe and the United States for the conservation of biodiversity in agricultural landscapes.It was pointed out that although China had made significant efforts in the conservation of biodiversity, it neglected the protection of agricultural landscapes.In recent years, urbanization and intensive agricultural development have further exacerbated the loss of biodiversity in agricultural landscapes.It was necessary to draw lessons from the European and American experiences to put forward a national strategy for the conservation of biodiversity in agricultural landscapes in China.The intensification of conservation and enhancement of biodiversity in agro-ecological landscapes can benefit both crop yield and quality.The protection of biodiversity in agricultural landscapes required an integrated management of agricultural landscapes at agro-ecological and agro-landscape scales in order to restore and improve biodiversity in agricultural landscapes and the related ecosystem services functions.With specific regard to the problems and requirements of sustainable agricultural development in China, we suggested the development of biodiversity conservation in agricultural landscapes from policy and regulation measures, monitoring and evaluation, engineering and technology, research and development, technology integration, eco-subsidy system, training and extension, etc.

Current situation, issues and countermeasures of crop rotation and land fallow in Jiangxi Province

HUANG Guoqin, ZHAO Qiguo

2017, 25(7): 1002-1007. doi: 10.13930/j.cnki.cjea.161030

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The "pilot projects of exploration of crop rotation and land fallow" proposed by the CPC Central Committee and the State Council is being implemented throughout the country in order to promote the planning, implementation and practice of crop rotation and land fallow for the improvement of environment.To conduct relevant research and develop relevant policies for Jiangxi Province and other regions under similar conditions, literature research methods, field visits and other forms of investigation were conducted in this study.The results showed that current crop rotation systems in Jiangxi Province were characterized by small cultivated areas, diverse patterns, wide distribution range and obvious benefits.The land fallow patterns in the province mainly included both conversion of degraded farm land into forest (grass) and leisure.The current crop rotation in the province was a small, poor management and low efficiency model.The land fallow was mostly passive, irrational, inappropriate, single model, abnormal cycle, not compensational, etc.Based on the above issues, this paper highlighted existing problems and put forward countermeasures for the promotion of land rotation and fallow systems in the region.This included:1) increasing propaganda and raising awareness of farmers, 2) developing scientific planning and classification guide, 3) developing clear and effective management strategies, 4) improving existing conditions and creating sustainable models, 5) determining reasonable compensation standards to protect interests of farmers, and 6) increasing investment and talent training.

Postponed nitrogen application enhances root morphology recovery and photosynthetic characteristics of summer maize waterlogging stressed at seedling stage

WU Wenming, WANG Shiji, CHEN Hongjian, CUI Quanren, JING Lili

2017, 25(7): 1008-1015. doi: 10.13930/j.cnki.cjea.160951

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Maize is one of the main summer crops in Anhui Province.However, maize production in this region is often subjected to waterlogging stress at seedling stage.Nitrogen (N) is a key nutrient that influencing growth, yield and quality of maize, but what role it plays in relieving waterlogging stress on summer maize remains unclear.Thus field experiments were carried out to determine the effect of N application on the recovery of root morphology and photosynthetic characteristics of summer maize cultivar'Longping 206'after waterlogging stress at seedling stage.Under both waterlogging and control (normal water) conditions, four treatments of different N application rates at land preparation, jointing stage, and big flare stage (N1:10:0:0;N2:7:3:0;N3:5:5:0 and N4:3:5:2) were set with a total N amount of 240 kg·hm^-2.The results showed that waterlogging stress at seedling stage significantly inhibited maize root growth.Root weight, length, surface area and diameter significantly decreased compared with those of the control.The degree of inhibiting effect on root morphology was in the order of total root length > root surface area > root diameter.Delayed N application had a compensation effect on root growth after waterlogging.Eighteen days after waterlogging, total root length of N1 to N4 treatments increased by 1.9-5.1 folds that before waterlogging.Root surface area and diameter increased by 6.3-10.3 folds and 0.7-1.0 folds, respectively.The degree of compensation effect of delayed N application on root morphology was in the order of root surface area > total root length > root diameter.Waterlogging stress at seedling stage significantly decreased leaf area index (LAI) at spinning stage by a range of 9.3%-22.5%.Compared with N1 treatment, N2, N3 and N4 treatments increased LAI within 3.2%-20.7% under waterlogging treatment.Waterlogging induced a noticeable decline in P_n, respectively by 16.1% and 28.9% compared with the control at mid grain-filling and late grain-filling stages.At late grain-filling stage, P_n decreased faster than that of control.Under waterlogging stress, non-stomatal restriction was the main factor driving the decline of photosynthetic capacity.Moreover, delayed N application improved photosynthetic capacity of ear leaf, which photosynthetic capacity was better than basal N application.In conclusion, the morphological characteristics of root and leaf along with the photosynthetic characteristics of maize under waterlogging responded positively to delayed N supplication.Therefore to improve the growth of maize in the study area (which could be affected by waterlogging at seedling stage), it was recommended to apply N at jointing and big-flare stages.

Comparison of fertilizer-effect models on winter wheat response to nitrogen and phosphorus fertilizers in saline soils in the Yellow River Delta

SHAN Jingjing, CHEN Xiaobing, YIN Chunyan, WEN Pei, YAN Kun, ZHANG Lihua, ZHANG Libin, FU Xiqiang, SUN Haishuan

2017, 25(7): 1016-1024. doi: 10.13930/j.cnki.cjea.160986

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Salt-affected soils distribute widely across the Yellow River Delta, which inhibit plant growth and crop yield in this area.Although fertilizer application can alleviate the adverse impact of salinization on crop, little remains known about the performance of different fertilizer-effect models on simulation of'3414'fertilizer experiments in winter wheat field in saline soils.Among the essential elements, nitrogen (N) and phosphorus (P) are usually the most important nutrients limiting plant growth in saline or non-saline soils.In this study, four fertilizer-effect models were used to simulate the impact of N and P fertilizers on wheat yield in a field experiment in Lijin County of Shandong Province.The study aimed at selecting suitable fertilizer-effect model for wheat grown in saline soils in the Yellow River Delta.Four levels of N and P fertilizers (N:0 kg·hm^-2, 135 kg·hm^-2, 170 kg·hm^-2, 405 kg·hm^-2; P:0 kg·hm^-2, 53 kg·hm^-2, 105 kg·hm^-2, 157.5 kg·hm^-2) were set in eight treatments based on the'3414'test in order to investigate the fit effect of the four fertilizer-effect models-linear plus plateau, unary quadratic, square root and binary quadratic.To ensure the accuracy of fertilizer-effect models, the least square method was used in the statistical regression analysis.The results suggested that the four fertilizer-effect models had an extremely significant level (P < 0.01) based on the fit test.Unary quadratic model of effects of N and P fertilizers was the best among unary fertilizer-effect models, which suggested that the highest income levels were 7 448.3 ¥·hm^-2 and 7 357.7 ¥·hm^-2 and the recommended N and P rates were 254.4 kg·hm^-2 and 98.6 kg·hm^-2, respectively.Compared with the unary models, binary model was better.In binary model, the best N and P application amounts were respectively 244.1 kg·hm^-2 and 94.2 kg·hm^-2, with N to P ratio of 2.6.In the model, the economic benefit and agronomic efficiency of N and P were 7 432.4 ¥·hm^-2, 6.2 kg (grain)·kg^-1(N) and 13.8 kg (grain)·kg^-1(P₂O₅), respectively.On the basis of the fitted curve, the binary quadratic model had the better economic fertilizer rate, agronomic efficiency, economic benefits than the unary models.Then the binary quadratic fertilization model was the best for wheat cultivation in saline soils in Yellow River Delta.

Effect of straw return and rotary tillage on soil physical properties and me-chanical sowing quality of maize in Central Sichuan

ZHU Min, SHI Yunxiang, SUN Zhiyou, WANG Xinglong, ZHANG Di, KONG Fanlei, YUAN Jichao

2017, 25(7): 1025-1033. doi: 10.13930/j.cnki.cjea.161124

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With continuous development of agricultural science and technology and improvement of ecological and environmental awareness in China, rational use of crop straw has become an efficient and sustainable agricultural practice.With the rapid development of winter wheat-summer maize rotation system, concerns have grown about the processing of soil barrenness, wheat straw waste and other cultivation issues.Irrespectively, researches targeting purple clay soils have been limited.Therefore, an experiment was conducted to determine a suitable straw return and tillage method of mechanically sowed maize under wheat-maize double-cropping system in purple soils in hilly areas in Central Sichuan.The study also investigated the problems of soil fertility and viscosity, sowing conditions and plough layer quality for high yields.The experiment consisted of four treatments-rotary tillage with straw return (RTS), none-tillage with straw return (NTS), rotary tillage without straw return (RT) and none-tillage (NT).The aims of the experiment were to study the effects of tillage patterns with wheat straw return on physical properties of purple clay soils, and on quality of mechanically sowed summer maize in hilly areas in Central Sichuan.The results showed that compared with RT, RTS significantly increased capillary porosity in the 0-10 cm soil layer at elongation stage, increased water content in the 0-10 cm soil layer under no-tillage treatment for the entire growth period, and significantly reduced the rate of emergence, and uniformity of mechanical sowing and seedling quality of maize.Compared with NTS, RT reduced soil bulk density and water content in the 0-10 cm layer, but increased capillary porosity, emergence rate, seedling height, stem diameter, leaf area and dry mass of mziae.Under wheat straw return condition, rotary tillage reduced soil bulk density at the 0-10 cm layer by 2.0%-12.1% as compared to no-tillage, significantly improved emergence rate (by 17.9%), plants per hill and uniformity of mechanical sowing and seedling uniformity of maize.Emergence rate of maize was significantly positively correlated with soil water content of the 0-10 cm layer.Both mechanical sowing uniformity and seedlings uniformity were significantly negatively correlated with soil bulk density of the 0-10 cm layer.It was thus clear that rotary tillage with straw return improved soil structure, increased soil water content, benefited the quality of mechanical sowing and quality of seedlings of maize under winter wheat-summer maize cropping pattern in hilly areas in Central Sichuan, China.

Response mechanism of photosynthetic characteristics of winter wheat to CO₂ concentration and soil water content

ZHOU Xiaoxu, ZHANG Yucui, WU Lin, SHEN Yiqun, JIANG Hanbing, SHEN Yanjun

2017, 25(7): 1034-1041. doi: 10.13930/j.cnki.cjea.161167

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Photosynthesis can reveal the response of plant to the environment.By fitting the light response curve, the physiological mechanism of plant under different growth conditions could be clarified.Under four treatments of two CO₂ concentrations (400 and 750 μmol·mol^-1) and two soil water contents[45%(drought stress) and 75%(suitable water condition) of field capacity], Li-6400 portable photosynthetic system was used to measure the light response curves of flag leaves of winter wheat.Five photosynthetic light response models, including rectangular hyperbolic model (RHM), non-rectangular hyperbolic model (NRHM), rectangular hyperbolic modified model (RHMM), exponential model (EM) and modified exponential model (MEM), were used to fit the light response curve of winter wheat.The effects on photosynthesis of winter wheat of different treatments were analyzed.The results showed that the light saturation point (LSP) and the max net photosynthetic (P_nmax) fitted by the rectangular hyperbolic model and the non-rectangular hyperbolic model were larger than the measured values.The rectangular hyperbolic model and the non-rectangular hyperbolic model could not fit the photoinhibition.Meanwhile, the exponential model could simulate well of LSP and P_nmax while could not show the photoinhibition, either.Although the modified exponential model could reveal the photoinhibition, there were serious bias in the parameters of light response curve, and the parameters were lower than the other models.In general, the rectangular hyperbolic modified model was the best model for the simulation of light response curve and its parameters.The increase of CO₂ concentration effectively improved the apparent quantum efficiency, light saturation point and maximum net photosynthetic rate of winter wheat, and reduced the light compensation point and dark respiration rate of winter wheat.Meanwhile, winter wheat energy conversion rate, maximum net photosynthetic rate, light use scope and initial photosynthetic efficiency were increased, which suggested that the increase of CO₂ concentration could effectively enhance the photosynthetic capacity of winter wheat.When the soil moisture content was low, the effects of drought stress was partly offset by increased initial photosynthetic efficiency of winter wheat, but the apparent quantum efficiency, light saturation point and maximum net photosynthetic rate were reduced obviously than the appropriate soil moisture content, namely the photosynthetic ability of winter wheat decreased significantly under drought stress.In addition, the increase of CO₂ concentration had a certain compensation effect on the decrease of photosynthesis caused by drought stress, and the enhancement effects of CO₂ concentration increase on photosynthetic capacity of winter wheat under drought stress was greater than that under appropriate soil moisture content.

Effect of high-temperature on the quality of pakchoi and its simulation

XUE Sijia, YANG Zaiqiang, LI Jun

2017, 25(7): 1042-1051. doi: 10.13930/j.cnki.cjea.161141

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To explore the effects of high-temperature stress on yield and quality of greenhouse pakchoi, a study was conducted from October 2015 to May 2016.In the study, we set three gradients of daytime/nighttime temperatures of 32℃/22℃, 35℃/25℃, 38℃/28℃, with 25℃/18℃ as the control, and the duration of each treatment was 3 d, 6 d, 9 d and 12 d, respectively.The results showed that:(1) the dry weight, fresh weight, leaf fresh weight, leaf length, leaf width, petiole width, SPAD and per unit area yield decreased with increased high-temperature stress.Furthermore, the decline aggravated with increasing treatment duration.(2) Petiole length and rolled leaf rate increased gradually with increased temperature and duration.High-temperature stress increased the content of crude fiber.Under short-term high-temperature stress condition, the contents of soluble sugar, soluble protein and vitamin C did not change obviously, but gradually decreased due to increased temperature degree and stress duration.(3) A mathematical model of rolled leaf rate and per unit area yield of pakchoi was established and validated by independent experimental data.The root mean square error and relative error of model of rolled leaf rate with minimum temperature and treatment time were small-respectively 7.59% and 0.189 4.The model for yield per unit area with maximum temperature and treatment time were smaller-also respectively 274.02 g·m^-2 and 0.073%.Our study suggests that high-temperature stress downgraded pakchoi appearance quality and internal quality with increasing stress time and degree.Besides, we defined high-temperature stress index and determined high-temperature stress degree for greenhouse pakchoi.The results provided scientific basis for the determination of meteorological indicators and for disaster prevention.

Quantitative study on cultivated land ecological compensation in the area around Beijing and Tianjin from the perspective of grain security

ZHAO Qing, XU Hao, GUO Niandong

2017, 25(7): 1052-1059. doi: 10.13930/j.cnki.cjea.161080

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Abstract:
There is renewed research on ecological compensation of cultivated lands towards food security, a necessary requirement for the stable development of a country and society.In order to promote coordinated development and construction of integration ecological environment for Beijing City, Tianjin City and Hebei Province, a grain-security-driven model was built to simulate ecological compensation of cultivated lands in the region.The model used ecosystem services value to calculate grain budget, overload index and compensation coefficient of cultivated land.The farmland ecological compensation of each county (city) was analyzed quantitatively for the Beijing-Tianjin environs using the calibrated and validated ecological compensation model for cultivated lands.The results showed that:1) the"ecological supply"and "ecological consumption" of farm lands in the Beijing-Tianjin environs were typically similar in terms of "ectopic space" phenomenon.While"ecological consumption"of cultivated lands was mainly concentrated in farmlands in the south of Beijing and Tianjin environs, "ecological supply" was mainly concentrated in cultivated farmlands in the west of Beijing and Tianjin environs.2) The value of ecosystem services of farmlands around Beijing and Tianjin in 2014 was 4.480 5×10¹⁰ ￥, whose situation continued to worsen with a total deficit of 7.834×10⁹ ￥.3) In the area around Beijing and Tianjin, Zhangbei County, Xinglong County, Weixian County, Shangyi County, Laiyuan County, on to a total of 17 counties had surpluses, and the other counties had deficits.Luannan County was highest in payment of farmland ecological compensation (5.173×10⁷ ￥), followed by Yutian County (4.864×10⁷ ￥) and then Dongguang County (4.849×10⁷ ￥).Although Zunhua County, Luanping County and Quyang County were compensable, their ecological conditions of cultivated lands were in bare balance.4) From the point of view of food security, there were several counties requiring for farmland ecological compensation in 2014 around Beijing and Tianjin, including Zhangbei County, Weixian County, Shangyi County, Yangyuan County, Laiyuan County and Quyang County.Several counties should pay for farmland ecological compensation, they were Luannan County, Yutian County, Xianxian County, Dingzhou City and Wuqiao County.Tangxian County, Laishui County and Fengning Manzu Autonomous County neither needed nor paid farmland ecological compensation.Compared with previous studies, this study on farmland ecological compensation provided a starting point for research on compensation for farmlands around Beijing and Tianjin.The results could promote economic development, ecological protection of farmlands, and sustainably efficient utilization of farmland resources around Beijing and Tianjin.Meanwhile, the application of this method provided the theoretical reference for quantitative study of ecological compensation of farmlands in similar regions.It could provide references for determining cultivated land protection index with ecological value for other area.It was vital to conduct further research on ecological compensation mechanisms in cultivated lands.

Effect of land use transformation pattern in 2000-2013 on ecosystem services in Hengyang City, China

WANG Kuan, CAI Zhenghua, QI Zengxiang, CHEN Jian, LI Hui, LI Tao, FENG Qian

2017, 25(7): 1060-1070. doi: 10.13930/j.cnki.cjea.160913

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Abstract:
Using ecosystem services assessment in regional ecological protection is one of the most important ways in ecosystem services mapping.In order to perfect the method of ecosystem services mapping, spatio-temporal variations in ecosystem services value (ESV) in Hengyang Region was simulated based on interpretation of multi-period remote-sensing images of Hengyang City, estimation of ESV with the equivalent factor method and incurred profit-loss due to transformation of land use.Also the results of methods such as spatial autocorrelation, high-low clustering and barycenter analysis were analyzed in ArcGIS 10.0 environment.The results showed that:1) the proportion of ESV components were different in the study area and decreased with the sequence of biodiversity conservation, water conservation, soil formation and conservation, climate regulation, gas exchange, raw material, waste disposal, entertainment and food production.The ESV for Hengyang City decreased slightly from 241.0 billion Yuan to 239.4 billion Yuan during 2000-2013.The transformation of forests and cultivated lands into construction lands and the transformation of forests into cultivated lands were identified as the main reasons for the decrease in ESV revealed by conversion matrix analysis.2) Areas with low ESV were nearly encircled by those with high ESV.While regions with losses in ESV were mainly distributed around the urban and county districts, value-added regions were located in the western zone of the study area.3) Spatial autocorrelation and value aggregation phenomena were obvious, which tends strengthened.The barycenter of ESV moved 245.73 meters west-northwest 9°.To improve ESV in the study area, measures including limiting transformation of forests and cultivated lands into construction lands, conducting "stock" or "reduction" policy on land use, and preserving and intensifying continuity of whole ecosystem patterns were required.Compared with previous studies, the spatial distribution of ESV was visualized in this study as more precisely expressing the income and transfer of ESV.This was critical for the promotion of more reasonable ecological protection planning and management works in the study area and beyond.

A review of water footprint assessment for agricultural products

GAO Fan, LI Yuzhong, GUO Jiaxuan, MEI Xurong, WANG Jingxian, ZANG Miao

2017, 25(7): 1071-1080. doi: 10.13930/j.cnki.cjea.170027

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Abstract:
Water footprint (WF) is an indicator for both direct (domestic water use) and indirect (water required for industrial and agricultural production) water use of a consumer or producer.It has also been widely used in the analysis of global or regional virtual water trade.In the last decade, assessment of WF has been the focus of the footprint of rapid development.WF has three components (green, blue and grey water).This paper discussed a comprehensive review of the assessment of WF for agricultural products at different spatial scales, including global, regional and country scales.The main goal of the assessment of agricultural WF before 2008 was to determine global virtual water trade via agricultural products.However, the goal shifted to the rigorously quantification of three components for specific agricultural products and in specific geographical areas after 2009.As the assessment of WF has obvious spatial distribution characteristics, it was necessary to consider the influence of regional geographical characteristics, soil physical and chemical properties, climate change, as well as production technology and ecological toxicity of pollutants for building accurate, comprehensive and objective information on the WF of agricultural products.It was also necessary to take into account green water, blue water and gray water footprints for agricultural products in decision making on water resources management.This was because blue WF for agricultural products represented the direct consumption of freshwater resources, which was critical in decisions on international water trade market.The grey WF for agricultural products more clearly reflected the effect of agricultural production on the environment.In order to reach global or regional objectives on water resources conservation and sustainable utilization, not only the utilization efficiency of water resources in agricultural production needed improvement, but also the structure of agricultural production and both pattern and direction of virtual water trade for agricultural products needed adjustment.Furthermore, it was necessary to reduce waste of water resources in agricultural product cycle and food consumption.

Why polluter-pays principle is difficult to implement in rural areas?——A case study of pig-farmer paying behavior under the third party govern-ance of pig-farming pollution in Nanping

ZHENG Huangshan, CHEN Shufeng, SUN Xiaoxia, SU Shipeng

2017, 25(7): 1081-1089. doi: 10.13930/j.cnki.cjea.170092

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Abstract:
In recent years, livestock breeding industry has significantly contributed to the development of rural areas, serving as the main industry of rural economy.But it also induces severe environmental pollution in rural areas for a long time.Dust, harmful gases and sewage produced in livestock breeding have not only affected the survival rate of livestock and poultry, but also endangered the health quality of residents in the surrounding areas.The professional third party governance of wastes is one of the fast developing trends of pollution governance, in which polluter paying pollution fees in time is not only a requirement of "polluter-pays principle", but also the key to the continuous operation of the third party governance system.However, in reality, many farmers fail to pay pollution fees in time.To ensure sustainable development of the third party governance and re-vitalization of animal husbandry areas, this paper used logistic regression model to analyze the key factors influencing payment behaviors of pig farmers in relation to individuals, family, production and business operations, and other external factors.The paper investigated the payment behaviors of 117 pig farmers in 7 villages of Luxia Town, Nanping City, Fujian Province.The results showed that:(1) the late/none payment of pollution fee greatly affected the normal operations of the third party governance.Although 73.50% of farmers believed that the fee should be paid, only 61.54% actually paid it in time.The main reason for the none/late payment was the farmers'judgment of the environment, which ignored the negative externalities of pollution on environment in the downstream areas.Other reasons included the lack of full understanding of "polluter-pays principle", effects of acquaintances in rural communities, public comparisons with other regions and the lack of law enforcement in punishing offenders.The performance of third-party governance was quite different from the expectations of the farmers.Also local governments did not have the means and mechanisms to efficiently implement the"polluter-pays principle".(2) The characteristics of production and management, and family and individuals had significant impacts on payment behaviors of farmers.The order of influence was operating type > education level of farmers > household head age > proportion of foreign capital > farming area > net income from breeding.(3) Due to small difference among external factors, their effect was not obvious, although the extent of effect was comparatively high.Therefore, enhancing environmental awareness, making full use of rural social capital and social network, promoting large-scale industry and intensive and enterprise management, strengthening development of new vocational farmers, improving effectiveness of assessment and information disclosure and setting up pricing mechanisms based on service levels were conducive for the implementation of the"polluter pays principle".These measures were also good for the promotion of sustainable development of the third party governance of pollution and the healthy development of livestock breeding.

Evaluation on the system of service organization for new agricultural modernization in Henan Province and its rules of spatial distribution

GAO Yanjun

2017, 25(7): 1090-1098. doi: 10.13930/j.cnki.cjea.161097

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Abstract:
Based on the requirements of agricultural development in line with the"Three Orientations"strategy presented by China's Central Government in 2014, an evaluation index system on the system of service organization for new agricultural modernization were established.With Henan Province as the case study, the paper explored the development level and the rules of spatial distribution of service organization system, aiming to provide references for its further improvement.The index system was consisted of 16 indexes included in 4 criteria layers, which were development indexes of rural land circulation organization, resources allocation organization, information service organization and industrial management organization.Then using 18 cites in Henan Province as the basic units, the comprehensive development level of service organization system, and the related rules of spatial distribution were determined.The results showed that the comprehensive development level of service organization system was low in Henan Province.Only Zhengzhou, Jiyuan and Luohe were in District Ⅰ and Ⅱ, and all the other 15 cities were in District Ⅲ, Ⅳ, Ⅴ and Ⅵ.The rules of spatial distribution of the 18 cities were regular.The development in western Henan was the highest, which included Luoyang, Jiyuan, Jiaozuo and Sanmenxia, all of which occurred under District Ⅱ or Ⅲ.The development in the central part ranked the second, where Zhengzhou and Luohe occurred under District Ⅰ or Ⅱ, while both Xuchang and Pingdingshan occurred under District Ⅴ.The development in the northern part ranked the third, where Hebi occurred under District Ⅲ and then Xinxiang, Anyang and Puyang all were under District Ⅳ or Ⅴ.The development in the southern part ranked fourth, where Nanyang, Xinyang and Zhumadian were under District Ⅴ.The development in the eastern part was the lowest, where both Shangqiu and Zhoukou were in District Ⅵ and Kaifeng was in District Ⅳ.The research showed that a perfect service organization system for new agricultural modernization should be established in Henan Province to guide large-scale circulation of rural land, increase organizational degree of line operation, promote agricultural transformation development and guarantee quantity and quality of agricultural products.It was an inevitable option to accelerate the development of agricultural modernization in the study area.

2017 Vol. 25, No. 7