中国生态农业学报(中英文)

Research progress on cropland phosphorus balance in China

JI Hongjie, ZHANG Huaizhi, ZHANG Weili, YUE Xianlu, LEI Qiuliang

2015, 23(1): 1-8. doi: 10.13930/j.cnki.cjea.141045

Abstract(2226) PDF(2110)

Abstract:
Although phosphorus is an essential element for plant growth, over surplus of phosphorus can also cause water environmental hazards such as eutrophication. Phosphorus balance (PB) is an indicator for phosphorus input and output extensively used in agricultural and environmental research. In this paper, PB in croplands in China was reviewed from four different aspects - calculation method, spatio-temporal variability analysis, crop type difference analysis and soil phosphorus content analysis. The study showed surplus PB in China's croplands and with increasing surplus levels. Regional variations in phosphorus surplus were significant, with farmland phosphorus deficiency in some areas which resulted in PB polarization. Due to differences in the calculation parameters or regional planning, vast differences were noted in different reports in terms of amounts of total surplus phosphorus, surplus phosphorus per hectare and spatial variation in surplus phosphorus. Irrespectively, the governing trends in temporal variations, effects of different planting on cropland PB and effects of PB on soil phosphorus content were basically identical. In order to control soil phosphorus polarization and to ensure a stable promotion of soil phosphorus pool in China, it was recommended that future research focused more on areas such as indicator evaluations, technical measurements, policy guides and public opinion propaganda.

Habitat management and plant configuration for biological pest control in agricultural landscapes

DAI Piaopiao, ZHANG Xuzhu, XIAO Chenzi, ZHANG Xin, YU Zhenrong, LIU Yunhui

2015, 23(1): 9-19. doi: 10.13930/j.cnki.cjea.140898

Abstract(2438) PDF(3341)

Abstract:
The negative environmental effect of massive applications of chemical pesticides in intensive agricultural production practices has been a significant global concern. Therefore the rapid development of biological pest control in recent years is directed towards alleviating the negative impacts of intensified modern agricultural practices on the environment. Habitat management is an important conservation biological control approach that creates habitat conditions favorable to natural enemies but unfavorable to agricultural pests. Essentially, habitat management aims to maximize the function of biological control by providing natural enemies with resources (such as additional foods like nectar, alternative preys/hosts, and shelter from adverse conditions), or to suppress pests by making their habitats unfavorable. The appropriate selection and sound configuration of plants in agricultural landscapes are critical to successful habitat management. In this manuscript, we reviewed the mechanisms of habitat management for pest control. It was concluded that elaborate establishment of non-crop habitats and design of cropping systems were important habitat management approaches for improving biological control. We further proposed potential plant configuration models for biological control of pests in agricultural landscapes in China.

Application and outlook of alien earth soil-improving technology in arsenic-contaminated soil remediation

HOU Liyun, ZENG Xibai, ZHANG Yangzhu

2015, 23(1): 20-26. doi: 10.13930/j.cnki.cjea.140797

Abstract(1533) PDF(2585)

Abstract:
Arsenic is a metalloid element with severe toxicity that poses a huge threat to human health. Arsenic-contaminated soils and the remediation of these soils have drawn widespread concerns from governments and the scientific community. There has been a growing interest in alien earth soil-improving technology in recent years, evident in the more frequent use of this technology in the remediation of contaminated soils that has so far proven to be one of the most effective methods. Based on the sources and toxicity of arsenic soils, a systematic review was conducted on the application of alien earth soil-improving technology in remediating arsenic- contaminated soils. The effectiveness of the physical, chemical and biological remediation techniques in arsenic-contaminated soils was also compared. In terms of serious arsenic pollution in some cultivated lands in China, alien earth soil-improving technology was noted to be an effective and practical method of restoration of contaminated soils. Based on this finding, further in-depth researches on the application and outlook of alien earth soil-improving technology in remediating arsenic-contaminated soils were proposed.

Effects of fertilization structures on soil fertility and rice growth in cold waterlogged paddy fields

LIU Jie, SUN Geng, LUO Zunchang, XIAO Xiaoping, QU Deming, HONG Xi, LUO Xianshu, LUO Zhiyong, YU Chongxiang

2015, 23(1): 27-33. doi: 10.13930/j.cnki.cjea.140783

Abstract(1654) PDF(1326)

Abstract:
Studies have shown low soil oxidation reduction potential, soil available nutrients contents and rice yield in cold waterlogged paddy fields due to long-term flooding in cold spring. A field experiment along with laboratory analysis was conducted to determine the effects of improving soil fertility and rice growth by application of pure chemical fertilizers, stabilized compound fertilizers, combined compound fertilizer with chicken manure, and combined compound fertilizer with composted chicken manure. The results showed that compared with pure chemical fertilizer treatment, the application of combined compound fertilizer with composted chicken manure treatment effectively increased the contribution of loose humus by 10.8% while reduced the contribution of compact humus by 15.5%. Thus organic matter content and active organic matter content of the soils increased respectively by 8.9% and 4.0%. Also soil cation exchange capacity increased by 10.2%, while soil bacterium content and microorganism activity increased respectively by 390.0% and 13.0% during early rice growth season. At the same time, the application of combined compound fertilizer with composted chicken manure increased soil aluminum phosphate salt and calcium phosphate salt contents by 40.0% and 28.0%, respectively. While percent aluminum phosphate salt and calcium phosphate salt increased, percent occluded phosphorus decreased. Soil insoluble phosphate was transformed into soluble phosphorus, and soil available phosphorus content significantly increased. As absorbed phosphorus and potassium increased respectively by 14.0% and 127.0% during early rice growth season, early and late rice yields increased respectively by 11.0% and 8.0%. The application of combined compound fertilizer with composted chicken manure improved soil fertility, and thereby increased rice yield in cold waterlogged paddy fields.

Spatial variability of soil organic carbon and related controlling factorsin Renshou County, Sichuan Province

LUO Youlin, LI Qiquan, WANG Changquan, ZHANG Xin, ZHANG Wei, JIA Li, YUAN Dagang, WU Deyong

2015, 23(1): 34-42. doi: 10.13930/j.cnki.cjea.141034

Abstract(1738) PDF(1055)

Abstract:
Accurately accessing soil organic carbon (SOC) content at regional scale has been very important in regulating soil carbon and global environmental changes. Spatial distribution characteristics of SOC and the main driving factors (such as soil type, land use and parent materials) in Renshou County, Sichuan Province, were analyzed for a total of 555 topsoil (0 20 cm) samples using variance analysis and regression analysis. The results show that SOC content in the study area was in the range of 3.36?37.10 g kg?1, with an average of 13.46 g kg?1. The coefficient of variation was 48.87%, suggesting that SOC in the study area had moderate variability. The nugget-to-sill ratio value was 66.7%, suggesting that SOC had moderate spatial dependence and that spatial variability of SOC was determined by co-effects of structural and random factors. The content of SOC in the northern area was much higher than that in the southern region. Analysis of variance showed that while the effects of land use and soil type on SOC were significant (P < 0.01), parent materials had no obvious effect on SOC content (P = 0.256). Regression analysis showed that soil type was related with soil classification. Soil group, subgroup and soil family explained respectively 23.7%, 27.0% and 27.1% of SOC spatial variability. Land use type independently explained 53.0% of SOC spatial variability, much larger than that of soil type and suggesting that land use was the main qualitative driving factor of SOC availability. Soil subgroup and family similarly explained spatial variability of SOC, suggesting that soil subgroup was applicable at the lowest level of soil classification in studying spatial patterns of SOC in the study area. Also land use type was the key regulating factor of the spatial variability of SOC in hilly areas of Middle Sichuan Basin.

Population characteristics of super-high-yielding wheat under rice stubble in Huanghuai area

LU Baiguan, DU Yong, LI Jun, WANG Baoxiang, ZHOU Zhenling, SUN Zhongwei, YANG Bo, QIN Derong, XU Dayong

2015, 23(1): 43-51. doi: 10.13930/j.cnki.cjea.140192

Abstract(1319) PDF(1463)

Abstract:
Studies on population characteristics of super-high-yielding wheat have recently attracted significant researches. These studies have revealed large differences in wheat population structure in different super-high-yielding wheat areas. The area of wheat under rice stubble in the Huanghuai region has reached 1.3 million hm², accounting for about 10% of cultivated wheat area in the Huanghuai region. Significant differences have been noted in the growth characteristics and ecological environments between dryland wheat and wheat under rice stubble. Current studies on population characteristics of wheat under rice stubble have focused mainly on production levels of 8 000 kg·hm^-2. Super-high-yielding wheat (yield is higher than 9 000 kg·hm^-2) was still in the infancy development stage, and studies on population characteristics of super-high-yielding wheat under rice stubble in Huanghuai area were less to be reported. To understand the population characteristics of super-high-yielding wheat-after-rice system in Huanghuai region, growth and yield formations of three semi-winter wheat varieties ('Lianma 6', 'Jimai 22' and 'Yannong 19') were investigated under high-yield (CK) and super-high-yield (SHY) cultivation measures. The results showed that wheat varieties had more grains per spike and higher 1000-grain weight under SHY than under high-yield wheat CK. There was no significant difference in spike number per unit area between SHY and CK. Compared with those under CK, wheat exhibited fewer tillers at the early growth stage (from tillering to jointing) but with higher rate of productive tillers to total tillers under SHY. While leaf area index and photosynthetic potential of SHY were lower than those of CK at the early growth stage, these attributes were significantly higher after heading. There was no significant difference in accumulated dry matter weight between SHY and CK at the early growth stage. Root-to-shoot ratio and root exudate amount under SHY were higher than those under CK at heading, milking and waxing stages. Also grain-to-leaf ratio, percent matter translocation from stem and sheath, and harvest index under SHY were higher than those under CK. Analysis of various attributes of rice yield and population showed that for SHY wheat in Huanghuai region, spikes per unit area, grains per spike, 1000-grain weight, productive tiller rate, total dry matter weight at maturity stage, grain weight/leaf area ratio, root/shoot ratio at heading stage, root exudate amount, harvest index were greater than 700×10⁴·hm^-2, 32, 42 g, 45%, 20 t·hm^-2, 14 g·cm^-2 (i.e., mg grain weight per cm2 leaf area), 0.28, 7.1 g·m^-2·h^-1, 0.45, respectively; while leaf area index at heading stage was 6.5 7.0.

Analysis of altitude adaptability of main flue-cured tobacco varieties in Kunming City

WANG Yujun, ZHOU Jiheng, LI Qiang, ZHANG Yiyang, SHEN Han, LU Xinlang, CHENG Changxin, YU Xi

2015, 23(1): 52-60. doi: 10.13930/j.cnki.cjea.140809

Abstract(1371) PDF(1206)

Abstract:
Ecological conditions greatly influence tobacco leaf quality, and elevation is a comprehensive index for ecological analysis. It is therefore critical to study the effect of altitude on tobacco leaf quality so as to guide three-dimensional optimization layout of flue-cured tobacco varieties. In this study, altitude adaptability of tobacco varieties of 'K326', 'Honghuadajinyuan' and 'Yunyan 87' were determined in 4 main tobacco growing townships in Shilin County and Yiliang County, Kunming City. Data were collected in experiments conducted at 12 sites at every 200 m in the altitude range of 1 400?2 200 m, where cultivation practices were largely consistent. The effects of altitude on physical properties, chemical properties and smoking quality of flue-cured tobacco were determined. The result suggested that the sensitivity of flue-cured tobacco varieties to altitude decreased in order as follows: 'Honghuadajinyuan' > 'K326' > 'Yunyan 87'. Also the chemical components of leaves were more sensitive to altitude than the physical properties and smoking quality of leaves. In the 1 400?2 200 m altitude range, altitude was significantly or extremely significantly correlated (negative) with leaf opening degree, total nitrogen content, nicotine content, potassium content, chlorine and main polyphenols contents. Also in the 1 400?2 200 m altitude range, altitude was significantly or extremely significantly correlation (positive) with moisture content, total sugar and reducing sugar contents and irritancy. In summary, the integrated analysis showed that leaf chemical components, polyphenol content and aroma properties of 'K326', 'Honghuadajinyuan' and 'Yunyan 87' were optimum at an altitude range of 1 400 1 800 m in Kunming City. Tobacco leaf quality decreased in order as follows: 'Honghuadajinyuan' > 'K326' > 'Yunyan 87'.

Effects of nighttime temperature increase on physio-chemical properties, yield and quality of flue-cured tobacco in high-altitude region of Yunnan Province

ZHOU Yue, FAN Xinglong, ZHOU Jiheng, HE Danfeng, LI Qiang, LIU Xiaoying, CHENG Changxin, YANG Yingming

2015, 23(1): 61-68. doi: 10.13930/j.cnki.cjea.140865

Abstract(1351) PDF(938)

Abstract:
This study used tobacco cultivars of 'Yunyan 87' and 'K326' to analyze the effect of nighttime temperature increase on physio-chemical properties, yield and quality of flue-cured tobacco in high altitude region of Yunnan Province. Through field experiment, the study evaluated the effects of nighttime temperature rise on the physical characteristics, chemical composition, micronutrients contents, economic characteristics, and sensory quality of tobacco. The study aimed to explore and improve the physical and chemical properties as well as inherent quality of flue-cured tobacco by the adjustment of ecological factors (temperature in this study). Based on the single factor randomized block design pot experiment, two temperature treatments were established. The first temperature treatment was to artificially keep warm at nighttime (18:00-6:00) under greenhouse condition. During this treatment, average nighttime temperature in the greenhouse was maintained at 16.7 ℃. The second temperature treatment was to keep a natural temperature in the greenhouse for purpose of comparison. In this treatment, the average natural temperature at night was 15.5 ℃. The study showed that rising nighttime temperature broadened the upper leaves and lengthened the lower leaves of 'K326' and 'Yunyan 87'. It also significantly increased single leaf weight and equilibrium moisture content of the upper leaves along with the single leaf weight of the middle leaves of 'K326'. With the rise in nighttime temperature, leaf thickness significantly decreased for the middle and upper leaves of 'K326' and the middle and lower leaves of 'Yunyan 87'. Also leaf stem content significantly decreased for all the leaves of 'K326' and the upper leaves of 'Yunyan 87'. Compared with those under natural nighttime temperature treatment, the contents of total sugar, reducing sugar and total nitrogen increased drastically in the middle and upper leaves of 'K326' under increased nighttime temperature treatment. Also the contents of total nitrogen and potassium increased in all the leaves of 'Yunyan 87'. However, decreases in the contents of nicotine and potassium in the middle and upper leaves of 'K326' were noted. Also the decreases in the total nitrogen in the lower leaves of 'K326', in the contents of total sugar, reducing sugar and nicotine in the upper leaves of 'Yunyan 87', in the content of nicotine in the middle leaves of 'Yunyan 87', and in the contents of total sugar and reducing sugar in the lower leaves of 'Yunyan 87' were observed too. Under nighttime temperature increase treatment, the contents of Zn and Cu significantly decreased while those of Fe and Mn increased in the upper and lower leaves of 'K326', compared with those under the natural temperature treatment. Also the contents of Zn, Cu, Fe and Mn increased in the upper leaves of 'Yunyan 87'. Compared with the natural temperature treatment, nighttime temperature increase treatment improved output, output value, average price and fine tobacco proportion of 'K326' respectively by 252.5 kg·hm^-2, 7 290 Yuan·hm^-2, 1.7 Yuan·kg^-1 and 6.54%. Similarly, these variables of 'Yunyan 87' increased respectively by 100.5 kg·hm^-2, 5 315 Yuan·hm^-2, 2.1 Yuan·kg^-1 and 4.65%. Thus increasing nighttime temperature significantly improved the physical characteristics, chemical component, production output and industrial value of flue-cured tobaccos in high altitude region of Yunnan Province.

Soil seed bank and its correlations with aboveground vegetation in ecological restoration zones of Wenchuan Earthquake Region

ZHANG Guangshuai, DENG Haojun, DU Kun, LIN Yongming, MA Ruifeng, YU Wei, WU Chengzhen, HONG Wei

2015, 23(1): 69-79. doi: 10.13930/j.cnki.cjea.141103

Abstract(1443) PDF(1377)

Abstract:
To determine the characteristics of soil seed banks and their relationships with aboveground vegetation in different climate zones, field surveys backed up with laboratory experiments were conducted in a typical ecological restoration zone in Weizhou Township (Wenchuan County) and Hanwang Township (Mianzhu City) of Sichuan Province. This zone was the epicenter of the massive Wenchuan Earthquake on May 12, 2008. We analyzed germination dynamics, quantity characteristics, species compositions, diversity characteristics and correlations with aboveground vegetation of soil seed bank in two climate areas (semi-arid dry warm river valley climate area, subtropical humid monsoon climate area) in ecological restoration zone of Wenchuan Earthquake Region. SBES (seed bank endemic species) and SAVS (seed bank aboveground vegetation species) were used as new indicators to describe the systematic process of soil SAVS system. The results suggested that while undestroyed sample plots had two germination peaks of seed bank, destroyed sample plots had only one germination peak. Seed banks in different climate areas had different germination potentials at different soil depths. The mean density of soil seed bank was 192?1 544 seeds·m^-2 and both the surface density and mean density of undestroy sample plots were greater than that in destruction sample plots. Also that in semi-arid dry warm river valley climate area was greater than that in subtropical humid monsoon climate area. A total of 50 species were identified in the soil seed bank using the germination method and herbaceous plants had the most significant advantage. Both the S?rensen and Jaccard similarity coefficients of species composition between soil seed bank and aboveground vegetation showed that HMD (destroyed sample plot in subtropical humid monsoon climate area) was greater than DHU (undestroyed sample plot in semi-arid dry warm river valley climate area), also greater than HMU (undestroyed sample plot in subtropical humid monsoon climate area) which was in turn greater than DHD (destroyed sample plot in semi-arid dry warm river valley climate area). SBES and SAVS of different sample plots had different life cycle patterns. In conclusion, climate and background conditions were needed for artificial propagation and restoration measures in Wenchuan Earthquake Region.

Analysis of the fungal community in continuous cropping cotton field of Xinjiang using 18S rDNA-PCR-DGGE

CHEN Yifeng, GAO Yanan, ZHU Jie, ZHANG Wei

2015, 23(1): 80-86. doi: 10.13930/j.cnki.cjea.141099

Abstract(1096) PDF(1200)

Abstract:
Long-term continuous cropping of cotton has caused dramatic soil-borne diseases in many places, leading to substantial agricultural losses. However, in some areas of Xingjang Uygur Autonomous Region, the obstacles caused by continuous cotton cropping can spontaneously restore and maintain high yields of cotton for many years. To analyze the variable spectrum of soil fungal communities and changes in the community structure in these spontaneously restored fields during cropping, soils at depths of 1 to 10 cm, 11 to 20 cm, 21 to 30 cm and 31 to 40 cm were sampled from cotton fields with a history of 0 a (unused field), 1 a, 3 a, 5 a, 10 a, 15 a or 20 a of cotton cropping in the Shihezi Region of Xinjiang Uygur Autonomous Region. The fungal communities in these samples were studied using 18S rRNA-based polymerase chain reaction-density gradient gel electrophoresis (PCR-DGGE). Fungal community diversity indices including the Shannon-Wiener diversity index, abundance index and evenness index were compared among these samples. Samples from the unused field had relatively high levels of those three indices. With increasing years of cotton cropping, the fungal abundance, diversity and evenness indices descend, whereas those three indices showed a different decrease in different depth. However, after 10 a of continuous cropping, all these indices were restored to their original values or reached a relative stable level. Cluster analysis of DGGE fragments indicated that the samples of each depth were clustered into different branches. Soil fungi of 21 30 cm plow layer was most significantly affected by continuous cropping. Soil fungi community obviously fluctuated in different depths. Principal component analysis (PCA) showed that at each soil depth, the first two principal components were of the greatest importance and had a combined variance contribution rate >60.1%. Except for the 11-20 cm and 21-30 cm depths of the 1 a continuous cropping soil, all of the cotton soils were positively correlated with the first principal component and fluctuated on the right of the first principal component between the positive and negative axes of the second principal component. Both cluster analysis and PCA results suggested that, compared to that from original uncropped field, the fungal community structure showed the most variation in samples from the depth of 11 30 cm of continuously cropped soils. Twenty-four clones were sequenced and submitted to GenBank (accessory no. JN572633 to JN572656). By aligning with the GenBank database, all sequences from DGGE were classified into three groups: Mitosporic fungi, Uncultured fungi, and Pyronemataceae. Further analysis demonstrated that the isolated sequences showed a homology of 98.5% 100% to known sequences in GenBank and 100% of the sequences belonged to fungium which were not cultured. No microbial data were correlated with soil-borne plant diseases of cotton. The study demonstrated that the age of cotton fields had significant effects on soil fungal diversity. Continuous cotton cropping exerted significant influences on the community structure of soil fungus in Xinjiang Uygur Autonomous Region, with an initial suppression effect on fungal diversity. However, the fungal community reached a stabilized level or a new balance compared with its original state after 10 a of continuous cropping.

Effects of simulated straw return of transgenic rice expressing broad-spectrum antifungal proteins on soil fungal community structure

CHEN Lihua, LYU Xin, LIN Bijiao, LI Wei, LI Yueren

2015, 23(1): 87-94. doi: 10.13930/j.cnki.cjea.140885

Abstract(1167) PDF(840)

Abstract:
There has been a growing public concern about the impact of the rapid introduction of genetically modified crops (GMCs) on soil ecosystem, especially soil microbial community. In order to verify the effects of decomposition of GMCs straws on soil fungal community structure, classical plate counting and denatured gradient gel electrophoresis (DGGE) were used to analyze cultivable fungi amount and fungal community diversity. Straw of transgenic rice expressing broad-spectrum antifungal proteins was degraded under simulated field conditions. The treatments included soil without straw (S), soil with straws of transgenic rice cultivar of 'Zhuanpin-1' (S-Z1), soil with straws of transgenic rice cultivar of 'Zhuanpin-8' (S-Z8) and soil with straws of non-transgenic rice cultivar of 'Qisiruanzhan' straw (S-CK). The results of traditional culture-dependent method showed significant differences in the amounts of cultivable fungi among transgenic treatments of S-Z1, S-Z8 and non-transgenic treatment of S-CK within 40 days after rice straw decomposition (P < 0.05). However, no significant differences were noted among the above treatments in the period from 40 to 90 days after rice straw decomposition (P > 0.05). The patterns of DGGE of 18S rRNA V1+V2 fragments showed no apparent differences in bands between transgenic and non-transgenic treatments as the different observed bands were largely weak or transient. The positions and lightness of DGGE bands were digitally analyzed using Quantity One software and then the derived Shannon-Wiener index, evenness and abundance to evaluate fungal diversity of different treatments. The results showed significant differences in Shannon-Wiener index and abundance between transgenic and non-transgenic treatments in individual periods of rice straw decomposition such as the first 30 days (P < 0.05). There were no significant differences in evenness between transgenic and non-transgenic treatments during the whole rice straw decomposition period (P > 0.05). Sequence analysis of DGGE-bands showed that most of the bands belonged to Ascomycota, Basidiomycota and Chytridiomycota and the different bands between transgenic and non-transgenic treatments belonged to Ascomycota. The study suggested transient effects of the straw decomposition of transgenic rice expressing broad-spectrum antifungal proteins, but no persistent effects on cultivable fungi count and fungal community structure.

Responses of growth and activities of antioxidant and detoxification enzymes of Misgurnus anguillicaudatus to transgenic Cry1Ab/Ac rice residues in water

SUN Yuandong, LIU Yufang, LI Fei, XIAO Lu, TAN Shuhua, GUI Fangyan, MO Shuyin, SUN Lichuan, LIU Wenhai, GE Feng

2015, 23(1): 95-101. doi: 10.13930/j.cnki.cjea.140824

Abstract(1180) PDF(1059)

Abstract:
A loach (Misgurnus anguillicaudatus) aquaculture experiment was conducted in phytotron with aquatic water added with straw power in different concentrations (10 mg·L^-1, 50 mg·L^-1, 100 mg·L^-1, 200 mg·L^-1) of different rice varieties, which were transgenic Cry1Ab/Ac rice variety of 'Huahui 1' (HH1) and non-Bt control rice variety of 'Minghui 63' (MH63). In the experiment, the loach basal fed without rice straw powder was set as the blank control. The specific growth rate, condition factor, and viscera somatic index as well as activities of antioxidant enzymes of superoxide dismutase (SOD) and catalase (CAT), and detoxification enzyme of glutathione-s-transferase (GST) of loach were investigated after culture for 100 days. The aim of the study was to explore effects of transgenic Bt rice on aquatic animal through simulating rice residues in paddy water. The results showed no significant differences (P > 0.05) in specific growth rate, condition factor, viscera somatic, and activities of SOD, CAT and GST between loaches cultured in aquatic water added with HH1 and MH63 straw powders with four concentrations. Compared with the blank control, the growth performance gradually decreased with increasing concentration of rice straw powder of both varieties. Furthermore, the specific growth rate, viscera somatic index and CAT activity of loach decreased obviously when loach was cultured in aquatic water with 200 mg·L^-1 of HH1 and MH63 straw powder. These results indicated that aquatic water with lower concentration of transgenic Cry1Ab/Ac rice straw powder had no obvious effect on growth performance and activities of antioxidant and detoxification enzymes of loach. When the concentration of rice straw powder was up to 200 mg·L^-1, the growth performance and activities of physiologic enzymes of loach decreased significantly, regardless of rice variety. It was suggested that higher level of rice straw powder in water hindered breathing of loach. In addition, the decomposition of rice straw powder in water induced decreasing of pH and dissolved oxygen.

Study on predation preference of Harmonia axyridis (Pallas) and Adonia variegata (Goeze) on red and green color morph pea aphids

DU Junli, WU Degong, LIU Changzhong

2015, 23(1): 102-109. doi: 10.13930/j.cnki.cjea.140739

Abstract(1485) PDF(1225)

Abstract:
In order to explore the inhibition effect of Harmonia axyridis (Pallas) and Adonia variegata (Goeze) on red and green pea aphids (Acyrthosiphon pisum Harris) populations and their predation preferences, pea aphids with total densities of 90 head dish^-1, 120 head dish^-1 and 150 head dish^-1 for H. axyridis, and 42 head dish^-1, 60 head dish^-1 and 78 head dish^-1 for A. variegate were used to determine predation preferences of H. axyridis and A. variegata on two color morphs of pea aphids. The results showed that when red and green pea aphids co-existed, female adults of H. axyridis were insensitive to red morph in low and medium total prey densities (90 head dish 1 and 120 head dish^-1), sensitive to red morph in high total prey density (150 head dish^-1), and insensitive to green morph in all total prey densities. Female adults of H. axyridis also variably switched to red pea aphids in different total prey densities, showing zero switch in 90 head dish^-1 density, and negative switch in 120 head dish^-1 and 150 head dish^-1 densities. However, female adults showed zero switch to green morph. When red and green pea aphids co-existed, female adults of A. variegate were insensitive to red and green morphs pea aphid in all total prey densities. Female adults of A. variegata also variably switched to the two morph pea aphids in different total prey densities, showing zero switch in 42 head dish^-1 density, and negative switch in the 60 head dish^-1 and 78 head dish ^-1 densities. Therefore while female adults of A. variegata had no obvious preference for the two morphs of pea aphids, female adult of H. axyridis had no preference for the two morphs of pea aphids in lower population density but had positive preference for red morph in higher population density. The results suggested that dominant natural enemies (ladybird) were among the many factors for the changes in the populations of the two types of color of pea aphids.

Risk assessment and zoning of drought for summer maize in the Huang-Huai-Hai Region

YANG Ping, ZHANG Lijuan, ZHAO Yanxia, JIANG Lanqi, QIAO Sainan, ZHANG Xiaohui

2015, 23(1): 110-118. doi: 10.13930/j.cnki.cjea.140667

Abstract(1936) PDF(1319)

Abstract:
The Huang-Huai-Hai Region is one of China's major grain producing areas, especially summer maize. Thus drought risk assessment of summer maize in the Huang-Huai-Hai Region is critical in developing countermeasures to ensure grain security. This article assessed and zoned drought risk for summer maize cultivated in the Huang-Huai-Hai Region using the principles of natural disaster risk assessment along with meteorological data, terrain data, land use data and other relevant data in the Huang-Huai-Hai Region. The study also used spatial analysis techniques such as weighted comprehensive analysis (WCA), analytic hierarchy process (AHP) and Geographic Information System (GIS) as well as information diffusion theory. There has been extensive research involving the use of the principles of natural disaster risk assessment in recent years. This study calculated comprehensive drought risk index from three angles - disaster hazard, sensitivity and vulnerability. The selection of hazard index is critical and indicators such as precipitation and standard precipitation index (SPI) hardly precisely calculate the probability distribution of a specific drought index. This defect could be compensated for by using information diffusion theory. Firstly, percent precipitation anomaly was used as basic hazard index in calculating probability distribution based on information diffusion theory. The probability distribution of percent precipitation anomaly was divided by drought grade. Secondly, a weighted comprehensive analysis was conducted to determine hazard degree. The final results were calculated by selecting corresponding indicators for sensitivity and vulnerability. In this way, drought disaster risk for summer maize in the Huang-Huai-Hai Region was zoned based on a comprehensive hazard, sensitivity and vulnerability risk index. The results showed significant spatial differences in hazard sensitivity, vulnerability and comprehensive risk index for summer maize in the Huang-Huai-Hai Region. Drought hazard was relatively high and drought frequency exceeded 64.36%. The highest hazard areas were mainly distributed in the northern parts of Hebei Province and Anhui Province. The drought disaster sensitivity of summer maize in the Huang-Huai-Hai Region was higher, areas with high sensitivity grades accounted for 20.80% of the total area, which was mainly distributed in the coastal areas of Shandong Province. Overall, the region's drought disaster vulnerability of summer maize was low. The highest and higher vulnerability areas accounted for 22.4% of the total area, and distributed in every province. The comprehensive drought risk index for the whole study area was high with the highest and higher risk areas accounting for 68.43% of the total area. The whole of Huang-Huai-Hai region was in high risk hazard zone, except for southeastern Anhui Province.

Using vegetation net primary productivity to determine theoretical and achievable farmland productivity

LI Yafang, GONG Jian, YANG Jianxin, JIN Qingxia

2015, 23(1): 119-126. doi: 10.13930/j.cnki.cjea.140573

Abstract(1262) PDF(779)

Abstract:
Food security is one of the main problems facing China and researches on establishing farmland productivity are of vital significance for food productivity and safety. Traditional calculations of farmland productivity have been based on farmland grading to establish functional relations among the natural quality of farmland, grade index, theoretical yield and achievable yield using sample surveys. The deficiencies that associated with this calculation method have included tedious data collection and strong subjectivity. In the attempt to avoid these deficiencies, this paper used vegetation net primary productivity (NPP) method to determine farmland productivity in Wuhan, Hubei Province. The paper used NDVI and EVI data, monthly average precipitation, monthly average temperature, monthly total solar radiation and other meteorological data to run the CASA model. The model then was used to calcu-late NPP of farmlands in the region and establish functional relations among theoretical and achievable yields, NPP of farmlands using sample survey data. The unit productivity (UP) was obtained by substituting NPP data into the established relation functions. Then productivities of different towns were aggregations of UP multipling its corresponding area, while the yields of towns were quotients of productivity divided by total farmland area of the towns. Theoretical and achievable productivities and yields in 75 townships in the study area were calculated using the NPP method. While townships with larger theoretical and achievable productivities were mainly in the northern and southeast regions, townships with larger theoretical and achievable yields were in the western and northeast regions of the study area. Also both theoretical and achievable productivities and yields were lower in peripheral townships in close proximity with main cities. By contrast, comparison of the NPP and traditional method showed that the calculated results by the two methods were highly consistent in terms of theoretical and achievable productivities, but not entirely consistent in terms of theoretical and achievable yields. The results therefore showed that it was feasible to apply NPP method on estimating the productivity of farmlands. The NPP method was advantageous over the traditional method because it not only avoided deficiencies inherent in the traditional method, but was also a quick way of calculating farmland productivity without need for farmland grading and rating.

2015 Vol. 23, No. 1