Current issue

• 2018 Vol.34 No.3 Published:01 February 2018

  Effects of Drought Stress in Different Growth Stages on Grain Cadmium Content of Rice 易亚科 and 周志波 2018, 34 (3):  1-5.  DOI: 10.11924/j.issn.1000-6850.casb16120114 Abstract + ( 1146 )   To explore the effect of water management on cadmium (Cd) content in rice, a pot experiment with 6 early-rice cultivars and 4 late-rice cultivars was conducted to study the effects of drought stress on grain Cd content in rice under different growth stage, including soil drying at tillering stage (T1), soil drying at booting stage (T2), soil drying at heading stage (T3), soil drying at milk stage (T4), soil drying at dough stage (T5), and whole growth season flooding (CK). The results showed that: the main effects of cultivar and water management as well as their interactive effects on Cd content in polished rice were significant (P<0.01); the Cd content in polished rice followed the sequence of T3>T1>T2>T4>T5>CK; W2 (‘C-liangyou 7’), W12 (‘Xiangwanxian 13’), W8 (‘Jinyou 59’) with low and stable Cd content in grain, can be widely planted in slight pollution soil. Significant (P<0.01) difference was observed in polished rice Cd content among cultivar types. Super hybrid rice had the highest Cd content, followed by conventional rice and hybrid rice. Growth duration had no significant effect on Cd content in polished rice.

  Effects of Water-nitrogen Interaction on Nitrogen Accumulation, Translocation and Use Efficiency of Summer Maize 2018, 34 (3):  6-9.  DOI: 10.11924/j.issn.1000-6850.casb17020088 Abstract + ( 847 )   To explore the way of high water nitrogen use efficiency and reduce nitrogen fertilizer pollution, we studied the effect of water nitrogen interaction on summer maize by setting different tests. The results showed that compared with no nitrogen treatment, nitrogen treatment significantly increased the amounts of nitrogen accumulation of plant, and the amounts of nitrogen accumulation eventually increased by 24%-35%; nitrogen treatment increased the amounts of nitrogen translocation before flowering in the stem, leaf and whole plant, irrigation increased the amounts of nitrogen translocation before flowering in stem, leaf, spike and whole plant, simultaneously the nitrogen and water treatment significantly increased the amount of nitrogen accumulation in grain, and all showed a trend of treatment 2＞1＞0. Compared with treatment 0, the total nitrogen amount in grain increased by 26.31% under nitrogen treatment, and increased by 24.89% under irrigation; N application and irrigation significantly increased nitrogen uptake efficiency and nitrogen fertilizer efficiency, the effect on nitrogen use efficiency was different. The experiment results showed that the comprehensive effect of N1W2 was the best, and it could be popularized and applied in production.

  Nitrogen Application Time and R/FR Ratio: Effect on Growth Physiological Characters and Yield of Maize 2018, 34 (3):  10-18.  DOI: 10.11924/j.issn.1000-6850.casb17010003 Abstract + ( 1206 )   The study aims on the effects of nitrogen application time and light quality (Red/Far red, R/FR) on the plant morphology and yield components of maize, and has significance for discussing the response mechanism of the growth and yield of maize under high density.‘Zhengdan 958’and‘Ludan 981’were used as materials, under the pot-cultivated basal fertilizer and dressing, artificial adding far red light LED lamp was used to set low R/FR ratio light environments, the response of maize growth physiological characters and yield to low R/FR was studied. Under low R/FR, plant height, total leaf area, specific leaf weight increased to different extents, while total leaf number remained the same as that of CK. Low R/FR treatment decreased SPAD of leaves but increased leaf net photosynthesis rate. Low R/FR treatment ultimately improved kernel numbers per row of maize ears, ear kernel weight and ear weight, but decreased the weight of ear axis, and the change of 1000 kernel weight was not significant in statistics. Low R/FR × cultivar interactions, low R/FR × nitrogen application time, the interactions of every agronomic character of the above treatments were not statistically significant. Low R/FR ratio could improve the ear kernel weight by increasing kernel number per row.

  Effect of Drought Stress and Nitrogen Forms on Root Morphology of Pea 李春春 and 曹智 2018, 34 (3):  19-25.  DOI: 10.11924/j.issn.1000-6850.casb16120140 Abstract + ( 1013 )   The paper aims to provide a theoretical basis for the growth regulation of pea in arid area by exploring the effects of drought stress and nitrogen forms on root growth of pea. Pot experiment was adopted to study the effects of 2 nitrogen forms and drought stress of 55% relative water content for 15 days on root growth of pea during different periods. The results showed that: the effects of nitrogen on root growth varied with nitrogen forms , and NO3--N promoted root elongation under normal water condition, while NH4+-N improved root diameter under normal and water stress condition; in addition, the influence of drought stress on root growth also varied with nitrogen forms, and the root length and volume as well as surface area under 3 drought stress forms during stress period and flowering stage significantly decreased under NO3-- N condition; furthermore, drought stress was beneficial to reducing root decay rate during maturity stage, which epitomized equivalent-compensation or over-compensatory effects on root growth. In conclusion, NO3--N was beneficial to promoting root growth and the compensatory effect of rewatering after drought stress during bud stage on root growth during maturity period was the best.

  The Fertilizer Application Status and the Approach of Fertilizer-reduce and Efficiency-increase in Yunnan Province 2018, 34 (3):  26-36.  DOI: 10.11924/j.issn.1000-6850.casb16120074 Abstract + ( 1081 )   Aims at the high application amount of fertilizer, the unreasonable fertilization structure, the low fertilizer use efficiency, the backward mode of fertilization and the gradually increasing application amount of fertilizer in Yunnan Province, the authors collected 410095 questionnaires of“Investigation on Fertilization of Soil Testing and Formulated Fertilization”, analyzed fertilization status of 410095 crop seasons of 351194 plots in 16 cities of Yunnan, and summarized the harm of excessive application of chemical fertilizer. Fertilization methods and technologies of appropriate kind, time and amount were suggested, combined with scientific field management and“fertilizer + ’to achieve the goal of zero growth of fertilizer. The results could provide guidance for agricultural production in order to ensure food security in Yunnan.

  Certification Requirements, Development Status and Risk Analysis of Seed in Organic Crop Production 2018, 34 (3):  37-41.  DOI: 10.11924/j.issn.1000-6850.casb16120061 Abstract + ( 750 )   Seeds are important production goods in agriculture. There are clear requirements of the seed source, GMO status and seed treatment in organic agriculture. One of the purposes of this paper is to identify the requirements, development status quo of organic seeds and the risk assessment of whether the seeds could meet the organic standards. Through the data collection, the requirements, status quo and risk of seeds in organic crop production were analyzed. It is concluded that the seeds source is not the main risk factor of organic crop certification. The introduction of genetically modified seeds and seeds treatment are the main source of certification risk. The risk assessment of GMO is mainly based on its commercial cultivation and research status which determines the risk of GMO seeds. Whether seeds are treated with chemicals is also a significant risk in the use of conventional seeds. By analyzing the risks of organic seeds, this paper could provide the producers and inspectors with the precautions that should be paid attention to in the seed section to improve the compliance of organic production.

  Increasing Organic Fertilizers on Improving Salt Resistance of Crop 2018, 34 (3):  42-50.  DOI: 10.11924/j.issn.1000-6850.casb17010002 Abstract + ( 610 )   This paper aims to find scientific methods to enhance the salt-tolerant ability of crops. Winter wheat and summer maize were planted in barrel. The effects of four kinds of organic fertilizers in different water conditions on the growth and development, physiology and biochemistry, and yield of winter wheat and summer maize with saline soil cultivation were studied. The application of organic fertilizers could improve the soil environment. The organic fertilizer‘Heyijia’had the best effect, it increased the total nitrogen, organic contents and total microbial amounts in soil by 8.4%, 16.7% and 55.8%, respectively. Under the high soil water content, leaf chlorophyll content of wheat and maize was increased by about 6.9% and 5.10% by applying organic fertilizer, and the highest increase of the biomass of wheat and maize was by 60.0% and 51.2%, respectively. Leaf photosynthesis of winter wheat was increased by up to 20.8% under the application of the organic fertilizers. The grains per spike, 1000 grain weight and yield of winter wheat increased by 44.4%, 24.9% and 61.9%, respectively. Those indexes were also enhanced in lower water content, but the amplification was not as obvious as that in high water content. The application of organic fertilizers benefited the growth of crops in high salt soils with higher water content. Nevertheless, adding some kinds of fertilizers which were rich in salts might increase the salt concentration of soil and cause damage to crops. Overall, adding organic fertilizer could achieve better effects under higher soil water content.

  Condition Optimization for Antibiotic Substances Produced by Bacillus subtilis Strain RSS-1 2018, 34 (3):  51-57.  DOI: 10.11924/j.issn.1000-6850.casb16120092 Abstract + ( 931 )   To determine the best condition for Bacillus subtilis strain RSS-1 to produce antibiotic substances, and increase the yield of antifungal active substance, the fermentation liquid inhibition for the activity of Sclerotinia sclerotiorum was used as index, the single factor experiment and orthogonal experiment were adopted to optimize the optimal fermentation medium composition and fermentation condition under the condition of shaking flask culture. The results showed that the optimum medium composition was cornflour 2.0% (W/V), tryptone 1.5% (W/V) and MgSO4·7H2O 0.05% (W/V). The optimal fermentation condition was the combination of initial pH value 6.0, culture temperature 28°C, fermentation time 5 d, medium capacity 25 mL/100 mL, inoculum volume 0.1%, and the rotate speed 180 r/min. The inhibitory activity of B. subtilis strain RSS-1 fermentation filtrate increased significantly after the optimization of medium composition and fermentation condition.

  Application of UDP-glucosyltransferase and Its Inhibitors in Plant Activator 2018, 34 (3):  58-69.  DOI: 10.11924/j.issn.1000-6850.casb16120107 Abstract + ( 738 )   The aim is to create the plant activator targeting at UDP-glucosyltransferases (UGT). We concluded the structural feature, the reaction mechanism, and the metabolism mechanism of UGT; then summarized the salicylic acid (SA) signal pathway regulated by UGT and the mechanism of inducing systemic acquired resistance (SAR) in plant host. Taking Imprimatins and ILA as samples, we elaborated the mechanisms of UGT inhibitor inducing SAR activity, and pointed out the development strategy of plant activator based on UGT and its application prospect.

  Induction of Anther Callus and Somatic Embryogenesis of Different Rubber Tree (Hevea brasiliensis Muell.Arg.) Clones 蔡海滨 and 2018, 34 (3):  70-75.  DOI: 10.11924/j.issn.1000-6850.casb17070056 Abstract + ( 774 )   In order to establish the embryogenesis and plant regeneration system of different rubber tree strains, [Method]take the anther of rubber tree ''Reyan106'', ''Reshi59'', ''Reshi62'' as the research material, using orthogonal design, to study the effect of different clone and the different plant growth regulator ratio medium on callus and somatic embryo induction. [Result]The results showed that the callus induction rates (CIRs) and embryogenesis induction efficiency (EIE) of three strains were very different, and the CIRs and EIE of one strain under different mediums were also very different. The plant growth regulators in the callus induction medium has an effect on the subsequent somatic embryo induction. According to the present study, for callus induction, 2,4-D 1 mg/L+NAA 2 mg/L+KT 1 mg/L is correspondingly best for ‘Reyan 106’, and 2,4-D 0.5mg/L+NAA 1 mg/L+KT 1 mg/L is correspondingly best for ‘Reshi 59’, and 2,4-D 1 mg/L+NAA 1 mg/L+KT 1 mg/L is correspondingly best for ‘Reshi 62’. For somatic embryo induction, KT 3 mg/L+NAA 0.05 mg/L+GA3 0.05 mg/L+6-BA 0.5 mg/L is correspondingly best for ‘Reshi 62’. [Conclusion]In the present study, the best medium of callus induction and somatic embryogenesis for different strains were obtained. The present study provided a method basis for the plant regeneration of multiple rubber tree strains.

  Leaf Color Change and Coloring Mechanism of Physocarpus amurensis 2018, 34 (3):  76-81.  DOI: 10.11924/j.issn.1000-6850.casb16120065 Abstract + ( 687 )   [OThis paper aims to investigate the leaf color change under different growing stages and coloring mechanism of different Physocarpus varieties. Three Physocarpus amurensis varieties, including P. amurensis, P. amurensis‘Luteus’and P. amurensis‘Diabolo’were used as materials, we investigated the leaf characteristics of five different leaf growth stages from youth to mature. In addition, comparative analysis was conducted on characteristics in terms of leaf color change. We also examined the spatial distribution of anthocyanins glycosides in P. amurensis. The results showed that the leaf areas significantly increased as the plants grew, and P. amurensis‘Diabolo’had the biggest value of leaf area. As the leaf grew, chlorophyll a， chlorophyll b, and the ratio of chlorophyll to carotenoids showed same increasing trend. The contents of chlorophyll a and chlorophyll b of P. amurensis were extremely higher than those of the other two varieties. The leaf anthocyanins glycosides were mainly distributed in the palisade tissue, while lower in the spongy tissue and surface cells. These results above clearly explained leaf characteristics and performance of color change of the three P. amurensis varieties, and provided a theoretical basis for the scientific and reasonable application.

  Effect Comparison of Different Interplanting Modes on Walnut Growth 张述斌,,, and 2018, 34 (3):  82-86.  DOI: 10.11924/j.issn.1000-6850.casb16120041 Abstract + ( 628 )   Aiming to figure out the growth status of walnut seedlings under different intercropping patterns in direct-seeding walnut orchard, the interspecific intercropping patterns of walnut-wheat-ouli, walnuts-wheat, walnut-wheat-yam were used to investigate the field microclimate and the SPAD, root development and seedling survival rate of annual walnut seedlings. The results showed that the walnuts-wheat pattern had the highest temperature (32.91℃), the walnut-yam pattern had the highest relative humidity (69.31%) while the field intensity (7068 lx), number of root development (48) and seedling survival rate (75.8%) of the walnut-wheat-ouli pattern were the highest among three intercropping patterns. Walnut-wheat-ouli might be the optimal pattern since its seedling growth was better than the other two intercropping patterns.

  Application and Optimization of VIGS Experimental Technology System in Rosa Hybrida 2018, 34 (3):  87-92.  DOI: 10.11924/j.issn.1000-6850.casb17090139 Abstract + ( 870 )   [Objective] The aim of this study is to establish an efficient and fast VIGS experimental system in Rosa hybrida, so that can improve the efficiency of infection by VIGS which is relatively low for Rosa hybrida and other woody plants and provide an experimental basis for further functional study of gene.[Method]The coding sequence of RhPDS was amplified from Rosa hybrida using RT-PCR method.Through double digested,pTRV2-RhPDS vectors were constructed.The test result was validated by gene sequencing and double digested,and then the VIGS expression vectors were transformed into Agrobacterium strain GV3101 by eletroporation.The whole plant was sprayed connected to a portable air compressor.The vacuum infiltration method was used for rose cuttings and tissue culture plant.The expression level of RhPDS gene was detected by RT-qPCR.[Result]The results showed that the recombinant vector pTRV2-RhPDS, which was verified by double enzyme digestion, showed a single band and was in good agreement with the expected target. In the method and material of infection, it is the most rapid and efficient way to infect tissue culture seedlings by vacuum osmosis. [Conclusion]In this research,we obtain an optimized technical system for VIGS which is improve the efficiency of infection by VIGS in Rosa hybrida and other woody plants and provide an solid experimental basis for further functional study of plant gene.

  Cadmium Stress: Effects on Growth and Cadmium Absorption of Chamaecrista rotundifolia Seedlings 2018, 34 (3):  93-97.  DOI: 10.11924/j.issn.1000-6850.casb16120057 Abstract + ( 641 )   The paper aims to explore the cadmium-tolerance of Chamaecrista rotundifolia. The authors studied the effects of Cd stress on the growth and development, mineral nutrient uptake, Cd accumulation and distribution of C. rotundufolia seedlings of different varieties (CIP86134 and ATF3248) by using nutrient solution culture experiment. The results showed that: Cd stress inhibited the growth of C. rotundufolia seedling, and the plant height and leaf emergence rate were lower than that of CK, and decreased the biomass accumulation of C. rotundifolia and the absorption of Ca, Mg, Cu and Zn; CIP86134 and ATF3248 were not Cd-tolerant plants, and their tolerance of the Cd concentration was 33.4 mg/kg and 33.1 mg/kg, respectively. By comparing morphological diagnosis, biomass and the amount of Cd absorption, the tolerance ability of CIP86134 to Cd stress was stronger than that of ATF3248. CIP86134 is more suitable for the ecological restoration of Cd polluted soil.

  Effects on Growth and 15N Absorption, Utilization and Distribution of Malus hupehensis Under Different Nitrate Nitrogen Levels 2018, 34 (3):  98-103.  DOI: 10.11924/j.issn.1000-6850.casb16120148 Abstract + ( 749 )   The absorption and rational distribution of nitrogen play an important role in growth and yield and quality of fruit trees. Suitable nitrogen application can realize the optimum growth of plants, and fully tap the growth potential of plants. Malus hupehensis seedlings and 15N trace technique were used to explore plant growth and the characteristics of absorption, distribution and utilization of N under different nitrate nitrogen levels (0.00, 4.00, 8.00, 12.00, 16.00, 20.00 and 24.00 mmol/L NO3- , taken as N0, N1, N2, N3, N4, N5 and N6, respectively). The main results were as follows: with the improvement of nitrogen levels, chlorophyll (SPAD), leaf area, biomass, root length, root surface area, number of root tips, root activity and total nitrogen of Malus hupehensis seedlings first increased then decreased, rose to their highest level at 12.00 mmol/L NO3- ; Ndff% values, 15N uptake and nitrogen use efficiency decreased with the improvement of nitrogen level. In low N levels (N1~N2), 15N was mainly distributed in leaf, 51.39% under treatment N1 and 45.9% under treatment N2, followed by that in root and stem. Under high N levels (N4~N6), 15N was transferred to root and accounted for 43.80%, 45.40% and 51.46% in N4, N5 and N6 respectively. To ensure the high nitrogen use efficiency at the same time, Hoagland nutrient nitrate nitrogen concentration of 12.00 mmol/L could significantly improve the growth of Malus hupehensis and plant root, the nitrogen distribution in each organ was relatively uniform and the growth was the best.

  Feasibility of Grifola frondosa Cultivation Under Grape Trellis in Sunlight Greenhouse 2018, 34 (3):  104-111.  DOI: 10.11924/j.issn.1000-6850.casb16120100 Abstract + ( 586 )   To improve the space and ground utilization of sunlight greenhouse, the authors studied the feasibility of Grifola frondosa cultivation under grape trellis in sunlight greenhouse. In early March, grow G. frondosa every 10 days under grape trellis, environmental factors and physical and chemical properties of G. frondosa of the four sowing periods were determined by temperature and humidity recorder, dry weighing method, Kjeldahl method and so on. From March to June, the daily average temperature range of grape leaf canopy and the humidity range was 15- 28℃ and 32%- 84% , respectively. The average temperature and humidity range at 20 cm above the ground was 13-28℃ and 55%-95%, respectively. The average temperature range at 10 cm under the ground was 15-26℃. The data showed that the requirements of temperature and humidity during the mushroom cultivation could reach those of grape in spring and summer. After the casing of the mushroom, water content of the media was 50%- 57% , and the pH value was acidic. The EC value increased since the formation of the primordium, while the carbon-nitrogen ratio continuously decreased with the final level of (36-38):1 at the end of the fruiting period. The cellulose and xylanase manifested the highest level during the primordium, while laccase activity reached its maximum during the fruiting stage. Amylase activity reached the highest level in the mycelial growth stage, followed by continuous decrease during fruiting and increase after maturation. The biological conversion rate of G. frondosa cultivation from early March using the present model could reach 40%, which was close to that of G. frondosa cultivation using standard imitative wild culture techniques.

  Simulation Study on Land Use Spatio-temporal Pattern in Qingpu District, Shanghai 阮俊杰,, and 2018, 34 (3):  112-119.  DOI: 10.11924/j.issn.1000-6850.casb16120085 Abstract + ( 572 )   Based on the CLUE-S model, combined with region total planning and　ecological protection red line, with an aim to predict the land use pattern in 2040 of the Qingpu District, Shanghai. At last, from the angle of minimum cumulative resistance, the ecological resistance was　compared and analyzed. The results are as follows. (1) To verify, the applicability of CLUE-S model in the study area, the accuracy test index of Kappa calculated and its value reached 95%, indicating the CLUE-S has good reliability in the study area. (2) Land use spatial pattern difference is significant, by 2040, Industrial land, traffic land, residential land, urban green land, forest land, cultivated land and other land present a decreasing trend. (3) Under the ecological protection red line constraint scenario, the ecology resistance of east Qingpu decreases, and the western region remain stable. With time, the land use spatial pattern changes tend to be more reasonable. The study conclusions will provide data reference and basic information of decision support for region future land use planning,management and policy-making.

  Correlation Analysis Between Organic Matter and Salinity in Cultivated Soil of Jiashi County 2018, 34 (3):  120-127.  DOI: 10.11924/j.issn.1000-6850.casb16120125 Abstract + ( 651 )   The purposes are to provide a basis for precise fertilization, waste reduction, salt content decrease in soil and crop rotation. The field samples, GPS positions, statistical analysis and space analysis methods were used in this study. Correlation analysis between organic matter and salinity in cultivated soil was studied based on the SPSS17.0 and ArcGIS 9+ software. The results showed that: (1) the average content of organic matters in melon planting soil was higher than that in maize and cotton planting soil; (2) the differences of variation coefficients in different layers of different cultivated soil were obvious, the organic matters and salt ions had different degrees of correlated characters, the organic matter and K++ Na+, Mg2+ salt ions showed significantly positive correlations in cotton planting soil, and the others had significantly negative correlations; the organic matters and CI-, Mg2+ salt ions had significantly positive correlations in melon planting soil, and the others had significantly negative correlations; the organic matters and SO42-, K++ Na+, Mg2+ salt ions showed significantly positive correlations in maize planting soil, and the others showed significantly negative correlations; (3) the content of salt in cotton planting soil gradually increased from surface to bottom; the content of salt in the surface layer of melon planting soil was high, while the contents of salt in the middle and bottom layers had no difference, the content of salt in maize planting soil had first increasing and then decreasing trend.

  Research Progress of Nitrifying and Denitrifying Microbial Communities in Grasslands 钟磊, and 2018, 34 (3):  128-133.  DOI: 10.11924/j.issn.1000-6850.casb17010057 Abstract + ( 599 )   Under the background of global climate change, the study on nitrogen (N) cycling in grassland soil has become an urgent issue. Greenhouse gas N2O mainly comes from nitrification and denitrification processes in soil, which is driven by microbial functional groups. In order to clarify the microbial mechanism of N2O in soil, from the microbial functional groups of nitrification and denitrification in grassland ecosystems, we reviewed the quantities, composition and relative influencing mechanism and geography pattern of microbial functional groups of nitrification and denitrification in global grassland ecosystems, summarized the progress of N2O production, analyzed the future direction of microorganisms research in grasslands, and discussed future research on N2O production mechanism in grassland.

  Dynamics of soil water storage in maize growing season in Shuozhou City 2018, 34 (3):  134-139.  DOI: 10.11924/j.issn.1000-6850.casb16120075 Abstract + ( 769 )   In order to grasp the variation of soil water storage in the maize growing season in Shuozhou City and improve the soil water use efficiency, the writer analyzed the variation of soil water storage in maize growth season. It is based on the decked change of soil water storage and related meteorological factors of soil water vertical changes in Shuozhou city growing season soil moisture by relating meteorological data from 1995 to 2015 in Shanxi city of Shuozhou province corn, correlation, soil water storage. The results showed that: the precipitation variation coefficient was more than 15% in the growing season of Maize in Shuozhou City. And the soil water storage increased by about 0.2mm with the precipitation increased by 1mm. The precipitation, the temperature, the relative humidity, the evaporation and other meteorological factors correlated with soil water reached more than 60% between 10cm and 20cm soil layer. The correlation coefficients above 30cm of each layer decreased significantly. Besides the 0-50cm soil water storage curve can be divided into ten day period, consumption, the precipitation in rainy season and Autumn period of soil water stable period the three stages of rapid elimination of dry season soil moisture; in the corn growing season (5-9 months) soil moisture vertical rule each month is similar to that of 0 ~ 20cm soil water storage variation coefficient is above 20%, the influence of meteorological factors on the 30 ~ 50cm layer is larger, the coefficient of variation is below 20%, the precipitation can not penetrate the soil layers, Other meteorological factors had little effect on deep soil, the soil water storage coefficient of variation.

  Drought Meteorological Insurance Index of Maize: A Case of Southeastern Gansu 邓卓雅 and 靳永才 2018, 34 (3):  140-144.  DOI: 10.11924/j.issn.1000-6850.casb16120076 Abstract + ( 747 )   Drought is the main factor that influences maize yield in southeastern Gansu. To explore the drought meteorological risk of maize planting in this region, the authors analyzed the occurrence frequency of all drought levels and their effect on maize yield, set up the drought meteorological insurance index and calculated the risk compensation amount of drought on maize yield based on the data of precipitation and maize yield of 7 weather stations in Tianshui from 1961 to 2015. The results showed that: the frequency of non- influence drought on maize was the highest, up to 27.9%; the frequency of heavy drought that appeared successively in spring, early summer and hot summer was 0.1%; the combination of heavy drought in spring and hot summer and medium drought in early summer had a frequency of 0.1% and the combination of heavy drought in early summer and hot summer and medium drought in spring had a frequency of 0.2%, they all belonged to small probability events; there were 9 kinds of drought combination free from compensation when the drought meteorological insurance index was ≤ 10%, 17 kinds of drought combination had the insurance compensation standard ranged from 0% to 10%, 38 kinds of drought combination had the insurance compensation standard ranged from 10% to 40%; there was no drought combination that had the insurance compensation standard (the drought meteorological insurance index was above 50%) above 40%.

  Temporal and Spatial Characteristics of Drought from 1979 to 2014 in Fen River Basin 2018, 34 (3):  145-151.  DOI: 10.11924/j.issn.1000-6850.casb16120143 Abstract + ( 601 )   The paper aims to comprehensively analyze the drought characteristics of Fen River Basin in recent years and effectively response to drought risk. The authors obtained the drought distribution characteristics on the time and space scale of Fen River Basin by using monthly precipitation data of 35 meteorological stations in the basin from 1979 to 2014 with drought evaluation indicator as standardized precipitation index and statistical methods like Mann-Kendall and so on. The results showed that: in the past 36 years, the yearly drought intensity and drought range showed a decreasing trend, while the drought intensity of the four seasons and drought range of summer, autumn and winter all showed a decreasing trend; the drought was most and covered the largest area in winter, and the regional drought was most in summer; the probability of continuous drought was the highest in autumn, winter and spring; on a multi-year average, the drought mainly distributed in the northern region, and also distributed more in the south basin in summer, while local drought frequencies were the highest in spring and autumn. The SPI well reflected the temporal and spatial variation characteristics of drought in Fen River Basin in recent 36 years

  Extractants and Extraction Conditions of Soil Available Selenium in Selenium-enriched Soil 2018, 34 (3):  152-157.  DOI: 10.11924/j.issn.1000-6850.casb16120132 Abstract + ( 752 )   Selenium-enriched soil in eastern Qinghai was used as test material to select optimum extractants (from NaHCO3、KH2PO4、K2SO4、EDTA、AB-DTPA and DTPA) and the corresponding extraction conditions for soil available selenium, and the optimum extractant and extraction condition were studied by wheat test. The results showed that the amounts of available selenium which extracted by six extractants all decreased with the ratio of soil to solution, and increased with the shaking time. The optimum ratio of soil to solution and shaking time of EDTA and DTPA were 1/20 and 30 min; the optimum ratio of soil to solution was 1/15 for K2SO4, ABDTPA, NaHCO3 and KH2PO4; and the optimum shaking time was 60 min for K2SO4 and AB-DTPA; and that for NaHCO3 and KH2PO4 was 90 min. There was a significantly positive correlation between the contents of available selenium in soil and the contents of selenium enrichment in wheat grain under the optimum extraction condition, but selenium amount that extracted by DTPA was the minimum, then was that extracted by K2SO4, which were only 16% to 47% and 36% to 85% of those of KH2PO4, NaHCO3, AB-DTPA and EDTA, so DTPA and K2SO4 were not suitable for available selenium extraction from selenium-enriched limy soil. The contents of selenium extracted by KH2PO4, NaHCO3, AB- DTPA and EDTA were not only significantly correlated with selenium contents in wheat grain, but also had high extraction rate, and the extraction process was simple and reproducible, so the four kinds of extractants could be used in selenium-enriched limy soil.

  Development of E-commerce in Poverty-stricken Areas and Influencing Factors of Agricultural Products Network Marketing: “Poverty Alleviation by E-commerce”in Weining, Guizhou 2018, 34 (3):  158-164.  DOI: 10.11924/j.issn.1000-6850.casb17060005 Abstract + ( 1192 )   Poverty alleviation by E-commerce is an important way of accurate poverty alleviation. The authors took Weining County of Guizhou Province as the research object, analyzed the key constraints in the development of E-commerce based on the status of local E-commerce, and put forward the policy measures to promote the development of E- commerce in Weining. Interviewing method, SWOT analysis and analytic hierarchy process were applied in this research, the current situation and problems of E-commerce in Weining were expounded and the internal and external factors were analyzed, strength, weakness, opportunities and threats in agricultural products network marketing were discussed, and by means of experts grading and AHP analysis, the weight of the above factors was calculated, and the strategies of E-commerce development were proposed. The results showed that the development of E-commerce was conducive to poverty alleviation, but the imbalance of purchase and sale was an important and inevitable obstacle. To overcome the obstacle, the factor of threats should be viewed as the biggest impact factor, followed by strength, and the third and fourth were opportunity and weakness. ST strategy could be chosen to promote the agricultural products network marketing in Weining, and the advantages of strength could be taken to resist threats, while taking SO strategy into account. Finally, there were several specific measures as follows: building“green brand”, reducing production and circulation costs; creating a better environment of E-commerce; promoting the service system and developing online tourism business.