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    20 June 2016, Volume 37 Issue 03
    A Review on Impacts of Climate Change on Water Resource and Agriculture in Africa
    YANG Di, XIONG Wei, XU Yin-long
    2016, 37(03):  259-269.  doi:10.3969/j.issn.1000-6362.2016.03.001
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    Africa shares the lowest portion of greenhouse gases emission in the world both in total and per capita, yet she suffers mostly from climate change. Climate change affects Africa’s water resources, agriculture, biodiversity, human health, and national security. Food and water security are the two major challenges facing Africa whilst have been deteriorated by climate change. This study reviews the new findings of climate change impacts on water system and agriculture in Africa and their limitations, with the attempt to facilitate and promote enhanced researches related to climate change impact and vulnerability. Observation shows that climate change has led to rapid melting of glaciers, reduced rainfall and increased variability. Hydrological simulation demonstrates that further climate change would decrease precipitation and runoff in some areas, worsening current fragile water supply in most of Africa. Africa’s agriculture faces unprecedented challenges under climate change. Both observation and simulation indicate climate change posed negative effects on Africa’s agriculture. Increased risks of drought, changed growth season and decreased crop yield, would likely threat food security in Africa. Uncertainties in these studies mainly come from climate scenarios, methods, quality and quantity of data. Compared to other regions, Africa is short of comprehensive and in-depth researches related to climate change impact and vulnerability, therefore expects substantial investment on such activities to devise effective strategies in mitigating the negative effects of climate change on water resources and agriculture.

    Impacts of Different Farming Managements on N2O Emission and Carbon Footprint for Maize from Brown Soil
    ZHAO Xun, GUO Li-ping, XIE Li-yong, SUN Xue, ZHAO Hong-liang, XU Jing, PAN Shi-mei
    2016, 37(03):  270-280.  doi:10.3969/j.issn.1000-6362.2016.03.002
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    In order to study the impacts of different farming measures on N2O emission for maize production and the carbon footprint during whole maize growth season, the field experiment was conducted in middle and lower reaches of Liaohe Plain in 2014. Five farming measures, including the non-nitrogenous fertilizer control (CK), the regular fertilization by farmers (F), the pyridine coated urea (FP), regular fertilization and biochar (FC), and regular fertilization and straw semi-farm return (FS) were taken in the experiment. The results showed that, (1) N2O emission in the soil was mainly affected by the fertilization time and fertilization amount, the N2O emission was keeping high after fertilization application. The N2O emission after base fertilizing and additional fertilizations accounted for 24.3%-27.3% and 32.0%-38.2% of the accumulated emission amount of N2O during whole growth season, respectively; (2) As the FP processing can inhibit the rapid transition of ammonium nitrogen in the soil to nitrate nitrogen, the accumulated N2O emission amount in the maize growth period through FP, FC and FS was reduced by 30.2%, 22.7% and 9.4% compared to regular fertilization (F). The emission effect of FP was optimum choice; (3) The carbon footprint of FP and FC processing was low, which was decreased by 19.5% and 14.8% respectively compared to F; The carbon intensity of FP processing was also the lowest, and its carbon efficiency was the highest. Compared to other farming measures, it belonged to a low-carbon fertilization one with high production and low emission; (4) The direct N2O emission with the application of nitrogen accounted for the largest share of carbon emission in the whole maize production process (accounting for 74.9%-89.0%), followed by the carbon emission in the fertilizer production process (accounting for 13.4%-17.8%). Therefore, the reduction of nitrogen application and the improvement of nitrogen utilization was the key to reduce the carbon footprint in the maize production process. The carbon emission reduction management measure specific to the spring maize production in the brown soil area in this research was the pyridine coated urea

     Effects of Reducing Irrigation and Organic Fertilization on N2O Emissions from Celery Field in Facilities
    YANG Yan, SUN Qin-ping, ZOU Guo-yuan, XU Jun-xiang, LI Ji-jin, LIU Chun-sheng, JIANG Li-hua
    2016, 37(03):  281-288.  doi:10.3969/j.issn.1000-6362.2016.03.003
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    In order to monitor the N2O emissions after irrigation and organic fertilization from vegetable soil in celery growing season, and make sure effective reduction measures were put forward, an experiment with 6 treatments was done in Beijing suburbs by using static chamber measurement techniques. The impact of the -5cm), NO3--N content, NH4+-N content and N2O emissions were analyzed. It was a split block experiment with irrigation and fertilization two factors. The 6 treatments were as fellows: conventional irrigation under the condition of conventional fertilization (HN), conventional fertilization <0.01), however, had no significantly influence on celery yield, WFPS and Nmin content of soil. Compared with conventional fertilization, the treatments of conventional fertilization with 1/3 decrement and no fertilization had no significantly influence on NH4+-N content of soil, however, significantly reduced NO3--N content of soil (P<0.01) by 43.96% and 76.42%, respectively. In addition, conventional fertilization with 1/3 decrement made the cumulative N2O emissions from the soil in the whole growing season of celery, significantly reduced by 62.04%, however, had no significantly influence on celery yield. In this field experiment, conventional irrigation with 20% decrement (L) and conventional fertilization with 1/3 decrement (N3) both significantly reduced N2O emissions, and had no significantly influence on the celery yield, furthermore, the combination of the decrement of irrigation and fertilization (LN3) can reduce the production costs at the same time.reductions of irrigation and organic fertilization (biogas residue) on the water-filled pore space (WFPS, 0with 1/3 decrement (HN3) and no fertilization (HN0), and conventional irrigation with 20% decrement under the condition of conventional fertilization (LN), conventional fertilization with 1/3 decrement (LN3) and no fertilization (LN0). The results showed that, conventional irrigation with 20% decrement reduced total N2O emissions by 32.23%, significantly lower than that of conventional irrigation (P )

      Combined Effects of Straw Mulch Cover & Organic Matter Input on the Erodibility of Purple Soil in Sloping Farmland
    HUANG Xin-jun, CHEN Shang-hong, LIU Ding-hui, ZHANG Qing-wen
    2016, 37(03):  289-296.  doi:10.3969/j.issn.1000-6362.2016.03.004
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    Based on the data from rainfall and field runoff plots in 2014, a field experiment was conducted in Sichuan to evaluate the runoff, sediment characteristics and soil erodibility of purple soil on the sloping farmland soil as affected by the straw mulch cover and organic matter input. There were four treatments as organic matter input (OM), straw mulch (SW), combined treatment of organic matter input with straw mulch treatment (OM+SW), and control group(CK). The sediment yield in unit area runoff plots by unit individual runoff depth (Kw) was used to describe the soil erodibility. The results showed that there was a positive linear correlation between runoff depth and sediment yield. More importantly, straw mulch and organic matter input can significantly reduce surface runoff in sloping farmland. Besides, the effects of four treatments in reducing surface runoff was ranked as: OM+SW>SW>OM>CK. Straw mulch and organic matter input can notably decrease unit sediment yields caused by runoff and thus reduce soil erodibility. The contribution of organic matter treatment (OM), straw mulch treatment(SW) and organic matter+straw mulch(OM+SW) treatment on the reduction to soil erodibility were on average 22.30%, 29.76% and 35.04%, separately. Additionally, the subtractive effects of straw mulch treatment (SW) on soil erodibility were more obvious than organic input treatment (OM), but the differences were not significant. Therefore, it is suggested to use organic matter input together with straw mulch as a practical tillage way to eliminate soil erodibility for this region.

    Effects of High Temperature Stress and Recovery on Photosynthesis and Stress Tolerance of Tea Leaves
    HAN Dong,YANG Fei,YANG Zai-qiang,JIN Zhi-feng
    2016, 37(03):  297-306.  doi:10.3969/j.issn.1000-6362.2016.03.005
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    In order to study the effect of high temperature stress on the photosynthesis rate, fluorescence characteristics, antioxidant enzyme activities and cell injury rates of Camellia sinensis in south region of the Yangtze River, four varieties of tea trees such as Fuding dabaicha, Jiukeng, Longjing 43 and Wuniuzao were investigated under different high temperature stress(35℃ and 40℃,with 25℃ as control)in artificial climate box for 6,12,18,24,48 hours, then recovered for 9 days. The results showed that high temperature stress inhibited the maximum net photosynthetic rate of tea and maximal photochemical efficiency (Fv/Fm) significantly, the maximum net photosynthetic rate and Fv/Fm declined faster when the processing was longer and the temperature was higher. In addition to Fuding dabaicha under 35℃, other varieties of tea could not be recovered to the normal level during a recovery. The SOD activities of Camellia sinensis leaves rose rapidly at the first 12 hours, and then decreased. The average of MDA contents achieved maximum when the temperature were conducted for 48 hours, the leaf cell injury rates increased with high temperature and processing time. The order of the heat resistance among four Camellia sinensis was Fuding dabaicha>WuniuzaJiukengLongjing 43. The study provided a basis for scientific research of Camellia sinensis.

    Growth Simulation of Major Rice Varieties in Single Cropping Rice Area of  Sichuan Province
    CHEN Chao, PANG Yan-mei, MO Zhi-hong
    2016, 37(03):  307-315.  doi:10.3969/j.issn.1000-6362.2016.03.006
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    To provide the reference for regional adaptation and application of ORYZA2000 in Sichuan province, the model was calibrated by the field data of five rice varieties at seven agrometeorological stations, and evaluated by the dataset from above stations with the five rice varieties. The daily meteorological data over the growing period of single cropping rice for the studied sites were used as driving variables in ORYZA2000 model. Management measures and soil data were used as the input of the model. By the comparison between measured and simulated values of development stages, leaf area index (LAI), biomass and yield, the simulation capacity and performance of ORYZA2000 model were evaluated in single cropping rice area. The results showed that nutrition stage growth rate of Hexi-39 was largest, but reproductive stage growth rate of Hexi-39 was smallest. The nutrition stage growth rate of Ⅱyou-838 was smallest, but reproductive stage growth rate of Dyou-63 and Xianyou-2 were largest. ORYZA2000 model could simulate the phenology of five rice varieties with 1-2 days’ difference for flowering and maturity stages. Furthermore, the normalized root mean square errors (NRMSE) of different development stages were less than 1%. While the NRMSE of other rice parameters were 5.26%-10.01% for yield, 10.37%-19.19% for leaf area index, 13.17%-18.69% for aboveground biomass, 14.31%-20.41% for stem biomass, 18.95%-24.74% for green leaves biomass, and 20.85%-25.39% for panicle biomass.These results showed that ORYZA2000 model could satisfactorily simulate the dynamical process of growth and yield of five major rice varieties. In general, we could conclude that ORYZA2000 model was adaptable and could be applied in scenarios analysis study in single cropping rice area of Sichuan province.

    Tempo-spatial Characteristics and Impact Factors of Radiation Use Efficiency of Wheat-maize Rotation System in Henan Province
    CHANG Qing, WANG Jing, YU Wei-dong, WANG Na, TAN Mei-xiu
    2016, 37(03):  316-325.  doi:10.3969/j.issn.1000-6362.2016.03.007
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    The tempo-spatial characteristics in radiation use efficiency (RUE) of wheat, maize and wheat-maize rotation system were analyzed based on crop production energy, total solar radiation during crop growing season and annual global radiation from the observed meteorological and crop data during 1981 to 2007 at 19 stations in Henan province. Subsequently, the contribution rates of the changes in global radiation and crop production energy to the change in RUE were calculated with the statistical regression method. The study further calculated the contribution rates of the changes in crop production energy of wheat and maize to the change in production energy of wheat-maize rotation system. The study results showed that RUE of wheat-maize rotation system varied from 0.75% to 1.61% in Henan province. The high value areas occurred at Tangyin in the northern Henan province and Lushi in the western Henan province, while the low value areas were in the northwestern, eastern and southern Henan province. Average RUE of wheat was 0.65%-1.63% with the highest values at Tangyin and Lushi, and following by most sites of the eastern Henan province, while the low value area in the northwestern and eastern Henan province. Average RUE of maize was 0.85%-1.81%, with the high value area at most of the sites in the northern and western Henan province except for the lowest value at Sanmenxia, while the low value area in the northwestern, eastern and the southern Henan province. RUE of wheat-maize rotation system at Ruzhou, Xiping, Xinxiang and Zhumadian showed a significant rising trend due to the decrease in annual global radiation and the increase in production energy of wheat-maize rotation system. The contribution rates of the decrease in annual total global radiation and the increase in production energy of wheat-maize rotation system to the increase in RUE were 4%-31% and 69%-96% respectively from 1981 to 2007. However, the increase in annual global radiation had a negative contribution rate on RUE of wheat-maize rotation system at Lushi. The contribution rates of the change in wheat production energy to the change in the production energy of rotation system were 65% and 90%, which were higher than those of maize with the values of 35% and 10% at Lushi and Ruzhou. However, contrasting results occurred at Xiping, Xinxiang and Zhumadian with higher contribution rates of 51%, 72% and 65% for maize than the contribution rates of 49%, 28% and 35% for wheat. In the future, improving crop production energy is still an effective method to increase radiation use efficiency and different areas should focus on diffident crops in Henan province.

    Effect of High Temperature on Rice Dry Matter Partition and Yield Component during Booting Stage
    LUO Zong-qiang,SHI Chun-lin,JIANG Min,LIU Yang, XUAN Shou-li, JIN Zhi-qing
    2016, 37(03):  326-334.  doi:10.3969/j.issn.1000-6362.2016.03.008
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    In order to explore the influence of dry matter partition and yield component to high temperature, a control experiment with different temperature levels and durations was conducted at booting stage with hybrid rice Lianyoupeijiu and conventional rice Nanjing45. The results showed that photosynthetic rate, harvest index and yield decreased with the increase of high temperature lever and duration. Compared with CK, the photosynthetic rate and yield of Liangyoupeijiu and Nanjing45 declined 44.6%, 81.6% and 28.8%, 87.7% respectively under high temperature treatment at 41℃ for 7 days. High temperature led to the decrease of seed-setting rate and the amount of spikelet, and hindered the movement of the photosynthetic material to the panicle, so the harvest index would be reduced. The stem biomass exceeded 70% of the total plant for Liangyoupeijiu and Nanjing45 under high temperature treatment at 41℃ for 6 days. High temperature resulted in the decrease of grain number per panicle, seed-setting rate and 1000-grain weight and the reducing extent related to high temperature strength and duration. Under heat treatment at 41℃ for 7 days, the grain number per panicle, seed-setting rate and 1000-grain weight of Liangyoupeijiu and Nanjing45 declined 41.9%, 93.5%, 25.3% and 50.1%, 79.6%, 23.7%, respectively. So the most sensitive factor to high temperature was seed-setting rate, and then grain number per panicle, 1000-grain weight.

    Simulation on Dry Matter Distribution Coefficient for Summer Maize in North China
    LI Hao, TAN Fang-ying, WANG Jian-lin, TAN Kai-yan, XU Ying, WANG Zhi-wei
    2016, 37(03):  335-342.  doi:10.3969/j.issn.1000-6362.2016.03.009
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    Dry matter distribution coefficient was a key parameter for driving maize growth model. Based on the field experimental data of two consecutive years (2013 and 2014) in Xiajin, Shandong province, Gucheng, Hebei province and Yuncheng, Shanxi province, the biomass sequence in the whole growth duration of maize was obtained by using the ratio method and linear regression correction method. On such a basis, the dynamic change model of dry matter distribution for summer maize in North China was established by taking the development stage of effective simulation of accumulated temperature as the independent variable. The results showed that: (1) There were same dynamic change characteristics for dry matter distribution coefficient of maize from three stations. The dry matter distribution coefficient for leaves kept reducing from seedling process, and the dry matter distribution coefficient for stems increased at the beginning and then decreased with the maximum value occurring at tasseling stage. The dry matter partitioning coefficient for ears increased after the tasseling and reached 1 after 20 days, which meant the dry matter was no longer allocated to leaves and stems. (2) Both dry matter distribution coefficients for leaves and stems of summer maize in North China could be simulated by piecewise nonlinear model. The dry matter distribution coefficient for leaves was distinguished at 10-15 days after tasseling, which could be simulated by three times polynomial dynamic model before tasseling along with the development process, and became 0 after tasseling. The dry matter distribution coefficient for stems was distinguished at 20-25 days after tasseling, which could be simulated by four times polynomial dynamic model before tasseling along with the development process, and became 0 after tasseling. The dry matter distribution coefficient for ears could calculated by the sum of the dry matter distribution coefficient for leaves, stems and ears, which was 1. The results indicated that the simulation effect of dynamic model for dry matter distribution coefficient of summer maize was proficient in North China.

    Analysis on Photosynthetic Characteristics of Maize Growth in “Water Transformation Dynamical Processes Experimental Device”
    TAN Li-ping, LIU Su-xia, MO Xing-guo, LIN Zhong-hui, HU Shi
    2016, 37(03):  343-351.  doi:10.3969/j.issn.1000-6362.2016.03.010
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    The influencing factors of leaf net photosynthetic rate (Pn) in different growth stages and leaf position under greenhouse condition were studied by analyzing the dynamic characteristic of photosynthetic characteristic and the correlation between Pn and the eco-physiological factors based on the “Water Transformation Dynamical Processes Experimental Device” (WATDPED). The results showed that there was only one peak of the variations of Pn, chlorophyll content (chl), stomatal conductance (Gs), N content (N) during the growth period. However, the maximum value of Pn, appeared in milk stage, was lower and one growth stage later than the previous research results of fields (the tasseling and silking stage). The Pn, chl and Gs showed higher value in middle leaf positions than in other leaf positions. During the growth period, the correlation coefficient between Pn and chl was the highest (0.94, P<0.05), followed by the coefficient between Pn and N and that between Pn and Gs (0.77, P<0.05). The variation of Pn in different leaf position was similar to that of Gs. The device is more suitable to be used to conduct some control experiment studying the influence of climate change, water and nutrient stress on the crops or ecosystems.

    Evaluation on Maize Chilling Injury Based on WOFOST Model in Hetao Irrigation Region in Inner Mongolia
    LI Xiu-fen, MA Shu-qing, ZHAO Hui-ying, WANG Ping, JIANG Li-xia, ZHU Hai-xia
    2016, 37(03):  352-360.  doi:10.3969/j.issn.1000-6362.2016.03.011
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    Based on observed data during maize growth and development, combining with the existing research results, the localization and adaptability test of WOFOST model was carried out. Based on daily meteorological data from 12 meteorological stations in research region from 1961 to 2010, the crop parameters were partitioned. By using WOFOST model, the maize development and growth processes were simulated. The tasseling stage delayed days, filling index were determined as maize chilling injury index, and storage organ dry weight fluctuation percentage production as evaluation index, the history and production of chilling injury were analyzed. The results showed that the localized WOFOST model was an effective method in Hetao irrigation regionin Inner Mongolia, which could be used in maize simulation. WOFOST model simulated well maize development degree and response of development degree to chilling injury. According to the WOFOST maize chilling injury index, there occurred 260 stations/times different degree maize chilling injury in the region in last 50 years, the severe chilling injury accounted for 37.3%, the light and medium chilling injury accounted for 62.7%, and 84.7% of severe chilling injury years showed yield reduction. Compared with the traditional method, the new method showed more clearly biological significance, so these indicators could be applied in the business of maize chilling injury monitoring and evaluation in Hetao irrigation region in Inner Mongolia.

    Difference of Dry and Wet Conditions during Dry Season in Western and Eastern of Guizhou Province
    CHI Zai-xiang, LI Gui-qiong, BAI Hui, LONG Xian-ju,PAN Xu-yan, XIAO Yan-lin
    2016, 37(03):  361-367.  doi:10.3969/j.issn.1000-6362.2016.03.012
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     Based on the data of daily air temperature, precipitation, a small amount of evaporation capacity from 85 meteorological stations from October 1960 to March 2010 in Guizhou province, by using the methods of linear trend, M-K mutation, Morlet wavelet, accumulated temperature dryness index(ATDI) and arid-wet index(I), the meteorological drought situation in dry seasons (from October to March of next year) of Guizhou province was analyzed. The results showed that the precipitation did not changed obviously in western and eastern region of Guizhou province, though with a little periodical change. In the western region, the precipitation had reduced since 2002, with the linear tendency -59.5mm·10y-1(P<0.01).In the eastern region, the precipitation had reduced since 2005, with the linear tendency -97.7mm·10y-1(P<0.01).The regional meteorological drought in western and eastern region of Guizhou Province increased in 1990s, and there was significant differenton the period of sudden change and periodical characteristics (P<0.05) for precipitation in the two regions.In the western region, the sudden change of amounts occurred in 1979, with the periodical concussion of 5-7 years. In the eastern region, the sudden change occurred in 1995, with the periodical concussion of 2-3 years. In last 50 years, the aridity index and arid-wet index in western region were larger and lower obviously than that of eastern region and the meteorological drought in western region was severe than that of the eastern region.The temperature dryness, the arid-wet index and the linear fitting rate of precipitation anomaly percentage were quite high in the two regions, and all of R2 exceeded 0.8,and the western region was higher than that of the eastern region.The temperature dryness and the arid-wet index could reflect the meteorological drought extent dry seasons in eastern and western region of Guihzou province.

    Regional Mapping of Light Use Efficiency for Paddy Rice by Using MODIS Photochemical Reflectance Index
    GUO Jian-mao, LIU Jun-wei, TONG Ying-xiang, FEI Dun-yue, WANG Qian
    2016, 37(03):  368-375.  doi:10.3969/j.issn.1000-6362.2016.03.013
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     In order to explore the potentiality of the Photochemical Reflectance Index(PRI) in predicting light use efficiency(LUE) at regional scales, eddy covariance flux data of Shouxian station and corresponding MODIS imagery were utilized to establish different models which concerned three formulations of PRIs calculated from a set of alternative reference bands at 488,551,667nm and LUE of site pixel. Then, the optimal model was chosen to create a regional LUE map for paddy rice. The results showed that, the relationships between MODIS PRIs from observations closer to the backscatter direction and LUE were always stronger, and PRI551 exhibited the strongest relationship with LUE among MODIS PRIs. Compared to regional LUE derived using the MOD17 algorithm, more realistic spatial heterogeneity of LUE was appeared in the MODIS PRI551-derived LUE map. Moreover, with multi-temporal imagery and appropriate gap-filling methods be used, MODIS PRI has certain feasibility on long-period and large-area monitoring of ecosystem LUE.Photochemical reflectance index|Light use efficiency| Eddy covariance| MOD17 algorithm| Enhanced vegetation index(EVI)