Investigation of crop evapotranspiration and irrigation water requirement in the lower Amu Darya River Basin,Central Asia

High water consumption and inefficient irrigation management in the agriculture sector of the middle and lower reaches of the Amu Darya River Basin(ADRB)have significantly influenced the gradual shrinking of the Aral Sea and its ecosystem.In this study,we investigated the crop water consumption in the growing seasons and the irrigation water requirement for different crop types in the lower ADRB during 2004–2017.We applied the FAO Penman–Monteith method to estimate reference evapotranspiration(ET0)based on daily climatic data collected from four meteorological stations.Crop evapotranspiration(ETc)of specific crop types was calculated by the crop coefficient.Then,we analyzed the net irrigation requirement(NIR)based on the effective precipitation with crop water requirements.The results indicated that the lowest monthly ET0 values in the lower ADRB were found in December(18.2 mm)and January(16.0 mm),and the highest monthly ET0 values were found in June and July,with similar values of 211.6 mm.The annual ETc reached to 887.2,1002.1,and 492.0 mm for cotton,rice,and wheat,respectively.The average regional NIR ranged from 514.9 to 715.0 mm in the 10 Irrigation System Management Organizations(UISs)in the study area,while the total required irrigation volume for the whole region ranged from 4.2×109 to 11.6×109 m3 during 2004–2017.The percentages of NIR in SIW(surface irrigation water)ranged from 46.4%to 65.2%during the study period,with the exceptions of the drought years of 2008 and 2011,in which there was a significantly less runoff in the Amu Darya River.This study provides an overview for local water authorities to achieve optimal regional water allocation in the study area.     

旱作覆膜玉米生长和水分利用对气候变化的响应

基于3 a连续冬小麦-夏玉米覆膜轮作试验校准和验证AquaCrop模型的适用性,模拟研究了气候变化对夏玉米生长、产量和水分利用的影响,分析了覆膜措施对气候变化的应对效果。结果表明:关中地区(以武功、宝鸡和西安地区为例)年平均温度呈逐年递增趋势,温度增加幅度由高到低依次为宝鸡、西安和武功,增温速率分别为0.20、0.12℃·10a~(-1)和0.09℃·10a~(-1);降雨量呈逐年递减趋势,减少幅度大小依次为西安、宝鸡和武功,减小量分别为3.59、3.23 mm·10a~(-1)和2.64 mm·10a~(-1)。AquaCrop模型在关中地区表现出了良好的适用性,可以较好地模拟连续覆膜条件下作物的产量指标、水分利用和生长的动态变化,冠层覆盖度模拟值和实测值之间的均方根误差(RMSE)介于1.1%～15.3%,生物量模拟值和实测值之间的RMSE介于0.626～2.540 t·hm~(-2),土壤贮水量模拟值和实测值之间的RMSE介于12.6～47.4 mm。模拟研究表明,上世纪60年代以来,随着气温不断升高,武功、宝鸡和西安地区的夏玉米生育期均呈逐年缩短趋势,特别是1980s以来,减少幅度达2.76、4.82 d·10a~(-1)和5.94 d·10a~(-1);在不同的降水年型下,覆膜处理产量均高于裸地处理,且其变异系数较小;在干旱气候条件下,覆膜处理依然可以获得一定的籽粒产量,与裸地处理相比,覆膜处理表现出了较好的稳产效应。同时,覆膜处理有效减少了玉米苗期土壤表层蒸发(平均减少7.6 mm),从而在土壤中保蓄更多的降雨;覆膜处理虽然增加了土壤耗水量,但其通过保蓄土壤水分,稳定作物产量,有效提高了玉米的水分利用效率。因此,关中地区旱作覆膜可以有效适应当地气候变化,在一定程度上应对干旱气候,具有较好的增产稳产效应。     

中国东北漫川漫岗典型黑土区沟道侵蚀特征

[目的] 通过对450 km²黑土区进行实测调查，旨在评估研究区沟道侵蚀现状。[方法] 选取沟道侵蚀严重的450 km²的漫川漫岗黑土区为调查区域，首先在谷歌卫星影像上进行侵蚀沟识别和定位，再对侵蚀沟立体形态进行实地测量。[结果] ①研究区土地利用以耕地为主，耕地、建设用地、林地、草地分别占研究区总面积的85%，8%，6%，1%。②研究区坡耕地占86%，坡度0.25°~3.0°占64%，大于5°的占12%。③共有侵蚀沟1 049条，其中耕地中侵蚀沟577条，占总侵蚀沟条数的55%；沟壑密度1.2 km/km²，按沟壑密度衡量沟蚀强度为中度；沟壑面积比例为2.89%，以此界定沟蚀强度为剧烈。④研究区侵蚀沟平均长度、宽度、深度和面积分别为996，13.1，2.7 m和2.4 hm²。[结论] 漫川漫岗黑土区沟道侵蚀严重，主要危害坡耕地，但侵蚀沟相对较小，易于治理。     

基于有效积温的中国水稻生长模型的构建

有效积温是指作物生长至某一生育阶段所需要积累的有效温度,是反映气象条件对作物生长影响的主要指标,研究有效积温对作物生长过程的影响对提高农业生产效率具有重要意义。该文以有效积温作为气象因子,收集中国气象数据网中的气象数据和已发表的学术论文中的水稻生长数据,建立了描述水稻生长过程的叶面积指数和干物质积累量的普适Logistic模型,并研究了水稻最大叶面积指数与最大干物质积累量、收获指数(作物经济产量与生物产量的比值)及降水量之间的关系。结果表明:有效积温为1000℃左右时,水稻叶面积指数最大,且此时干物质增长速率最大;水稻最大叶面积指数与最大干物质积累量之间表现为线性关系;最大叶面积指数和收获指数、降水量之间为二次抛物线关系,当降水量为670.5 mm时,最大叶面积指数为7.93,对应的水稻收获指数达到最大值0.50。该研究对于构建其他作物的生长模型具有一定的参考意义。     

基于极化分解和集成学习的PolSAR影像分类

为实现Pol SAR数据极化信息的充分利用,以进一步改善分类效果,该研究提出了一种基于极化分解和集成学习的Pol SAR影像分类方法。该方法首先利用多种极化分解方法从Pol SAR影像中提取极化参数;将提取的极化参数组合成一幅多通道影像;然后对多通道影像进行分割和特征提取,分别提取出各目标极化分解方法所对应的特征;并进行特征选择和分类,得到各目标极化分解方法的分类结果;最后利用集成学习技术对各分类结果进行集成。该研究以吉林省长春市部分区域为研究区,Radarsat2影像为数据源,将提出的方法应用于土地覆被分类中,取得了较好的分类效果,总体精度和Kappa系数分别达到了92.49%和0.90。此外,该研究还将提出方法与其他基于多种极化分解的分类方法进行比较,对比方法的总体精度和Kappa系数分别为90.74%和0.88,比提出方法分别低1.75%和0.02,对比结果进一步证明了提出方法的优越性。     

华北平原不同种植制度对粮食作物氮素利用和土壤氮库的影响

冬小麦-夏玉米一年两熟是华北平原粮食作物的主要种植制度，存在氮肥利用率低、土壤氮素过量累积问题。为探索华北平原氮素高效利用的适宜种植制度，采用15N示踪技术，基于3 a田间定位试验，对一年两熟冬小麦-夏玉米的常规水氮和优化水氮、两年三熟冬小麦-夏玉米-春玉米与冬小麦-夏大豆-春玉米及一年一熟春玉米3种种植制度的作物产量、15N利用率、氮素去向和土壤氮库表观平衡进行研究。结果表明，两年三熟的冬小麦-夏玉米-春玉米产量为32 248.52 kg/hm2，分别比一年两熟和一年一熟提高22.16%和52.88%；15N利用率为33.36%，比一年一熟提高26.12%。3种植制度的氮肥去向最高为土壤残留，其次为作物吸收和损失，两年三熟冬小麦-夏玉米-春玉米的作物吸氮量最高为151.82 kg/hm2，土壤氮库表观盈余量为21.22 kg/hm2，显著低于其他种植制度。综合分析，冬小麦-夏玉米-春玉米两年三熟在稳产高产和提高氮素利用率上具有可持续的潜力，是华北平原未来较为理想的种植制度。     

Interactions between crop biomass and development of foliar diseases in winter wheat and the potential to graduate the fungicide dose according to crop biomass

Foliar pathogens such as Zymoseptoria tritici and Puccinia striiformis causing septoria leaf blotch and yellow rust respectively can cause serious yield reduction in winter wheat production, and control of the diseases often requires several fungicide applications during the growing season. Control is typically carried out using a constant fungicide dose in the entire field although there may be large differences in crop development and biomass across the field. The objective of the study reported in this paper was to test whether the fungicide dose response curve controlling septoria leaf blotch and other foliar diseases in winter wheat was dependent on crop development and biomass level. If such a biomass dependent dose response was found it was further the purpose to evaluate the potential to optimize fungicide inputs in winter wheat crops applying a site-specific crop density dependent fungicide dose. The study was carried out investigating fungicide dose response controlling foliar diseases in winter wheat at three biomass densities obtained growing the crop at three nitrogen levels and using variable seed rates. Further the field experiments included three fungicide dose rates at each biomass level, an untreated control, and 75%, 50% and 33% of the recommended fungicide dose rate and the experiments were replicated for three years. Crop biomass had a significant influence on occurrence of septoria and yellow rust with greater disease severity at increasing crop biomass. In two of three years, the interaction of crop biomass and fungicide dose rate had a significant influence on disease severity indicating a biomass-dependent dose response. The interaction occurred in the two years with high yield potential in combination with severe disease attack. If the variation in crop density and biomass level obtained in the study is representative of the variation found cultivating winter wheat in heterogeneous fields, then there seems to be scope for optimizing fungicide input against foliar diseases site-specific adapting the dose according to crop density/biomass.     

吉林省西部新开发水田遥感动态监测研究

为了响应土地整理开发项目的政策,吉林省西部地区开发了大面积的水田。为掌握新开发水田的动态变化,有必要对吉林省地区进行土地利用分类。以吉林省前郭县为例,利用2010年环境卫星数据进行不同土地利用分类方法的比较,进而对另外3景图像进行信息提取,分析4个年份新开发水田的分布及变化情况。结果表明,支持向量机法比最大似然法的耕地分类精度高约5%,其产品和用户精度分别为95%和84%。加入纹理信息没有显著提高分类精度。2009~2012年水田面积分别增加-67.7 km2,111.7 km2和265.01 km2。     

基于机载LiDAR数据的玉米叶面积指数反演

以机载LiDAR离散点云数据为数据源,基于植被冠层孔隙率与叶面积指数的关系,提出一种反演大田玉米叶面积指数的方法。对反演LAI和实测LAI进行对比分析,结果表明:基于Axelsson改进的不规则三角格网加密方法可以将地面点和非地面点分开,结合高分辨率影像能够提取出玉米冠层点云;基于孔隙率反演LAI,尼尔逊参数的选择对结果影响很大,利用扫描天顶角模拟尼尔逊参数,LAI反演结果接近于真实情况。利用机载LiDAR点云数据能精确地反演大田玉米LAI,该研究方法适用于中等高度的农作物,可以扩展到甜菜、甘蔗等其他中等高度农作物。     

Relationship between Polyamines and Other Cold‐induced Response Mechanisms in Different Cereal Species

To find a connection between polyamines and various protective effectors involved in the development of cold tolerance, eight different cereal genotypes, including wheat, barley and oat species, were investigated during the acclimation phase to low temperature. Exposure to low temperature induced different changes in the levels of polyamines, and other signalling molecules, such as salicylic acid and abscisic acid, and of other protective compounds, namely flavonols, sugars and antioxidant enzyme activity, and in the lipid composition of certain membrane factions. The most remarkable differences were observed in the oat varieties compared to the other cereal genotypes, which was manifested in the lack of spermidine accumulation and of decrease in trans‐Δ³‐hexadecanoic acid content, in lower initial and not cold‐inducible abscisic acid content and guaiacol peroxidase activity after cold treatment. Correlation analysis revealed that spermidine shows strong positive relationship with flavonols, abscisic acid and ascorbate peroxidase, while was in negative relationship with trans‐Δ³‐hexadecanoic acid. These results suggest that spermidine may have a crucial role in the cold acclimation signalling processes in cereals.