Xu Xiangying, Gao Ping, Zhu Xinkai, Guo Wenshan, Ding Jinfeng, Li Chunyan
Jiangsu Provincial Key Lab of Crop Genetics and Physiology/Wheat Research Institute, Yangzhou University, Yangzhou, Jiangsu Province, China.
Meteorological Bureau of Jiangsu Province, Nanjing, Jiangsu Province, China.
PLoS One. 2018 Jan 12;13(1):e0191217. doi: 10.1371/journal.pone.0191217. eCollection 2018.
Jiangsu is an important agricultural province in China. Winter wheat, as the second major grain crop in the province, is greatly affected by moisture variations. The objective of this study was to investigate whether there were significant trends in changes in the moisture conditions during wheat growing seasons over the past decades and how the wheat yields responded to different moisture levels by means of a popular drought index, the Standardized Precipitation Evapotranspiration Index (SPEI). The study started with a trend analysis and quantification of the moisture conditions with the Mann-Kendall test and Sen's Slope method, respectively. Then, correlation analysis was carried out to determine the relationship between de-trended wheat yields and multi-scalar SPEI. Finally, a multivariate panel regression model was established to reveal the quantitative yield responses to moisture variations. The results showed that the moisture conditions in Jiangsu were generally at a normal level, but this century appeared slightly drier in because of the relatively high temperatures. There was a significant correlation between short time scale SPEI values and wheat yields. Among the three critical stages of wheat development, the SPEI values in the late growth stage (April-June) had a closer linkage to the yields than in the seedling stage (October-November) and the over-wintering stage (December-February). Moreover, the yield responses displayed an asymmetric characteristic, namely, moisture excess led to higher yield losses compared to moisture deficit in this region. The maximum yield increment could be obtained under the moisture level of slight drought according to the 3-month SPEI at the late growth stage, while extreme wetting resulted in the most severe yield losses. The moisture conditions in the first 15 years of the 21st century were more favorable than in the last 20 years of the 20th century for wheat production in Jiangsu.
江苏是中国重要的农业省份。冬小麦作为该省的第二大粮食作物，受水分变化影响很大。本研究的目的是通过一种常用的干旱指数——标准化降水蒸散指数（SPEI），调查过去几十年小麦生长季节水分条件的变化是否存在显著趋势，以及小麦产量如何对不同水分水平作出响应。该研究首先分别采用曼-肯德尔检验和森斜率法对水分条件进行趋势分析和量化。然后，进行相关性分析以确定去趋势化的小麦产量与多尺度SPEI之间的关系。最后，建立多元面板回归模型以揭示产量对水分变化的定量响应。结果表明，江苏的水分条件总体处于正常水平，但由于气温相对较高，本世纪略显干燥。短时间尺度的SPEI值与小麦产量之间存在显著相关性。在小麦发育的三个关键阶段中，生长后期（4月至6月）的SPEI值与产量的联系比苗期（10月至11月）和越冬期（12月至2月）更为紧密。此外，产量响应呈现出不对称特征，即该地区水分过多导致的产量损失高于水分亏缺。根据生长后期3个月的SPEI，在轻度干旱的水分水平下可获得最大产量增幅，而极端湿润则导致最严重的产量损失。21世纪前15年的水分条件比20世纪最后20年更有利于江苏的小麦生产。
