Abstract:

Wheat grain yield in Jianghan Plain suffers widely for water logging.The research was carried out based on the analysis of rainfall distribution of Jingzhou from 1983 to 2013,by field experiment and potted experiment,with the highgrainyield cultivars Zhengmai 9023.Based on waterlogging at jointing stage and booting stage,plant height,photosynthetic rate in flag leaf,the rate of leaf yellowing,and their effects on dry matter accumulation and grain yield were studied.The results indicated that monthly precipitation in Jingzhou from 1983 to 2013 was unimodal distribution and most of the precipitation distributed in May,June and July.Moreover,the maximal amount of precipitation from jointing stage to booting stage in Jianghan Plain from 1983 to 2012 was 1944 mm,and more than 1/3 from 1983 to 2012 was 80.2 mm precipitation or more， indicating that it would induce water logging easily.The precipitation from April to June,the reproductive stage for wheat,was also enough.Monthly mean precipitation from April to June was above 1457 mm,and the max precipitation was 4275 mm (May,1998).In our experiment,waterlogging at jointing stage and at booting stage both decreased plant height.At heading stage,the plant height decreased 61%-91%,and at maturity,the plant height decreased 19%-42%,which indicated that under removing water logging the plant height could increase at some extent and the effect of water logging at booting stage was larger than that at booting stage.Moreover,waterlogging at jointing stage and at booting stage both decreased photosynthetic rate in flag leaf.At anthesis,the photosynthetic rate of flag leaf in the treatment with water logging at jointing stage decreased 58%,and at midfilling stage it decreased 139%.The corresponding decrease percent of photosynthetic rate of flag leaf in the treatment with water logging at booting stage was 347% and 571%.Waterlogging at jointing stage and at booting stage both increased leaf yellowing rate,and the effect of the treatment with water logging at booting stage was larger than that of the treatment with water logging at jointing stage.Waterlogging at jointing stage and at booting stage both decreased dry matter accumulation,and finally induced lower grain yield.Compared with CK,the grain yield of the treatment with waterlogging at jointing stage deceased 163 %,and that of the treatment with waterlogging at booting stage decreased 218%.Above all,waterlogging at jointing stage and at booting stage both decreased photosynthesis indices,and led to lower dry matter amount and lower grain yield than CK.And the effects of the treatment with waterlogging at jointing stage were larger than that of the treatment with waterlogging at booting stage