Waterlogging stress at different growth stages might have different effects on winter wheat yield,but the quantitative effects of waterlogging stress duration on wheat yield and its components are still unclear. To comprehensively evaluate the effects of waterlogging stress on winter wheat yield,Yangmai 13 was selected as the experimental cultivar,and pot experiment with different waterlogging stress duration (0,5,10 and 15 d) was conducted at jointing,booting and grain-filling stages,respectively,in the present study. Variations of winter wheat yield and its components under different treatments were investigated. Results of the two-year pot experiment showed that,waterlogging stress at different growth stages all caused yield losses of winter wheat,and the yield at different growth stages all showed a significant loss (P<0.05) as the increase of waterlogging stress duration. The waterlogging induced yield losses showed a tendency that booting stage> jointing stage> grain-filling stage. The yield per plant was decreased by 0.79,0.59 and 0.48 g,respectively,for an extra day under stress,indicating that booting stage is the most sensitive growth stage of winter wheat to waterlogging stress,compared with jointing and grain-filling stages. Furthermore,waterlogging stress at different stages showed distinctly different effects on yield components. Waterlogging stress at jointing stage led to a reduction in spike number per plant,kernel number per spike and thousand-kernel weight simultaneously. And the yield loss at jointing stage was mainly resulted from the reduction of kernel number per spike. Waterlogging stress at grain-filling stage had a limited effect on spike number per plant and kernel number per spike,due to that the two yield components had been determined at early growth stage. The yield loss at grain-filling stage was mainly resulted from the reduction of thousand-kernel weight. Booting stage is the stage when vegetative growth converts to reproductive growth. Thus,waterlogging stress at this stage always induced more yield losses. By comparing the yield component,the reduction of spike number per plant and kernel number per spike were more severe under waterlogging stress at booting stage than that at grain-filling stage,while reduction of thousand-kernel weight was more severe under waterlogging stress at booting stage than that at jointing stage. The results could explain why waterlogging stress at booting stage,compared with the other two growth stages,was most sensitive to the winter wheat yield,and induced a more severe yield loss. To prevent the yield loss caused by waterlogging stress,meteorological conditions around booting stage should be paid close attention to,and ditching for drainage should be conducted simultaneously in the field for winter wheat production. Results of the present study showed that yield losses caused by waterlogging stress were closely related to the growth stage of winter wheat. |