Effects of Flooding Duration and Growing Stage on Soybean Growth Based on a Multi-Year Experiment

Flood stress on crops severely constrains food production. From 2011 to 2018, a plot test was conducted to investigate the effects of flooding duration and growth stage on soybean plant height, the number of solid pods, 100-grain weight, yield, and dry matter mass, and their interannual variation. The results showed that the soybean indicators were significantly influenced by the year, flooding duration and growth stage, and their interaction. Under the same flooding duration and growth stage, the smallest plant height, number of solid pods, 100-grain weight, and dry matter mass were observed in 2016; and the largest plant height, number of solid pods, yield, and dry matter mass were observed in 2011. The soybean critical flooding duration for the number of solid pods, yield, and dry matter mass was 3 days, and that for 100-grain weight was 6 days. The flooding duration had no significant effect on plant height. The flooding-sensitive growth stage for soybean plant height and dry matter mass was the seedling stage, and that for the number of solid pods, 100-grain weight, and yield was the flowering-podding stage. When investigating the effects of flooding stress on soybeans, the impacts of interannual variation such as high temperatures and drought on soybean growth and yield should be integrated.