Effects of Excessive Soil Moisture at Different Growth Stages on Seed Yield of Summer Buckwheat.

Abstract

At three developmental stages, i.e., the first leaf emergence, the flowering, and the ripening stages, (5, 18, and 31 days after emergence, respectively), buckwheat plants (Fagopyrum esculentum Moench. cv. Kitawasesoba, summer ecotype) grown in pots were exposed to excess moisture (water table of 5 to 7cm below the soil surface) or flooding (water table of 2 to 3cm above the soil surface) for various days, and seed yield and yield components were investigated. The earlier the developmental stage at the treatment and the longer the treatment, the severer the effects of excessive soil moisture on seed yield. When plants were treated with excess moisture at the first leaf emergence or the flowering stages for 3 days and at the ripening stage for 6 days, the seed yield decreased less than 10%. However, it decreased markedly when the treatment period was prolonged. When the plants were treated with flooding only for 1 day at the first leaf emergence stage and more than 3 days at the flowering or the ripening stages, seed yield decreased markedly. One of the main reasons for the decreasing seed yield caused by excess moisture and flooding at the first leaf emergence and the flowering stages was the shortage of the number of seeds due to the reduction in the number of flowers per branch. The decrease in seed yield caused by flooding at the flowering and the ripening stages ratio was not decreased by excessive soi moisture.