Effects of Waterlogging on Physiology and Yield of Wheat Plants at Booting Stage

  Objective  Effects of waterlogging, a major abiotic stress ill-affecting the wheat production in the middle and lower reaches of the Yangtze River, at booting stage on the physiology and yield of wheat were studied.

  Method   The growth and yield of Yangmai 16 and Zhongmai 895 wheat plants subjected to flooding at booting stage by controlled water supply in pots were analyzed.

  Result  (1) Waterlogging significantly reduced the chlorophyll content in wheat leaves. The longer the stress lasted, the greater the decline on SPAD and the more severe the injury, the greater SPAD reduction on the leaves. More serious damage was observed on the top second leaf than on the top first flag leaf of a plant. (2) The activities of antioxidant enzymes, such as CAT, SOD, and POD, changed in an inverted V pattern as the waterlogging prolonged. The content of reactive oxygen species (ROS) either decreased or increased slowly in the early stage of waterlogging but increased sharply in the late stage. (3) At booting stage, the wheat plants might respond to the waterlogging stress to increased slightly on the effective number of ears per plant, grain number per ear, 1000-grain weight, and other yield factors. (4) Waterlogging at wheat heading stage exerted no significant effect on the plant height. On the other hand, lasting waterlogging significantly decreased the grain yield with declined effective panicle number, grain number per panicle, and 1000-grain weight. After 15 d of continued flooding, the yields per plant of Zhongmai 895 and Yangmai 16 decreased by 51.47% and 43.99%, respectively, over CK.

  Conclusion   Waterlogging imposed on wheat plants at booting stage significantly reduced the leaf chlorophyll content, disrupted the oxygen metabolism, and upset the delicate balance of the antioxidant enzyme system. As a result, the excessively accumulated ROS in the plant could induce the peroxidization of lipid cellular membrane and impair the cell structure and functions that was detrimental to the photosynthesis as well as the nutrient transfer and accumulation of the plant. In the end, the much-reduced biomass and grain-filling but significantly increased number of empty, deflated, and unusable grains meant a final crop reduction. Insofar as resistance to waterlogging stress is concerned, Yangmai 16 was found to be stronger than Zhongmai 895.