Waterlogging Effects on Yield and Photosynthesis in Eight Winter Wheat Cultivars

Winter wheat (Triticum aestivum L. emend. Thell.) yields in Louisiana are consistently below the national average because of a combination of biotic and abiotic environmental factors prevailing in the Gulf Coast region. This study was undertaken to estimate the yield loss for wheat that is attributable to soil waterlogging and to compare physiological performance under waterlogging‐stressed conditions by cultivars grown in Louisiana. In a 3‐yr pot study conducted in a greenhouse, waterlogging stress was imposed by raising the water level to the soil surface. This treatment reduced the soil redox potential in the pots from an average of 409 to 149 mV, indicating an absence of free oxygen in the rootzone. Compared with a well‐drained control treatment, grain weight was depressed 37 to 45% by waterlogging in the eight cultivars tested. In a field experiment with ‘Coker 9877’, grain weight was depressed 51% in poorly drained plots compared with well‐drained plots. Yield depression was due to reduced kernel number and kernel weight rather than to an effect on stand establishment. In the greenhouse experiments, flag‐leaf photosynthesis correlated well with grain weight in the cultivars tested. Waterlogging caused only a small suppression of flag‐leaf photosynthesis and leaf conductance, and there were no significant interactions between treatment and cultivar. These commercially available cultivars showed an equally poor tolerance of waterlogging stress. The results emphasize the need for identification of waterlogging tolerance in wheat cultivars developed for the Gulf Coast states.