Losses in wheat due to waterlogging

Waterlogging stress is one of the limiting factors influencing wheat (Triticum aestivum L.) production, especially in the lower Mississippi valley. A rain-shelter experiment was designed to evaluate the trend response of nine wheat genotypes to four levels of waterlogging treatment: 0, 10, 20, and 30 d of flooding. Genotypes planted in polyvinilchloride (PVC) containers 25 cm long by 10 cm in diameter were waterlogged in plastic tanks under controlled rain conditions. Results indicated significant linear responses for kernels per head and tillers per plant, significant linear and quadratic responses for yield and chlorophyll content, and significant linear and cubic responses for plant height. The linear trend was the most important component, explaining from 92 to 99% of the variability due to waterlogging. Linear prediction equations were obtained to describe the relationship between different traits and waterlogging stress. Losses in yield and yield components were evaluated in a field experiment with 15 genotypes under control and waterlogging treatment. Average yield losses of 44% were mainly caused by a decrease in tiller number and kernels per head. Under waterlogging treatment, tiller number and kernels per head were reduced by 41 and 20%, respectively. Screening of wheat genotypes revealed the potential for waterlogging tolerance in breeding material and identified tolerant cultivars useful for waterlogged environments. 'Terral LA 422', 'Shelby', and 'Pioneer 2691' were the most adapted genotypes for waterlogging treatments. Because of a significant interaction with waterlogging treatment, some of the high-yielding genotypes under non-flooded conditions such as 'Coker 9663' and FFR 502W' showed low tolerance to waterlogging. The results provided information on the methods quantifying losses from waterlogging and identified selection criteria for waterlogging tolerance in wheat.