Evaluating Wheat Cultivars for Waterlogging Tolerance

Waterlogging is a serious environmental stress on winter wheat (Triticum aestivum L.) grown in the Gulf Coast region. We hypothesized that waterlogging tolerance differs in currently available lines and cultivars and that suitability of physiological parameters to distinguish yield responses could be evaluated. Three types of studies were conducted: a 2-yr greenhouse study of eight cultivars, a 4-yr irrigated field study of 20 cultivars and breeding lines, and a 3-yr field study of six cultivars under rain-excluding shelters which allowed comparison of performance under waterlogged and well-drained conditions. In the rainshelter study, waterlogging caused a 45% decrease in grain weight, resulting from a 45% decrease in number of kernels and a 5% decrease in kernel weight. Cultivars differed for grain yield under waterlogged conditions in the field (P = 0.1), and Coker 9877 and line LA 862A16-3-3-X yielded 32 and 33% above the mean, respectively. Greenhouse measures of photosynthesis under waterlogging were weakly predictive of yield (r 2 = 0.61) and correlated to measures under well-drained conditions (r 2 = 0.87). Yield was well correlated with biomass (r 2 = 0.84) and root mineral content (Fe + Mn + P) (r 2 = 0.94). Waterlogged yields x cultivar did not correlate with yield under well-drained conditions (r 2 = 0.14) and the same differential response to waterlogging was shown for biomass and root mineral content. The negative correlation between root mineral content and yield was attributed to processes involved in the formation ofa mineral plaque on the surface of the wheat roots. This emphasizes the need to explore differences in root function when selecting wheat lines for enhanced waterlogging tolerance.