The response of sorghum and sunflower to short-term waterlogging

Summary The effect of waterlogging on sunflower and sorghum was investigated in relation to stage of development (sunflower-6-leaf, buds-visible, anthesis; sorghum-5-leaf, initiation, anthesis) and duration of waterlogging (3, 6 and 9 days) under glasshouse conditions. Additionally, the potential adaptation of the two crops was observed by waterlogging some plants at all three growth stages. With sunflower, leaf expansion and stem extension were inhibited by waterlogging at the 6-leaf and buds-visible stage although these effects did not always persist until maturity while, with anthesis waterlogging, rapid desiccation of leaves was observed. Yield was most affected by the anthesis waterlogging but no consistent effect on seed number or 1000 seed weight was recorded.Waterlogging sorghum plants suppressed normal tillering but had little effect on dry weight of the main stem. Late tillering was stimulated by waterlogging. Reductions in leaf area occurred at all stages of development in response to waterlogging with these effects being more marked at initiation. Similarly, yield was most reduced by the initiation waterlogging largely as a result of reduced seed number.In neither species was there a clear relationship between duration of waterlogging and subsequent reduction in growth and yield. With respect to yield, stage of development seemed to be of greater importance than the duration of waterlogging. The growth and yield of multiple-waterlogged sunflowers was less affected by the anthesis treatment than that in plants experiencing a single waterlogging, suggesting that some form of adaptation was induced. In contrast, no such response was seen in sorghum.