Investigation of waterlogging stress effect on yield and yield components of rapeseed (Brassica napus L.)

In order to evaluate the waterlogging stress effects on yield and yield components of rapeseed, a pot experiment was conducted at Gorgan University of Agricultural Sciences and Natural Resources during 2010-2011. The experiment design was completely randomized with factorial arrangement and three replications. Examined factors were developmental stage (seedling, stem elongation, flowering and grain filling) and duration of waterlogging stress (0, 3, 6 and 9 days). An exponential decay and linear models were fitted to quantify waterlogging stress on yield and yield components. Maximum slope of grain number reduction were recorded at the seedling stages (-1.45 per day) while the lowest slope belonged to the number of seeds per pod in the grain filling stage (-0.94 per days). Maximum slope of grain yield reduction (-1.73 per day) observed in the flowering stage while the lowest was recorded at stem elongation (-0.6 per day). Control plants had the highest yield (5.1 g per plant) while imposing 9 days waterlogging either flowering or grain filling stages (0.18 and 1.4 g per plant, respectively) decreased the seed yield. Most proteins levels were in grain filling stages and 3 days of waterlogging (28.7%) and lowest was in the flowering stage and 6 days of waterlogging (17.7%). Also oil percentage ranged between 47.5% in stem elongation and 6 days of waterlogging to 32.1% at flowering stage and 6 days of waterlogging. Allayet analysis of data indicated that high direct and indirect effect of biologic yield was in plant yield in waterlogging stress.