Investigation of waterlogging stress on some morphologic and physiological traits of rapeseed in different developmental stages

In order to investigation of waterlogging stress effects on morphological and physiological traits of rapeseed (Brassica napus L.) in different developmental stages, 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). Leaf area, leaf dry matter, shoot high and shoot dry matter, root volume and root dry matter, chlorophyll fluorescence, chlorophyll content and grain yield were measured. An exponential decay and linear models were fitted to quantify waterlogging stress on morphological traits and yield. Waterlogging conditions decreased leaf area and leaf dry matter, then leaf senescence occurred and fall down it So, plant less biomass transmit in to the shoot and root, then, shoot high and shoot dry matter, root volume, root dry matter, FV/FM, chlorophyll content and finally grain yield decreased. 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. Generally, results of the present research indicated that in order to damage of vegetative organs and their lack of proper functioning rather then control markedly decreased seed yield of rapeseed throughout four developmental stages.