Ionic and growth response of rapeseed Sarigol cv. to varied level of salt stress at different growth stages

Most crops are sensitive to salt stress, however, this sensitivity was differ in different growth stages. In current research, the effect of varied salt stress levels (0.4, 4, 7 and 10 dS m-1) in different growth stages (5 leaf, stem elongation and flowering) was examined on morpho-physiological, and content of sodium and potassium in rape seed Sarigol cultivar in a controlled experiment based on a completely randomized design with three replications at College of Agriculture, Shiraz University in 2014. Salt stressed plants had the lowest amount of plant height (27%), leaf number (30%), leaf area (31%), shoot (45%) and root dry weight (40%) and shoot (47%), and root K concentrations (54%) and had the greatest amount of chlorophyll content index (20%) and shoot (5 flod) and root Na (1.8 flod) concentrations; which this change was intensified by increasing in salinity level. Salt stress changed sodium distribution, so that in saline conditions shoot/root Na was significantly more than non-saline conditions. With the delay in stress applying, the negative effect of salinity was reduced; 10 dS m-1 salinity at 5 leaves and flowering were respectively associated with 78.8 and 30.2 percent reductions in shoot dry weight and with 68.6 and 26.7 percent reduction in root dry weight, compared to control. Although salt stress at 5 leaves had more and at flowering had less impact; however, increasing in stress level in all three stages intensified negative effects of salinity. If the current results were confirmed in complementary and long term researches, rape seed could be irrigated with relative saline water at late of the growing season under limited fresh water regions.