effect of salt stress and hydropriming on germination characteristics of mungbean (vigna radiata (l.) wilczek)

introduction legumes are the most important source of vegetable protein supply. mungbean (vigna radiate (l.) wilczek) produces seeds contain 22-25 percent protein and high nutritional value for human and also is a major source of protein in most modern societies. rapid seed germination and emergency, is an important factor determining the ultimate yield of the plant. salinity is the most important non-life-threatening of plants, especially in the bean. drought has affect plant growth by reducing water potential in the root zone or create toxicity the sodium and chlorine ions in seedling and or through nutrient imbalance by decrease in absorption rate or a reduction in the transmission rate of the shoots. nowadays the seed pretreatment technique has introduced as an agent for improvement, seed germination and plant establishment under environmental stress. seed priming with using pure water is a very simple and cost-effective method that reduce the time required for water absorption in seeds, the mean and percent of germination is improved and expedited emergence and establishment of seedling. materials & methods this study was conducted to evaluate the effect of hydropriming on germination component of mung bean under salinity stress, with a factorial experiment using a rbd design with four replications. the hydropriming at 4 levels (0, 8, 16 and 24 hours) and the salinity stress at 5 levels of 0, 2, 4, 6 and 8 dsi/m were used. before running the test, seeds were washed with a solution of 10% sodium hypochlorite disinfectant for 15 minutes and then 3 times with distilled water.to hydropriming, seeds were soaked according to levels specified time in distilled water at 25 °celsius (room temperature). then 25 seeds were placed within a sterile petri dish with filter paper. the potential of zero bar was used for distilled water. five ml of nacl solution with the potential of 0, 2, 4, 6, 8 ds/m was added to each petri dish. then petri dishes were coated by parafilm and placed in germinator at 25 ° celsius and in the dark for 8 days. the average and percent germination, the radicle and plumule length, fresh weight and dry weight, allometric index, seedling water percent and seed vigor of mung bean were measured. results & discussion the results showed that there were significant differences between treatments for all the variables.in addition, the interaction of hydropriming with salinity stress had a highly significant effect on radicle and plumule length, fresh weight and dry weight, allometric index, seedlings, water percent while there was no significant differences in treatments for average and percent germination and seed vigor. mean comparisons showed that the highest percentage of germination, radicle and plumule length, dry weight and seed vigorwere related to distilled water and 24 hours hydropriming treatment. the highest radicle and plumule fresh weight and allometric index were related to distilled water and 8 hour hydropriming. the lowest of seedling water percent was related to distilled water and 24 hour hydropriming. the lowest traits were observed in plants under salinity stress at 8 dsi/m and non-hydropriming except seedling water percent. the results of this study showed that with increasing of salinity all indicators of germination decreased. hydropriming treatment improves seed germination indicators under salt stress in mungbean plant. hydropriming improves cell division and growth seedling, increases the rate of net photosynthesis and protein synthesis and with modification of osmotic balance fixes turgor pressure in seedling and prevents plasmolysis of seedling. hydropriming by increasing the availability of atp, increase the integrity of cell membranes, change membrane components such as fatty acids and prevent spills out of the seeds during seed priming and thus increase seedling growth can improve germination indices. conclusion since the hydropriming is easy, low cost and low risk method, can be used as an effective strategy to increase the germination percentage, speed and uniformity of germination (mcdonald, 2000), emergence of seeds and improving quality and quantity of the yield under the adverse conditions (ma et al., 2006) and increase resistance to salinity in plants.