Influence of seed pretreated in sodium chloride on the salt tolerance of cherry radish (Raphanus sativus L.).

Abstract

This study was conducted to evaluate the effect of sodium chloride (NaCl) seed soaking on seed germination and plant growth of cherry radish (Raphanus sativus L.) under saline conditions. Seeds were pretreated by soaking in NaCl solutions at concentrations of 0, 1500, 3000 and 4500 ppm. The pretreated seeds were divided into two groups: the first group was germinated in Petri dishes, and the second group was sown in pots. Both groups were irrigated with different concentrations of salinity (tap water, 1000, 2000 and 3000 ppm NaCl). The results indicated that the salinity of the irrigation water decreased the seed germination percentage and leaf chlorophyll content under a salinity level of 3000 ppm. On the other hand, pretreatment of seeds with NaCl solution led to a gradual increase in germination percentage and total chlorophyll content of leaves. Pretreatment with 4500 ppm NaCl gave comparable values to the effect of control treatment under irrigation conditions with 1000 and 2000 ppm salinity. However, pretreatment of seeds with NaCl led to a gradual decrease in germination percentage, reaching 60% under a salinity level of 3000 ppm, and no obvious effect was seen on the leaf chlorophyll contents. Pretreatment of seeds by NaCl solutions increased the root and shoot fresh and dry weights, while shoot and root weight gradually decreased with the increasing salinity of irrigation water and regardless of the effects attributed to seed pretreatment. The increase in irrigation water salinity also led to a decrease in leaf area, and root length and root diameter, as well as root water contents. In contrast, the salinity led to a gradual increase in leaf specific weight, while the value of leaf number and leaf water contents were not affected. Therefore, the increased specific leaf weight as a result of the salinity of the irrigation water gave an indication that soaking the seeds in saline solutions increased the plant tolerance to salinity that lead to better plant growth.