Chiang Mai Journal of Science

Soaking seeds in NaCl before planting them is a method which can promote seed germination and growth of a variety of seedlings. In this experiment, seeds of Chinese white radish (Raphanus sativus L. var. longipinnatus Bailey, Brassicaceae) were soaked in sodium chloride (NaCl) solutions at concentrations of 0, 20 and 150 mM for 18 hours. The seeds were then planted in a sand culture and watered every day for 7 days. Growth and physiological parameters including percentage of germination, germination index, seedling yield, fresh shoot and root weights, shoot height, root length, leaf number, stem diameter, contents of Na+, K+, K+/ Na+ ratios, chlorophylls, proline, vitamin C and phenolic compounds of the leaf and stem parts were determined in the 7-day-old seedlings. The results showed that seeds that had been soaked with a low concentration of NaCl (20 mM) before being planted displayed a slightly higher accumulation of Na+ in the leaves and stems compared to the control, which resulted in an increase in yields with regard to the contents of chlorophyll a, chlorophyll b and phenolic compounds in the leaves of Chinese white radish seedlings. However, seeds that were soaked in a high NaCl (150 mM) solution before being planted displayed significantly higher accumulations of Na+, which led to decreases in the percentages of germination, germination index, yields and contents of chlorophyll a, chlorophyll b and phenolic compounds in the leaves. The results of this study indicated that soaking Chinese white radish seeds in 20 mM NaCl displayed positive effects for the production of seedlings.