Effects of salt sources and concentrations on germination, early seedling growth and varietal difference of salt tolerance in rice (Oryza sativa L.)

This study was conducted to clarify suitable salt concentrations for checking the varietal difference of salt tolerance during germination and early seeding stages and to examine the utility of table salt solution for salinity tolerance test instead of sea water. Twelve rice cultivars (Tongil-type: 6, Japonica: 6) were tested for germinability under five salinity levels of 0, 0.5, 0.9, 1.3 and 1.7 % at constant 32deg C. Also, same materials were subjected to salt treatments with six salinity levels of 0, 0.3, 0.5, 0.7, 0.9 and 1.1 % at early seedling stage. Germination percentage, plumule and radicle length, seedling height and degree of salt injury were investigated at each of salinity levels. There was no significant difference between two kinds of salt treatments; table salt solution and sea water, during germination and early seedling stage. Salt concentration of 1.3 % was most suitable for testing the varietal difference of germinability in salt water. Japonica varieties showed outstandingly higher germinability than Tongil-type varieties. Sobaegbyeo and Chucheongbyeo were most tolerable while Chilseongbyeo and Nampungbyeo were intermediate and Jungweonbyeo was extremely susceptible. The salt concentration of 0.7 % was the most suitable level for checking the salt tolerance at early seedling stage. Nampungbyeo, Pungsanbyeo and Seomjinbyeo Showed tolerance to salinity at seedling stage while Yeomyeongbyeo, Chucheongbyeo and Yongmunbyeo reacted susceptibly. The critical salt concentration causing the salt injury was largely different between germination and early seedling. Germination was considerably possible under the salt concentration of 1.3 % but salt injury at early seedling stage was very severe under the lower levels of salt concentration than 0.9 %. Varietal difference in germinability under salt water treatments showed quite different tendency with varietal salt tolerance at seedling stage. There was significant negative correlation between rough rice yield in saline field and salt injury at seedling stage