VARIATION IN GROWTH AND ION UPTAKE IN RICE CULTIVARS UNDER NaCl STRESS IN HYDROPONICS

The study was planned to screen rice genotypes against different levels of salinity. Nursery was sown in sand. At two leaf stage, nursery was shifted to iron tubs floating over Yoshida nutrient solution in wire house-based hydroponics unit at three salinity levels (60 mol m -3 , 100 mol m -3 and 150 mol m -3 ) using CRD factorial arrangement. Phenotypic performance based on survival of tolerant and susceptible genotypes was evaluated after 28 days of salt (NaCl) stress. Results of trial showed that the increase in salinity level decreased the growth of the seedlings of rice genotypes. However, decrease was more pronounced at 150 mol m -3 NaCl concentrations in the growth medium. Genotype KS-282 performed best at all levels of salinity on basis of shoot, root fresh and dry weight basis, respectively. Chemical analysis of shoots using flame photometer showed an increase in Na+ contents and reduction in K+ contents with each increment in salinity, irrespective of rice genotypes. A rapid increase in the K+:Na+ ratio in shoots was mainly the result of a high accumulation of Na + . The genotype KS-282 exhibited a low accumulation of Na + contents and high accumulation of K + contents followed by IR-6 when compared to the other genotypes in saline environment. The physio-chemical analysis indicated that KS-282 was the most tolerant and KS-412 was the most sensitive genotypes. However, the selectivity of K+ over Na+, as exhibited by KS-282 and IR-6, appeared to be an important salt tolerant determinant.