Effects of salinity stress on growth, chlorophyll content and ion accumulation in two indica rice (Oriza sativa L.) cultivars differing in salinity tolerance

Rice (Oryza sativa) is particularly sensitive to salt stress during the reproductive stage. Physiological responses to salinity were evaluated for contrasting genotypes, during the reproductive stage. Two rice genotypes differing in their tolerance of salinity were evaluated in a set of greenhouse experiments under o and 6 dSm -1 of salinity during reproductive stage. Salt stress increased chlorophyll b concentration in leaves of a tolerant (FL485) rice genotype, but significantly decreased chlorophyll a in both cultivars and reduced chlorophyll a/b ratio just in susceptible cultivar and this is probably one of the reasons for the higher tolerance of FL485 compared with IR29. Salinity caused higher accumulation of K+ in sensitive cultivar than tolerant one but the Na+ level in leaf of IR29 was more than FL485. Grain yield and 1000 grain weight of both genotypes decreased with the application of NaCl. Our results indicated that the tolerant genotype had mechanisms to prevent high Na + accumulation in leaf. These mechanisms help plant to prevent tissue death and enable to continue its growth under saline conditions.