Response of Two Indica Rice Varieties to Salt Stress

Salinity is one of the most challenging problems that adversely affects growth and development of plants. Therefore, understanding of the mechanisms that enable plants to adapt to salinity stress will ultimately help in the selection of stress tolerant cultivars for exploiting saline soils. The main objective of this study was to examine the effects of NaCl on some physiological and biochemical characteristics of two rice varieties, IR29 (salt sensitive) and FL485 (salt tolerant), exhibiting different sensitivities to NaCl. NaCl induced a progressive increment in Na+ concentration of both cultivars, however, it was more marked in the sensitive cultivar IR29. A higher level of sugar and a delay in chlorophyll degradation together with less chlorophyll degradation were observed in the salt tolerant rice. Salt stress may promote sugar accumulation, thus preventing the degradation of chlorophyll. Salinity stress induced an accumulation of starch in cv. FL485. It is possible that adjusted carbon partitioning could have an important implication on salinity tolerance. It is suggested that allocation of sugars into starch may involve in salinity tolerance by avoiding metabolic alteration.