Salt tolerance in two rice cultivars differing salt tolerant abilities in responses to iso-osmotic stress

Abstract

The aim of this investigation was to study on the salt tolerant ability of Thai jasmine (KDML105) salt sensitive and Homjan (HJ) salt tolerant cultivars grown under iso-osmotic stresses. Growth, ion contents, relative electrolyte leakage (REL), photosynthetic pigments and net photosynthetic rate (Pn) in iso-osmotic stressed seedlings were collected. Growth characters including shoot height, fresh weight, dry weight and leaf area of salt-stressed rice seedlings were inhibited, depending on NaCl concentrations and rice genotypes. Sodium ion (Na+) in salt-stressed tissues was rapidly accumulated, especially in KDML105, while potassium ion (K+) was quickly decreased. Na:K ratio and proline content in salt-stressed leaves were increased, relating to salt concentrations. The Na+ accumulation in the salt stressed seedlings was positively related to osmolarity, causing to membrane injury or high REL with pigment degradation. The degradation of total chlorophyll (TC) and total carotenoids (Cx+c) in salt-stressed seedlings grown under osmotic stresses were positively correlated with Pn, leading to growth retardation. The salt tolerant mechanisms in HJ salt tolerance should be further investigated as well as utilized as parental line for salt-tolerant breeding program. Southern Cross Journals ©2009.