Multivariate Physiological Indices for Salt Tolerance Classification in Indica Rice (oryza Sativa L. Spp. Indica) Suriyan Cha-um

summary. The aim of this investigation was to identity effective criteria for classification of salt tolerance and salt sensitivity in rice cultivars by using multivariate characters. Osmolarity in salt-stressed leaves decreased, and was positively related to low water potential (Ψ w) (r 2 =0.99 and r 2 =1), leading to chlorophyll a degradation (r 2 =0.65 and r 2 =0.77) in both salt-tolerant (HJ and Pok), and salt-sensitive cultivars (PT1 and IR29). Chl a , Chl b , TC and C x+c in salt-stressed seedlings decreased by 0, 8.88, 1.37 and 0% in the salt-tolerant lines, respectively, whereas the same pigments in the salt-sensitive lines were reduced by 41.06, 20.74, 35.96 and 41.40%, respectively. Multivariate parameters of pigment degradation and chlorophyll a fluorescence diminution were used to classify salt-tolerant (HJ and Pok) and salt-susceptible (PT1 and IR29) rice cultivars. In addition, salt-tolerant HJ, 21 and Pok (positive control), moderately salt-tolerant 26, 409 and 306, and salt-susceptible PT1, 31, 20, IR29 (negative control), 598, 18 and 2 were classified using the multivariate parameter indices.