Multivariate physiological indices for salt tolerance classification in indica rice (Oryza sativa L. spp. indica).

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 (Ψw) (r 2=0.99 and r2=1), leading to chlorophyll a degradation (r2=0.65 and r2=0.77) in both salt-tolerant (HJ and Pok), and salt-sensitive cultivars (PT1 and IR29). Chla, Chlb, TC and Cx+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. 1National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Paholyothin Rd, Klong 1, Klong Luang, Pathu mthani 12120, Thailand