Evaluation of some rice cultivars' response to salinity stress using resistance indices

Parts of paddy fields in Mazandaran Province, northern Iran, are confronted with soil and water salinity. To screen proper rice cultivars, an experiment was performed with eight modified rice cultivars under four levels of irrigation water salinity (1, 2, 4 and 6 dS m(-1)) with three replications, in Amol, northern Iran. The objective of the present study was the evaluation of eight screening indices for identifying salinity tolerance of these cultivars, so that suitable cultivars can be recommended for the cultivation with saline irrigation water in paddy fields. To evaluate the resistance of these cultivars to salinity stress, different indices were calculated. The results showed that Khazar cultivar was the most salt-sensitive cultivar in all salinity levels. In the irrigation salinity levels of 2 and 4 dS m(-1) Neda cultivar and in the level of 6 dS m(-1) Dasht cultivar were the most salt-resistant cultivars. In the two irrigation salinity levels of 4 and 6 dS m(-1), the mean productivity index was the most effective in the screening of salt-resistant cultivars. Harmonic mean, geometric mean productivity, stress tolerance index and mean productivity indices were found to be the best indices in screening resistant cultivars.