PHYSIOLOGICAL PERFORMANCE OF PINTO BEAN CULTIVARS UNDER SALINITY

Salinity is one of the major abiotic stresses that adversely affect crop productivity and quality in many arid and semi-arid parts of the world. Effects of four levels of salinity (0, 4, 8 and 12 dS m-1 NaCl) on performance of three pinto bean cultivars (COS16, Talash and Khomain) were investigated in 2010. A factorial experiment based on randomized complete block design with three replications was carried out at the Greenhouse of University of Tabriz, Iran. Ten seeds were sown in each pot filled with 900 g perlite. After emergence, seedlings were thinned and 4 plants were kept in each pot. Results indicated that At the most stages of development, leaf chlorophyll content index (CCI) under severe salinity (12 dS m-1) was lower than that under other saline and non-saline conditions. Proline accumulation in leaf tissues increased gradually with the increase of salinity up to 8 dS m-1 and thereafter slightly decreased. The highest CCI and proline content were found in Talash compared with other cultivars. Root/shoot ratio of COS16 was higher than that of Talash and Khomain. Flowering and podding were delayed under moderate and severe salinities, but grain yield decreased as salinity increased. The highest and the lowest grain yield per plant were obtained from Khomain and COS16, respectively. However, differences in grain yield between Khomain and Talash and between Talash and COS16 were not statistically significant. It was concluded that pinto bean is a sensitive crop to salinity, but the extent of sensitivity differs among cultivars.