Effects of salinity stress on growth, chlorophyll content and osmotic components of two basil (Ocimum basilicum L.) genotypes

Abstract

Salinity stress is a severe environmental factor limiting crop yield worldwide. To better understand salt stress responses in crop plants, we compared effects of salinity stress on growth, chlorophyll content and osmotic components in two basil genotypes. Seedling of two basil genotypes (B1 = Ociumum basilicm L and B2=Ociumum minimum L.) were grown in controlled environment in Hoagland nutrient solution containing 0, 3 and 6 ds/m NaCl, respectively. Proline, soluble carbohydrates, chlorophyll ‘a, b’ and carotenes of leaves were determined 20 days after initiation of salinity stress. The results reveal that salinity caused significant decreases in growth of basil plants as measured by fresh weight. By increasing NaCl levels from 0 to 6 ds/m, the content of chlorophyll a and b, and carotenes reduced. Maximum reduction was observed at 6 ds/m of NaCl. Mean values of data showed that B2 = O. minimum had the maximum reduction of chlorophyll a and b, and carotenes under salinity stress. This indicates that the B2 genotype was more susceptible to salinity stress than B1 genotype. In this study, salinity had no significant effect on soluble carbohydrate but the proline content varied among the basil genotypes whether the plants were grown with or without salinity stress. With 6 ds/m NaCl applied, proline content was enhanced in two genotypes. B2 = O. minimum had the maximum proline content in leaves when plants were exposed to high salinity level. Key words: Salinity, basil, chlorophyll content, osmotic components.