Effect of Irrigation Water Salinity on Growth and Physiology Characteristics of Three Cucumber Cultivars

Studying the response of different plant cultivars to salinity stress and introducing the resistant cultivars is one of the most important strategies to increase cucumber yield under salinity stress. This study was done to investigate the effect of irrigation with different levels of salinity on growth and physiological characteristics of several cucumber cultivars. For this purpose, a factorial experiment with two factors including cultivar (Keyhan, 485 and Nahid 484) and salinity (0.5, 3.1 and 6.2 dS m-1), each at three replications was conducted. The results showed that salinity stress affected the plant growth and photosynthetic pigment content. At the highest salinity level as compared to the control, the chlorophyll a in Keyhan, Nahid 484 and 485 cultivars decreased by 47, 21 and 19%, respectively, while the total chlorophyll was reduced in Keyhan cultivar by 34% and in the other two cultivars by 22%. Under salinity stress, the highest amount of carotenoids was observed in Nahid 484 and 485. The results also indicated that with increasing salinity level to 6.2 dSm-1, the plant height in Keyhan, Nahid 485 and Nahid 484 cultivars decreased by 30, 23 and 11%, respectively. In addition, the percentage of leaf fall at the highest salinity level was observed in Keyhan cultivar with a 28% reduction as compared to the control. Cultivar 485 showed the highest reduction of root dry weight by 40%. In general, different cultivars showed different responses to salinity stress. Among the cultivars, Nahid 484 showed the hegighest resistance in response to salinity stress, therefore it can be introduced as a tolerance cultivar in terms of salinity stress.