Growth, Physiological and Biochemical Responses of Two Greek Cotton Cultivars to Salt Stress and their Impact as Selection Indices for Salt Tolerance

Soil salinity is a major constrain of crop productivity. Upland cotton (Gossypium hirsutum L.) is an important fiber crop worldwide and a major agricultural product in Greece. Two commercial cotton cultivars ('Hersi' and 'ST 318') were studied to compare their response under non-saline and saline conditions in a greenhouse experiment. Salt stress on plants was imposed by two different approaches: a gradual and an initial acclimatization to a non-lethal NaCl concentration (150 mM). To explore salt stress responses, growth (height of plants, roots, shoots and leaves dry weight, reproductive shoots, Salinity Sensitivity Index), gas exchange (Photosynthetic rate, Stomatal conductance, Transpiration rate and Water Use Efficiency) and biochemical parameters (proline, H2O2 and MDA content), were examined as well as ion homeostasis. 'Hersi' had significantly higher dry weight of roots, shoots and leaves, lower salinity sensitivity index of roots compared to 'ST 318'. In this regard, it appears that 'Hersi' cultivar performed better than 'ST 318' to increased salinity conditions, due to better control of gas exchange parameters and K+/Na+ homeostasis as well as better membrane integrity. Furthermore, the gradual acclimatization to the 150 mM NaCl concentration had a milder effect on both cultivars compared to the initial acclimatization.