Effects of exogenous abscisic acid on antioxidant system of salt tolerant and salt sensitive cotton cultivars

Summary Salinity is one of the most imperative global problems that affect crop productivity on a large scale. Salinity impairs plant growth and development by imposing various stresses. Therefore it is vital to decode those stress factors and identify possible solutions to improve agriculture productivity. However, the adaptive mechanisms under saline conditions of glycophytes have not been studied. The present study was undertaken to determine the effects of exogenous abscisic acid (ABA) on salinity tolerance in cotton plants. Some patterns of resistance development were revealed on the seedlings of two cotton cultivars, a salt-tolerant (Gulistan) and a salt-sensitive one (C-4727). Moreover, the antioxidant potentials of these cultivars were compared. The activities of ascorbate peroxidase (APX), super-oxide dismutase (SOD), as well as the quantity of endogenous ABA, malondialdehyde (MDA), and free proline (Pro) were determined in control and post treatment. Our results demonstrate significant differences between the salt- tolerant and sensitive cotton seedlings in response to saline stress, i.e., high levels of Pro and endogenous ABA, but lower MDA concentrations, and higher activity of APX and SOD for the salt-tolerant cultivar, Gulistan, as compared to the salt stress-sensitive cultivar C-4727.