Leaf water status, proline content, lipid peroxidation and accumulation of hydrogen peroxide in salinized Chinese kale (Brassica alboglabra)

Abstract

In responding to stress, plant cells may secrete compatible compounds and at the time demonstrate an increase in others which would reflect the status of reactive oxygen species (ROS) scavenging capacity of plants under oxidative stress. In this study the ability of four cultivars of Chinese kale (Brassica alboglabra) to tolerate salinity stress was evaluated. Four diverse cultivars of Chinese kale (cv. 'Standard kailan', 'Hong Kong kailan', 'Kale Curly Leaf' and Hong Kong stem flower') were subjected for 14 days to varying levels of NaCl, i.e. 0, 25, 50 and 75 mM in Hoagland's nutrient solution in a static aerated hydroponic system. Salinity induced changes in all assayed parameters. Leaf relative water content (RWC) was reduced by 7.6, 13.3 and 15.5% relative to the control as NaCl concentration increased at 25, 50 and 75 mM, respectively. In addition, accumulation of proline in leaf tissue was induced significantly at high NaCl concentration. However, 'Standard kailan' contained the lowest concentration of proline among cultivars. Salinity stress noticeably raised the concentration of H 2O 2 in leaves with their respective values of 47.5, 56.0 and 56.2% for 25, 50 and 75 mM compared to control. Almost similar response was also recorded for accumulation of malondialdehyde (MDA). The level of MDA in leaves, which represents the rate of lipid peroxidation process, was considerably increased under saline condition. Lower concentrations of H 2O 2 were found in leaf tissues of 'Standard kailan' and 'Hong Kong kailan' compared to those of 'Curly leaf' and 'Hong Kong stem flower'. The lowest amount of MDA in leaf tissues of cv. Standard kailan in comparison with others, suggests that the cv. Standard kailan is better protected from oxidative damage under salinity stress and being more tolerant.