Exogenous Application of Thiourea Ameliorates Salt Stress Effects by Alleviation of Oxidative Damage in Hybrid Maize

Abstract

Salinity is the most damaging factor towards crop production. The aim of this study was to investigate the possible role of thiourea in salinity tolerance. These experiments were carried out on two maize hybrids (DK6789 and 33M15) using the optimized thiourea level (400 µM) in autumn and spring seasons, and the growth and physiological attributes were observed. Salt stress caused a substantial suppression of growth, and damaging effects were observed, as reduction in shoot and root length, their fresh and dry weights, decreased root number and shoot/root ratio, increased accumulation of H 2 O 2 , malondialdehyde (MDA) in root and shoot tissues, and enhancement in activities of some key antioxidant enzymes (catalase, peroxidase and superoxide dismutase) with altered ascorbate peroxidase level in leaves of both maize hybrids. Medium supplemented thiourea was found to be very effective in improving growth may be due to decreased H 2 O 2 , MDA and further enhanced the activities of antioxidants with higher accumulation of ascorbate peroxidase under control and saline conditions. Salinity tolerance induced by thiourea was superior in the spring than in autumn grown maize. From the changes in the growth and physiological attributes of maize, it can be concluded that thiourea application has a great potential to alleviate the deteriorating effects of salt stress on maize and is recommended for improving growth in marginally to moderately saline soils.