COMPARATIVE ACTIVITIES OF TRIADIMEFON, THIDIAZURON, AND CHLOROCHOLINE CHLORIDE AS SALINITY STRESS PROTECTANTS IN MAIZE (Zea mays L.) PLANT

Abstract

The combined effects of salt stress (150 mM NaCl) and triazole compound systemic fungicide-plant growth regulator triadimefon (TDM), cytokinin-like plant growth regulator thidiazuron (TDZ), and plant growth retardant chlorocholine chloride (CCC) on plant growth, antioxidative enzymes, and nutritional status of maize (Zea mays L. cv. DK 647) were investigated. Plants were grown in greenhouse conditions from April to June. Except for control, seedlings were treated with foliar applications of TDM, TDZ and CCC at concentrations of 75, 100, and 750 mg L-1, respectively. Compared to maize leaves from plants grown under non-saline conditions, salinity stress decreased shoot fresh and dry weight, relative water content, chlorophyll-carotenoids levels, and PPO (Polyphenol oxidase) enzyme activity. It also increased membrane permeability (EC%), proline content, and the activities of SOD (Superoxide dismutase), and POX (Peroxidase). Furthermore, the salinity treatment reduced Ca2+, K+, and P concentrations in the leaves and roots. The macronutrient content of leaves and roots increased with TDM, TDZ and CCC treatments. In general, all symptoms of damage were largely alleviated by the TDM. TDM was also the most effective stress protectant in protecting maize leaves from damage caused by salinity. TDM improved the growth rate of maize seedlings subjected to salinity stress and increased photosynthetic pigments contents, and relative water content compared to the control. It is concluded that while the PGR's have the potential to be stress protectants, TDM was consistently the most effective, while and CCC were found to be the least effective.