Effects of plant growth regulators on drought resistance of two maize cultivars

Seeds of drought-resistant (PAN 6043) and drought-sensitive (SC 701) maize (Zea mays) cultivars were soaked in different concentrations of uniconazol, brassinolide and methyl jasmonate and then germinated. Seven-day-old seedlings were subjected to water stress by PEG treatment (−1.0MPa) for 2days. Uniconazol, brassinolide and methyl jasmonate were able to maintain a higher relative water content and diffusive resistance, and decreased the relative conductivity and transpiration rate in the seedlings of the drought-resistant cultivar, PAN 6043, during water stress periods. Increased drought resistance was obtained with 5mgl−1 uniconazol, 12.5mgl−1 brassinolide and 25mgl−1 methyl jasmonate, respectively. These treatments decreased the relative water content in seedlings of the drought-sensitive cultivar, despite influencing relative conductivity, transpiration rate, and diffusive resistance in a positive way. This indicates that plant growth regulators can be used as a seed pre-treatment in order to lower crap loss due to drought, but that evaluation of individual maize cultivars might be necessary