paclobutrazol and salicylic acid application ameliorates the negative effect of water stress on growth and yield of maize plants

somayyeh bayat and ali sepehri * department of agronomy and plant breeding, faculty of agricultre, bu-ali sina university of hamedan, iran       *corresponding author: e-mail. [email protected], [email protected]   received: 31 may 2012  accepted: 8 october 2012   abstract growth and yield of maize is seriously restricted by water deficit. salicylic acid (sa) and paclobutrazol )pbz) induces biotic and abiotic stress tolerance in crops. in order to evaluate effect of antitranspiration substances and water stress on growth, yield and yield components of maize (zea mays l.) an experiment was conducted in 2009, hamedan, iran. the experiment was laid out in randomized complete block design with split plot arrangement. the plants were sprayed with the salicylic acid (0.5 mm) and paclobutrazol (50 ppm). the results showed that vegetative growth indices such as total dry weight, leaf area index and crop growth rate, was considerably affected by application of sa and pbz under different irrigation regimes. interaction between sa and 100, 70 and 40% of full irrigation significantly increased grain yield by15.85, 20.81, 29.74 percentage, weight of 1000 seeds by 11.40, 15.77, 20.17 percentage and biological yield by 15.41, 19.38, 23.19 percentage compared to untreated plants, respectively. grain yield and 1000-grain weight significantly decreased under pbz treatment by 8.60, 8.64 percentage compared to untreated plants under non-water stress. grain yield and weight of 1000 seed displayed a significant increase in response to rate of the pbz compared to untreated plants under low and high water stress. exogenous sa application was advantageous under three irrigation levels, but exogenous pbz application was advantageous only under stress conditions.