Effect of salicylic acid and humic acid on some physiological characteristics and yield of forage maize (Zea mays L.) under drought tension conditions

 In order to investigate the effect of salicylic acid and humic acid to mitigate the impact of drought tension during pollination of forage maize, the present experiment was conducted as split plots based on randomized complete blocks design with three replications at Isfahan University of Technology. Drought tension levels included: without tension (control), mild tension (75 percent crop capacity) and severe tension(50 percent crop capacity) in the main plots and type of growth regulator (without growth regulator, salicylic acid and humic acid) in sub plots were investigated. The results showed that drought tension significantly reduced relative water content of leaves, chlorophyll, leaf area index, leaf weight, stem weight, ear weight, forage yield and water use efficiency compared to optimal irrigation. The use of salicylic acid in comparison to control and humic acid under mild tension conditions significantly increased leaf relative water content (61/2 and 39/3 percent), leaf weight (60/5 and 41/6 percent, respectively), stem weight (14/5 and 25/09 percent, respectively), ear weight (13/1 and 23/7 percent, respectively), proline content (16 and 32/3 percent, respectively), forage yield (24/5 and 24/2 percent, respectively) and water use efficiency (respectively, 15/21 and 34/28 percent, respectively). Application of salicylic acid treatment due to reduction of tension damage for forage yield and water use efficiency in drought  tension conditions showed a significant difference at five percent probability level compared to humic acid. Regarding the obtained results, although drought tension reduced yield, the effect of salicylic acid could compensate for the reduction of yield due to drought tension.