Effect of Salicylic acid and Paclobutrazol on growth and physiological traits of basil under water deficit stress conditions

Drought stress is a limiting factor for production in agriculture. In order to evaluate the impact of plant growth regulators, Salicylic acid and Paclobutrazol on growth and physiological traits of Sweet Basil (Ocimum basilicum) under drought stress condition, a factorial pot experiment based on Randomized complete design with 4 replication was carried out at research greenhouse of Mohaghegh Ardabili University, at 2012. experimental treatments were including water deficit stress (100, 60 and 30% percent of field capacity), two times foliar spraying with 100 and 200 ppm of salicylic acid and Paclobutrazol with two weeks interval. Controls sprayed by distillated water. Results indicated that the effects of water deficit stress, salicylic acid and Paclobutrazol foliar spraying on plant height, leaf dry matter, number of leaves, leaf area, stomatal conductance, relative water content and phosphorous content of leaves were significant (p&le0.01x). Parallel to raising water deficit stress, plant height, leaf dry weight, leaf surface area, phosphorus content and relative water content were reduced. Foliar spraying of salicylic acid and Paclobutrazol significantly increased relative water content, chlorophyll and proline content of basil leaves under drought stress condition. for conclusion, the research work revealed that application of salicylic acid enhanced tolerance against drought stress in basil plants, and the highest values for most of traits obtained by 200 ppm foliar spraying of salicylic acid.