The Effect of Abscisic acid regulator on yield, antioxidant enzymes activity and ‎proline content of lavender (Lavendula angustifolia cv. Organic Munestead) in ‎response to deficit irrigation

Drought is one of the most important factors limiting plant growth worldwide and the most common environmental stress. In response to environmental stresses, abscisic acid (ABA) plays an important role in initiating and coordinating many physiological and biochemical processes in reducing oxidative stress. To study the effects of abscisic acid on some antioxidant enzymes and proline of Lavendula angustifolia cv. Organic Munestead under deficit irrigation stress, a pot experiment was conducted as factorial based on randomized complete block design with three replications. The treatments were four levels of irrigation regimes (30-40, 50-60, 70-80 and 90-100 percent field capacity (FC)) and ABA including three levels (0, 15 and 30 mM/L). Traits evaluated in flowering stage. The highest level of drought resulted an increasing 91% in proline and decreasing 29.88% in carotenoid compared to control. Abscisic acid had a significant effect on all traits, except of carotenoid content. Abscisic acid 30 mM/L spray and irrigation regimes 30-40 percent FC induced the highest content of CAT, POD and SOD, while the maximum of antioxidant activity (70.54 mg/g DW) has resulted in ABA 15 Mm/L application and irrigation regimes 50-60 percent FC and the maximum of proline (2.51 mg/g DW) has resulted in ABA 15 mM/L application and irrigation regimes 30-40 percent FC. The highest fresh and dry weight of shoot and root were obtained from non-application of ABS in irrigation of 90-100% FC. It is determined abscisic acid application in deficit irrigation stress conditions increased the activity of antioxidant enzymes of lavender to counteract the negative effects of deficit irrigation stress.