Investigation of the effects of drought stress and abscisic acid foliar application on yield, physiological and biochemical properties of lavender (Lavandula angustifolia cv. Organic Munstead)

Lavender is widely cultivated worldwide with its economic and ornamental potential and its high use in the cosmetic and pharmaceutical industries. Drought is one of the most important factors limiting plant growth worldwide and the most common environmental stress. In general, drought is considered to be the major environmental factor causing disturbance in water status and having a key impact on physiological and biochemical processes such as increased plant osmolality. In response to environmental stresses, abscisic acid plays an important role in initiating and coordinating many physiological and biochemical processes in reducing oxidative stress. Due to the fact that drought and water deficit in Iran is always one of the most important agricultural problems and due to the unique medicinal properties of lavender, the present study was conducted to evaluate the yield, physiological and biochemical properties of Lavandula angustifolia cv. Organic Munstead in irrigation regimes and application of abscisic acid was performed in order to understand how to induce drought tolerance.

In order to study the effects of drought and abscisic acid on physiological and biochemical characteristics of Lavandula angustifolia cv. Organic Munstead, a pot experiment was conducted as factorial based on randomized complete block design with three replications at Plant Production faculty of Gorgan University of Agricultural Sciences and Natural Resources, during growing season of 2017-18. The first factor was irrigation regimes in four levels (30-40, 50-60, 70-80 and 90-100% field capacity) and the second factor was abscisic acid spry including three levels (0, 15 and 30 µM/L). Traits evaluated were wet and dry weight and leaf area index, total phenol, total flavonoid, DPPH antioxidant activity, proline, carotenoid, RWC and soluble carbohydrate.

The results showed that drought increase phenol (151.42 mg/g) and carotenoid (46.32 mg/g) compared to control. Abscisic acid had significant effect on all traits except of phenol and carotenoid. Also interaction effect of drought and abscisic acid was significant for all traits except of phenol and carotenoid content that were the highest in abscisic acid 30 µM/L and drought 30-40 and 50-60 percent field capacity increase antioxidant activity 47.56 and 53.93 percent and 55.20 and 65.72 percent soluble carbohydrate, respectively. abscisic acid 30 µM/L spray and drought 30-40 increase proline 120.17 percent. Also, the highest RWC amount (78.74 percent) from interaction abscisic acid 30 µM/L and drought 90-100 percent field capacity.

Generally, abscisic acid 30 µM/L application and drought 30-40 and 50-60% field capacity Introduces the best treatment, due to the lower consumption of water and the use of abscisic acid in stress conditions, higher levels of abscisic acid can be achieved in inducing drought tolerance.