The Improvement of Growth, Water Relations, and Oxidative Reduction of Pistachio Rootstock in Drought Stress Conditions with Beta-Aminobutyric Acid Pretreatment

Environmental stresses are inevitable during the plant growth. The β-aminobutyric acid (BABA) induces systemic resistance in plants. The efficiency of BABA pretreatments (0.5 and 10 mM) in inducing drought tolerance in the ‘Akbari’ pistachio rootstock in controlled environmental conditions was investigated. The BABA solutions were sprayed three times every two days on pistachio seedlings at the 15-leaf stage. Subsequently, the irrigation of plants was withheld for 25 days, and the effects of BABA pretreatments on the growth, water relations, and oxidative damage indices in plants were investigated. The BABA pretreatments prevented the reduction of shoot dry and fresh mass under a drought stress by inhibiting the leaf abscission and maintaining the relative water content. Owing to the leaf abscission, leaf water potential and turgidity of drought-stressed plants were similar to the control plants. However, the measurement of osmotic potential indicated that the BABA pretreatments improved turgor potential in leaves of the drought-stressed plants by inducing osmotic regulation. A declined membrane stability index and chlorophylls, as well as the malondialdehyde accumulation in line with the hydrogen peroxide accumulation in the leaves, indicated the development of oxidative damage under drought. Still, the BABA pretreatment restricted the severity of oxidative damages. In this regard, a 5 mM BABA pretreatment was the most effective one in the anti-drought plant protection.