Effects of 5-Aminolevulinic Acid (5-ALA) on Morphological and Physiological Characteristics of Grapevine against Salt Stress

Abstract

Salinity, one of the most significant abiotic stress factors restricting plant production, causes the destruction of agricultural lands and reduces productivity. In recent years, the utilization of 5-aminolevulinic acid (5-ALA) applications, which have important effects in terms of avoiding and providing tolerance to factors by impacting the physiology and metabolism of the plants, has been on the agenda. In this research, the impacts of foliar treatments of different levels of 5-ALA (0, 0.3, 0.6 and 0.9 mM) on morphological and physiological traits of 41 B American grapevine rootstocks under salinity stress (NaCl solution starting with 25 mM and reaching 150 mM concentration) were investigated. Salinity stress caused significant decreases in growth parameters, chlorophyll content, RWC and stomatal conductance, and significant increases in leaf temperature, proline and MDA content, physical damage and membrane damage degree. Under salinity stress, 0.9 mM 5-ALA treatments resulted in significant increases in shoot length (14.67 cm), root length (34.50 cm), leaf thickness (0.23 µm) leaf area (31.37 cm2), leaf number (8.67 pieces), chlorophyll content (21.83 SPAD), RWC (80.20%), proline content (0.19 μmol.g-1) and stomatal conductance (78.05 mmol.m-2.s-1); and significant decreases in physical damage degree (1.00 scale degree), membrane injury degree (15.46%) and MDA content (28.20 nmol.g-1) compared to non-ALA treatments. According to the results of this study, 5-ALA can be recommended as an alternative application to provide salinity tolerance in plants in order to reduce the damage caused by salinity stress in agricultural lands.