Exogenous application of certain compounds can reduce the harmful effects of water stress. This exper-iment was carried out to study the effects of -amino butyric acid (BABA) on the morpho-physiologicaltraits and antioxidative enzyme activity in sweet cherry (Prunus avium L. cv. Takdaneh Mashhad) underwater-stress conditions. Sweet-cherry saplings were exposed to three water-stress treatments (well-watered, −0.6 and −1.2 MPa based on soil water potential) and three root-applied BABA treatments (0,0.8 and 1.6 mM). The results indicated that drought stress decreased the number of leaves, leaf area, leafdry weight, root volume, root dry weight, total dry weight, trunk dry weight, trunk diameter increment,relative water content (RWC), membrane stability index (MSI), leaf chlorophyll and carotenoids content.It increased free proline, total soluble sugars (TSS), malondialdehyde (MDA), hydrogen peroxide (H2O2),protein content and activity of peroxidase (POD) and ascorbate peroxidase (APX) content of leaves. Water-stress conditions with the application of BABA reduced the number of leaves, leaf dry weight, leaf area,the content of MDA and H2O2, but enhanced the trunk diameter increment, root volume, root dry weight,total dry weight, RWC, MSI, chlorophyll a, b and total chlorophyll, carotenoids, free proline and TSS, PODand APX activities in leaves compared to unprimed water-stressed plants. Application of BABA, partic-ularly at 1.6 mM, had a significant effect on some morpho-physiological and biochemical attributes andmitigated some detrimental effects of water stress.
