Boron × Rootstock Interaction Effect on Growth, Physiological and Biochemical Characteristics of Apple cv. Golden Delicious

Boron toxicity is considered as one of the most important plant growth disorders in arid and semiarid regions. This experiment was carried out in order to evaluate boron (B) × rootstock interaction effect on growth, physiological and biochemical characteristics of apple cv. Golden Delicious. In this study, boron was applied at five concentration levels (0, 15, 30, 45 and 60 mg kg-1 soil) on four rootstocks; MM106, M26, M9 and P22 in two years. Results revealed that with increases in boron supply; plant height, LAI, leaf fresh and dry weight, chlorophyll index and vegetative growth reduced in all rootstocks as compared to control. Vegetative growth on all rootstocks stopped as boron level increased, except in M26 and P22, however, vegetative growth in M26 and P22 reduced in comparison with control. Also, electrolyte leakage and malondialdehid increased as boron level increased in soil. Leaf superoxide dismutase activity increased in 0 to 30 mg kg-1 boron, and then decreased with increasing boron levels in soil. Leaf boron concentration in M26 and P22 was less than other rootstocks. Results indicated that cv. Golden Delicious on M26 rootstock was more tolerant to boron toxicity than on other rootstocks in more than 30 mg kg-1 boron in soil.