WATER stress is one of the most important abiotic stresses that
…….....may limit agriculture production worldwide. This work was
carried out on mango trees (Mangifera indica L.) to
study the effect of exposure to different levels of drought stress (65, 75,
85 and 100 % of full irrigation requirements), in addition, to evaluating
the role of using some plant growth promoting rhizobacteria (PGRP);
such as Azospirillum and Azotobacter, in alleviating drought-induced
changes. Physiological and biochemical changes were determined in
mango leaves after two seasons of different treatments. Results
indicated that membrane stability, photosynthetic pigments and
insoluble sugar contents were significantly decreased with increasing
drought levels, while electrolyte leakage, soluble sugars, total
carbohydrates and proline content were sharply increased compared to
control. Lipid peroxidation level and the activities of superoxide
dismutase (SOD), peroxidase (POD) and catalase (CAT) enzymes
showed progressive increases with drought levels. Application of biofertilizers
may be effective in alleviating the adverse effect of water
stress. Bio-fertilizers caused marked increase in photosynthetic
pigments and carbohydrate contents and a decrease in proline content
compared to control.