THE EFFECTS OF PHOSPHORUS DEFICIENCY AND RHIZOBACTERIA ON PHOSPHORUS CONTENTS OF TWO SOYBEAN (Glycine max L.) CULTIVARS GROWN AT LOW WATER SUPPLY

Phosphorus (P) deficiency and low water supply are major environmental constraints for agricultural production in many regions. Compared to cereal crops, the soybean (Glycine max. L.) is more susceptible to phosphorus insufficiency and drought. A soil pot experiment was conducted in the greenhouse to investigate the effects of phosphorus deficiency and pseudomonas florescence and azotobacter chroococcum strains on phosphorus uptake by soybean grown under temporary drought conditions. Soybean cultivars Zodiac and Horboveanca were grown on soil-sand mixture with P deficiency at two water regimes - 70% water holding capacity of soil (WHC) and 35% WHC. Plants were harvested and analyzed for P contents in each organ after 12 days of water deficit at the setting pod stage. Phosphorus deficiency significantly decreased nutrient uptake by all plant parts especially in drought conditions. Leaves have shown a higher sensitivity to P deficiency than roots. Application of rhizobacteria induced P uptake in both cultivars but their effects were more pronounced in Horboveanca under both well watered and dry soil conditions. Phosphorus fertilization alone of plants significantly increased P accumulation irrespective of soil moisture regime and Horboveanca displayed a higher response than Zodiac cultivar. The P accumulation in the roots of both cultivars and in the pods of Zodiac enhanced after the application of bacteria or P fertilizer under temporary drought. Interactive effects of applied bacterial strains and water soil regime depend on the cultivar used. From the results of the present experiment it can be concluded that biofertilizers seem to be particularly beneficial to P uptake in normal as well as in water limiting environment.