Effect of Phosphate Solublizing Bacteria on Plant Growth

Abstract

The phosphorous content in the soil can be increased by using phosphate solublizing bacteria as inoculants, which further increase crop yield. The most powerful phosphate solublizing bacteria genera are Pseudomonas, Bacillus and Rhizobium. The mechanism of phosphate solublization includes production of organic acids in soil. Bacterial isolates number 3 and 6 were isolated from soil, which were able to increase the phosphatase activity. Acid phosphatase activity increased when rockphosphate and tricalcium phosphate were added in comparison to soil only. Phosphatase activity observed have maximum increase when isolate number 3 or 6 were added along with rockphosphate and tricalcium phosphate.

Acid phosphatase activity was 0.192 units/ml in wheat crop soil, and 0.218 units/ml in ladyfinger, whereas the acid phosphatase activity was observed to increase further when rockphosphate and isolate number 3 was added in soil. It is observed during the studies for acid phosphatase activity that isolate number 3 was more effective in comparison to isolate number 6. In case of alkaline soil activity it increases more in rockphosphate and bacterial isolate number 6 were added. Alkaline soil activity was 0.243 units/ml in wheat and 0.283 units/ml in lady finger in comparison to control and negative control.

Maximum efficiency for phosphate solublization in tricalcium phospahate was observed to be 98.7% in isolate no 3 and 6 both, in 72 hours. In case of rockphosphate maximum efficiency for phosphate solublization was observed to be 98.5% which stabilized after 96 hours. Isolate number 3 showed maximum efficiency of 98.8% as compared to control which was 96.6% in 24 hours. Isolate number 6 shows maximum efficiency of 97.7% in 24 hours which increased to 98.5% in 72 hours. Chlorophyll content was also found to be more in soil in the presence of Isolate number 3 in comparison to Isolate number 6.