Role of endomycorrhizae, rhizobacteria and compost to improve phosphorus availability in onion

Phosphorus (P) is 2nd most important macronutrient for the growth of plants. The soils of Pakistan are alkaline and calcareous in nature which causes precipitation of P and making it less available to the plants. To overcome this issue, excessive P fertilization is used, some part of fertilizer is used by plants while remaining is either fixed as unavailable form or lost due to runoff. So deficiency of P affects the plant growth while runoff of excess fertilizer may result in eutrophication of our aquatic systems. Use of arbuscular mycorrhizal fungi (AMF) may be an appropriate method to enhance the P uptake efficiency of plants and reduce the use of P fertilizers. Plant growth promoting rhizobacteria (PGPR) are also well known for solubilization of P. Therefore, a pot experiment was conducted in 2019 at Research Farm of Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Pakistan to check the efficiency of compost, PGPR and AMF to enhance availability of P in onion. The impact of PGPR and AMF were evaluated separately and in combination. At harvest, data regarding plant fresh and dry weight, onion bulb circumference, bulb fresh and dry weight, chlorophyll a and b, carotenoids, and P concentration in plants were analyzed. Results showed that combined inoculation of endomycorrhizae and rhizobacteria improved plant fresh and dry weight, onion bulb circumference, bulb fresh and dry weight, chlorophyll a and b, carotenoids. Overall, integrated application of endomycorrhizae and rhizobacteria enhanced P uptake by 77% as compared to control treatment.