Effect of Phosphorous and Potassium in Combination with Vam-Fungi on Growth, Root Colonization and Uptake of Npk in Soybean

The ability of VAM fungi to solubilize phosphorus and potassium salts is well know supplement of phosphorus, as single super phosphate in mycorrhizal soil greatly affected the colonization of soybean roots by two VAM fungi. The colonization was best at lower doses with a maximum at 100 mg SSP/pot after which it registered a decrease at higher doses. Increase in plant dry weight and nutrient content was recorded on higher doses with optimum at 300 mg SSP/pot and a decrease thereafter. The use of rock phosphate also gave similar results as shown by phosphorus. However, mycorrhizal soil also supported best plant growth and nutrient uptake at 100 mg SSP/pot. The potassium supplement has also shown identical trend. Similarly the different concentrations of potassium supported significantly better plant height, dry weight of shoot and root in mycorrhizal soil of both test VAM fungi i.e. Glomus fasciculatum and Glomus mosseae. The effect was maximum at 100 mg concentration of K20 followed by 50 and 20 mg/pot. However, VAM colonization was less in K20 treatments compared to VAM fungi alone. Though, the per cent colonization has improved significantly at 100 mg K2O/pot. In VA-mycorrhiza inoculated plants the colonization decreased with increase in level of potassium (Muriate of potash) right after the lowest dose used (20 mg/pot). Glomus fasciculatum was found to be more efficient than Glomus mosseae.