Author : Sombun Techapinyawat

Summary : The interaction between vesicular-arbuscular (VA) mycorrhiza and Rhizobium sp. strain L-15 and varying phophorus levels using sterile Macolod clay loam soil from Puting Lupa, Mount Makiling, Philippines, and their effects on growth of Leucaena leucocephala were studied. Mixed mycorrhizal spores obtained from rhizosphere of L. leucocephala was more efficient in improving growth of Leucaena compared to the other mycorrhizal types used in the inoculation treatment. Leucaena-Rhizobium symbiosis enhanced nutrient uptake. Double inoculation with Rhizobium and mycorrhiza increased the uptake of N, P, K, Ca, Mg, and improved growth of Leucaena greater than that of either Rhizobium or mycorrhiza treated plants, especially in soil with low phosphorus and nitrogen availability. Rhizobium and mycorrhizal inoculations stimulated nutrient uptake, nodulation, nitrogen fixation, and growth of Leucaena with low phosphorus application in the soil. Phosphorus levels above 30 kg P (subscript 2) O (subscript 5)/ha depressed mycorrhizal development and activities. These results showed that double symbiosis with Rhizobium and mycorrhiza were synergistic and stimulated nodulation, nitrogen fixation, nutrient uptake and improved growth of Leucaena leucocephala.