The effect of inoculation with vesicular-arbuscular mycorrhizal fungi on soybean yield and mineral phosphorus utilization in subtropical-tropical soils

Abstract

Two species of vesicular-arbuscular (VA) mycorrhizal fungi (Glomus fragilis andGlomus fasciculatum) and four subtropical-tropical soils (Taichung moderately acidic silt loam, Pingtung strong acidic silt loam, Changhua calcareous silt loam and Tainan calcareous sandy loam) were used in a pot experiment to observe the effects of with VA mycorrhizal fungi inoculation on the yield and mineral P utilization by soybeans (Glycine max L. Merrill). The results show that the inoculation increased soybean yields by about 7–45% over the noninoculated treatment depending on the soil. In soybeans inoculation withG. fasciculatum yield by 33–45%. The P concentration of the soybean grains was significantly improved in the inoculated treatments. The rhizosphere soil was used to measure the difference of P uptake by the soybean plants. Soybeans in non-inoculated treatments took up mainly Al−P in acidic soils, and Ca−P in a calcareous soil, and non or little of Fe−P in all soils. Inoculation by each of the two mycorrhizal fungi improved the uptake of Al−P by soybean in Pingtung, Changhua and Tainan soils, and increased the uptake of Ca−P in Changhua and Tainan calcareous soils.G. fasciculatum significantly enhanced the uptake of Fe−P by soybean in taichung, Changhua, and Tainan soils. These results indicated that VA mycorrhiza can enhance the uptake of the fixed soil P, and indicated that the efficiency of utilization of various froms of P mineral by mycorrhizal plants depends on the species of mycorrhizal fungi present and on the soil type.