Effects of sheared-root inoculum of Glomus fasciculatum on tobacco grown at different phosphorus levels in alfisols

Abstract

Southern light soils (SLS) of Andhra Pradesh are known for low fertility and poor phosphorus status. Tobacco is the main commercial crop grown in this area. Lack of phosphate in these soils is the most important constraint in tobacco plant growth. Nearly 80-85% of P applied to these soils is unavailable to plants because of their inaccessibility, fixation and immobilization (4). Research in the past years has proved that vesicular-arbuscular mycorrhiza (VAM) can improve plant growth through increased uptake of phosphorus and other mineral nutrients, especially in low fertile soils (2). In general, AM fungi improve the P uptake of their host plant especially under P limited conditions. VAM fungi explore the soil more thoroughly and hence are able to locate and use the point source of P (8). The use of AMF may contribute to reducing chemical fertilizer inputs and sustaining plant productivity in agriculture (6), yet according to Medina et al. (5) introduced isolates differed in their ability to stimulate plant growth in natural soils in the presence of indigenous fungi. The present study was conducted under field conditions for three years (2005-07) to assess the effectiveness of the introduced AMF Glomus fasciculatum on tobacco growth at different P-levels in alfisols.