Efficacy of vesicular arbuscular mycorrhizae as influenced by phosphorus application in wheat (Triticum aestivum) under rainfed conditions of Kashmir

Abstract

A field experiment was conducted for 3 consecutive winter (rabi) seasons during 2002-05 to study the effect of phosphorus levels and vesicular arbuscular mycorrhizae on root colonization, spore density, yield and yield attributes, uptake, availability and P-use efficiency in wheat (Triticum aestivum L. emend. Fiori & Paol.). Inoculation of vesicular arbuscular mycorrhizae alone showed significantly higher root colonization (24.80 and 35.86%) and its spore density (118.0 and 240.0 spores/50 g soil) over all the treatments but increasing levels of phosphorus with or without vesicular arbuscular mycorrhizae inoculation significantly reduced it at tillering and harvest stages of plant growth. Yield and its attributes were recorded maximum with 26.2 kg P/ha + vesicular arbuscular mycorrhizae. The response in terms of grain yield was 33.3% with the application of 26.2 kg P/ha + vesicular arbuscular mycorrhizae which was higher than 17.5 kg P/ha + vesicular arbuscular mycorrhizae (31.4%) and 26.2 kg P/ha (29.3%). Maximum net returns Rs 11 881 and B : C ratio (1.86) was recorded with addition of 17.5 kg P/ha + vesicular arbuscular mycorrhizae. All the treatments significantly increased the uptake of P in grain and straw over the control. However maximum being with 26.2 kg/P ha + vesicular arbuscular mycorrhizae. The available P was recorded maximum with addition of 35 kg P/ha which was significantly higher over the control, vesicular arbuscular mycorrhizae inoculation, 8.75 kg P/ha and 8.75 kg P/ha + vesicular arbuscular mycorrhizae. The agronomic phosphorus use-efficiency and apparent phosphorus recovery were recorded maximum with the application of 8.75 kg P/ha + vesicular arbuscular mycorrhizae whereas, per cent soil P utilization and phosphorus harvest index was maximum with vesicular arbuscular myconhizae inoculation alone and control respectively.