Influence of Vesicular Arbuscular Mycorrhizal Fungi and Applied Phosphorus on Root Colonization in Wheat and Plant Nutrient Dynamics in a Phosphorus-Deficient Acid Alfisol of Western Himalayas

Abstract

Vesicular arbuscular mycorrhizal (VAM) fungi symbiosis confers benefits directly to the host plant's growth and yield through acquisition of phosphorus and other macro- and micronutrients, especially from phosphorus (P)–deficient acidic soils. The inoculation of three VAM cultures [viz., local culture (Glomus mosseae), VAM culture from Indian Agricultural Research Institute (IARI), New Delhi (Glomus mosseae), and a culture from the Centre for Mycorrhizal Research, Energy Research Institute (TERI), New Delhi (Glomus intraradices)] along with P fertilization in wheat in a P-deficient acidic alfisol improved the root colonization by 16–24% while grain and straw yields increased by 12.6–15.7% and 13.4–15.4%, respectively, over the control. Uptake of nitrogen (N), P, potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) was also improved with VAM inoculation over control, but the magnitude of uptake was significantly greater only in the cases of P, Fe, Zn, and Cu. Inoculation of wheat with three VAM cultures in combination with increasing inorganic P application from 50% to 75% of the recommended P₂O₅ dose to wheat through the targeted yield concept following the soil-test crop response (STCR) precision model resulted in consistent and significant improvement in grain and straw yield, macronutrient (NPK) uptake, and micronutrient (Fe, Mn, Zn, Cu) uptake in wheat though root colonization did not improve at P₂O₅ doses beyond 50% of the recommended dose. The VAM cultures alone or in combination with increasing P levels from 50% to 75% P₂O₅ dose resulted in reduction of diethylenetriaminepentaacetic acid (DTPA)–extractable micronutrient (Fe, Mn, Zn, Cu) contents in P-deficient acidic soil over the control and initial fertility status, although micronutrient contents were relatively greater in VAM-supplied plots alone or in combination with 50% to 75% P₂O₅ dose over sole application of 100% P₂O₅ dose, thereby indicating the positive role of VAM in nutrient mobilization and nutrient dynamics in the soil–plant system. There was significant improvement in available N and P status in soil with VAM inoculation coupled with increasing P levels upto 75% P₂O₅ dose, although the greatest P buildup was obtained with sole application of 100% P₂O₅ dose. The TERI VAM culture (Glomus intraradices) showed its superiority over the other two cultures (Glomus mosseae) in terms of crop yield and nutrient uptake in wheat though the differences were nonsignificant among the VAM cultures alone or at each P level. Overall, it was inferred that use of VA-mycorrhizal fungi is beneficial under low soil P or in low input (nutrient)–intensive agroecosystems.

Keywords:

• Glomus mosseae
• Glomus intraradices
• micronutrient
• nutrient dynamics
• phosphorus
• vesicular arbuscular mycorrhizae

Acknowledgments

Authors are thankful to the Indian Council of Agricultural Research, New Delhi, India, for providing financial assistance for this study under the World Bank–funded National Agricultural Technology Project (NATP).