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.
Highlights
Phosphorus (P) is an important plant nutrient, which constitutes 0.2% of a plant’s dry weight (Schactman, Reid, and Ayling 1998)
Since the vesicular arbuscular mycorrhizal (VAM) inoculated plants can withstand the water stress conditions (Harrier and Watson 2003), in the present study, we have investigated the influence of VAM fungi and applied P on crop productivity as well as macro- and micronutrient uptake in rainfed wheat and their availability in P-deficient acidic alfisols in the western Himalayas
It was observed that with either of three VAM cultures, the rate of increase of root colonization was greater with application of the 50% P2O5 dose compared to VAM cultures alone, but further increase in applied P to 75% P2O5 dose lowered the rate of root infectivity in local VAM culture (Glomus mosseae)
Summary
Phosphorus (P) is an important plant nutrient, which constitutes 0.2% of a plant’s dry weight (Schactman, Reid, and Ayling 1998). A number of field studies carried out in various parts of the world, tropical as well as temperate regions, have shown significant beneficial effects of VAM fungi inoculation in maize, wheat, soybean, cotton, barley, oats, white clover, lucerne, cowpea, potato, peach, and citrus (Carling, Roncadori, and Hussay 1989; Vejsadava, Drinkryl, and Vancura 1990; Karagiannidis and Hadjisavva 1998; Singh and Kapoor 1999; Kelly et al 2001) These effects are mainly attributed to the fact that the VAM hyphal network in soil matrix increases the mobilization and absorption of plant nutrients from the rhizosphere and outside the rhizosphere in the soil system (Harrier and Watson 2003), allowing an increase in the uptake of macronutrients (especially P) and micronutrients by the crops (Liu, Shen, and Qiu 1994; Bagayoko et al 2000; Khan, Ahmad, and Ayub 2003). Since the VAM inoculated plants can withstand the water stress conditions (Harrier and Watson 2003), in the present study, we have investigated the influence of VAM fungi and applied P on crop productivity as well as macro- and micronutrient uptake in rainfed wheat and their availability in P-deficient acidic alfisols in the western Himalayas
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