Abstract
The objective of the present investigation was to estimate the total hyphal length of maize and groundnut grown under field condition and to evaluate the influence of arbuscular mycorrhizal (AM) hyphae for predicting P influx with the mechanistic model. The field experiments were carried out with three P levels, i.e., P0 (no P), Ps50 (50 mg P kg-1 soil), and P400 (400 mg P kg-1 soil). Test crops were maize and groundnut. Four harvests were made to cover whole growing season and at each harvest, hyphal length was determined at all P levels. Application of P fertilizer reduced hyphal length by 30-50% in maize and by 25-50% in groundnut. In general, hyphal length was higher in maize (5.4 m g-1) than in groundnut (3.8 m g-1). To assess the importance of mycorrhizal hyphae, nutrient uptake model (NST 3.0 Version) was used. When root hairs were substituted by hyphae, the calculated influx further increased by a factor of 1.5 to 2 for plots receiving no P. This emphasizes the importance of considering hyphae in P uptake, particularly at low P supply. Concentration profile around the root cylinder at P0 showed that hyphae were able to decrease the soil solution concentration more than root hairs.
