Foliar Phosphorus and Molybdenum Interventions Modulate Growth Dynamics, Nodulation, and Productivity of Blackgram (Vigna mungo L.)

Abstract

A field experiment was conducted during the kharif season of 2025 at the Agronomy Research Farm, School of Advanced Agriculture Sciences and Technology, Chhatrapati Shahu Ji Maharaj University, Kanpur, to evaluate the response of blackgram (Vigna mungo L., cv. Azad-1) to varying foliar levels of phosphorus (P) and molybdenum (Mo) applied at the pre-flowering stage. The experiment was structured in a Randomised Block Design (RBD) with nine treatment combinations replicated three times: three sole Mo levels (0.25, 0.50, and 0.75 g L⁻¹), three sole P levels (2.5, 3.0, and 3.5 g L⁻¹), and three combined P + Mo sprays. The baseline soil was sandy loam, alkaline (pH 7.9), non-saline (EC 0.38 dS m⁻¹), low in organic carbon (0.27%), low in available nitrogen (83.50 kg ha⁻¹), and low-to-medium in available phosphorus (16.80 kg ha⁻¹). The results demonstrated that the combined foliar application of phosphorus @ 3.5 g L⁻¹ + molybdenum @ 0.75 g L⁻¹ (T9) significantly improved vegetative growth attributes, functional root nodulation (50.2 nodules plant⁻¹ at 50 DAS), dry matter accumulation, and crop growth rate. Yield attributes and productivity peaked under T9 (seed yield 1185 kg ha⁻¹; straw yield 2410 kg ha⁻¹; harvest index 32.96%), which was statistically at par with treatment T8 (P @ 3.0 g L⁻¹ + Mo @ 0.50 g L⁻¹, seed yield 1120 kg ha⁻¹). Total nutrient uptake (N, P, K, and Mo) and post-harvest soil available nitrogen and phosphorus were also maximised under combined treatments. Economic analysis revealed the highest net returns and benefit-cost ratio under T9, followed by T8. Under the conditions of the present study, foliar application of P @ 3.0–3.5 g L⁻¹ in combination with Mo @ 0.50–0.75 g L⁻¹ showed potential for improving blackgram productivity and economic returns in sandy loam soils of Central Uttar Pradesh. However, broader recommendations require further validation under appropriately controlled factorial experiments.