Deciphering optimal boron management impact on crop productivity, physiology, calcium-boron ratio, mobility and...

Boron (B) deficiency, a critical constraint in acidic soils of Northeast India, adversely impinges crop productivity and nutrient use efficiency, necessitating precise micronutrient management to optimize B levels for sustainable vegetable production. Introspecting this rationale, a research trial was executed to examine the implication of differential B application rates (0, 0.5, 1.0, 1.5, and 2.0 kg ha^-1) on a cauliflower-cowpea-okra sequence (CCOCS) in acidic Northeast Indian soils. Boron was applied exclusively to cauliflower, followed by systematic phasing out during subsequent cowpea and okra cultivation to monitor its concomitant residual effects. In both study years, nutrient management entailed the sequential application of recommended fertilizer doses and farmyard manure (FYM) uniformly to all crops. Empirical findings demonstrated that optimal B application of 2 kg ha^-1 (B_2.0) significantly leveraged crop yields, with cauliflower exhibiting a 25.1 % increase (19.11-23.90 Mg ha^-1), cowpea demonstrating a 23.5 % improvement (6.59-8.14 Mg ha^-1), and okra achieving an 18.4 % rise (21.25-25.15 Mg ha^-1). Physiological metrics, including chlorophyll content, crop growth rates, and nutrient concentrations (B and Ca), improved with optimal B application (B_2.0). The Ca:B ratio in leaves and edible parts diminished with escalating external Ca:B levels, implying Ca:B sufficiency. However, the mobility of Ca:B from leaves to edible parts declined under higher Ca:B applications, signalling restricted translocation. Soil recovery coefficient (SRC) was lowest (0.21) at B_2.0, substantiating sufficient B availability. A positive B balance (406 g ha^-1 year^-1) was observed with B_2.0, while residual crops exhibited B depletion. This study advocates B_2.0 as the optimal dose for sustaining yield and nutrient efficiency in CCOCS, providing a sustainable approach for micronutrient management for sustaining and leveraging crop yield and nutrient dynamics, in a diverse cropping sequence, particularly in acidic soils.