Optimizing sowing time and foliar boron application improves soil moisture use, physiological efficiency, and yield...

Rice fallow agroecosystems across South Asia provides a major opportunity for sustainable pulse crop-based intensification. However, productivity of post-rice crops are constrained by delayed sowing, rapid depletion of residual soil moisture and micronutrient deficiencies. Field pea (Pisum sativum L.), a short-duration cool-season legume/pulse crop, is well suited to this rice fallow system, but its yield stability is often limited by terminal moisture stress and boron (B) deficiency during reproductive development. This study examined whether optimization of sowing time with residual soil moisture availability, combined with foliar boron nutrition, could improve physiological resilience, reproductive performance, yield and profitability of field pea. A two-year field experiment was conducted in split-plot design with four sowing dates and four foliar boric acid concentrations applied at pre-flowering and pod initiation stages. Early sowing during 10-20 November maintained root-zone soil moisture above critical thresholds during flowering, extended crop duration by 14-17 days and increased grain yield by 22-47% compared with late sowing. Delayed sowing accelerated soil moisture depletion, reduced plant water status and impaired photosynthetic capacity, accompanied by lower plant B concentration, pollen viability, and pollen germination. Foliar application of 0.2% boric acid improved relative leaf water content by 3-6%, photosynthetic rate by 8-15%, pollen viability by 15-16% and grain yield by 25% over the untreated control, while the response plateaued at 0.3%. The combination of 20 November sowing with two sprays of 0.2% boric acid produced the highest grain yield, net return and B: C ratio, recording 1557 kg ha^-1, ₹53,983 ha^-1 and 2.12, respectively compared with 637 kg ha^-1, ₹3,591 ha^-1 and 0.92 under late sowing without boron. Multivariate analysis indicated that yield response was governed by an integrated trait axis involving soil moisture availability, plant water status, photosynthetic capacity, reproductive traits and plant B concentration. Timely sowing with moderate foliar boron application can therefore improve field pea productivity and profitability in rainfed rice-fallow systems, although multi-location validation is required before wider recommendation.