Yield-water relationships of lentil grown under different rice establishments in Lower Gangetic Plain of India

In the Indian subcontinent, lentil (Lens culinaries Medik) is cultivated mainly on carry-over residual soil water and nutrients in rainfed rice (Oryza sativa L.), coincided with increasing temperatures during the reproductive period, thus limiting seed yield. We examined the effect of rice establishment method (REM) viz. direct-seeded rice (DSR) and puddled-transplanted rice (PTR), tillage viz. zero tillage (ZT) and conventional tillage (CT), and nutrient management viz. improved package of practices (IP) including basal (20:40:20::N:P2O5:K2O) and foliar fertilization (2% urea, 0.5% Zn and 0.25% B) and farmers’ practice (FP) with no fertilization on the performance of cool-season lentil concerning soil water retention, crop water stress affecting actual evapotranspiration (ETa), yield and water productivity (WP) on an Aeric Haplaquept, clay loam soil in rainfed rice-fallows of Lower Gangetic Plain (LGP) of India during 2014–15 and 2015–16 cropping seasons. Among the treatments, PTR–ZT had significantly higher profile water storage i.e. 158.84, 141.74, 129.28, and 104.84 mm at sowing, vegetative, flowering, and pod formation periods, respectively. However, at the time of initiation of flowering DSR–CT achieved 0.8 MPa tension as compared to 0.3, 0.2, and 0.1 MPa for PTR–CT, DSR–ZT, and PTR–ZT. Bulk density was increased exponentially with the time that reduced root penetration except for PTR–ZT which maintained the lowest bulk density of 1.43 Mg m−3 at the reproductive stage with minimum soil water stress coefficients (Ks). Treatment combinations of PTR–ZT–IP produced the highest ETa (80 mm) with maximum seed yield (1281 kg ha−1) and WP (1.62 kg m−3), and also exhibited the lowest yield response factor (Ky = 0.87) of lentil which made the plant tolerate to water stress and enhanced the productivity even above the national average. An average of 1% relative yield loss per 1% decline in relative ET suggests the suitability of growing of lentil crop in this post-rice residual water regimes of LGP.