Effect of irrigation and nitrogen management on rice (Oryza sativa) under system of rice intensification and its residual effect on lentil (Lens culinaris)

A field experiment was conducted to study the effect of irrigation scheduling and nitrogen management on growth, yield, quality and relative economics of hybrid rice (Oryza sativa L.) (cv. PHB 71) under SRI and their re- sidual effect on lentil (Lens culinaris Medik) (cv. HUL 57) on sandy-clay loam soil of Varanasi, Uttar Pradesh dur- ing rainy (kharif) and winter (rabi) seasons of 201415 and 201516. The experiment was laid out in split-plot de- sign assigning 3 irrigation scheduling [irrigation at 2 days after disappearance of ponded water (DADPW), 5 DADPW and 8 DADPW] in the main-plots and 5 nitrogen management practices, [Recommended dose of nitrogen (RDN), RDN + Sesbania aculeata Poir as co-culture with rice, 75% RDN + Sesbania aculeata Poir as co-culture with rice, RDN + blue green algae (BGA) and 75% RDN+BGA] in the sub-plots, with 3 replications. Results re- vealed higher growth parameters, yield attributes and grain and straw yields (6.67 and 8.43 t/ha, respectively) un- der scheduling of irrigation at 2 DADPW as compared to 8 DADPW although it was statistically at par with sched- uling of irrigation at 5 days after disappearance of ponded water. The magnitude of increase in grain and straw yield of hybrid rice under SRI by scheduling of irrigation at 2 DADPW over 8 DADPW was 14.0 and 10.3%, re- spectively on pooled basis. The NPK uptake by the crop and hulling, milling and head rice recovery of rice grain were found to be higher under scheduling of irrigation at 2 DADPW. Among the nitrogen management practices, RDN+BGA produced markedly higher leaf-area index (4.78), dry matter accumulation/hill (67.6 g), effective tillers/ m2 (262), panicle length (31.7 cm), grains/panicle (190), weight/panicle (5.64 g), 1,000-grain weight (24.8 g), grain yield (6.78 t/ha) and straw yield (8.66 t/ha) over other nitrogen management practices. The residual effect of scheduling of irrigation at 5 DADPW applied to rice exhibited higher value of pods/plant, 1,000-grain weight, yield of grain and stover of lentil as well as NPK uptake by the crop. Further, application of RDN (150 kg N /ha) along with BGA (12 kg BGA powder/ha) to rice recorded the highest pods/plant, 1,000-grain weight and grain and stover yield and NPK uptake by succeeding lentil.