Effect of in-situ and ex-situ green manuring and zinc fertilization on growth and productivity of Basmati rice (Oryza sativa) under rice-wheat cropping system

A field experiment was conducted at the research farm of ICAR-Indian Agricultural Research Institute, New Delhi, India during summer and rainy (kharif) seasons of 2015 and 2016 to study the effect of in-situ and ex-situ green manuring crops and zinc fertilization strategy on growth, yield attributes and productivity of Basmati rice (Oryza sativa L.). The experiment was conducted in a split-plot design, keeping 2 in-situ green manuring crops viz. Sesbania aculeata Poir (dhaincha) and Vigna umbellata Thunb. (rice bean), 1 ex-situ green manuring crop viz. Leucaena leucocephala (subabul) and summer fallow as main-plot treatments and 4 zinc (Zn) fertilization treatments viz. 5 kg Zn through chelated Zn-EDTA as soil application, 2.5 kg Zn through chelated Zn-EDTA as soil application + 1 foliar application of 0.5% solution of chelated Zn-EDTA at flowering, foliar application of 0.5% solution of chelated Zn-EDTA at active tillering + flowering + grain filling, foliar application of 0.5% solution of chelated Zn-EDTA at 20, 40, 60 and 80 days after transplanting (DAT) and a control (no Zn) in sub-plots and was replicated thrice. Results showed that the incorporation of Sesbania aculeata green manure @ 34.7 t/ha (based on fresh weight) prior to transplanting of Basmati rice (based on mean of 2 years) produced higher growth parameters, viz. plant height, effective tillers, dry-matter; yield attributes, viz. panicle length, panicle weight and 1, 000-grain weight, correlation between yield and yield attributes and yields than Vigna umbellata, Leucaena leucocephala and summer fallow. Foliar application of 0.5% solution of chelated Zn-EDTA at 20, 40, 60 and 80 DAT was better than soil application of Zn with regard to growth parameters and grain yield (5.1 t/ha), correlation between yield and yield attributes like grain yield and panicle length (91.3%), grain yield and panicle weight (75.5%) of Basmati rice. Incorporation of Sesbania aculeata green manure generated highest net income (43.0 × 10³ /ha) among green manure treatments, while among Zn application treatments application of 0.5% solution of chelated Zn-EDTA at 20, 40, 60 and 80 DAT fetched the highest net returns (64.9 × 10³ /ha) from basmati rice cultivation.