Phenophase-based nitrogen and zinc scheduling for yield and zinc biofortification of direct-seeded rice (Oryza sativa)

A field experiment was conducted during the rainy (kharif) season of 2015 at Varanasi, Uttar Pradesh, to assess the effect of phenophase-based nitrogen and zinc scheduling on yield, and zinc content of direct-seeded rice (Oryza sativa L.). The experiment was laid out in a factorial randomized block design with 3 replications, having 3 nitrogen levels (N₀, 0 kg N/ha; N₁, 120 kg N/ha (50% at sowing + 25% at G + 25% at G₂₁); N₂, 160 kg N/ha (50% at sowing + 25% at G₂₁+ 25% at G₃₂) and 5 zinc scheduling (Zn₀, 0 kg Zn/ha; Zn, 5₁ kg Zn/ha basal + 0.3% ZnSO₄. H₂O spray at G₄₅ and G₆₁; Zn, 10 kg Zn/ha basal + 0.3% ZnSO₄. H₂O spray at G₄₅ and G 61; Zn₃,5 kg Zn/ha basal + 0.3% ZnSO₄. 2H₂O spray at G ₅₁+ G₇₃; Zn, 10 kg Zn/ha at basal + 0.3% ZnSO₄. 2H₂O spray at G₅₁ + G₇₃). Significantly highest effective tillers, panicle length, grains/panicle, panicle weight, 1,000–grain weight, grain and biological yields were recorded with independent application of N₂ and Zn₂ over the others, however the highest zinc content and uptake in grain recorded with N₂ and Zn₄ treatments. Nitrogen levels and Zn scheduling also positively interacted and recorded the highest grain yield with N₂ × Zn₂, however the highest grain N and Zn content were recorded with N₂ × Zn₄.