Nitrogen regimes affect agro-physiology, carbon assimilation and sink behavior of scented rice

Agro-physiology, C-assimilation & its contribution in sink development; and crop yield can be augmented through N regimes for higher productivity of scented rice (aromatic and basmati). Being scented rice sink limited crop; we loomed to enhance sink capacity by augmenting leaf area index (LAI) though nitrogen (N) regimes in new environment. In order to establish N-relationship with sink capacity (SC) & filling efficiency (SFE) and to determine N-related agro-physiological behavior a field experiment for two years conducted in middle IGP. Four N levels (control, low, moderate and high) tested for two aromatic and two basmati rice varieties under split plot design. The basmati rice varieties reported 37.81-52.13% higher grain yield (GY) with lesser N over short grained aromatic varieties. Dry matter, its translocation and pre-anthesis contribution, tiller number and physiological traits at growth stages were also comparatively higher in HUBR 10–9 over short grained HUR 917 and comprehended parity level with HUR 4–3. The SFE was negatively correlated with SC and LAI across nitrogen dose and varieties. Higher LAI at moderate N produced larger sink; higher SFE was at low N. On contrary to short grained HUR 917; BS varieties (HUBR 10–9 & HUBR 2–1) produced larger sink. Economic N was lower for BSV’s (126.48–131.52 kg N ha⁻¹) with GY potential of 5.11–6.01 Mg ha⁻¹.