Real-Time Nitrogen Management Using Leaf Colour Chart In Rice (Oryza Sativa) Genotypes

A field experiment was conducted during 2012 and 2013 at Shalimar, Jammu and Kashmir, to study the response of rice (Oryza sativa L.) genotypes to real-time nitrogen (N) management as guided by leaf colour chart (LCC). Treatments included 2 rice varieties ‘Jhelum’ and ‘SR 2’ and 8 rates of N application [control (No N), recommended practice (120 kg N/ha), LCC ≤ 3 (4 splits of 20 kg N/ha each -N₈₀ and 3 splits of 30 kg N/ha each -N₉₀), LCC ≤ 4 (5 splits of 20 kg N/ha each -N₁₀₀ and 4 splits of 30 kg N/ha each -N₁₅₀) and LCC ≤ 5 (6 splits of 20 kg N/ha each -N₁₂₀ and 5 splits of 30 kg N/ha each -N₁₅₀)]. Variety ‘SR 2’ recorded significantly higher grain yield (7.3 t/ha) than ‘Jhelum’ (6.6 t/ha). Total N uptake and agronomic efficiency were significantly higher in ‘SR 2’ than ‘Jhelum’. LCC ≤5 (150 kg N/ha applied in 5 splits) recorded significantly higher grain yields (8.2 t/ha) than recommended dose of 120 N/ha (7.1 t/ha) and LCC ≤ 3 (80 and 90 kg N/ha), but remained at par with 120 kg N/ha applied in 6 splits through LCC ≤ 5 @ 20 kg N/ha (7.9 t/ha). The LCC ≤ 3 (80 and 90 kg N/ha applied in 4 and 3 splits respectively) was statistically at par with recommended dose of 120 kg N/ha with respect to yield. The total N uptake and nitrogen-use efficiency were significantly higher with LCC-based N management than the recommended N management. Further higher agronomic efficiency (33.8 kg grain/kg N applied) was recorded with LCC ≤3 @ 20 kg N/ha (80 kg N/ha) applied in 4 equal splits.