Real-time nitrogen management using leaf colour chart in rice (Oryza sativa) genotypes

Abstract

A field experiment was conducted during 2012 and 2013 at Shalimar, Jammu and Kashmir, to study the re- sponse 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), rec- ommended practice (120 kg N/ha), LCC ? 3 (4 splits of 20 kg N/ha each -N and 3 splits of 30 kg N/ha each -N ), 80 90 LCC ? 4 (5 splits of 20 kg N/ha each -N and 4 splits of 30 kg N/ha each -N ) and LCC ? 5 (6 splits of 20 kg N/ha 100 120 each -N and 5 splits of 30 kg N/ha each -N )]. Variety SR 2 recorded significantly higher grain yield (7.3 t/ha) 120 150 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 respec- tively) 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 man- agement. 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.