Physiological indices, biomass and economic yield of maize influenced by humic acid and nitrogen levels

Nitrogen and humic acid are important factors affecting physiological, biomass and economic yield of maize. Experiment was conducted at New Developmental Farm of the University of Agriculture Peshawar during kharif 2011. Maize (cv. Azam) was sown at proper moisture condition on 30th June 2011. Three levels of humic acid (1.5, 3 and 4.5 kg ha–1) were applied at sowing whereas four nitrogen levels (80, 120, 160 and 200 kg ha–1) were applied 1/3rd at sowing, 1/3rd at 4–5 leaf stage and remaining 1/3rd at tasseling stage. A control treatment was used with no humic acid and nitrogen. The experiment was laid out in 2-factorial randomized complete block design having four replications. Nitrogen and humic acid were significantly affected leaf area (cm), CGR (crop growth rate) (g m–2 day–1), biomass and economic yield. Leaf area index (LAI) and NAR (net assimilation rate) (g cm–2 day–1) were not affected by humic acid but affected with nitrogen. Net assimilation rate (NAR) (g cm–2 day–1) and CGR (crop growth rate) (g m–2 day–1) were significantly affected by stages. Application at the rate of 4.5 kg HA ha–1 and 160 kg N ha–1 is better as compared to other treatments and is recommended for higher physiological indices, biomass and economic yield.