Impact of Dose and Time of Nitrogen Application on Phenological Stages and Leaf Development of Spring Maize (Zea mays L.) under Northwestern Indo-Gangetic Plains of India

Spring maize in the Northwestern Indo-Gangetic Plains is high-yielding and nutrient-demanding, especially for nitrogen. Proper split nitrogen application at key growth stages enhances leaf growth, biomass, and productivity while improving nitrogen use efficiency. A field experiment was conducted during spring seasons of 2013 and 2014 at Regional Research Station, Uchani, Karnal of CCS Haryana Agricultural University. The treatments consisted of four nitrogen doses (N1-150, N2-165, N3-180, N4-195 kg ha-1) and four different time of nitrogen application viz., S1- 50% + 25% + 25% (sowing + 8 leafed stage + tassel initiation stage), S2- 25% + 25% + 25% + 25% (sowing + 4 leafed stage + 8 leafed stage + silking), S3- 20% + 30% + 40% + 10% (sowing + 6 leafed stage + flowering + grain formation) and S4- 20% + 30% + 40% + 10% (2 leafed stage + 6 leafed stage + tassel initiation stage+ grain formation) allocated in main and sub plots, respectively. The results revealed that maximum days to four (24.75 and 25.83 days) and eight leafed stage (50.55 and 51.84 days) were recorded with N1, whereas higher nitrogen doses (N3 and N4) recorded minimum days. Among times of nitrogen application, the crop took maximum number of days to four (25.00 and 26.08 days) and eight leafed stage (48.98 and 50.92 days) under S4 which was at par with S3 but significantly more than S1 and S2. Higher dose of nitrogen (N4) significantly increased days to flowering (68.30 and 70.68 days), silking (73.46 and 74.45 days), grain formation (81.56 and 83.89 days) and maturity (109.89 and 113.08 days), remain at par with N3. Treatment of S3 was recorded maximum duration for these stages which was at par with S4. Growth parameters were also influenced by nitrogen doses. The highest number of leaves plant-1 (14.08 and 13.87), leaf area (5809.18 and 5316.92 cm2 plant-1) and LAI (4.84 and 4.43) were observed under N4 and it was statistically similar with N3. The treatment of S2 recorded higher leaf area (6042.9 and 5394.61 cm2 plant-1) and LAI (5.04 and 4.50) which was at par with S1.