Influence of nitrogen on phenology, yield and quality of forage maize under various spatial arrangement

Experiments were conducted on forage maize with different levels of nitrogen and crop geometries at Punjab Agricultural University, Ludhiana during late kharif season of 2003 and 2004. The forage maize had taken 46–48, 52–53, 58–59 and 51–52, 59–60, 67–68 days after sowing for initiation, 50 and 100 per cent tasseling and silking under the different levels of nitrogen, respectively. Maize took the same number of days for initiation, 50 and 100 per cent tasseling and silking under the various plant geometries as 60x20, 60x15, 45x20, 45x15, 30x20 and 30x15 cm. It indicated that tasseling and silking started 46 and 50 days after sowing and completed up to 59 and 68 days after sowing. Maize took total 12 and16 days for complete tasseling and silking, respectively. The seed yield was increased significantly with each successive increase in nitrogen up to the highest level tried 150 kg ha⁻¹. The plant geometry of 60x15 cm gave significantly higher seed yield over 60x20, 45x15, 30x20 and 30x15 cm which was at par with 45x20 cm plant geometry. Protein content in plant was decreased considerably with age of plant under all the levels of nitrogen and plant geometry. The maximum protein content in plant was recorded at 45 days after sowing. It was increased significantly with the application of nitrogen up to 120 kg ha⁻¹ but further increase in nitrogen did not prove beneficial to increase the protein content in plant at 45, 60 and 75 days after sowing. The mean protein content in plant varied from 6.52 to 7.48 per cent. The highest protein content in plant was observed under the plant geometry of 60x20 cm as compared to closer plant geometry of 60x15, 45x20, 45x15, 30x20 and 30x15 cm under all growth stages. Protein content in seed significantly increased with the each successive dose of nitrogen up to the highest level of 150 kg ha⁻¹ during both the years of study. The highest protein content was recorded under the plant geometry of 60x20 cm as compared to 60x15, 45x20, 45x15, 30x20 and 30x15 cm. The crop received 150 kg N ha⁻¹ recorded maximum nitrogen, phosphorus and potassium uptake in seed and straw. The similar trend was observed in the total uptake of nitrogen, phosphorus and potassium in seed and straw. The highest nitrogen and potassium uptake in seed and straw was recorded with 60x15 and 30x20 cm plant geometry, respectively. Maximum total uptake of nitrogen and potassium was recorded under the plant geometry of 30x20 cm.