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NITROGEN  LEVELS  AND  ITS  TIME  OF APPLICATION INFLUENCE LEAF AREA, HEIGHT AND BIOMASS OF MAIZE PLANTED AT LOW AND HIGH DENSITY

AMANULLAH^1*, KHAN BAHADAR MARWAT², PAIGHAM SHAH¹, NOOR MAULA³ AND SHAHNAZ ARIFULLAH⁴

Abstract: Field experiments were conducted at the New Developmental Research Farm of NWFP Agricultural University, Peshawar during 2002-03 and 2003-04 to investigate the impacts of nitrogen (N) rate and its time of application on leaf area, plant height and biomass yield of maize (Zea mays L., cv. Azam) planted at low and high density. Factorial experimental treatments comprising two plant densities (P1 = 60,000 and P2 = 100,000 plants ha^-1) and three nitrogen rates (N1 = 60, N2 = 120 and N3 = 180 kg N ha^-1) were kept in main plots, while six split application for N in different proportions were kept in subplots at different growth stages of maize in two equal (S1), three equal (S2), three unequal (S3), four equal (S4), five equal (S5) and five unequal splits (S6) at sowing and with 1^st, 2^nd, 3^rd and 4^th irrigation at two weeks intervals. Mean single leaf area (MSLA), and plant height was significantly higher in 2002-03 than in the 2003-04. Maize produced significantly taller plant and ear heights as well as biomass yield at high than at low density. MSLA and leaf area per plant (LAPP), plant and ear heights as well as biomass yield showed a remarkable increase with increasing N rate and number of N split applications. It is concluded that growing maize at high density with application of 50% higher N rate (180 kg ha^-1) than the recommended rate of N (120 kg ha^-1) in four to five splits can increase leaf area and plant height that could result in maximum biomass yield of maize and hence increase productivity of maize crop.

^*1Department of Agronomy, NWFP Agricultural University, Peshawar, Pakistan

²Department of Weed Science, NWFP Agricultural University, Peshawar, Pakistan

³Department of Extension Education, NWFP Agricultural University of Peshawar, Pakistan

⁴IDS, NWFP Agricultural University of Peshawar, Pakistan.