Response of Specific Leaf Area (SLA), Leaf Area Index (LAI) and Leaf Area Ratio (LAR) of Maize (Zea mays L.) To Plant Density, Rate and Timing of Nitrogen Application

Abstract: Nitrogen is considered as one of the most important inputs needed for increasing productivity of field crops. Balanced amount of N application at proper time according to the need of the maize decreases N losses, increases yield and quality. There is also a need to understand how levels and timing of N application affect the physiology of maize is an attempt to explore further avenues for proper nutrient management for improving yield on sustainable basis. Thus the experiment was designed and planted at the Agriculture Research Farm of the NWFP Agricultural University, Peshawar for two consecutive years (summer 2002 and summer 2003) with a an objective to study the effect of plant density, N rates and timing on SLA, LAI and LAR of maize. All the three parameters i.e. SLA, LAI and LAR enhanced to a maximum with increasing plant density, N rate and 2 1 number of splits for N application. SLA, LAI and LAR enhanced at the rate of 0.152 cm g, 0.0065 and 2 1 2 1 0.023 cm g, respectively with one kg increase in N rate. The highest SLA (324.8 cm g), LAI (4.59) and 2 1 LAR (63.03 cm g) was recorded in those plots to which N was applied in five splits with greater proportion 2 1 2 1 at later stages, while the minimum SLA (275.70 cm g), LAI (3.66) and LAR (53.46 cm g) was recorded in the plots which received N only in three splits with greater proportion at the sowing time. Plots maintained at a high-1 density (100,000 plants ha) produced the higher SLA, LAI and LAR than the plots maintained at low density 1 (60,000 plants ha). Key words: maize nitrogen plant density SLA LAI and LAR