Vertical Profile of Leaf Nitrogen Distribution at Different Densities of Plant And Different Levels of N Fertilizer on Corn Hybrids Canopy

Abstract

In this study, the distribution of leaf nitrogen of two corn hybrids during the growing season, in response to the density and N supply were studied. There were two corn hybrids (S.C. 704 and maxima (MV 524)) under three levels of nitrogen: Recommended (300 kg N/ha); RDN plus 25% (375 kg N/ha); RDN plus 50% (450 kg N/ha) and were three levels of population. Recommended (RDN) (7 plants m -2 ); RDN plus 10% (7.7 plants m-2); RDN plus 20% (8.4 plants m -2 ).Regular samplings were made from 40 days after sowing until crop maturity. Every 2 weeks, a 1 m2 sample of the canopy was cut in four successive vertical layers of equal thickness. Leaf area and N concentration (%) in each layer were measured. The vertical N gradient became more marked with ongoing vegetative development. The whole canopy photosynthetic benefit that would accrue from maintaining the N gradient is likely to be accentuated. The rate of decline in leaf N concentration in a layer was not related to either the initial concentration in the leaves within the layer.