INTERCEPTATION OF PHOTOSSINTETIC ACTIVE RADIATION AND GRAIN YIELD OF MAIZE UNDER HIGH PLANT DENSITY

The objective of this work was to evaluate the behavior of light attenuation (PAR) in maize hybrids, cultivated under different population densities in narrow row spacing (0,45 m). An experiment was installed to evaluate six hybrids (A 2555, A 2288, AG 9010, AG 6690, P 30F88 and Valent), cultivated in five plant densities (40, 53, 71, 84 and 97 thousand plants for hectare), in Goiânia, Goiás state, in the growing season 2002/2003. The experimental design was randomized blocks with split plot, arranged in a 6x5 factorial with four replicates. The interceptation of photossintetic active radiation was evaluated measuring photon flux density: above the canopy, in the height of the ear, and in soil surface. The results showed a positive correlation between grain yield and light attenuation. The increment on plant density in narrow row spacing resulted in a greater absorption of PAR, and consequently enhancements in grain yield. In these conditions, the results also showed that the light attenuation on maize canopy occurs in the superior part of the canopy, above the ear height.