DISTRIBUITION AND POPULATION OF PLANTS AND MAIZE GRAIN YIELD

With the purpose of evaluating the effect of plant population (30,000; 60,000 and 90,000 plants ha-1), under two width rows (0.40 and 0.80 m), on the grain yield of three maize genotypes with open (AG 1051), semi-erect (AG 7575) and erect (DKB 911) leaf architecture, a field experiment was carried out in Piracicaba, São Paulo, Brazil between November 20th, 2000 and April 10th, 2001. According to the results: a) in high population (90,000 plants ha-1), the reduction of width row (from 0.80 m to 0.40 m) increases grain yield on the open-leaf-architecture genotype, and b), until 60,000 plants ha-1, regardless of genotype, the grain yield is crescent with an increase in plant population. With the plant population increasing from 60,000 to 90,000 plants ha-1, the grain yield: a) increases in the erect-leaf-architecture genotype, b) stabilizes on the semi-erect-leaf-architecture genotype, c) stabilizes under reduced spacing (0.40 m), and decreases under spacing of 0.80 m in the open-leaf-architecture genotype.