Plant density and nitrogen studies with irrigated hybrid maize in the Lock-yer Valley, Queensland

Abstract

In 3 trials using standard 36-in. row spacing and plant populations of 12, 000-24, 000/ac, higher plant populations gave the highest yields; in 2 trials with row spacings of 30-42 in. and plant populations of 12, 000-28, 000/ac, yields increased as populations increased up to 24, 000 in one trial, and up to 16, 000 in the other. In only 1 of 3 trials was there a significant response to row width; in this trial, yields from 30-in. rows were significantly higher than from greater row widths. Applications of N depressed yields, probably as a result of early lodging. Ear percentages decreased with increasing plant density and were highest for the 30-in. row width. Grain weight/ear rose with plant density but was not affected by row width or applied N. % of nubbins (poor-quality ears) increased as plant density was reduced to 16, 000, but row spacing and N had no significant effect.-F.A.S.