Effect of Plant Spacing and Fertilizer Levels on Yield and Dry Bulb Weight of Onion cv. Texas Grano 502

Abstract

The effect of five different row spacings (90, 60, 45, 38 and 30 cm) and two fertilizer levels (111 and 222 kg/ha) each of N, P₂O₅ and K₂O, on yield, dry bulb weight, and diameter of onion cultivar Texas Grano 502, were evaluated in a San Antón loam (Cumulic Haplustolls), fine-loamy, mixed, isohyperthermic on the sourthern irrigated coastal plain of Puerto Rico, and in a Fraternidad soil (Udic Chromusterts), very fine, montmorillonitic, isohyperthermic in the southwestern part of the island. The fertilizer was side-dressed in one application immediately after planting. Main results were as follows: At Fortuna yields from the 30 cm spacing were statistically superior to those from all other treatments, except those of the 60 cm spacing; the lower fertilizer level produced significantly higher yields than the higher level. At Lajas there were no significant differences among the yields of the various treatments; 90 cm between rows seems to be the most practical planting distance. Some mechanical weeding could be possible at this spacing. There were no significant differences between the two fertilizer levels; thus the lower level could reduce fertilizer costs. There were no differences in either bulb weight or size due to plant density.