EFFECTS OF NITROGEN AND PHOSPHORUS FERTILIZATION ON SEED CROP OF ONION (ALLIUM-CEPA L) IN A SEMIARID TROPICAL SOIL

The effects of N and P fertilization and their interaction on the onio n (Allium cepa L.) seed crop, cv. D77, in a semiarid tropical soil wer e studied from November to April over a three-year period (1988-91) un der irrigation at Kadawa, Nigeria. Five N rates (0, 50, 100, 150, and 200 kg N ha(-1)) and P rates (0, 25, 50, and 75 kg P ha(-1)) were test ed. The main effects of N and P and their interaction on number of umb els per original bulb, seed weight per umbel, and seed yield were sign ificant. There were no significant effects of N and P and their intera ction on plant stand, and weight of 1000 seeds. At 50 kg P ha(-1), the application of 50 or 100 kg N ha(-1) gave significantly higher seed y ield than other N and P rate combinations tested.