ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 77 Number 3
Yield, bulb size distribution, and storability of onion (Allium cepa L.) under different levels of N fertilization and irrigation regime. (145)
Onion (Allium cepa L.) is one of the most important vegetable crops grown in the dry seasons of northern Nigeria. The value of the crop depends on the bulb size and storability. Field experiments were conducted during the 1993-94 and 1994-95 dry seasons at Kadawa in the Sudan Savannah ecological zone of Nigeria (11 °39' N, 08°02' E) to investigate the effect of four N levels (0, 55, 110, or 165 kg ha-1) and four irrigation regimes (40 mm, 60 mm, or 80 mm cumulative pan evaporation, and seven-day irrigation interval) on bulb yield, size distribution, and storability of onion. Nitrogen application positively increased the bulb yield, average bulb weight, and number of large bulbs per plot. While N had no effect on per cent storage loss up to 19 weeks after harvest (WAH), it affected per cent loss at 16 WAH in 1995. Irrigation at seven-day intervals produced higher bulb yield, average bulb weight, and number of large bulbs per plot. There was no significant effect on the per cent loss at any of the sampling periods during both years except at 6 WAH in 1994. Onion yield was correlated negatively and significantly with the number of small bulbs per plot, but positively correlated with the number of large bulbs per plot in both years. There was no correlation with per cent storage loss which was never >7% during the 19- or 16-week storage periods.
Keywords: Onion; Nitrogen; Irrigation; Bulb size; Storage