Onion: Effect of sowing date on maturity, yield, and quality of ‘pukekohe longkeeper‘ and ‘early longkeeper’

Abstract

Three field experiments, in successive seasons from 1981 to 1983, tested the effect of six sowing dates, at c. 3-week intervals from early May, on maturity, yield, and quality of the onion cultivars, Allium cepa L. ‘Pukekohe Longkeeper’ (PLK) and ‘Early Longkeeper’ (ELK). Sowing date had little effect on crop maturity date, which was about 22 days earlier for ELK than for PLK. Maximum total yield was recorded for the third sowing date for PLK (95 t/ha) and for the second sowing date for ELK (82 t/ha), and declined steadily with later sowing dates. The earlier sowing dates resulted in a high proportion of bulbs that bolted for both cultivars and severely reduced marketable yield. Reduction in total yield at the later sowing dates was caused by a reduction in average bulb size. The yield of marketable bulbs of > 57 mm diameter declined from 75 t/ha and 57 t/ha for PLK and ELK at the third and second sowing dates respectively, to 30 t/ha and 14 t/ha at the sixth sowing date. The effect of sowing date on the balance between quantity and quality of yield suggests that the optimum time to sow onions at Pukekohe is early June for ELK and late June for PLK. © 1986 Taylor & Francis Group, LLC.