MATURITY AND STORAGE EFFECTS ON POSTHARVEST ONION QUALITY

Abstract

A two-year field study was conducted to evaluate the effects of maturity and storage on fresh market onion quality. Four short day onion cultivars (NuMex BR1, NuMex Sunlite, NuMex Starlite and Buffalo) were seeded in early October of both years. Bulbs were harvested at 5 different times, with harvest #1 when 20% of the bulbs in a plot had mature necks. The second harvest was when 80% of the bulbs in a plot had matured. Harvests #3, #4 and #5 were at 5, 10 or 15 days after the second harvest date. After curing, bulb firmness and weight, and the incidence of bulb diseases were evaluated for the 5 harvest dates. Bulbs were re-evaluated after 10 and 20 days storage in a shed under ambient conditions. Average bulb weight increased from 181.6g to 274.1g as harvest was delayed. Bulb firmness decreased from 56N to 52N. Percent diseased bulbs increased for all cultivars as harvest was delayed in 1991, while in 1992 this trend was not observed. In storage, average bulb weight and firmness decreased, while the incidence of bulb diseases increased greatly regardless of harvest date. Storage diseases were primarily Aspergillus niger and bacterial soft rot.