Spear height at harvest influences postharvest quality of asparagus (Asparagus officinalis)

Abstract

Asparagus (Asparagus officinalis L.) spears harvested at intervals during a 24-h cycle exhibited a clear diurnal pattern in postharvest shelf-life, with spears harvested at 0200 h lasting 1.1 days longer at 20°C than spears harvested at 1400 h. Susceptibility to tip rot did not appear to fluctuate with harvest time during the day, but was clearly influenced by time of season. Early season harvests were less susceptible to tip rot, and short spears (50 mm) were less susceptible than tall spears (250 mm). Tall spears had lower levels of soluble carbohydrate, and much greater proportions of axillary bud tissue than short spears. First signs of tissue damage during tip rot development were observed in floral buds with collapse of the generative tissue. As damage increased, bracts, then vegetative buds, and the main stem axis were affected. Microbial growth developed on the surface of damaged tissue. Starch grains present in the stem axis or pith tissue disappeared within a day of harvest, but starch localised in a distinct band eight cells in from the cuticle remained until Day 5 after harvest. The postharvest management of longer grades of asparagus spears will be more difficult than shorter grades, and spears harvested in cool conditions will be higher quality than spears harvested in warm conditions.