A study of the effect of the environment during growth on sprouting of bulb onions in store

The partition of dry matter between leaf and bulb with sheath was studied in relation to the post-harvest physiology of cvs Bola and Robusta grown at three sites for two seasons and dried and stored under standardized conditions. Foliar fall-over was synchronous at all sites in each season but the effects of site showed that crops either partitioned dry matter to the bulb early, lost less fresh weight in drying and sprouted later in store, or partitioned dry matter late, lost more fresh weight in drying and sprouted sooner in store. Crops showing the former behaviour were associated with low rainfall and a high number of day degrees between 6° and 20°C during early growth. There was up to 10 days difference between the sites in 50% sprouting dates. Bulbs of cv Bola sprouted earlier than those of cv Robusta, and bulbs harvested when foliar fall-over was negligible sprouted before those from later harvests. There were no site effects on plant maturity, on bulb growth regulator content (cv Robusta one year only), on sugar content at harvest or during storage, on bulb respiration rates at the end of drying or in the spring, or on bulb weight loss during storage.