DELAYED HARVEST EFFECTS ON YIELD, FRUIT SIZE AND STARCH CYCLING IN AVOCADO (PERSEA-AMERICANA MILL) IN SUBTROPICAL ENVIRONMENTS .2. THE LATE-MATURING CV HASS

Effects of early and delayed harvest were investigated in 'Hass' avoca do, at Childers, a warm subtropical site (over 4 years), and at Maleny , a cool, mesic subtropical site (over 3 years) in S.E. Queensland. Ea rly harvesting at 25 to 30% flesh dry matter (DM) sustained high produ ctivity (especially at the cooler site), but a delayed harvest up to 4 months later at 35% flesh DM eventually depressed yield (at Childers) and precipitated alternate bearing. Split harvests (early and late) w ere less detrimental to sustainability of high yields (> 20 t ha(-1)). Where alternate bearing was already entrenched at the start of the ex periment at the cooler site (Maleny), early harvest was insufficient t o break this pattern. Starch cycling in trunk wood and new shoots foll owed predictable seasonal patterns, and peak concentrations were reduc ed by heavy fruiting, Pre-flowering starch concentrations in shoots (C hilders) or trunks (Maleny) were directly correlated to the following seasons' yield.