Use of paclobutrazol sprays at mid-anthesis for increasing fruit size and yield of avocado (Persea americanaMill. cv. Hass)

Abstract

SummaryMid-anthesis foliar sprays of paclobutrazol (PB) at 2.5, 1.25 and 0.62 g a.i. I-1 reduced spring growth and altered dry-matter distribution in fruiting spring shoots of ‘Hass’ avocado.(Persea americana Mill.) trees. There was a decrease in dry matter allocation to vegetative components and an increase in allocation to fruit. The starch concentration in the wood of spring shoots on trees treated with 2.5 g a.i. I-1 foliar PB was increased by ca. 70% compared with spring shoots from trees of other treatments. The mid-anthesis foliar treatments also reduced summer growth by ca. 20%. Trunk injection of PB at 0.2 g a.i. m~2 of canopy silhouette area when the spring growth matured, in addition to a mid- anthesis foliar spray of 1.25 g a.i. I-1, reduced the length of summer shoots by 36% when compared with untreated trees. The spray treatments of 2.5 and 1.25 g a.i. T1 PB at mid- anthesis increased the mean fruit size at harvest by 16 and 11% respectively. Fruit yield was not significantly affected by PB ...