PROHEXADIONE-CALCIUM AND NAA SPRAYS INCREASE FRUIT WEIGHT OF ‘CASTLEBRITE’ APRICOT

Over a three year period, several experiments were performed to compare the effect of pruning method, trunk girdling, thinning date and plant growth regulator sprays on fruit weight and yield efficiency of ‘Castlebrite’ apricots (Prunus armeniaca). Trials were done in a mature commercial orchard in the central part of Chile (33°45’ S; 70°41’W). Trees were planted at 4×2.5 m and V trained.
Pruning treatments were: heading back of shoots arising from laterals along the V axes, and stubbing back of laterals to promote renewals of them along the axes.
Trunk girdling was performed at the beginning of pit hardening (BPH). Thinning date at BPH and at petal fall was compared.
CPPU (15 mg•L^-1; 15 days before harvest), Prohexadione-calcium (P-Ca, 3 sprays) (Regalis^®, BASF, Germany), NAA (15 mg•L^-1; 1 or 2 sprays) and Triclopyr (Maxim^®; 10 mg•L^-1; 1 spray) applications were also assessed.
No effect of pruning method was detected.
Fruit size was increased 5% with girdling, and 40% when thinning was performed at petal fall in a season of extremely high fruit set.
P-Ca, NAA (2 year trial) and Maxim^® (tried 1 year) showed 10 to 20% fruit size increase.
The greatest PGR effect on fruit size was obtained with P-Ca or two NAA sprays, but severe growth stunt was evident when they were applied in the same treatment.
No effect on fruit size was detected with CPPU.

IX International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems

G.H. Reginato, K.G. Mesa

Prunus armeniaca, girdling, thinning time, CPPU, pruning

https://doi.org/10.17660/ActaHortic.2011.903.117