SURVEY OF RATES AND TIMING OF NAA SPRAYS AS FRUIT THINNER IN THREE PEAR VARIETIES IN CHILE

NAA was sprayed in rates of 10, 15 and 20 ppm between 10 to 26 days after petal fall (dapf) in the cultivars Winter Nellis, Bartlett and Sensation Summer Red Bartlett (S.R. Bartlett). Each combination of timing and rates was sprayed on two trees.
The thinning effect was evaluated (50 days after blooming) as fruits per 100 spurs when natural fruit finished.
At harvest time the yield and fruit weight per tree and also the amount of fruit per cm² of trunk cross sectional area (TCSA), were evaluated.
Results were analyzed through regressions and correlations.
In S.R. Bartlett, no correlation was found at harvest time between the different crop loads expressions and fruit weight.
No correlations between crop load and rate or timing of NAA application were found.
In Bartlett and W. Nelis the highest correlation was found between crop load and fruits/cm² TCSA (r² =0.51 and r²=0.43 respectively). For both W. Nelis and Bartlett, crop load was dependent on timing and NAA rates (r²=0.56 and r²=0.57). In Bartlett, NAA tend to increase crop load over the non-treated trees as the spraying is delayed.
In W. Nelis all combinations had effect on fruit thinning.

VII International Symposium on Pear Growing

G. Reginato, R. González

Pyrus communis L., chemical fruit thinning, crop load

https://doi.org/10.17660/ActaHortic.1998.475.46