EFFECT OF DORMANT PRUNING REGIMES ON CANOPY LIGHT DISTRIBUTION, FRUIT AND SPUR QUALITY, AND FRUIT PACKOUT OF `MCINTOSH' APPLES.

Abstract

A randomized complete block study was initiated in 1991 in a fifteen year old `Rogers Red McIntosh'/9-106 interstem orchard to investigate the effect of three dormant pruning regimes- an unpruned control, selectively thinned, and heavily structured or “tiered”, on tree canopy light distribution and fruit and spur quality. Fruit quality parameters being measured for the 1991 and 1992 harvests include skin color (% red blush), weight (g.), flesh firmness (kg.), soluble solids concentration (% Brix), and packout (% fancy grade). Pruning treatment effect on fruit spur quality, in terms of spur bud diameter (mm.) and spur efficiency (leaf dry weight/spur), is also being evaluated at time of harvest. Light distribution is being measured (% PAR, umol/s/m2.) within the tree canopy from petal fall through harvest. Preliminary findings indicate there is a difference in tree canopy light distribution and some fruit quality measurements, including red skin color, between pruning regimes. Complete analysis of results from 1991 will be presented.