The effect of time of scoring on yield, fruit and shoot growth and reproductive bud development on 'Royal Gala', 'Fuji' and 'Cripps' Pink' apple trees
2011
Pretorius, J.J.B. | Theron, K.I. | Midgley, S.J.E.
The effects of scoring of apple tree trunks at one, two, four, six or eight weeks after full bloom (WAFB) were investigated with respect to fruit and shoot growth, yield and return bloom. Scoring at one and two WAFB improved fruit set (higher yield efficiency) on ‘Royal Gala’, but not on ‘Fuji’ or ‘Cripps’ Pink’. The high crop load on ‘Royal Gala’ trees scored one WAFB resulted in smaller fruit size from the second harvest (main crop) compared to the other treatments. Compared with control trees, scoring (all scoring times) reduced final extension shoot length only on ‘Fuji’ trees. Final fruit size was improved on ‘Fuji’ (practically but not statistically significant) and ‘Cripps’ Pink’ trees scored two or four WAFB compared with all other treatments. Scoring improved reproductive bud development on all cultivars and on all bud types. On ‘Royal Gala’ and ‘Cripps’ Pink’, the efficacy of scoring to stimulate reproductive bud development on old and new spurs declined four WAFB and thereafter. In ‘Fuji’, scoring later than one WAFB showed a decreasing positive response on old and new spurs. In contrast, reproductive bud development on long shoots increased with later scoring (six and eight WAFB) on all cultivars. It seems that the most beneficial time for scoring is two to four WAFB, as early as possible during the cell division stage of fruit growth, but not before natural initial fruit set has occurred, and as soon as possible after the cessation of bud elongation.
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