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Gibberellic acid sprays, girdling, flower thinning and potassium applications affect fruit splitting and yield in the ‘Ellendale’ tangor

1996; Taylor & Francis; Volume: 71; Issue: 2 Linguagem: Inglês

10.1080/14620316.1996.11515397

0022-1589

E. Rabe, Peet Jansen van Rensburg,

Postharvest Quality and Shelf Life Management

SummaryThis study quantified the effect of fruit set treatments on preharvest fruit splitting, a serious problem in the 'Ellendale' tangor, as well as treatments aimed at alleviating fruit splitting incidence. Treatments, during the full bloom period, aimed at increasing fruit set, viz. GA3 sprays and girdling, increased fruit splitting to between 30 to 60% of final yield. This related to a significant shift/delay in the normal fruit drop pattern. Only the girdling treatment during fullbloom significantly (P<0.05) increased final yield. The blossom GA3 sprays increased yield only slightly while the postbloom GA3 sprays, varying from 10 to 20mgl–1, did not affect final yield at all. In this study various approaches to reduce fruit splitting in 'Ellendale' tangor were tested: (i) specific chemical and mechanical flower thinning treatments reduced fruit splitting, without adversely affecting yield; (ii) potassium sprays, applied from ten weeks before fullbloom to six weeks after full bloom achieved limited success, possibly due to an increase in initial fruit set levels. No clear correlation was obtained between the rainfall pattern during the growing season and fruit splitting levels at specific intervals. Evidence is presented that the potential for fruit splitting is determined during the early stages of fruit growth, suggesting that any treatment aimed at alleviating fruit splitting should be applied early. Late treatments, such as reducing crop load by late thinning, as observed in this study, had no beneficial effect in lowering fruit splitting. Any treatment causing high initial fruit set increases fruit splitting.