ISHS Acta Horticulturae 463: VIII International Symposium on Plant Bioregulation in Fruit Production
GA SPRAYS DELAY AND REDUCE PHYSIOLOGICAL FRUIT DROP IN PONKAN MANDARIN (CITRUS RETICULATA BLANCO) |
| Author: | S. Tominaga |
| Keywords: | Ponkan mandarin (Citrus reticulata Blanco), gibberellic acid, fruit with and without pedicel, abscission pattern |
| Abstract:
This study was conducted to clarify the effects of exogenous gibberellic acid (GA) on fruitlet abscission in ponkan mandarin, (Citrus reticulata Blanco cv. Yoshida), and a low yielding citrus cultivar. GA sprayed at or one month after anthesis it increased fruit set by about 65%. GA application at anthesis decreased drop of both fruitlets with or without pedicels, while application at one month after anthesis decreased mainly the drop of fruitlets without pedicels. Abscission of fruitlets without pedicels began about 10 days later in trees sprayed at anthesis compared to the control. In those sprayed one month after anthesis it began one month later than the control. Of the two observed major fruitlet abscission peaks, GA delayed the second peak, this occurred early to mid-June in the control, late-June in the anthesis-application and lastly early to mid-July in the one-month post-anthesis application. Fruits on sprayed trees were comparatively smaller in size and had less number of seeds. Seed reduction was more severe in smaller fruits (1–2 seeds/fruit) than large ones but the large fruits on sprayed trees had similar seed number to those on the non-sprayed control (5–6 seeds). Fruit quality was not affected although peel disorders were ameliorated by GA application. | |
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