EFFECTS OF AUXINS SPRAYS ON YIELD, FRUIT SIZE, FRUIT SPLITTING AND THE INCIDENCE OF CREASING OF ´NOVA´ MANDARIN

J. Greenberg, I. Kaplan, M. Fainzack, Y. Egozi, B. Giladi
Effects of the plant growth regulators (PGRs) 2,4-dichlorophenoxyacetic acid (2,4-D, 40 mg•L-1), naphthaleneacetic acid (NAA, 300 mg•L-1) and 3,5,6-trichloro-2-piridil oxyacetic acid (3,5,6-TPA, 15 mg•L-1) on yield, fruit size, fruit quality, fruit splitting and the incidence of creasing of ‘Nova’ mandarin [hybrid of Citrus clementina Hort. ex Tanaka × (Citrus paradisi Macf. × Citrus tangerina Hort. ex Tanaka)] were studied. All PGR solutions were tank-mixed with ‘Bonus-NPK’ fertilizer (5%). Sprays were applied to whole trees twice: early spray –at 13-mm fruitlet diameter and late spray – at 26-mm fruitlet diameter. Most fruit splitting occurred between the beginning of October and the beginning of November and the total fruit drop in the unsprayed controls, caused mainly by splitting, accumulated to 150 fruits/tree (35% of the fruit). The early spray of 2,4-D decreased fruit splitting to 25%, increased yield to 50 kg/tree compared to 37 kg/tree in the control, increased fruit size and had no effect on the incidence of creasing. The early NAA spray, thinned fruitlets, increased fruit size, decreased splitting to 30%, decreased the incidence of creasing to 28% compared to 36% in the control, and had no effect on the yield. The late NAA spray did not thin fruit and had no effect on fruit size but the number of fruit harvested and yield was increased to 52 kg/tree due to reducing split fruit drop to 21%, and the incidence of creasing was reduced to only 10% of the fruit. The early 3,5,6-TPA spray caused strong fruitlet drop and only 44 fruit/tree were harvested. The late 3,5,6-TPA spray did not thin fruit, had no effect on fruit size, reduced the incidence of creasing to 22% and reduced fruit splitting to 17%, increasing yield to 52 kg/tree. These data suggest that late sprays of auxins on fruitlets that do not affect fruit size and do not thin fruitlets anymore, are effective for reducing fruit splitting and the incidence of creasing of 'Nova' mandarin.
Greenberg, J., Kaplan, I., Fainzack, M., Egozi, Y. and Giladi, B. (2006). EFFECTS OF AUXINS SPRAYS ON YIELD, FRUIT SIZE, FRUIT SPLITTING AND THE INCIDENCE OF CREASING OF ´NOVA´ MANDARIN. Acta Hortic. 727, 249-254
DOI: 10.17660/ActaHortic.2006.727.28
https://doi.org/10.17660/ActaHortic.2006.727.28
Citrus, fruit thinning, 2,4-D, NAA, 3,5,6-TPA, Nova mandarin [hybrid of Citrus clementina Hort. ex Tanaka × (Citrus paradisi Macf. × Citrus tangerina Hort. ex Tanaka)]
English

Acta Horticulturae