EFFECT OF N-PHENYL-N’-(4-PYRIDYL)UREA (4-PU) ON FRUIT SIZE: APPLE JAPANESE PEAR, GRAPEVINE AND KIWI FRUIT

Applications of N-phenyl-N'(4-pyridyl)urea (4-PU) or gibberellin A4 plus 4-PU after full bloom (AFB) increased fruit weight of apple and Japanese pear. 4-PU treated fruits were longer with prominent well developed calyx lobes.

Application of 25 ppm gibberellin A3 plus 5 or 10 ppm 4-PU at 10 days AFB increased berry weight of grape cv.
Kyoho by 15% over that of untreated control.
On young fruit of cv.
Hayward kiwifruit a single dipping treatment of 5 to 20 ppm 4-PU plus Atrox at 10, 20 and 30 days AFB enhanced fruit weight by 50% to 60% over that of the untreated control.
However, application of higher concentrations of 4-PU caused fruits to develop abnormal calyx lobes and to develop cracking around the base of the fruit.

VI International Symposium on Growth Regulators in Fruit Production

R. Ogata, T. Saito, K. Oshima

https://doi.org/10.17660/ActaHortic.1989.239.66