SINK STRENGTH AS RELATED TO CPPU MOBILITY AND APPLICATION SITE IN APPLE AND KIWIFRUIT SPURS.

The cytokinin-like substance CPPU is known to promote cell division and to increase fruit size when applied during the first stages of fruit development of apple and kiwifruit.
Little information is available on its translocation and ability to reach the fruit and to change relative sink strength.

Labelled-CPPU application to leaves resulted in greater recovered activity and measurable distribution in other plant parts; however, neither in apple nor in kiwifruit did untreated fruits accumulate the chemical.
CPPU application to leaves, to fruitlets or both to leaves and fruitlets, did not change ¹⁴CO₂ assimilation of treated or untreated apple leaves, the average recovery of the applied ¹⁴CO₂ being 30% in all the tested models.
Fruit ability to divert assimilates depended upon the type and the development stage of leaves more than upon CPPU application.
CPPU-sprayed bourse-shoot leaves of apple showed less ability to export assimilates three weeks after full bloom and completely recovered two weeks later.

VII International Symposium on Plant Growth Regulators in Fruit Production

D. Neri, R. Biasi, S. Tartarini, N. Sugiyama, R. Giuliani, S. Sansavini, G. Costa

https://doi.org/10.17660/ActaHortic.1993.329.11