The synthetic auxin 3,5,6-TPA stimulates carbohydrate accumulation and growth in citrus fruit

Abstract

The application of the synthetic auxin 3,5,6-TPA at the cell enlargementstage increased hexoses in developing fruit from foliated and fully defoliatedplants of Satsuma mandarin, cv. ‘Okitsu’ (Citrusunshiu Marc.). Although the sucrose concentrations also increased,ingeneral the differences were not statistically significant. The plant growthregulator reduced fruit abscission in defoliated trees while it stimulatedfruitgrowth in the foliated ones. The carbohydrate accumulation induced by 3,5,6-TPAindicates that its stimulatory effect on fruit growth might operate viapromotion of sink strength. The results also suggest the occurrence of pathwaysfor induction of fruit abscission, linked to carbon availability, relativelyindependent of the stage of development.