Effect of a Synthetic Auxin on Fruit Size in Two Cultivars of Apricot

The aim of the present research was to study the effect of treatments with 3,5,6-TPA sprayed at different concentrations (4 ppm, 8 ppm, 12 ppm and 16 ppm) on yield and some fruit qualitative traits of an early-ripening ('Ninfa') and a late-ripening apricot cultivar ('Pellecchiella') in comparison with untreated (control) trees. Treatments induced an increase in fruit yield/ha, due to the increased fruit size. An advanced ripening period was recorded in all treatments compared to untreated plants. The most effective application was the 16 ppm treatment that allowed harvesting 60% of the whole yield at the first picking compared to nearly 38% of control trees. Treatments did not affect fruit quality significantly. Indeed, some physical and chemical parameters, such as skin colour, flesh firmness, soluble solids content and titratable acidity at harvest were similar in fruit from control and sprayed trees. Thus, these treatments appeared to accelerate fruit growth and ripening, without any apparent undesirable effect on fruit quality. The effects of 3,5,6-TPA application on fruit weight and total yield per tree are discussed.