Auxin (triclopyr) and cytokinin (forchlorfenuron) differentially affect fruit physiological, organoleptic and phytochemical properties of two apricot cultivars

Abstract

Two plant growth regulators (PGRs), one auxin analog i.e. triclopyr and one cytokinin i.e. forchlorfenuron were applied on two apricot cultivars (“Nafsika” and “Niovi”) during the early stages after fruit set (cytokinin) and at the beginning of pit hardening (auxin). The two PGRs were applied either alone or in combination, each at the time indicated above. The fruit growth rate along with fruit physiological, organoleptic and phytochemical characteristics was assessed during two successive years. In all treatments where auxin was included, the growth rate of the fruits was significantly enhanced. Fruit weight increased significantly with auxin (by 30% in “Niovi” and 34% in “Nafsika”), as well as the diameter in chicks and suture line along with fruit length, without altering fruit shape, as confirmed by fruit shape index and sphericity calculations. Although the concentration of carbohydrates was not significantly different among treatments, the overall carbohydrate content of the fruit was significantly enhanced by auxin application. Total phenolic compounds as well as individual phenolic ones and antioxidant capacity of the fruit were not influenced by PGRs application. Cytokinin did not enhance fruit quality parameters, while at the same time retarded maturation, as the fruits retained the green color, firmness was quite high as were also the total organic acids and titratable acidity. The present findings support even further the use of auxin as the PGR of choice for stone fruits and especially for apricot, while cytokinin do not seem to be able to improve fruit quality characteristics.