Spring application of growth regulators affects fruit quality of `Blood Red' sweet orange

Spring applications of two plant growth regulators (GA3 and 2, 4-D) alone and in combination, were tested on 'Blood Red' sweet orange trees at full bloom. Ultimate effects of these growth regulators were studied on external and internal fruit quality. Fruit weight, diameter, peel thickness and peel quantity were significantly decreased by the growth regulator treatments compared with control while juice contents (%), pulp (%), reducing sugars, non-reducing sugars and total sugars, seeds quantity and quality were significantly improved by GA3 treatments compared with control. TSS (%), Vitamin C contents were increased by growth regulators treatments compared with non treated ones. In organoleptic tasting, taste, peel colour, pulp colour and appearance were also improved by growth regulator treatments compared with control. In conclusion mixture treatments performed best with regards to biochemical parameters compared with control.