Abstract

Aim: The study was carried out to investigate effect on tree yield and fruit quality characteristics at harvest and during shelf life.

Materials and Methods: The study was conducted during 2015 and 2016 seasons on ten years old Washington navel orange trees grown in clay soil which were sprayed three times in  July, September and November with gibberellic  acid  at 30ppm and  ascorbic acid, citric acid  and salicylic acid each at 400ppm (for all spraying times). Trees were harvested in the end of January (late season).

Results: All sprayed substances delayed fruit peel ageing, fruit color break and decreased preharvest fruit drop. It was also indicated that gbberellic acid treatment increased canopy volume index, shoot length, fruit peel thickness, leaf calcium and fruit peel resistance. Moreover ascorbic acid sprays led to an access in fruit length, fruit diameter, leaf nitrogen, potassium and calcium, V.C., TSS and TSS /Acidity. Citric acid increased leaf area whereas ascorbic acid and citric acid treatments gave higher trunk across, total and reducing sugars. Salicylic acid application enhanced chlorophyll a and b, yield, fruit peel thickness, acidity and fruit peel resistance. Application of previous antioxidants then storage at room temperature for a week and two weeks revealed that ascorbic acid application increased VC, TSS, TSS/acidity and total sugar. Also, ascorbic acid and citric acid treatments increased reduced and unreduced sugar. Citric acid spraying led to an increase of weight loss than all other treatments. Gibberellic acid and salicylic acid application enhanced Fruit peel resistance.  All antioxidants treatments reduced decay as compared with control. The  TSS, TSS/Acidity, total and non reducing sugars, fruit weight loss percentage decay  of citrus fruits were increased  whereas, acidity, reduced sugar and fruit peel resistance  were decreased gradually and significantly by increasing storage periods.

Conclusion: It was concluded that gbberellic acid treatment increased canopy volume index, shoot length, fruit peel thickness, leaf calcium and fruit peel resistance. Moreover ascorbic acid sprays led to an access in fruit length, fruit diameter, leaf nitrogen, potassium and calcium, V.C., TSS and TSS /Acidity.

Statistics