Impact of Citric Acid, Ascorbic Acid and Some Nutrients (Folifert, Potaqueen) on Fruit Yield and Quality of Washington Navel Orange Trees

The present study was conducted on 11-year-old Washington navel orange trees budded on sour orange rootstock grown in loamy sand soil under surface irrigation system at a private orchard at Manzala village, Toukh region, Qalubia Governorate, Egypt during 2015 &2016 seasons. to investigate the influence of foliar application with citric acid (CA) 1 g/L, ascorbic acid (AA) 1 g/L, Folifert 1.5 g/L and Potaqueen 3 g/L on fruiting aspects and fruit quality. However, the beneficial effect varied greatly from one investigated treatment to another. Anyhow, the treatment T12 (Ascorbic acid at 1 g/L+ Folifert at 1.5 g/L + Potaqueen at 3 g/L) was statistically the superior for Washington navel orange trees during two experimental seasons. Also T11 (Citric acid at 1 g/L+ Folifert at 1.5 g/L+ Potaqueen at 3 g/L) came second. The reverse was true with the water sprayed treatment (control) which ranked statistically the last rank during the two experimental seasons the trend was true almost with all the investigated measurements, fruiting aspects (fruit set, fruit retention and yield as No. or weight of harvested fruits per trees besides yield per one tree, and fruit quality: a- physical properties (average fruit weight, fruit dimension s, shape index, peel thickness and fruit juice volume), b- chemical properties (TSS%, total acidity %, TSS/Acid ratio, total sugars and vitamin C contents). On the other hand, nine other investigated treatments were in-between the aforesaid two extremes, in spite of the statistically varied as compared to the abovementioned superior (T12) and inferior (T1) treatments during two experimental seasons.