This study was carried out through two consecutive seasons 2016 and 2017 to investigate the effect of spraying with some antioxidants on vegetative growth, yield, fruit quality and nutritional status of twelve years old Navel orange trees on sour orange rootstock grown in a private orange orchard in Qalubia Governorate, Egypt cultivated in a silty clay loam soil. This experiment involved three antioxidant materials named (salicylic acid, citric acid and folic acid) and each one spraying by three levels of each of with (250, 500 and 1000 ppm) from each salicylic, citric and folic acid plus control treatment so the experiment included ten treatments. Selected trees were spraying three times (at the beginning of the growth cycle in March, just after fruit setting in May and just after June drop in July) by aqueous solution of salicylic acid, citric acid and folic acid until the point of runoff. The highest values of vegetative growth were obtained by spraying 500 ppm salicylic acid, 1000 ppm citric acid and 500 ppm folic acid. Regarding to yield, results pointed out that the foliar spraying with 500 ppm salicylic acid, 500 ppm citric acid and 250 ppm folic acid gave the highest values of yield. Treatments 500 ppm salicylic acid, 250 ppm citric acid and 250 ppm folic acid gave the highest values of physical and chemical fruit properties. In respect to nutrients content, the highest values of macronutrients were obtained by spraying 250 ppm folic acid, while that spraying 1000 ppm salicylic acid and 250 ppm folic acid gave the highest values of micronutrients. Therefore, using treatments 500 ppm salicylic acid, 500 ppm citric acid and 250 ppm folic acid may be recommended from economical point of view and as good treatments for enhancing Navel orange growth, yield, fruit quality and nutritional status especially under old citrus orchards.

The protective effect of folic acid (FA) on he-patic oxidative stress in aged rats exposed to oxi-dative stress by supply drinking water with 1% H2O2 (v/v) was studied. Rats were divided into two groups, the first group was considered as standard one (F1) which was fed on basal diet and administrated 1 mg FA/ Kg body weight (BW) daily by stomach tube without addition H2O2 in drinking water. The second group was divided into five subgroups, the first subgroup was the control (F2) which fed on basal diet free from folic acid (FF) with 1 % H2O2 in the drinking water, while other groups from F3 to F6 were adminis-trated different concentrations of folic acid (1, 20, 40 and 80 mg FA/ Kg BW), respectively. Weight gain, total feed intake, feed efficiency, liver weight and its relative weight were estimated. Bi-ochemical assay: activity of antioxidant enzymes system such as superoxide dismutase (SOD), cata-lase (CAT); lipid peroxidation level as malondial-dehyde (MDA), hydrogen peroxidase (H2O2); and liver functions [alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phos-phatase (ALP) and gamma glutamyl transferase (γ-GT), and lactate dehydrogenase (LDH)], were determined. Additionally, total protein (TP), al-bumin, globulin, A/G ratio, total bilirubin, direct bilirubin, indirect bilirubin; and kidney functions [creatinine, urea, and uric acid]; and lipid profile as [total cholesterol, HDL-cholesterol and LDL-cholesterol, and triglycerides] were also, carried out. The obtained results showed accumulated weight gain which significantly increased in rats group administrated 40 and 80 mg/ Kg BW/d folic acid. No changes in relative liver weight among tested rat groups were recorded. No significant difference was observed in lipid profile, LDH and SOD between groups (F1 and F6). Data also indi-cated that F1 group recorded the best one which was low in MDA and high in CAT, followed by F6. Folic acid showed no effect on kidney func-tions. No histopathological changes were observed in liver of rat groups administered 40 or 80 mg folic acid / Kg BW/d, thus indicating that supple-mentation with high doses of FA had a protective effect from the hepatic oxidative stress in liver of tested rats.