The present investigation was conducted to investigate the possible changes
in the growth, photosynthetic pigments and metabolic activities associated with foliar
application of ascorbic acid at the concentrations of 0, 200, 400 and 600 mg/I when
applied to two cultivars of tomato plants after 4 weeks from transplanting, Plant height, number of leaves and number of flower per plant were stimulated with lower concentrations of ascorbic acid in both cultivars of tomato plants. The data showed .that increasing ascorbic acid concentrations up to 600 mg/I had no significant effect on plant height on both cultivars of tomato plants while dry weight of leaves, stems and roots per plant were significantly decreased, Photosynthetic pigments (chl.a, chl.b and carotenoids) were enhanced as a result of foliar application with ascorbic acid. Moreover, the most effective treatments for enhancing. chlorophyll a, b , a + band carotenoids in leaf tissues was observed at higher concentration of ascorbic acid (600 mg/I) in Ace cultivar and at lower concentrations of ascorbic acid (200 and 400 mg/I) in Castierock cultivar, Ascorbic acid treatments tended to decrease carbohydrate fractions in different organs (leaves, stems and roots) of tomato cultivars. Whereas, nitrogen
fractions was improved at most treatments of ascorbic acid, The marked increase in
the level of photosynthetic pigment contents was accompanied by lower accumulation
in dry matter and carbohydrate fractions in different organs of tomato plants, could be
due to the effect of ascorbic acid on the utilization and translocation of assimilates into
different organs of tomato plants,