Effect of ascorbic acid on some morphological and physiological characteristics of Pelargonium graveolens under iron deficiency

In order to study the effect of ascorbic acid (AsA) on quantitative and qualitative characteristics of Pelargonium graveolens under iron (Fe) deficiency stress, a pot experiment was carried out. Three levels of Fe (0, 20 and 40 µM) and three levels of AsA (0, 1 and 2 mM) were combined factorially based on a completely randomized design with six replications. Uniform rooted cutting were planted in sand and grown hydroponically. After plant establishment, Fe and AsA treatments were applied through half-Hoagland nutrient solution. Results showed that as Fe in nutrient solution decreased, growth characters i.e. plant height, stem diameter, number and length of axillary shoots and leaf area decreased. Moreover, as Fe in nutrient solution decreased, leaf fresh and dry weight, stem fresh and dry weight, decreased, while, oil content increased. Growth responses to AsA was different in plants grown in nutrient solution with 0 µM Fe compared with those in plants grown in nutrient solution containing 20 µM Fe. Daily application of AsA (especially with 1 mM concentration in nutrient solution) increased biomass and oil content. Oil yield, Chlorophylls and carotenoids contents decreased with decreasing Fe, while, AsA increased them under Fe deficiency. Overall, AsA could improve growth and yield of geranium under 20 μM Fe nutrition, however, it was less effective at 0 μM Fe.