Effect of Proline and Glycine betaine in Improving Vegetative Growth of Washington Navel Orange (Citrus sinensis L.) Under Salinity Conditions


The current experiment was conducted to study the effect of proline and glycinebetaine at two concentrations for each i.e. 50 and 100 mM in addition to control and two salts; sodium chloride and calcium chloride at tow concentrations 25 and 50 mM in addition to control, in vegetative characters of Washington navel orange (Citrus sinensis L.) grafted on volkamer lemon or swingle citrumelo rootstocks. Salts were added to the irrigation water and seedlings were irrigated with saline water three times at three month interval. After one week of the irrigation with saline water, seedlings were sprayed with the osmo protectants (three sprays). Treatments were arranged in Random Complete Block Design (R.C.B.D.)as a factorial experiment with three replications. The results revealed that the two rootstocks had no effect on the vegetative parameters measured except the total chlorophyll content in leaves for seedlings grafted on swingle citrumelo rootstocks. The use of the two protectants at all concentrations caused significant increase in seedling height, leaf area, number of leaves, dry weight of shoot and roots and the total chlorophyll content in leaves, while they did not affect the number of branches. Glycine betaine was superior in its effect compared to proline. Also, the two salts had inhibitory effects on most of the parameters measured exceptleaf area. The combination between rootstocks and osmoprotectants had significant effect on most growth parameters. In general, most of the two combinations had pronounced effects. The combination of the three factors are also effect the parameters significantly. From the above results, we can conclude that the two salts had an inhibitory effect on growth characters which can be improved by the addition of glycine betaine and proline.