EFFECT OF NPK AND GIBBERELLIC ACID ON GROWTH AND QUALITY OF CYCAS REVOLUTA”THUNB.”

A series of pot experiments was consummated in open field at the nursery of  Hort. Res. Inst., Giza, Egypt during 2014 and 2015 seasons to find out the effect of NPK at 2 g/pot, gibberellic acid at 500, and 1000 ppm concentrations (as a foliar spray 6 times with one month interval) and their interaction on vegetative and root growth and chemical composition of 1-year-old Cycas revoluta,Thunb. plants grown in 20-cm-diameter plastic pots filled with about 2.5 kg of a mixture of washed sand, and compost (3:1, v/v). The obtained results indicated that all fertilization treatments significantly improved all vegetative and root growth traits of plants used in this study compared to control, especially the combined treatment between NPK at 2 g/pot  and gibberellic acid at 1000 ppm as well as, the leaves content of chlorophylls a and b, carotenoids and total carbohydrates, N, P and K% which were significantly increased in response to the different treatments employed in the present study, with the superiority of the combination between NPK at 2 g/pot and GA3 at 1000 ppm. The least record, on the other hand, was found due to NPK at 5 g/l alone. A similar trend was also obtained concerning the contents of chlorophyll a, b, carotenoids, N, P and K%. Hence, in order to get the best vegetative and root growth it is recommended to treat the plants with NPK at 2 g/pot per 20-cm-diameter plastic pot plus spraying the foliage to run-off with 1000 ppm of GA3 solution 4 times with 1 month interval.