INFLUENCE OF FOLIAR CHITOSAN SPRAYS ON GROWTH OF MOKARA AND PHALAENOPSIS SEEDLINGS

Abstract

Chitosan is a natural compound which acts as a plant elicitor. This research was conducted to investigate the responses of Mokara and Phalaenopsis seedlings to chitosan applications. Seedlings taken from in vitro propagation were soaked in a chitosan solution at 0 (control), 10, 20 or 40 mg/L for 5 min and subsequently transplanted into coconut fiber. Thereafter, seedlings were sprayed weekly with chitosan in a combination with a foliar fertilizer (21-21-21). The fresh weight, number of leaves and leaf area were measured monthly, whereas shoot and root dry matter were weighed at 12 months after transplanting. Cultivar and chitosan concentration had significant effects on fresh weight, leaf number, leaf area and shoot to root ratio. Mokara seedlings treated with 20 mg/L chitosan had the highest fresh weight while fresh weight of Phalaenopsis seedlings treated with 10 and 20 mg/L chitosan were higher (36.9 and 34.8 g, respectively) than that of seedlings treated with 40 mg/L chitosan (27.3 g) and the control (27.2 g). Phalaenopsis seedlings treated with 10 and 20 mg/L chitosan had the maximum leaf area (12.6 and 15.7 cm 2 , respectively), while Mokara seedlings treated with chitosan at the concentration of 40 mg/L had the maximum leaf area with respect to other treatments. Twelve months after transplant, chitosan sprays significantly affected the fresh and dry weight of both Phalaenopsis and Mokara seedlings. Mokara seedlings had higher shoot to root ratio compared to that of Phalaenopsis. Shoot to root ratio of Mokara applied with foliar chitosan at 20 and 40 mg/L were the highest (2.3 and 2.4, respectively). Whereas, Phalaenopsis sprayed with chitosan at 40 mg/L had the highest shoot to root dry matter ratio compared to other concentrations.