The Effects of Ethylene on the Growth and Development of Ptilotus sp

Abstract

Prilotus is an Australian native plant which has potential uses as ornamental plant. Due to early flowering, the natural characteristic of the plant, this research aimed at improving its vegetative growth which is essential for commercial propagation. One-year-old of Ptilotus nobilis were treated with 500 mg L ethephon 2 days before pruning. 1 week and 2 weeks after pruning. The application of ethephon 2 days before pruning decreased the number of total inflorescence and all ethephon treatments increased the total number of shoots. Deflasked young plants of P. nobilis which were treated with two rates of ethephon diluted in distilled water (150 and 300 mg 1.) applied either weekly or fortnightly, showed significant effects in plant height, number of new inflorescence and number of dead shoots. Ethephon application 300 mg L either weekly or fortnightly reduced plant height, number of new shoots and number of new inflorescence. Weekly application either 150 or 300 mg L gave the higher number of dead shoots than fortnightly application. Plantlets of P. nobilis exposed to ethylene gas in in vitro condition with the rates between 0 to 300 mg L for 1 hour, showed significant increase in number of total shoots and height, three weeks after application. However, exposure of 100 mg L. ethylene gas gave the best growth in height and number of total shoots in P. nobilis. On the other hand, ethylene gas on plantlets of P spicatus did not affect the number of lateral shoots, the plant height and the flowering. Ethylene induced rooting both in ex vitro and in vitro plants. Cuttings obtained from plants treated with 300 mg L. fortnightly had roots earlier than cuttings obtained from other treatments. Ethylene increased the percentage of rooting plantlets in P. nobilis by 100 mg L exposure and in P. spicatus by 200 mg 1. exposure. This study have shown that ethylene effects on Prilotus vary depending on the plant species, the age of plants, the concentration of ethylene and the frequency of application.