EFFECTS OF PLANT GROWTH SUBSTANCES ON IN VITRO FIBER DEVELOPMENT FROM UNFERTILIZED COTTON OVULES

Fertilization of cotton ovules was prevented by removal of styles and stamens on the morning of anthesis. Forty-eight hr later ovaries were harvested and ovules were aseptically transferred to liquid culture medium supplemented with various plant growth substances. In the absence of phytohormones, ovules browned and failed to increase in size or produce fibers. Indoleacetic acid and gibberellic acid provided for ovule growth and fiber development. Kinetin provided for ovule growth only. The ovule's capacity for indoleacetic acid- or gibberellic acid-stimulation of fiber development was reduced by high concentrations of kinetin or abscisic acid. Low concentrations of kinetin partially reversed the inhibitory effect of abscisic acid.