EMASCULATION EFFECTS ON FILAMENT GROWTH IN IPOMOEA NIL (CONVOLVULACEAE)

Filament growth in the morning glory Ipomoea nil is promoted by gibberellic acid (GA₃) and inhibited by ethylene production during the earlier stages in development (Koning and Raab, 1987). The effects of anther removal on filament growth were examined in I. nil. Three-quarters of the calyx and corolla tissues were removed in order to emasculate the stamens. This removal caused filament growth to be inhibited in the intact stamens (69 hr before anthesis) as well as the emasculated stamens (69 to 21 hr before anthesis). When the ethylene biosynthesis inhibitors CoCl₂ and aminoethoxyvinylglycine (AVG) were applied in separate experiments (to eliminate wound ethylene generated by the damaged tissues), filament growth was promoted to control levels observed in intact flower buds (69 hr before anthesis). Our data suggest that the wounding effect from the calyx and corolla tissues and subsequent reduction in filament growth override any observable effects with anther removal on filament growth. Apparently, the removal of the calyx and corolla tissues severs a normal hormonal relationship between these floral organs and the developing filament.