EMASCULATION EFFECTS ON THE STAMEN FILAMENT OF NIGELLA HTSPANICA AND THEIR PARTIAL REVERSAL BY GIBBERELLIC ACID

Abstract

Anther removal from stamens whose filaments are 1–3 mm long restricts filament elongation to approximately 60% of the normal length. Removal of one‐third to one‐half of the anthers affects only the antherless filaments and does not appear to inhibit the growth of the other organs of the flower. Filament growth inhibition induced by anther removal involves both an inhibition of epidermal cell elongation along the length of the filament and also an inhibition of cell division. There is no evidence that the inhibition of filament growth is a response to damage caused by anther removal. Rather, it is suggested that anther removal severs a normal hormonal relationship existing between the anther and the developing filament. The application of gibberellic acid (GA3) in lanolin paste stimulated the elongation of the antherless filaments to achieve an average of 87% of the filament length of adjacent intact stamens. The closer a filament is to having attained its final number of cells before anther removal, the closer does its length come to reaching the final length of filaments in intact stamens. The elongation of these antherless filaments with the application of GA3 was accompanied by elongation of the epidermal cells of the filament to normal, or in some cases greater than normal, lengths. There is no evidence that GA3 application affected the inhibition of epidermal cell devision induced by anther removal. The results of this study support the suggestion of Plack that emasculation‐induced inhibition in the growth of floral organs and its reversal by GA3 is a general phenomenon.