Physiological Aspects and Experimental Reversion of Flowering in Fargesia murieliae (Poaceae, Bambusoideae)

Abstract

From about 1993 to the present (1998), millions of plants of Fargesia murieliae, an ornamental bamboo, were flowering monocarpically in western Europe. All plants being ramets of a single genet, introduced in Europe about 80 years ago, the simultaneous flowering of all these ramets constitutes a single giant compound inflorescence. Flowering plants were subjected to different conditions of light intensity and temperature yielding different modes of development of flowering. Under low light intensity and high ambient temperatures (22-250C), reversion offlowering is ultimate- ly observed by development of vegetative shoots from basal buds offlowering culms. Under conditions that induce oxidative stress (full sun and drought) flowering and senescence proceed rapidly. The process of senescence is linked to oxidative stress as measured in elevated activities of superoxide dismutase and ascorbate peroxidase in the semelauctant inflorescences. By strong photoreduction of catalase activity, high light intensity is directly responsible for inactivation of one of the major defence mechanisms of the cells, thereby effectively accelerating flowering and senescence. In blades of spathes subtending the semelauctant inflorescences (short paracladial zone), DNA replication as well as loss of DNA from nuclei is observed. As this phenomenon is observed in green spathes prior to the development of the terminal inflorescence, DNA replication is a very early marker for senescence. A role for extra DNA synthesis prior to senescence is suggested in cytokinin biosynthesis.