Cytogenetics of tropical bulbous ornamentals. IX. Breeding systems in Zephyranthes

Abstract

Zephyranthes is a rather versatile genus and contains self-incompatible and self-compatible taxa coupled with positional barrier between stigma and anthers. The two may augment or run counter to each other. Furthermore, the genus also contains sexual and agamospermous species. The latter are often self-pollinated and pseudogamous. Z. sulphurea (2n=48) when pollinated with Z. candida (2n=40 and 41) has consistently given rise to seedlings with maternal chromosome number and morphology. Z. lancasteri and cv. 20 also behave similarly. This is a strong pointer for their being agamospermous, although a final proof will come from an embryological study. The intraspecific polymorphism within agamospermous taxa in the genus may be the result of autosegregation. On the other hand, the crosses involving sexual species like Z. candida (2n=41) as the female parent have generated a large heterogeneous progeny ranging in chromosome number from 2n=33 to 48 depending upon the number in the male parent. Such versatility of the breeding system together with chromosomal repatterning, hybridization, polyploidy and vegetative multiplication/apomixis explains the origin and preservation of an astonishing range in chromosome numbers from 2n=18 to 96.