The Cytology, Breeding System and Flowering Behaviour of Panicum coloratum

Abstract

A collection of 47 accessions of Panicum coloratum was classified into five morphologically distinct types. One of these was uniformly hexaploid (2n = 54) and another was diploid (2n = 18). The other three were mainly tetraploid (2n = 36) but some pentaploid (2n = 45) plants and one septaploid (2n = 63) plant were found. Meiosis was regular in all euploid plants but nine univalents were usually present in the pentaploid plants. A variable number of accessory chromosomes were found in somatic and generative cells in some plants of two of the types, and hybridization studies indicated a close relationship between these. It is suggested that both tetraploids and hexaploids are allopolyploids and that the hexaploid has two genomes in common with the tetraploids.

All accessions set adequate seed following open pollination, but shed seed readily at maturity. There was variation in the degree of self-incompatibility both within and between types. In some accessions up to 33% of the florets were capable of setting seed when self-pollinated.

P. coloratum grew best and flowered earliest in long days (I6 hr) and a day temperature of 27-30°C.