Radiation Breeding of Apomictic Prostrate Dallisgrass, Paspalum dilatatum Var. Pauciciliatum1

A study was made of spaced plants and progeny of the meiotically irregular prostrate dallisgrass from seed untreated and treated with l5 and 30 hours of thermal neutron and 20 and 30 Kr of x rays. It was concluded that the best radiation treatment, 20 hours of thermal neutrons, increased the frequency of R1 vegetative and tloral mutants over 4-fold and nearly doubled the number of vegetative mutant classes. Radiation-induced mutants continued to reproduce by apomixis. Radiation did not induce sexuality in this obligate apomict. No evidence of ergot resistance could be found in some 4,000 R2 and some 16,000 R2 plants. Since radiation did no break apomixis, R2 plants should be designated R1A1 (first radiation generation followed by the first apomictic generation), The limited radiation breeding practiced in this study failed to lead to the development of higher yielding strains capable of producing more and higher quality seed.