Breeding and testing early-flowering strains of yellow-flowered serradella (Ornithopus compressus)

Abstract

A mutation breeding program is described, aimed at producing early-flowering cultivars of yellow-flowered serradella. Some 40 mutants of CV. Pitman were isolated, flowering from two to four or more weeks earlier than the parent. Selected lines were tested for vernalization response, yield, and reaction to light and heavy defoliation. All lines remained fully responsive to vernalization. Growth rates at least equalled that of Pitman, although final dry matter yields under extended growing season conditions were reduced in proportion to earliness. All mutant lines tested produced substantially more seed than Pitman, even with spring irrigation. Total yields of all lines were reduced by defoliation. Cutting had no effect on commencement time of flowering, but when continued during or after flowering it prolonged growth, delayed maturity, and greatly reduced seed yields through removal of flowers and pods. Implications for strain selection and grazing management are discussed, and it is suggested that spring deferment of grazing may be desirable for best performance of serradella pastures. A mutant line flowering about three weeks earlier than Pitman has been registered as CV. Uniserra and released to Western Australian seed producers.