Heritability of morphophysiological traits and inbreeding effects in grazing-type lucerne

To estimate heritability and inbreeding in grazing‐type lucerne, 14 parent genotypes and their half‐sib and selfed progeny were grown under spaced‐plant conditions. Dry‐matter weight (four cuts), plant height, basal plant diameter, stem density, and late‐autumn vegetation were recorded on a plant basis. Genetic coefficients of variation for the three germplasm groups, and broad‐sense heritability on a plot basis for parents were computed from variance component estimates; narrow‐sense heritability was estimated from progeny‐parent regression. Genetic variation was generally greater among selfed than half‐sib progeny. Broad‐sense heritability was high, while narrow‐sense heritability was much lower for all traits except plant diameter. Inbreeding effects, assessed with comparison between parents and selfed progeny, were notable for plant weight and late‐autumn vegetation only. The high correlation coefficients computed between parents and either progeny suggested the equivalent value of self‐ and polycross‐progeny tests for selecting superior parents.