Reproductive growth inLolium 1. Evaluation of genetic differences within an established variety by means of a diallel cross
- 20 Downloads
A genetic evaluation of S23 perennial ryegrass has been made by means of a 6 × 6 diallel cross. The characters studied were those associated with seminal reproduction and included seed yield and several of its primary components.
The pattern of variation between the parents indicated a mainly additive system, itema of the Hayman analysis being significant for yield and all the other characters. Maternal effects were not a constant feature, but were evident for seed yield, plant weight and spikelet numbers/inflorescence. Dominance was a prevalent feature and invariably acted in the direction of the greater expression of the character.
While a high level of incompatibility was evident from the paucity of seed setting on selfing, the variation between progeny yields following open pollination gave a range from the highly acceptable levels of commercial production to very low uneconomic levels. The results indicate that improvement in seed yield is feasible by breeding even though in this variety selection pressure has tended towards a restriction of variability for essentially agronomic features.
KeywordsSelection Pressure Variety Selection Seed Yield Seed Setting Prevalent Feature
Unable to display preview. Download preview PDF.
- Beddows, A. R., Breese, E. L. &Lewis, B., 1962. The genetic assessment of heterozygous breeding material by means of a diallel cross. 1. Description of parents, self and cross-fertility and early seedling vigour. Heredity 17:501–513.Google Scholar
- Breese, E. L., 1960. The genetic assessment of heterozygous breeding material. Proc. 8th Int. Grassl. Conf. 45–49.Google Scholar
- Breese, E. L., Hayward, M. D. andThomas, A. C., 1965. Somatic selection in perennial ryegrass. Heredity 20:367–379.Google Scholar
- Cooper, J. P., 1954. Studies on growth and development inLolium. IV Genetic control of heading responses in local populations. J. Ecol. 42:521–556.Google Scholar
- Ferwerda, F. P., 1956. Recurrent selection as a breeding procedure for rye and other cross-fertilized plants. Euphytica 5:175–84.Google Scholar
- Hayman, B. I., 1954. The theory and analysis of diallel crosses. Genetics 39:789–809.Google Scholar
- Hayward, M. D., 1967. The genetic organisation of natural populations ofLolium perenne. II. Inflorescence production. Heredity 22:105–116.Google Scholar
- Jenkin, T. J., 1931. The method and technique of selection, breeding and strain building in grasses. Bull. Bur. Pl. Genet. Aberystwyth 3:5–34.Google Scholar
- Kersey, M. J., 1965. Biometrical analysis of a random mating population. A comparison of five experimental designs. Heredity 20:205–235.Google Scholar
- NIAB 1968. Farmers leaflet. Recommended Varieties of grasses. NIAB Cambridge, 24 pp.Google Scholar
- Thomas, R. L., 1966. The influence of seed weight on seedling vigour inLolium perenne. Ann. Bot. N.S. 30:111–121.Google Scholar
- Thomas, R. L., 1967. Interpopulation variation in perennial ryegrass. I. Population means. Heredity 22:481–498.Google Scholar