Abstract:
Lolium multiflorum Lam. is, as a pasture grass, the most widely used annual temperate grass species in the higher rainfall areas of South Africa, particularly so in the Natal Midlands, the Eastern Highveld, the Eastern Cape and the winter rainfall areas of the Western Cape. Under irrigation, the popularity of the species is rapidly increasing in areas other than those mentioned above. These pastures are expensive and used primarily for high-producing animals, such as dairy cows and fat lamb production. Cultivars that are mixtures of Italian and Westerwolds type plants are, because of their production value, well adapted to South African conditions. Italian and Westerwolds type plants, however, have different requirements for the induction of flowering. Thus, correct management of seed production units consisting of mixed cultivars is of vital importance if genetic shift and reduced seed yield are to be avoided. The aim of this study was to determine the vemalization requirements of seed and plants of some L. multiflorum cultivars, as well as the possible translocation of the vernalization stimulus. Different vemalization techniques were introduced and the use of biotechnological techniques was investigated. It was concluded that seed production units containing Italian type plants should be planted in autumn, in order to be vernalized as plants in winter. These plants must go through a juvenile phase before becoming receptive to vernalization. Translocation of the vernalization stimulus did not occur in this study. It is recommended that the close down date for seed production units should be revised, if maximum seed yield, genetic stability and the composition of mixed cultivars are to be maintained.
