COMMERCIAL DEVELOPMENT OF STYLOSANTHES PASTURES IN NORTHERN AUSTRALIA- I - CULTIVAR DEVELOPMENT WITHIN STYLOSANTHES IN AUSTRALIA

Approaches to the development of new Stylosanthes cultivars from large collections of naturally occurring genotypes are described. The clima tic, edaphic and biotic constraints to adaptation are summarised and t he criteria for the selection of 'new' cultivars are discussed. The pr ocess of evaluation used in northern Australia is described. It consis ted of 3 stages: (a) nursery rows; (b) small sward trials; and (c) gra zed pastures. The statistical techniques used for analysing multi-site small-sward experiments are described, as well as the limitations to adaptation caused by ineffective root-nodule bacteria in species that have highly specific Bradyrhizobium requirements.