Subterranean clover (Trifolium subterraneum): its history and current and future research in New Zealand

This review covers the history of subterranean clover (Trifolium subterraneum) and its present occurrence in New Zealand; a review of research and conclusions to be drawn from this; and examines past and future research directions. Subterranean clover has been important in terms of area of use in New Zealand since the late 1930's. Today it makes a significant contribution to pasture production on steep, north-facing North Island hill country where effective rainfall is low, and in other areas where soil moisture drops below wilting point for between 2 weeks and 5 months of the year. Research has identified the superiority of cultivars possessing a compact, ground-hugging habit of growth, and flowering late, in late October - early November, for use in North Island hill country. In drier areas, more research is needed to identify superior cultivars, although there is evidence that lines in the mid-season or early mid-season flowering groups may be appropriate. A major problem for the use of subterranean clovers in New Zealand is the slow breakdown of hardseededness. About 7 M ha of land in New Zealand is mapped as being subject to slight to severe moisture deficit (an area which could with advantage support subterranean clover), but further research is needed to identify appropriate cultivars for 4.8 M ha or more of this area. Key words: history, New Zealand, research, Trifolium subterraneum