White clover evaluations in Northland

One hundred and twenty overseas and New Zealand lines of white clover (Trifolium repens L.) were grown on flat land at Kaikohe, northern New Zealand. The scoring of performances relative to that of 'Grasslands pitau', the best commercial cultivar for the region, indicated scope for substantial further genetic improvement of white clover. The superiority of lines known to be resistant to stem eelworm (Ditylenchus dipsaci (Kiihn) Filipjev) indicated this pest has an important effect on relative performances of white clover in this study. Portugal and Italy were indicated as potentially useful sources of germplasm. Some material from the U.S. and Europe crossed with New Zealand plants showed improved warm-season productivity, as did some locally selected plants. Most significant for future breeding were double-cross hybrids between New Zealand and Mediterranean plants, which provided excellent cool-season production, with some improvement also in spring and summer growth.