Selection for persistence in red clover: Influence of root disease and stem nematode

摘要

Abstract The cause of death of red clover plants (Trifolium pratense L.), and attributes associated with persistence of survivors, were investigated in two field plot experiments on land previously used by plant breeders for evaluating persistence of different red clover genotypes. In the first experiment, using ‘Grasslands Hamua’ red clover, most plants developed foliage symptoms of stem nematode (Ditylenchus dipsaci (Kühn) Filipjev) infestation and/or developed severe cortical rot or stele necrosis in their tap roots, during the first year. Cylindrocladium scoparium Morgan, Trichocladium basicola (Berk. & Br.) Carmichael, Verticillium dahliae Kleb., Fusarium solani (Mart.) Sacc., and F. oxysporum Schlecht. were isolated from diseased roots. An internal breakdown of the upper tap root occurred following necrosis of pith tissue. The proportion of dead plants increased rapidly during the second year, and only 12.5% of plants had survived 2 years after sowing. Most plants which persisted for 2 years had dev...