Evaluation of Methods for Screening of Cultivars of Subterranean Clover (Trifolium-Subterraneum) for Resistance to Phytophthora-Clandestina

Abstract

Different methods of screening of cultivars of subterranean clover for resistance to Phytophthora clandestina were evaluated. This involved inoculation of peeled seeds and 3- and 10-day-old seedlings growing in water agar with mycelial plugs and zoospore suspensions of the fungus, and of seedlings growing in pasteurised potting mix with vermiculite infested with the fungus. The resistance of four cultivars of subterranean clover to three races of the pathogen was determined by all methods. The most reliable screening method was inoculation of seedlings growing in pasteurised potting mix with infested vermiculite and recording relative severity of root rot 1 week after inoculation. Inoculation, using either mycelial plugs or zoospore suspensions, of approximately 10-day-old seedlings growing in water agar and measuring the length of root discoloration and/or root colonisation can be regarded as an alternative method which uses less space and materials