SELECTION OF SHIITAKE STRAINS GREATLY COMPETITIVE TO ANTAGONISTIC FUNGI TRICHODERMA SPP

Trichoderma species cause a large crop loss in the log cultivation of shiitake mushroom, Lentinula edodes (Berk.) Pegler, thus new shiitake strains greatly competitive with the Trichoderma species are required for their successful production. We examined the competitive ability o f L. edodes against Trichoderma attack mainly using the dual culture o n sawdust media to establish a useful selection method for L. edodes s trains which have great competitive abilities. The degree of L. edodes competitive ability against Trichoderma attack varied depending on th e difference of qualities and quantities of nutritional components sup plemented into the sawdust medium, and the sawdust medium mixed with 1 /3 volume of rice bran was useful in estimating the competitive abilit ies of dikaryotic strains of L. edodes. Further more, greatly competit ive Lentinula dikaryons selected by the dual culture appeared to be ab le to repel Trichoderma attack in outdoor log cultivation. The test us ing sawdust medium with 1/3 volume of rice bran revealed that the comp etitive abilities of dikaryons did not correlate with the competitive ability of their parental monokaryons. However, selection of monokaryo ns which produced greatly competitive dikaryons was possible: each mon okaryon was crossed with several test monokaryons, and the mean of the competitive abilities of the resultant dikaryons was determined.