Absence of Cistus Incanus from Basaltic Soils in Israel: Effect of Mycorrhizae

The development of Cistus incanus was explored in a dark basaltic soils and a calcareous terra—rosa, in relation to mycorrhizal establishment. Plants transplanted to the laboratory degenerated in native dark basaltic soils and in sterilized terra—rosa, where infections with mycorrhizal fungi did not occur. They grew in calcareous terra—rosa, where mycorrhizae developed. Successful development of C. incanus in unfertilized soils depended on ectomycorrhizae; infection and could be demonstrated several weeks after germination. Plants developed without mycorrhizae in both soils when irrigated with a complete nutrient solution. We conclude that when mycorrhizae are absent, C. incanus plants degenerate in unfertilized soils because of a mineral—nutrient deficiency. We suggest that absence of C. incanus and possibly some other batha—forming plants from dark basaltic soils in Israel is related to failure of ectomycorrhizal development in these soils.