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SUMMARYThe growth effects of three mycorrhizal Endogone endophytes on tobacco, tomato and maize were examined. The extent of the stimulus obtained depended on nutrient conditions and the subsequent level of infection developed in the root system. Marked stimulation occurred with low phosphate availability and high root infection.

SUMMARYVarying amounts of soluble phosphate were applied over different periods during the growth of mycorrhizal maize. The amount of the endophyte produced within the root system and the growth of the host were related inversely. Repeated small doses of soluble phosphate over long periods depressed the production of the fungus more than when given over shorter periods. Large single applications of soluble phosphate applied early in the growth of the host also reduced the amount of the endophyte more than when given later. The role of mycorrhiza in relation to phosphate nutrition is discussed.

SUMMARYAll the grasses and nearly all the dicotyledonous plants growing on three coal tips in Scotland were infected by vesicular-arbuscular mycorrhizal fungi. Infection levels ranged from 20 to 90%. Three main types of fungal endophytes were identified, two being Endogone spp. and one with very narrow hyphae. Mixed infections were present in some plants and there was some evidence that the endophytes occurred in different areas of the tips. The ecological importance of the mycorrhizas in these habitats is discussed.

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SUMMARYScanning and transmission electron microscopy were used to study microfiora of roots of three species of sand dune grasses. Observations were made on the mucigel on intact epidermal cells and the colonization of sloughing superficial root cells by bacteria and actinomycetes. Thin sections of the same root samples showed that bacteria penetrated epidermal cells either by perforating the cell wall or by exploiting the middle lamella between adjacent cells as an avenue of entry. Cortical cells of all three species contained vesicular-arhuscular endophytes. Several phases of the mycorrhizal association could be identified.

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