Ecology Of Soil Fungi Research Articles

COMPARATIVE RESPONSE OF TWO SAPROPHYTIC AND TWO PLANT PARASITIC SOIL FUNGI TO TEMPERATURE, HYDROGEN-ION CONCENTRATION, AND NUTRITIONAL FACTORS

The behavior of two soil saprophytes, Trichoderma viride and Trichocladium asperum, and two root-infecting fungi, Ophiobolus graminis and Fomes annosus, was compared under various conditions in laboratory culture.On an agar-solidified organic medium optimum temperatures for growth were approximately: T. viride 25–30 °C, T. asperum 20–25 °C, O. graminis 20–25 °C, F. annosus 25 °C. T. viride rapidly outgrew the other fungi in the optimum range but this relationship changed at lower temperatures, its growth rate being equalled by that of O. graminis at 10 °C. T. viride was the only fungus to grow at 35 °C. In a synthetic liquid medium adjusted to pH values from 3.0–7.0 with a citrate–phosphate buffer, growth of O. graminis and F. annosus was sharply reduced at pH values below 5.0. T. viride made good growth at pH 3.1 and reduction in growth of T. asperum occurred only below pH 4.0. Both parasites required thiamine for growth in a synthetic medium and O. graminis also required biotin; in addition they showed a preference for organic as opposed to inorganic nitrogen sources. T. viride and T. asperum grew well with KNO3 as nitrogen source and neither required vitamins. D-Glucose, D-fructose, and D-mannose were readily utilized, and D-arabinose poorly utilized, by all four fungi. Utilization of other hexoses, pentoses, disaccharides, and polysaccharides varied considerably between the fungi.The relationship of the results obtained to the observations of others on the ecology of soil fungi is discussed and the possibility that combinations of physical and nutritional factors may favor specific fungi in the soil is considered.

The Ecology of Soil Fungi

The Ecology of Soil Fungi

The Ecology of Soil Fungi

The Ecology of Soil Fungi

Ecology of Soil Fungi

Ecology of Soil Fungi

Experimental studies on the ecology of fungi in soil

When fungal conidia and sporangiospores are placed on soil they decompose, this being true even of the spores of organisms that are native to the soil. Natural plant materials are more effective than soluble chemical amendments in reducing the rate of this decomposition. Partially decomposed plant materials as found in soil are also effective. Such plant materials can be utilized in the soil by both native and alien fungi. Only native fungi, however, were able to make the fullest use of them in this situation, by successful colonization and survival for longer than 6 months. This was due to a high degree of competitive saprophytic ability under the conditions found in soil. The bearing of these findings on the ecology of fungi in soil is discussed.

The ecology of soil fungi

The influence of soil type and soil horizon on the distribution of microfungi in five natural grassland soils at Lakenheath Warren has been investigated. The soils, which are all very dry and sandy, vary from a shallow, highly alkaline soil to a deep, highly acid podsol. One hundred and forty-eight species of fungi have been isolated from these soils by the soil-plate method.The most common genera are Penicillium and Mortierella , followed by Absidia, Cephalosporium, Fusarium, Gliocladium, Gliomastix, Mucor, Thielavia, Trichoderma and Zygorrkynchus . The occurrence of fungal species in twenty profile samples of each soil has been recorded, and the distribution of the more important species is discussed in detail. It has been shown that the number of fungal species and colonies in a profile falls off with depth, the rate of reduction being dependent on the depth of the soil and the nature of the soil horizons. Most species occur most abundantly in the surface layers of the soil. A few species were commoner in subsurface layers, and a few were abundant near the chalky boulder clay of the C horizons. Fungi show different distributions in the five soils, and two large groups may be distinguished: those common in the acid soils and those common in the alkaline soils. Species of Penicillium were particularly abundant in the acid soils. Microscopic examination of soil has shown that fungi are present both as spores and mycelium. Study of incubated soil plates stained with lactophenol cotton blue has shown that most of the colonies develop from humus particles. Viable spores have also been found in these soils, especially the acid ones.