Volume 4 Part 1 Article 15: The Functions of the Compost and Casing Layer in Relation to Fruiting and Growth of the Cultivated Mushroom (Psalliota (Agaricus) hortensis)

Volume 4 Part 1 Article 15
Year 1960
Title: The Functions of the Compost and Casing Layer in Relation to Fruiting and Growth of the Cultivated Mushroom (Psalliota (Agaricus) hortensis)
Author: P.B. Flegg

Abstract:

The work on the casing layer, hitherto carried out at the Mushroom Research Association’s station at Yaxley, has been continued at the Glasshouse Crops Research Institute at Littlehampton. As a result of this more recent work it is now possible to resolve at least some of the mystery surrounding the function of this layer. There is, of course, still much more to be learned of the processes involved in the initiation and development of the sporophore. During the course of these investigations information has also been obtained on some important aspects of the compost which have perhaps been neglected.

Throughout this paper reference is made to the moisture stress in the compost and casing layer, and by this is meant the restraining factors which reduce the availability of the moisture in the medium. The total moisture stress is the sum of the moisture tension, due to surface tension effects, and the osmotic pressure, due mainly to dissolved salts.

The experimental details of the work at the Glasshouse Crops Research Institute have been described elsewhere (5, 6 and 7), but the main results are briefly summarised in this paper.

The characteristic response of the mushroom to additions of soluble salt to the casing layer is a delay in the start of fruiting and a decrease in the number of sporophores; those fruit bodies which do form are much heavier but the total yield is usually, although not always, reduced. The effect of the soluble salts has been found to be related to their influence on the electrical conductivity of aqueous suspensions of the casing layer irrespective of the specific inorganic salt used. Of those used (seven in all), no salt showed any evidence of a specific effect. It has, therefore, been concluded that the response of the mushroom is related to the resulting increase in osmotic pressure and, hence moisture stress in the casing layer.

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