Sectoring Strain Selection and Development

As myceiium grows out on a nutrient agar, it can display a remarkable diversity of forms. Some mycelia are fairly uniform in appearance others can be polymorphous at first and then suddenly de- velop into a homogeneous looking mycelia. This is the nature of mushroom mycelia—to constantly and evolve. 

When a mycelium grows from a single inoculation site and several divergent Types appear, iT is 

In a dish That is largely covered with a cottony mycelia, a fan of strandy myceiia would be called a rhizomorphic sector, and vice versa. Sectors are common in mushroom culture and although little is known as to their cause or function, it is clear that genetics, nutrition and age of the mycelium play important roles. 

Commercial Agsricus cultivators have long noted that the slower growing cottony myoelium is inferior to the faster growing rhizomorphic mycelium. There is an apparent correlation between cot-lonu 3931 2nd the later occurrence of stroma , a dense mat-like growth of myoelia on 

Rhizomorphic mycelia run faster, form more primordia and in the final analysis yield more mushrooms than cottony mycelia. One example of this is illustrated in Fig. 37. A single wedge of mycelium was transferred to a petri dish and two distinct mycelial types grew from it. The stringy sector formed abundant primordia while the cottony sector did not, an event common in agar culture. 

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