Growing oyster mushrooms
Grow oyster mushrooms on bags of straw. Change the room's temperature, the dampness of the air and how the straw was treated, and find the conditions that give the biggest harvest.
Core concept
Mushrooms are fungi: they cannot make food, so they absorb it from the straw; they grow best when it is warm (about 20 to 25 °C), the air is damp and the straw has been pasteurised to kill moulds
Topic: Mushroom
A mushroom is the fruiting body of a fungus. Most of the fungus is hidden: fine white threads called hyphae (together, the mycelium) that spread through the straw and absorb food from it, because a fungus has no chlorophyll: The green colouring in leaves that catches sunlight for photosynthesis. All key words and cannot make its own food. When conditions are right, the mycelium pushes up mushrooms, whose gills release spores. Oyster mushrooms (kanya chyau) are grown all over Nepal. Farmers soak and pasteurise chopped straw in hot water to kill moulds and bacteria, mix it with spawn (grain covered in mycelium), pack it in plastic bags and hang them in a dark, damp room. In this lab you start with 10 kg of dry straw and change the room's temperature, the dampness of the air and whether the straw was pasteurised.
What you will learn
- Describe the parts of a mushroom and how a fungus gets its food.
- Identify the conditions oyster mushrooms need to grow.
- Explain why straw is pasteurised before spawning.
- Describe how mushrooms are harvested and stored.
Before you start
- Know that fungi cannot make their own food.
Materials
- Chopped paddy straw, oyster mushroom spawn, plastic bags
Equipment
- A big pot for hot water, a thermometer, a sprayer for water
Procedure
- Record the harvest at 25 °C, with 90 % damp air and pasteurised straw.
- Record at four or more room temperatures.
- Record with drier air (50 %).
- Record with untreated straw.
How this simulation is simplified
- 10 kg of dry straw gives at most 8 kg of fresh oyster mushrooms.
- The temperature and dampness are kept the same for the whole crop.