Grains affect on spawn quality: cereal grain, a solid substrate, is used popularly for production of pure culture of mycelium, called Spawn. Just as seed quality is important to crop production, so is spawn quality to mushroom production. Cereal grains affect on spawn quality and the spawn has a fundamental role in global agricultural productivity. The success of mushroom cultivation and its yield depend to a large extent on the quality of the spawn used.
Grain preparation, inoculation and testing on Pleurotus spp.: Used grain sources consisting of wheat, rye, oat and barley grains. They were washed in clean water three times to do away with chaff, dust, and different particles, and then soaked in water for 12-14 h for most absorption of water. Soaked grains had been again boiled in water for 20 minutes. Water was decanted and the grains were spread on a wire-mesh for surface drying of grains. Each grain was supplemented with 1.3% CaCO3. Supplemented grains were filled into spawn Petri dishes with 30 g grain/petri dish and sterilized by autoclave at 1210C, 17psi for 60 minutes. After cooling, each petri dish was once inoculated with 5mm mycelium disc of oyster mushroom Pleurotus spp. Inoculum was placed in the middle of each petri dish and special care was taken to keep the cylinder mycelium in direct contact with each substrate and was incubated at room temperature (22 ± 20C) under dark conditions. The diameter of the mycelium growth was measured after 3 days for 7 days. The maximum and minimum growth rates were also found and compared among different grain sources. Levels of mycelial density among the treatments were compared visually and categorized by thin, somewhat thin, compact and somewhat compact. From results, we can identify the best grain source which is the most suitable for the growth of mycelium on each oyster mushroom strain.
The quality of spawn is a decisive factor in getting successful crop hence growers need to use qualified seed for commercial production. The grain substrates on which spawn is made affect mycelium growth. In general, larger grains such as wheat, rye, oat and barley supported faster mycelial growth. The large grains can also preserve the mycelium for longer periods of time because they have a greater food reserve. The advantage of barley and oat was dense and fast mycelial growth with comparable to wheat grain on oyster mushrooms.
Some researchers found that larger surface area and pore of substrates contributed to faster mycelium growth rate. For this reason cereal grains are large and have large pore space hence increased oxygen concentration leading to increased mycelium growth. Mycelia growth increases with increase in oxygen concentration within spawn grain substrates.