Knowing the main metrics will improve your understanding of growing mushrooms if you are just starting out with mushroom cultivation. Besides, these metrics will also help you to be successful in the long run.
When it comes to measuring the health of your mycelium, the following two metrics – mycelium growth measured in distance or time as well as the mycelium run rate will give you a good indication.
If you measure the distance the mycelium grows during a specific time frame, you will get the mycelium growth expressed in mm or cm. The second way is to measure the time it takes for the mycelium to fully colonize the culture media. In this case, the mycelium growth is expressed in days. If you then divide the distance by the time, you will end up with the mycelium run rate, expressed in mm per day or cm per day.
In the following table 1, the time required for completion of mycelium running (measured in days) and the distance (measure in cm) are given.
If we divide, for example, 15.59 cm by 21 days, we will get a mycelium run rate of 0.74 cm per day.
These three numbers, day, distance, and running rate, give you a better understanding of the influence of the culture media on the mycelium and the health of the mycelium itself.
If we move to the next phase of mushroom cultivation, several metrics are important.
The first parameter you should pay attention to is the number of days for the spawn run. This metric is the time it takes for the mycelium to fully colonize the substrate expressed, as the name indicates, in days.
After the substrate is fully colonized, the following metric you should keep tracking is the number of days to primordia formation. This metric gives you the time it takes for the mycelium to start pin heading after the bag is cut and the initiation was started.
If you measure the time it takes from pinhead formation until fully grown fruit bodies, you will get the number of days to harvest.
The following graph 1 summarizes the three metrics. The first values are the number of days for the spawn run. The difference between the first and second values is the number of days to primordia formation. And finally, if we subtract the second value from the third, we get the number of days to harvest.
Knowing these three metrics helps you to make informed decisions about the following steps.
- When to start the next production cycle.
- When to initiate the primordia formation.
- At what point do you have to adjust the cultivation parameter for fruiting and
- When to change the cultivation parameter for harvesting.
When it comes to harvesting, the following metrics are essential to know and to understand. The NOFB is the number of fruiting bodies you can harvest from one flush or the average of several flushes.
We then have the yield and the economic yield. While the yield is the weight of the fresh harvested mushrooms, the economic yield is the weight of the fresh harvested mushrooms without debris. But the economic yield is also influenced by the length of the stem. Meaning the longer the stem, the higher the economic yield and vice versa.
The biological efficiency is the ratio between the weight of the fresh harvested mushrooms and the weight of the substrate expressed in percent. This metric can be calculated in two ways.
- By using the weight of the dry substrate or
- By using the weight of the wet substrate.
If you use the dry substrate, then a biological efficiency of 100 means you will get 1 kg of fresh mushrooms from 1 kg of dry substrate. If you are instead using a wet substrate to calculate the biological efficiency, a biological efficiency of 100 means that you will get 1 kg of fresh mushrooms for every 4 kg of moist substrate.
If you want to run a profitable mushroom business, it is recommended that the biological efficiency should be greater than 75.
But even if you reach this value, you still do not know if you should grow this mushroom. Here the production rate can help you out.
The production rate is the ratio between the biological efficiency and the culture cycle. With the culture cycle, the time from the initiation of the primordia formation until the last harvest. The following table 2 shows four different production rates.
Here, for example, the strain IE-623 has a production rate of 0.63, which calculated by dividing the biological efficiency of 50.8 by the culture cycle of 75. Given this formula, we see that the production rate can be improved by either increasing the biological efficiency or by reducing the culture cycle.
Speaking of the culture cycle. You should be familiar with several other terms describing specific periods or cycles throughout the production. The first is the term flush which describes the harvesting period meaning the time frame to harvest mushrooms. Depending on the type of mushroom, you can have one or multiple flushes per cropping cycle.
The harvesting period is followed by the rest period or rest phase, which is the time until the next primordia formation. The culture cycle, also called the cultivation cycle or cropping cycle, starts with the first initiation of the primordia formation and ends with the last harvest.
All process steps combined – starting with the substrate preparation until the end of the cleaning process of the cultivation room – are called the production cycle.
Each one of these metrics giving you insides into your mushroom production. Combining these metrics with other metrics can create an evaluation system which helps you to identify the best mushrooms to grow.
Which other metrics I used to create such an evaluation system are found in the following video.
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 Mondal, S., Rehana, J., Noman, M., & Adhikary, S. (2011). Comparative study on growth and yield performance of oyster mushroom (Pleurotus florida) on different substrates. Journal of the Bangladesh Agricultural University, 8(2), 213–220. Retrieved from https://www.banglajol.info/index.php/JBAU/article/view/7928
 Girmay, Z., Gorems, W., Birhanu, G. et al. Growth and yield performance of Pleurotus ostreatus (Jacq. Fr.) Kumm (oyster mushroom) on different substrates. AMB Expr 6, 87 (2016). https://doi.org/10.1186/s13568-016-0265-1. http://creativecommons.org/licenses/by/4.0/
 Dulce Salmones, Rigoberto Gaitan-Hernandez & Gerardo Mata, «Cultivation of Mexican wild strains of Agaricus bisporus, the button mushroom, under different growth conditions in vitro and determination of their productivity», BASE [En ligne], Volume 22 (2018), Numéro 1, 45-53 URL : https://popups.uliege.be/1780-4507/index.php?id=16281.