**Transcript**

While mushrooms grow on all sorts of organic substrates to cultivate them profitable, the substrate must be optimized.

Hence, today’s research paper investigated different substrate formulas for the two mushrooms Pleurotus florida and Pleurotus sajor caju. The authors used fermented sawdust, added different amounts of rice bran to it, and sterilized the mixture for 1 hour at 15 psi.

While both mushrooms behave similarly, we still see differences. If we compare the mycelial growth rate of the two, we see that Pleurotus florida has a higher growth rate than Pleurotus sajor caju. Both mushrooms reach the maximum growth rate at 10% to 15% rice bran.

When it comes to the number of days for the spawn run, we see for both mushrooms that with increasing content of rice bran, the time drops from 39 and 33 for Pleurotus florida and from 43 down to 33 for Pleurotus sajor caju. Increasing the amount of rice bran to 20% increases the time.

Besides influencing the time, the amount of rice bran impacts the quality of the mushrooms. By increasing the content up to 15%, the cap diameter, cap thickness, stipe diameter and stipe thickness increased. Increasing the amount of rice bran to 20% led to a decreased of these values. That means that by varying the amount of rice bran, the size of the mushrooms can be adjusted to the customers’ preferences.

What also can be adjusted is the total yield per production cycle. Increasing the amount of rice bran increased the total yield from 450g to 850g for Pleurotus florida and from 490g to 880g for Pleurotus sajor caju. And thus by 89% and 80% for Pleurotus florida and Pleurotus sajor caju respectively.

These values then lead to the following biological efficiencies, which reached the maximum at 15% rice bran.

As different substrate formulas have different carbon-to-nitrogen ratios, and these data are available, we can analyze the effect of the C/N ratio on various parameters. Before we do, let us examine how the amount of rice bran changes the C/N ratio.

The unsupplemented sawdust mixture has a C/N ratio of 105. Adding, for example, 15% rice bran led to a C/N ratio of 73. Now to the effect of the C/N ratio on the total yield. The following graph shows that with increasing C/N ratios, the total yield drops.

This behavior can be visualized by calculating the correlation factor between the two parameters. In our case, we find a negative correlation of -0.62 between the C/N ratio and the total yield.

A negative correlation means that the two parameters behave opposite. Meaning increasing one of them decreases the other. In our case, the increase of rice bran led to a decrease of total yield. The C/N ratio also influences the growth rate as the correlation between the two was between -0.68 and -0.75. Here, the negative effect is stronger for Pleurotus sajor caju than for Pleurotus florida.

If you are interested to learn more about the impact of different substrate formulas, then the playlist on the right is for you. In this playlist, I am adding over time more and more different substrate formulas for different types of oyster mushrooms.

Talk to you there.

**Source**

📝Guerrero, M.B., Aragones J. A., Balane, N.M; Rantugan, H.G., andPelagio, V.P. Evaluation of Different Formulations of Substrate Materials for the Growth and Yield of Two (2) Species of Oyster Mushrooms (Pleurotus florida and Pleurotus sajor caju Jack.et Fr).

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