Supplementary nutrition and using time effects on quantitative, qualitative and biochemical indicators of button mushroom

The decrease in yield and quality levels of button mushrooms during the cultivation period is one of the important challenges of the mushroom production industry, due to the reduction of substrate nutrients and the accumulation of undesirable compounds. One of the solutions to prevent the decrease in yield and qualitative characteristics of edible mushrooms during different flushes is to enrich compost with nutrient supplements.

In order to investigate the effect of supplementary nutrition at different times on the yield indicators of button mushroom, a factorial experiment based on completely randomized design was conducted. Experimental treatments included four concentrations (C) of supplementary nutrition (0 (C1), 20 (C2), 40 (C3) and 60 (C4) g/L) (combination of two phases, the liquid phase includes micro and macro elements and amino acids, and the solid phase includes sucrose and dextrin) and two application times (one day after harvesting the first flush (T1) and the beginning of the second flush and the formation of pin (T2).

The findings of this research indicated the highest number of button mushroom was observed in C3T2 treatment by 215.89, which demonstrated a 20.35% increase compared to C1T2 treatment. The lowest single mushroom weight was measured in the first time of foliar spraying in C1T1 treatment and the highest single mushroom weight was obtained in the second time of foliar spraying in C3T2 and C2T2 treatments, respectively. The maximum length of the mushroom base was obtained in C2T2 treatment by 1.36 cm. Along with the increase in the concentration of nutritional solutions; the diameter of the cap showed a significant increase at T1 time, while at T2 time, this value showed a decreasing trend after the treatment of 20 g/L of nutrient solution. In addition, no significant difference was observed between the cap diameter of mushrooms treated with 20 and 40 g/L in treatments of C2T2 and C3T2, and the maximum cap diameter of mushrooms in these treatments was 3.73 and 3.67 cm, respectively. Enrichment of button mushroom compost by nutritional supplements can prevent severe yield reduction during different flushes.
The number of mushrooms produced in two different times was not significant. It showed that the effect of using time of supplemental nutrition was more effective on the rapid growth of the formed pins than growth of new pins. The formation of pins and the number of mushrooms were under the influence of the amount of inoculation and used spawn in the compost. The positive results obtained from the foliar application of the nutrients showed that its compounds, including sucrose and dextrose and highly consumed elements such as nitrogen, phosphorus, potassium and amino acids, have played an important role on the number, single weight of mushrooms and the cap diameter of mushroom.
The use of nutrient solution in C3T2 treatment compared to C1T2 increased nitrogen percentage by 66.43%, protein by 66.22%, tissue firmness by 71.44% and biological efficiency of substrate by 66.32%, respectively. Pervious study showed that, the effect of different concentrations of three amino acids asparagine, glutamine and glycine on some quality indicators and performance components of white button mushroom was investigated and the results indicated that asparagine 150 ppm improved the yield and increased the protein content. High NPK content in mushroom substrates significantly shortens the rate of mycelium propagation and increases oyster mushroom growth. One of the basic criteria for a good mushroom substrate is the carbohydrate and nitrogen content to support mushroom growth.
Also, using a concentration of 40 g/L of nutrient solution at the time of emergence of the second pin, in comparison with C1T2 treatment, increased the yield of the second flush by 64.15%, the yield of the third flush by 71.17%, the yield of all flushes by 26.79% and the total yield of composted by 26.76%, respectively. Carbon, with its structural role and presence in most organic compounds and providing energy for metabolic reactions, plays a significant role in the growth of button mushrooms. On the other hand, button mushrooms are able to use amino acids as a source of nitrogen. Therefore, it seems that the use of the above compounds in the nutrient solution used in this research has been able to produce favorable results both quantitatively and qualitatively in the studied button mushrooms. On the other hand, it seems that the presence of widely used elements such as phosphorus and potassium in the nutrients used in this research and the positive role of these elements in the production of nucleic acid, adenosine triphosphate, membrane phospholipids and enzyme reactions has been able to play a key role in increasing the quantitative and qualitative properties of button mushrooms.

The use of 40 g/L concentration of nutritional supplement at the time of the appearance of the second flush by affecting the percentage of dry matter, protein and tissue firmness increased the quality level of button mushrooms and enhanced quantitative level by improving yield indicators such as the number of mushrooms, single weight of mushroom, total yield of flushes and percentage of total yield of compost.