Mushroom Biology and Mushroom Products. Sánchez et al. (eds). 2002
UAEM. ISBN968-878-105-3
Effect of treating post-composting supplements with different concentrations of formaldehyde on the yield of Agaricus bisporus.
B. Vijay1, S.R. Sharma1, and T.N. Lakhanpal 2
1National Research Centre for Mushroom,
ICAR, Chambaghat, Solan (HP) 173 213, India;
2Department of Bio Sciences, H.P. University,
Shimla (HP) India.
ABSTRACT
Post composting supplementation of Agaricus bisporus substrate with different organic materials is reported to increase the yield. These supplements must be sterilized and denatured with formaldehyde before their application to the compost. Studies carried out at this Centre indicate that 6000 ppm formaldehyde treatment of soybean meal added to the compost at spawning is essential to get increased A. bisporus yield. Low yields were obtained when soybean meal was added to the compost without any formaldehyde treatment or with low formaldehyde doses, mainly due to the incidence of competitor fungi. A 4000 ppm formaldehyde treatment of the soybean and cotton seed meal was sufficient when applied to these supplements at casing.
INTRODUCTION
It has become a routine cultural practice to supplement the ready to spawn compost at spawning or at casing with different organic materials to increase the yield of the white button mushroom. These supplements, which are generally carbohydrate- or protein-rich, may carry or favour the growth of various weed moulds and their application to the compost as such may infect the crop, leading to decreased yield or complete crop failure. The situation may be aggravated when these supplements are added into compost prepared by the long method (unpasteurized compost) which is not as selective as the short method (pasteurized compost). Further breakdown and utilization of these supplements by mushroom mycelium and other organisms present in the compost may result in the heating up of the compost, potentially resulting in partial or complete crop failure. To overcome these two problems, supplements are often treated with formaldehyde, which serves a dual role. It sterilizes the supplements and at the same time partially denatures the proteins present in the supplements resulting in slow release of nutrients, thus reducing the tendency of the compost to heat up.
To know the exact dose of formaldehyde required for sterilization and denaturing the supplements, detailed investigations were carried out with different doses of formaldehyde on soybean meal and cotton seed meal added into the compost at spawning and at casing.
MATERIALS AND METHODS
Compost preparation
Compost for the present study was prepared by the short method following Vijay and Gupta (1997) using wheat straw 1000 kg, poultry manure 400 kg, urea 14.5 kg, brewer’s grain 72 kg and gypsum 30 kg.
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Mushroom Biology and Mushroom Products. Sánchez et al. (eds). 2002
UAEM. ISBN968-878-105-3
Supplements used
Soybean meal and cotton seed meal were used as the supplements Both the supplements were coarsely ground and were then treated with different concentrations of formaldehyde. When supplements were to be added at spawning 0.0, 1000, 2000, 3000, 4000 and 5000 ppm of formaldehyde were used for their treatment. For their addition at casing 0.0, 3000, 4000, 5000, 6000 and 7000 ppm of formaldehyde were used. All the treated supplements were kept in closed polyethylene bags for 24 hours before their application to the compost.
Addition of treated supplements to the compost
Rate of supplementation was 1% fresh weight of compost. For supplementation at spawning, treated supplement (soybean meal) was thoroughly mixed in the compost along with spawn (strain S-11 @ 0.5%). This supplemented compost was then filled into polyethylene bags 45.7cmX30.4cm (18”x12”). For supplementation at casing, completely spawn-run compost from poly bags was shredded in a sterilized tub and thoroughly mixed with the supplements (soybean and cotton seed meal), treated with different doses of formaldehyde, and then refilled into the bags. Two control sets - ruffled and unruffled compost bags - without any addition of supplements, were taken for comparison. For the ruffled control, completely spawn-run bags were shredded in a sterilized tub, refilled in the bags and cased. For the unruffled treatment, completely spawn-run bags were cased as such. Besides these two treatments, results were also recorded for the supplements added to the compost without any treatment of formaldehyde.
Cultural practices
Standard cultivation practices were followed (Vijay and Gupta 1997). Five kg compost were placed in each bag and the experiment was replicated four times. Data on duration/condition of spawn run, days taken for first harvest, number of fruitbodies and their weight were recorded. Yield data were taken for six weeks and they were subjected to statistical analysis.
RESULTS
Supplementation at spawning:
Excellent spawn run was noticed in all the treatments except in the bags which were supplemented without any formaldehyde treatment (0.0 ppm) and with 3000 ppm of formaldehyde. These treatments attracted many contaminants, especially Trichoderma, Aspergillus and Penicillium species. Supplemented bags resulted in early cropping, ranging between 33-35 days from spawning, as compared to 40-43 days in both the ruffled and unruffled controls with no supplement added (Table 1). Average fruit body weight ranged from 6.43 to 9.67g in different treatments, showing no correlation among them. The highest mushroom yield as compared to both the control sets and the 0.0 ppm formaldehyde treatment was obtained with 6000 ppm treatment of soybean meal (Yield was 21.00 kg/100 kg compost). A gradual increase in yield with higher concentrations of formaldehyde was noticed up to 6000 ppm. Reduction in yield was however noticed at 7000 ppm concentration (Table 1).
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Mushroom Biology and Mushroom Products. Sánchez et al. (eds). 2002
UAEM. ISBN968-878-105-3
Table 1. Effect of different doses of formaldehyde treatments of soybean meal added at spawning in short method composting on yield of Agaricus bisporus.
Treatment/Formaldehyde ppm / Soybean MealDays taken for 1st harvest / Av. wt. of fruit body (g) / Yield kg/100kg compost
0 / 34 / 7.23 / 14.50
3000 / 34 / 9.67 / 16.30
4000 / 35 / 7.91 / 15.60
5000 / 35 / 6.90 / 17.70
6000 / 33 / 8.26 / 21.00
7000 / 35 / 8.29 / 18.20
Control (no supplement) Ruffled / 43 / 6.43 / 14.60
Control (no supplement) Unruffled / 40 / 8.38 / 13.00
CD 0.05 5.94
Supplementation at casing:
Poor recolonization of spawn was noticed in 0.0 and 1000 ppm formaldehyde treatments of soybean meal, while it was fairly good in 2000-3000 ppm treatments. Excellent recolonization of spawn was observed in the other treatments. Fruit bodies were harvested after 36-43 days of spawning in different treatments. More days for fruiting were required with lesser concentrations of formaldehyde. Average fruit body weight ranged between 6.4-9.02 g among the different treatments with no correlation among them, as observed also at spawning.
Table 2. Effect of different doses of formaldehyde treatments of soybean meal and cotton seed meal added at casing in short method composting on yield of Agaricus bisporus.
Treatment/ Formaldehyde ppm /Soybean Meal
/Cotton Seed Meal
Days taken for 1st harvest / Av. wt. of fruit body (g) / Yield kg/100 kg compost / Days taken for 1st harvest / Av. wt. of fruit body (g) / Yield kg/100 kg compost0 / 43 / 9.18 / 9.60 / 42 / 7.47 / 10.50
1000 / 39 / 7.76 / 11.30 / 43 / 6.78 / 10.66
2000 / 42 / 7.75 / 15.40 / 40 / 6.98 / 14.16
3000 / 36 / 9.02 / 19.90 / 41 / 7.25 / 15.06
4000 / 37 / 8.44 / 22.13 / 41 / 8.50 / 19.90
5000 / 38 / 7.25 / 22.85 / 39 / 6.54 / 18.76
Control (no supplement) Ruffled / 43 / 6.43 / 14.66 / 43 / 6.47 / 14.66
Control (no supplement) Unruffled / 40 / 8.38 / 13.00 / 40 / 8.38 / 13.00
CD 0.05 / 7.27 / 5.20
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Mushroom Biology and Mushroom Products. Sánchez et al. (eds). 2002
UAEM. ISBN968-878-105-3
Significantly higher yields were obtained with 4000 and 5000 ppm formaldehyde treatments (22.13 and 22.85 kg mushrooms, respectively) compared to both the controls and 0.0, 1000 and 2000 ppm formaldehyde-treated supplements. Data were recorded weekly for six weeks. Supplements treated with lower concentrations (0.0-2000 ppm) of formaldehyde gave almost no yield in first week of cropping. Good harvest was, however, obtained with the 3000-5000 ppm treatment during this period. In the third week, a very good crop was harvested irrespective of the treatments. A similar trend was observed with cotton seed meal, where significantly higher yields were also obtained with 4000 and 5000 ppm formaldehyde treatments (19.9 and 18.76 kg mushroom respectively).
DISCUSSION
The present study was conducted to determine the dose of formaldehyde required for the sterilization and denaturing of supplements added to the compost at spawning or at casing. It was also one of the objectives of the study to determine the suitability and timing of supplement application to the compost for increased yield of the white button mushroom.
Data obtained indicated that supplementation at spawning or at casing significantly increased the yield. However, it was more beneficial at casing. Gerrits (1986) has also found supplementation at casing better than at spawning. This is probably due to the fact that extra nutrition provided by the supplements at this stage is directly utilized by the mushroom mycelium for increased yield. Supplementation at spawning is generally associated with rise in temperature and incidence of weed moulds, which may jeopardize the yield obtained when this practice is followed at casing. Similar results have been reported by Dhar and Kapoor (1990) and Vijay and Gupta (1992).
Treatment of the supplements with formaldehyde is essential to achieve desired results. In the present case, low yields were also obtained when untreated supplement(s) were used as such without any formaldehyde treatment. Lower doses of formaldehyde were also not effective. Best results were obtained when soybean meal was treated with 6000 ppm formaldehyde when added at spawning and with 4000 ppm treatment of both the supplements when added at casing. Similar results have been reported by Gerrits (1986). Low yields were generally obtained with lower doses of formaldehyde treatment of both the supplements, mainly due to the incidence of competitor fungi and probably due to the non-denaturing of supplements. Gerrits and Moore (1986) have also indicated that supplementation with improperly treated soybean meal increased the number of fungi in the compost, resulting in dramatically decreased yields. However, Stoller (1979) attributed increased yield with supplementation to formaldehyde’s controlling weed moulds present in the compost
REFERENCES
Gerrits, J.P.G. and L.M. Moore. 1986. Bijvoeden in on kruid schimmels. Der Champignon Cultuur. 30: 319-325.
Gerrits, J.P.G. 1986. Supplementation with formaldehyde treated soybean meal. Mush. J. 161: 169-174.
Gupta, Y. and B. Vijay. 1990. Post composting supplementation in Agaricus bisporus under seasonal growing conditions. Mush. Res.1(2) : 115-117.
Dhar, B.L. and J.N. Kapoor. 1986. Post composting nutrient supplementation for increased mushroom yield. Indian Phytopath. 43: 74-76.
Stoller, B.B. 1979. Synthetic casing for mushroom beds. Mush. Sci.10(2):187-216.
Vijay, B. and Y. Gupta. 1997. Cultivation of white button mushroom (Agaricus bisporus). Tech. Bull.4. NRCM, Solan.83.
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