Pine sawdust-based mushroom cultivation: A cost-effective strategy for livelihood improvement in Uttarakhand

Introduction

Uttarakhand, India's 27 th state, is blessed with large forest resources, making it one of the places with significant forest wealth and natural biodiversity. Because they keep the environment in balance, these woods are an essential natural resource for both humans and wildlife. The total area of Uttarakhand is 53,483.36 km², of which around 65% is covered by forests and roughly 93% is made up of mountainous terrain (Negi & Kumar, 2016) [12] . The forests of Uttarakhand cover several altitude zones and change in nature with increasing elevation. Broad-leaved deciduous forests are widespread in the low-lying Tarai and Doon plains. Dense pine forests spread upward into the valleys and mid-altitudes. Coniferous forests that have evolved to harsher climates are found in the icy alpine regions, while mixed oak forests flourish further up in the temperate belt (Sati et al., 2018) [16] . People living in rural areas of Uttarakhand rely on forest resources (CEDAR 2010) for essentials like fuelwood, fodder, and food. They also practice community-based forest management through local councils known as Van Panchayats, a system that was first introduced in 1920 (Phartiyal et al., 2006) [14] . Approximately 16% of Uttarakhand's total forest area (between 1000 and 1800 m asl) is covered by Chir Pine (Pinus roxburghii) forests (Negi, 2019) [11] . Pine commonly known as "chir pine" or "long needle pine", is a native species of the Himalayan region (Kaushik et al., 2010). It is among the most widely distributed forest trees in Uttarakhand (Khanduri & Sharma (2000); Kala (2004) and Kaushik et al., (2010)) [8,5,6] . In the forests of Uttarakhand, five distinct species of pine are naturally found growing in the wild. These include Pinus roxburghii, locally known as chir pine; P. wallichiana, commonly called blue pine; P. gerardiana, referred to as chilgoza pine; P. kesia, known as Khasi pine; and P. bhutanica, which is recognized as Bhutan white pine (Pandey and Nautiyal, 2025) [13] .

Since ancient times, people have depended on these pine trees for a variety of functions. A significant amount of this state's annual income comes from chir pine, which is also a common source of various commercially significant raw materials including resin, timber, turpentine oil, etc (Singh et al., 2017) [17] . Chir Pine forests are mainly responsible for the spread of forest fires. The chir pine tree is an economically significant species due to its high resin content. However, the same characteristic makes its needle litter extremely flammable and susceptible to forest fires. Every year, pine trees are burned to eliminate needle litter, which makes it difficult for people and livestock to walk through the forest areas (Chandran et al., 2011) [3] . The forests of Uttarakhand are mostly underutilized while being commercially viable and a significant source of income for rural people. The reason for this is the forest areas are far away and not easy to reach (Sati and Bandooni 2018) [16] . Its more sustainable use is limited by the cliffs and slopes. On the other hand, human activities such as forest fires, overgrazing, cutting trees for fodder and fuel, along with the removal of leaf and wood litter from the forest floor, have emerged as major pressures on plant diversity in the Uttarakhand Himalaya (Malik et al., 2016) [10] . The primary aim of this study was to explore the use of pine sawdust in oyster mushroom cultivation, turning locally available forest waste into a sustainable agricultural resource. By utilizing this material, the study aimed to promote eco-friendly practices while generating income and livelihood opportunities for local communities, especially since the environmental conditions in the region are highly favourable for oyster (Pleurotus florida) mushroom production.

Materials and Methods

Mushroom culture and spawn preparation:

The pure culture of P. florida was obtained from the Directorate of Mushroom Research (DMR), Solan, Himachal Pradesh. Wheat grains were washed thoroughly to remove impurities and then boiled until soft but intact. The boiled grains were drained and shade-dried to remove excess moisture. After drying, the grains were mixed with calcium sulphate (2%) and calcium carbonate (0.5%) to maintain pH 6.5-7.0. The prepared grains were filled up to three-fourths in polyethylene bags, plugged with non-absorbent cotton, and sterilized at 121°C for 1.5 hours. After cooling, the bags were inoculated with master spawn under sterile conditions and incubated at 25 ± 1°C until complete colonization.

Substrates preparation:

For the sterilization of substrate the method is used as followed: For chemical sterilization, substrate such as Pine sawdust was soaked in fresh water overnight to achieve a moisture content of approximately 70-75%. After soaking, the excess water was allowed to drain off then the pre-soaked straw was submerged in a 200-liter metal drum containing a solution of lime @ 15g per kg straw, 125 ml formalin and carbendazim @ 15 g per 100 litres of water. After both treatments, the substrates were then left to attain a moisture content of about 65% before spawning.

Spawning and incubation:

The substrates were layered into polythene bags, and a multi-layered spawning technique was used, applying spawn at a rate of 2% after that the spawned bags are incubated in the cropping room under controlled conditions, maintaining a temp. of 21-25°C and R.H. around 70-80% to facilitate spawn run.

Harvesting:

The fruiting bodies were harvested before curling of fruit body and well-formed gills, because over matured fruit body is fragile and difficult to handle. Harvesting was done by hand holding the stipes at the base and twisting lightly.

Results and Discussion

Pleurotus florida growth on pine sawdust had distinct phenological phases with total colonization of the substrate and development of fruiting bodies within the predicted experimental period. The spawn run was accomplished with 34.67 days and pinheads have appeared at 41 days revealed in figure I. The fruiting body formation was observed at 46.67 days, which is the beginning of reproductive stage. It indicated complete colonization of the substrate by mycelium. Pinhead initiation was recorded at 41 days, followed by the initiation of fruiting bodies at 46.67 days. These observations indicate that the developmental stages progressed steadily on pine sawdust, though the duration for each stage was relatively extended. Comparative evidence, however, shows that these are duration is considerably lengthened. In case of P. florida, wheat straw gave spawn run in 18.25 days and pinhead formation in 22.38 days, whereas other Pleurotus species on wheat straw produced spawn run in 18-21 days followed by pinhead formation in 5-7 days (Jamil et al., 2019; Thakur et al., 2025) [4,18] . Tirkey et al., 2017 [19] reported 15-21 days for mycelium run and 17-26 days for primordium initiation of P. florida on different substrates. Sawdust substrates resulted in least days for pin head formation for P. florida than corn cobs, which was not observed on pine sawdust, as Kinge et al., 2016 [9] reported. This indicates that pine sawdust alone is not as good as other sawdust types or other substrates for P. florida production. [7] found that the yield of Pleurotus ostreatus was "maximum" in the first flush, followed by the second and third flush, while Ram et al. (2013) [15] reported "maximum" yield in the 1st and 2nd flush, but reduced yield in 3rd flush. The decrease is probably a result of a lack of nutrients in the substrate and changes in enzyme activity. Bánfi et al. (2015) reported that the activities of the lignocellulolytic enzymes measured which are important in the degradation of the substrate exhibited different trends depending on the cultivation cycles, with the highest activities in flush and harvest stage for cellulose and hemicellulose degrading enzymes. This is the first flush, and its concentration has practical importance for cultivation efficiency and economic planning in the mushroom cultivation.

Conclusion

The present study proved that the pine sawdust which is abundantly available in forest area of Uttarakhand is an economically and ecologically viable and effective alternative substrate for production of oyster mushroom (Pleurotus florida).

The substrate however, had a slight delay in the spawn run and in the initiation of fruiting compared to conventional substrates and was successful in crop establishment but yielded a satisfactory total yield. Biological efficiency was at its best during the first flush and was decreasing gradually through the successive production cycles. The pine sawdust has not only a biological feasibility but because it is a by-product of pine trees, it can solve two major problems in the region: waste management and income generation and livelihood diversification for the rural population. The direct use of this underutilized resource in mushroom farming is aligned with sustainable agricultural practices and optimizing the use of resources in areas rich in biodiversity.

Recommendations

1. Further research is needed to assess the nutritional value of mixing pine sawdust with the agriculture residues that contain high levels of nitrogen (such as wheat straw, rice bran or pulse husks) to shorten the spawn run phase time and reduce the initiation time for fruiting. 2. Efficacy of different pre-treatments (either physical, such as composting or leaching, or biological) of pine sawdust to degrade complex lignocellulosic bonds and possible resinous inhibitors that might retard colonization rate should be evaluated. 3. An extensive cost benefit analysis needs to be done to determine the net economic gain for rural smallholders for collection, processing and spawn cost versus the regional market for Pleurotus florida. 4. In Uttarakhand, local agricultural extension centers and cooperative societies should prepare localized training modules to transfer this cultivation technology to the rural communities in the state to promote eco-entrepreneurship and offer sustainable employment.

References

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