Palm Press Fibre and Rice Straw for Cultivation Grey Oyster Mushroom (Pleurotus sajor-caju)

Sains Malaysiana 51(5)(2022): 1305-1315 http://doi.org/10.17576/jsm-2022-5105-03

ABSTRACT Sawdust (SD) usually sourced from rubber plant is commonly used as substrate to cultivate the grey oyster mushroom Pleurotus sajor-caju in Malaysia. However, the market price of SD is increasing because of its declining availability. Thus, this study aimed to discover an alternative substrate to cultivate grey oyster mushroom. The raw materials used in the substrate were oil palm pressed fiber (PPF), rice straw (RS) and SD, either alone or in combination with different ratios including T1: 90% SD + 10% rice bran (commercial substrate as control); T2: 30% RS + 20% SD + 50% PPF; T3: 50% RS + 50% PPF; T4: 100% RS; and T5: 100% PPF. The suitability of the substrates was determined based on growth, yield, nutrition and mineral content in the mushrooms. The growth and yield of the mushroom fruiting body on the different substrates showed significant differences. The shortest harvesting day was obtained in T4 (100% RS) after 29 days, whereas the longest harvesting day was obtained in T1 (90% SD + 10% rice bran) after 51 days. The highest yield was obtained in T4. Nutrition analysis showed significant difference among the treatments. The highest amounts of protein (26%) and ash (1.29%) were found in T5. Overall, the results showed that mushroom yield performance was good in RS but nutritional content was the highest in PPF. Therefore, RS and PPF have good impact for mushroom growers either in commercial production or in functional food industry to reduce SD dependency. 

INTRODUCTION Mushrooms belong to the phylum Basidiomycota under the kingdom Fungi. Mushrooms are heterotrophs that obtain food from decaying materials, such as dead bodies of organisms or debris from plants. Mushrooms are classified as edible, non-edible, and medicinal depending on their functions. Edible mushrooms are highly consumed by humans because of their rich nutrition, such as high amount of protein and low amount of carbohydrate. Currently, 17 major types of mushroom, including grey oyster, white oyster, straw mushroom, split gill mushroom, shiitake, and button mushroom, are commercially cultivated in Malaysia (MOA 2011). Grey oyster is the most popular species cultivated and marketed for household consumption, followed by shiitake or button mushroom that widely used in hotels and catering services. Nevertheless, mushrooms are used in various sectors, including the pharmaceutical, cosmetic and functional food industries (Tarmizi et al. 2013). Mushroom cultivation could directly enhance livelihoods through economic, nutritional and medicinal contributions (Marshall & Nair 2009). Mushroom cultivation does not require much land, and the business scale requires modest-to-low capital investment and labor use. The cultivation can become a viable and attractive activity for side income and a part-time enterprise for rural farmers and peri-urban dwellers.

The crop can also be cultivated on agricultural waste, making it an environmentally friendly. In Malaysia, the current practice is to cultivate this mushroom using sawdust (SD) from either rubber plant or any other plants, but dependency on SD causes problems in supply shortage and cost for the new grower. Both oil palm and paddy or rice are the utmost cultivated plants in Malaysia. However, massive production of residues from crops and very limited utilization for further downstream operations from these residues create problems in agriculture. The approximate number of agricultural residues has been utilized either as fuel in the timber industry and manufacturing. After cultivation of paddy, only 1% of rice straw (RS) is used for livestock, fertilizer, paper making, and activated carbon material, and the remaining RS is disposed by open burning, which negatively affects the environment and human health (Rosmiza et al. 2014). Straw left in the field can also lead to environmental problems with the release of methane, which is the major contributor to greenhouse gas (GHG) emissions, sharing approximately 80% of the total GHG emissions from the cultivation stage (Rosmiza et al. 2014; Silalertruksa & Gheewala 2013; Weil & Brady 2017). 

Nutrients in the straw include nitrogen, phosphorus, potassium and sulfur, and in addition the cell wall structural composition (e.g. cellulose and lignin) of straw enriches mushroom cultivation (Rosmiza et al. 2014). On the other hand, the production of waste from the oil palm industry was estimated to be approximately 65.5 million tons per year. It exists in various forms, such as palm empty fruit bunches, palm kernel shell (PKS), palm pressed fibers (PPF), and palm oil mill effluents. PKS and PPF are usually utilized as fuels for the generation of steam and electricity for palm oil mills. Nevertheless, excess unutilized fiber and shell are still available, leading to an accumulation problem. This biomass contains cellulose, hemicelluloses and lignin, which have potentials as renewable raw material (Noorhalieza et al. 2013). The nutritional and mineral contents of the grey oyster mushroom Pleurotus sajor-caju might be influenced or induced by the substrate components, which need to be studied for commercial functional food production. Therefore, the suitability of locally available substrates of RS, PPF, and SD either alone or in combination for the cultivation of grey oyster mushroom was determined. The growth performance and nutritional and mineral contents of the cultivated mushrooms were also analyzed. 

Sains Malaysiana 51(5)(2022): 1305-1315 http://doi.org/10.17576/jsm-2022-5105-03