Bioscience Evidence 2026, Vol.16, No.4, 316-328 http://bioscipublisher.com/index.php/be 323 than insufficient or excessive nitrogen supply. This indicates that shiitake substrates require an appropriate nutrient balance rather than simply increasing nitrogen availability. 4.3 Substrate regulation of fruiting body formation Fruiting body formation in shiitake mushrooms represents the transition from vegetative growth to reproductive growth after sufficient nutrient accumulation by the mycelia. This process is jointly regulated by nutrient supply, physical structure, and moisture conditions of the substrate. Therefore, substrate evaluation should not only focus on the number of fruiting bodies but also consider its effects on fruiting patterns and morphological characteristics. For fresh-market shiitake production, large fruiting bodies with thick flesh generally have higher commercial value. Therefore, substrates should support sufficient nutrient accumulation and fruit body development. In contrast, processing-oriented production may place greater emphasis on mushroom number and total yield per cultivation area. Bansal and Ravi (2024) used different woody agricultural residues as main substrate materials and supplemented them with rice bran and wheat bran. They evaluated substrate performance by comparing mycelial growth, primordium appearance time, cap diameter, stipe length, and final yield under different treatments. The eucalyptus + poplar + rice bran + wheat bran combination promoted rapid mycelial expansion and earlier formation of mycelial films and primordia, showing faster reproductive transition. However, although the poplar + mango + rice bran + wheat bran treatment did not form primordia the earliest, it produced larger fruiting bodies, with a total yield of 666.03 g and a biological efficiency of 66.63%. In addition to basic woody materials, supplementary additives can also modify fruiting body development patterns. Zied et al. (2024) investigated the effects of different charcoal powder addition levels and compared the responses of different strains in terms of yield, mushroom number, and individual mushroom weight. Charcoal supplementation showed clear regulatory effects on fruiting body formation, and the 4% addition level had the most obvious influence on yield and morphological traits. The study also found a negative relationship between mushroom number and individual fruit body weight. Some treatments promoted the formation of more fruiting bodies but resulted in smaller individual mushrooms, whereas other treatments reduced mushroom number but increased individual mushroom weight. 5 Quality Formation of Shiitake Mushroom and Substrate Management 5.1 Formation of commercial appearance quality The commercial value of shiitake mushrooms is mainly determined by fruiting body appearance, including cap color, cap thickness, individual mushroom weight, stipe characteristics, and overall uniformity. Although these traits are expressed during the fruiting stage, their formation is closely related to nutrient supply and physical properties of the substrate. The composition of lignocellulosic materials, particle size, and nutrient release rate in the substrate influence mycelial growth status and primordium development, thereby affecting final commercial appearance. Changes in the proportion of woody materials in the substrate can significantly modify shiitake appearance characteristics. Replacing hardwood sawdust with 50% or 100% bamboo sawdust resulted in lighter cap color and reduced melanin and chitin contents (Xu et al., 2026). Among these treatments, the 50% replacement treatment did not reduce fruiting body weight, whereas complete replacement decreased individual mushroom weight. This indicates that an appropriate replacement level is needed to balance substrate substitution, commercial quality, and yield performance. In different sawdust mixture systems, individual mushroom weight varied significantly between the first and second flushes, suggesting that substrate composition influences nutrient distribution among different fruiting stages. Plant residues such as mugwort and stevia can improve both yield and nutritional quality when used as suitable partial substitutes for sawdust (Asdullah et al., 2025) (Figure 4).
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