Effects of Temperatures and Alternative Substrates on the Growth and Development of King Oyster Mushroom（Pleurotus eryngii）

• Main Authors: Lao-Dar Juang, 莊老達
• Other Authors: Shiesh-Ching Chang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/74513108016828301950

博士 === 國立中興大學 === 園藝學系所 === 100 === Recently, the cultivation of king oyster mushroom (Pleurotus eryngii) has increased rapidly, making it the 3rd largest commercially cultivated mushroom in Taiwan. Temperature is the key factor controlling the transition (or differentiation) from vegetative mycelium growth to reproductive fruiting-body formation, therefore, temperature-controlling devices are commonly used to grow the mushroom in Taiwan. Sawdust is the most popular basal ingredient in synthetic formulation of substrate used to cultivate the mushroom. However, the extensive cultivation scale of the mushroom has consumed large quantities of sawdust and caused a shortage of wood supply. Thus, two objectives were proposed in this study. The first objective is to determine the optimum temperature for P. eryngii fruiting-body differentiation and development. A temperature range between 11℃ and 23℃ was tested. The second objective is to explore alternative substrates suitable for cultivation of P. eryngii. The PDA media with various horticultural residues were inoculated with P. eryngii to evaluate the characteristics of mycelium growth and to test their suitability for P. eryngii cultivation. Three substrate materials that can be stably obtained from locally field-grown Poaceae crops including napiergrass, rice straw, and bagasse were evaluated for their potential replacement of sawdust. Partial replacements of sawdust in ratios of 25％, 50％, 75％, and 100％ were individually performed using the three above-mentioned substrate materials. Mycelium extension, fruiting-body production, biological efficiency and nutritional value of fruiting-body, and changes in the physical and chemical properties of the substrates were characterized to determine their potential use as alternative substrates. The influence of temperature on primordia formation and fruiting-body development was assessed between 11℃ and 23℃. The results indicated that the production of fruiting-body was highest at 17℃. Primordia became visible on the 5th -7th days after stimulation with low temperatures and fruiting-body grew rapidly and became economically mature 6th -8th days thereafter. Biological efficiency increased forty fold, from the initial 1.41％ to a final of 56.75％ during the eight day period. However, vegetative mycelium was unable to form reproductive fruiting-body when the temperatures were above 21℃. Moreover, fruiting-body development was inhibited when it was continuously subjected to a temperature below 11℃ or under 1℃ for more than five days. The low-temperature stress affected not only the yield but also the morphogenesis of the fruiting-body. Nevertheless, yields were significantly higher when colonized substrates were pretreated with a temperature of 12℃ for 3 or 5 days or of 15℃ for 5 days relative to the control (a constant temperature of 17℃). These results demonstrated that significant increase of fruiting-body production of P. eryngii is induced by sufficient and optimal low temperature treatment. The PDA media containing 37 horticultural residue extracts （HRE） were prepared to evaluate the potential uses of these residues as alternative substrates for P. eryngii cultivation. The results indicated that most HRE showed positive effect on mycelium growing, except HRE of Pouteria caimito Radik, Averrhoa carambola, Dimocarpus longan, Acronychia pedunculata and Pyrus pyrifolia （Taichung No. 3）. Moreover, mycelium growth was increased in PDA media containing low concentration of HRE of mango, avocado, sapodilla, persimmon, peach and plum but decreased at high concentration. The speed of mycelium extension differed in various substrates including sawdust（S）and sawdust substitutes with 25〜100％ local agricultural residues of napiergrass （N）, rice straw（R） and bagasse （B）. The highest mycelium growth rate, 8.93 mm/day, was recorded in the S substrate followed by the B, R and N substrates. On the other hand, the minimum mycelium extension rate, 3.55mm/day, was observed in the substrate with 100％ N. Days from inoculation to complete colonization were negatively correlated with mycelium extension rate. Sawdust substrate and 100％ N substrate were completely colonized by P. eryngii mycelium within periods of 18.67 days and 51 days, respectively. The highest yield of fruiting-body, 219.7 g/bag, was produced using the substrate of 25％ B ＋ 75％ S, followed by a yield of 215.3 g/bag produced with the substrate of 25％ R＋75％ S. Both substrate ingredients were superior to the 100％ S substrate with a yield of 171.2 g/bag. As for the biological efficiency（BE）, the maximum BE of 66.28％ was recorded in the substrate of 25％ R＋ 75％ S, followed by 53.64％, 52.62％, and 52.24％ in the substrates of 25％ B＋ 75％S, 50％N＋50%S, and 75％R＋25％S, respectively. All of the above-mentioned BEs were better than the BE of 48.28％ present in the sawdust substrate. Substrates with 100％ N and 100％ R were not suitable for the king oyster mushroom cultivation. Based on the yield and BE data, the best alternative substrate ingredients for P. eryngii cultivation appeared to be those with sawdust substrate substituted by 25%, 50％, and 25% of napiergrass, bagasse, and rice straw, respectively. After substrate was inoculated with P. eryngii., pH value of the substrate decreased gradually and reached the lowest point just before primordial formation. It was then slightly increased after primordia had become visible. Conversely, EC value increased gradually as mycelium extended. The degree of degradation among different lignocellulosic components varied with different substrates. In several different treatments, higher lignin and cellulose contents were observed in the spent substrate compared to those in the initial substrate. The rate of lignocellulosic decomposition was highest for hemicellulose followed by lignin and cellulose. For most substrates tested in this study, higher amounts of macroelements (such as N, P, Ca, and Mg) as well as microelements (such as Fe, Mn, and Cu) were detected in the spent substrate relative to those in the initial substrate. P. eryngii has become increasingly popular because of its high nutritional value and health-promoting effects. Contents of carotenoids, flavonoids, phenolic acids and tocopherols, and antioxidant ability of fruiting-body were compared among different harvest days after receiving low temperature stimulation. The results indicated that all chemical compounds as well as the antioxidant ability of fruiting-body were the highest when harvested at the 10th day after cold stimulation, followed by the 12th day, and were the lowest at the 15th day. The nutritional value in different parts of fruiting-body was also compared. The results showed that pileus had higher mineral-element content and free radical scavenging ability. On the other hand, stalk contained higher amount of phenolic compounds and soluble proteins.