Shiitake Emphasis Type="Italic"Lentinula edodes

Authors: Takeshi Nitta Ichiro Kamei Kazuhiro Sugamoto Sadatoshi Meguro

Publish Date: 2016/06/30

Volume: 62, Issue: 5, Pages: 452-459

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Abstract

The effects of the gaseous phase rate of kunugi Quercus acutissima sawdust media mixed with sugi Cryptomeria japonica determined by a threephasestructure analysis of the fruiting body yields of shiitake were investigated The fruiting body yield on kunugi media was significantly lower than that on commercially available hardwoodsawdustmixture HSM media with 64  water content Threephasestructure analysis showed that the gaseous phase rate in kunugi media was lower than that in HSM media When the gaseous phase rate in kunugi media was increased to the level in HSM media by decreasing the water content to 56  the fruiting body yield on kunugi media also increased These results suggested that kunugi sawdust could be used for shiitake cultivation if the gaseous phase rate in the media was optimized Because sugi has a lower specific gravity and higher porosity than kunugi mixing sugi sawdust up to 30  with kunugi media caused an increase in the gaseous phase rate and the fruiting body yield reached the same level as that in HSM media These results suggested that kunugi media could be used for shiitake cultivation by mixing with sugi sawdustKunugi Quercus acutissima wood has been mainly used for the production of dried shiitake Lentinula edodes Berk Pegler by bedlog cultivation in Kyushu Shikoku and west central Honshu and has also been most commonly used in Miyazaki Prefecture In the past the nurturing of kunugi seedlings had been promoted by Miyazaki Prefecture to compensate for the increased demand for kunugi logs However dried shiitake production has recently decreased due to the decline in price and the aging of the growers If the demand for kunugilogs continues to drop the current volume of growing kunugi forests would be too aged and they would eventually be left unused The sprout growth function of kunugi is weakened in trees that are 30 or more years old as reported by Tanaka 1 Therefore acceleration of the effective use of overgrown kunugi logs is required to keep kunugi forest habitats sound in the future Shiitake production by means of sawdustbased cultivation has recently increased to about 90  of the total fresh shiitake production in Miyazaki The increase of prices due to the increase of the cost of transportation of raw materials is becoming a problem since most of the sawdust for shiitake production is imported from other prefectures in hardwoodsawdustmixture HSM form The possible use of kunugi wood instead of HSM as the substrate for sawdust media would benefit the growers in Miyazaki but kunugi sawdust is not popular with the growers because shiitake cultivation takes longer on this medium than on HSM mediaOn the other hand Miyazaki Prefecture is one of the most prosperous areas in Japan for the production of sugi wood Cryptomeria japonica D Don The demand for sugi sawdust has recently increased for supply of the woody biomass generation 2 3 However the use of a large quantity of forest residue and lower sugi wood is still issue and a large quantity of sugi sawdust is produced in sawmills as factory waste every year Thus the price of sugi sawdust for mushroom cultivation is estimated to be around onethird of that of HSM 4 The cost of production of fresh shiitake would be reduced if the plentiful and inexpensive sugi sawdust could be used for the cultivation However Nakajima et al 5 reported that ferruginol in methanol extracts of sugi inner bark inhibited shiitake mycelial growth Matsui et al 6 also showed that mycelial growth inhibition of shiitake is probably due to a synergistic effect of ferruginol and sandaracopimarinol which are the major terpenoids in sugi wood These results suggest that the poor shiitake mycelial growth on sugi wood meal compared with that on hardwood is caused by the inhibitory effects of extractives contained in sugi wood 7 In addition the mycelial growth of shiitake on sugi media was found to be only about 60  of that on konara Q serrata Murray media even if extractfree sugi sawdust was used 7 Therefore shiitake cultivation on media using only sugi sawdust seems to be difficultIn our previous study 8 threephasestructure analysis was used to investigate the changes of the physical properties of the sawdust media that result from mixing them with volcanic ash The results suggested that the change in the threephasestructure of sawdust media by mixing it with ash or the decrease in volume of the gaseous phase caused the reduction in shiitake yields Thus the fruiting body yields of shiitake should be significantly affected by the physical properties of sawdust media illustrated as by their threephasestructure If the disadvantages of kunugi sawdust which requires a longer incubation period than HSM can be conquered by optimizing the threephasestructure of the media the growers could use kunugi sawdust instead of HSM as the substrate of media for shiitake cultivationA commercial dikaryotic strain of shiitake L edodes No 1791 the variety registration number of Ministry of Agriculture Forestry and Fisheries Japan was used in this study This strain has been extensively used in the sawdustbased cultivation of shiitake in Miyazaki The sawdust spawn was obtained from a commercial source and was used for the experiment involving the flushing of the fruiting body A strain subcultured on potato dextrose agar media Nissui Co Ltd was used for the experiment in which mycelial growth was measuredCommercially available sawdust namely hardwoodsawdustmixtures abbreviated as HSM Castanopsis spp Quercus spp with the exception of Q acutissima and Q serrata others = 532 wt/wt dry weight was used for the substrate of the media HSM has been commonly used for the sawdustbased cultivation of shiitake in Miyazaki Kunugi Q acutissima and sugi C japonica that were supplied from mushroom cultivator in Miyazaki and had been seasoned for over 3 months were also used The particle size distribution of sawdust used for flushing the fruiting body was as follows under 10 mm 10–20 mm over 20 mm = 271 The sawdust used for the measurement on mycelial growth and the analysis of the threephasestructure was sieved to a particle size of 10–20 mm constituted with 70  of sawdust used for flushing the fruiting body Moreover the particle size of the sawdust used in the experiment involving the measurement of physical properties was 025–100 mm similar to that described by Hu et al 9

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