Bed Logs Research Articles

Variability in radiocesium activity concentration in growing hardwood shoots in Fukushima, Japan

The radiocesium contamination caused by the Fukushima Daiichi Nuclear Power Plant accident has made it difficult to use coppice woods as bed logs for mushroom cultivation. Evaluating the variability in the radiocesium activity concentration of logs is necessary in order to predict how many coppice woodlands are available for producing mushroom bed logs. To clarify the variability in radiocesium activity concentrations and to estimate the sample size required to estimate these concentrations with sufficient accuracy, we modeled the log-transformed radiocesium activity concentrations in growing shoots of hardwoods. We designed two models: (1) a model with mean concentrations that varied among stands with a standard deviation that was the same among stands, and (2) a model with varying means and standard deviations. We fit the data pertaining to only Quercus serrata to both models and calculated the widely applicable information criterion values. Consequently, we adopted the simpler model (1). Applying the selected model to data for all species, we examined the relationship between the number of measurement individuals and the predictive distribution of the expected concentration. Based on previous recommendations and measurement costs, we proposed that five individuals would be appropriate for estimating radiocesium activity concentration in a stand.

Seasonal stability of 137Cs in coppiced Quercus serrata current-year branches: Toward the estimation of trunk 137Cs activity concentrations without felling

Radiocesium (137Cs) remains in forests in the Fukushima region due to the Fukushima Daiichi Nuclear Power Plant accident. To resume the use of bed logs in this area for shiitake mushroom (Lentinula edodes) cultivation, estimating 137Cs activity concentrations in the trunk of konara oak (Quercus serrata) using current-year branches has been proposed as an alternative to felling. To establish this method, the seasonal stability of 137Cs in current-year branches is one of the study issues that must be assessed. We monitored current-year branch 137Cs activity concentrations in coppiced konara oaks at six study sites in the Fukushima area from 2018 to 2020. We also investigated relationships between current-year branches and leaves/previous-year branches. Our intensive sampling revealed that the current-year branch 137Cs activity concentration rapidly decreased during the flushing stage (May–June) before becoming relatively stable in July. We confirmed that the current-year branch 137Cs activity concentration was stable during the dormant stage (November–April), indicating it is a suitable representative value for estimating the trunk 137Cs activity concentration. Furthermore, 137Cs activity concentration during the dormant stage could be estimated using current-year branches obtained in the gradual growing stage (July–October) by multiplying the values by 0.75 ± 0.10; however, it could not be accurately estimated in July with measurements above 200 Bq/kg. The 137Cs activity concentrations in the leaves and current-year branches were similar in some periods (e.g., late December to February), and the relationship between current-year and previous-year branch measurements tended to stabilize in August. However, leaves and previous-year branches do not make ideal substitute samples for current-year branches due to the difficulty of sampling (e.g., few withered leaves remain on branches during winter months). Therefore, to estimate the 137Cs activity concentration of the trunk, we recommend the use of current-year branches obtained August–April (correction is required for the period during August–October).

Factors affecting the cesium transfer factor to shiitake (Lentinula edodes) cultivated in sawdust medium

The transfer factor (TF) of radioactive cesium-137 (137Cs) to shiitake (Lentinula edodes) cultivated on bed logs varies greatly. Therefore, the present study investigated which factors affect the TF using stable cesium-133 (133Cs) and sawdust medium with 5% rice bran as a model, which had similar 133Cs TFs to bed-log cultivation. It was found that the Cs concentration and nutrient concentration (represented by the nitrogen concentration) concerned with the TF in the model sawdust medium. In addition, the TFs calculated using total 137Cs and 133Cs concentrations differed in both bed-log cultivation and the model sawdust medium cultivation, while the TFs calculated using exchangeable 137Cs and 133Cs concentrations were the same in sawdust medium cultivation, indicating that exchangeable Cs in the medium is the source of Cs for the fruiting body and the former difference was due to the presence of other chemical speciation of Cs that could not be absorbed. One purpose of the TF on the mushroom farm is to determine the fruiting body 137Cs concentration at the start of bed-log cultivation, therefore the prediction method of TF are discussed considering the future changes of 137Cs concentrations in trees.

Stimulatory growth effect of lightning strikes applied in the vicinity of shiitake mushroom bed logs

Since ancient times, the anomalous occurrence of mushrooms has been observed in and around locations struck by lightning. Based on this phenomenon, various cultivation techniques using a high voltage to cultivate shiitake mushroom in bed log (wood) have been proposed. Undoubtedly, the fruiting capacity of shiitake mushrooms is significantly promoted by direct application of a high voltage to the cultivation bed logs. However, mushroom bed logs are rarely struck directly by lightning in the natural environment. Thus, it is important to devise a stimulation method that matches conditions in the natural environment. In this study, we performed experiments involving indirect lightning strikes using a new method that mimics the natural environment as closely as possible. Specifically, we used the electric discharge created by an impulse voltage generator to create lightning but did not apply it directly to the cultivation bed log. Instead, the cultivation bed logs were placed a few meters away from the lightning rod. Subsequently, the fruiting capacity of the shiitake mushrooms with and without the indirect lightning strikes was compared. The experimental results indicated that, with the indirect lightning strikes, the extent of shiitake fruiting almost doubled compared to the case without the indirect lightning strikes. Furthermore, the results confirm that an increased shiitake mushroom production is possible using lightning strikes, even if the associated high voltages are not applied directly to the bed logs.

Reduction of radiocesium in Shiitake (Lentinula edodes) bed logs and fruit bodies by culture with nanoparticle insoluble Prussian blue dispersion liquid and cesiumsorb filter sheet

Reduction of radiocesium in Shiitake (Lentinula edodes) bed logs and fruit bodies by culture with nanoparticle insoluble Prussian blue dispersion liquid and cesiumsorb filter sheet

Potassium supply reduces cesium uptake in Konara oak not by an alteration of uptake mechanism, but by the uptake competition between the ions

Radiocesium contamination of forests has been a severe problem after the Fukushima Daiichi Nuclear Power Plant accident in 2011. Bed logs of Konara oak (Quercus serrata Murray), used for mushroom cultivation, were an economically important product from the forests prior to their contamination. One of the potential countermeasures to reduce radiocesium content in trees is potassium fertilization, but the evidence for the effect of K+ in reducing Cs+ uptake has not been obtained yet in the woody plant. Therefore, we investigated the ability of rhizospheric K+ to suppress uptake and translocation of Cs+ in Konara oak seedlings through hydroponic experiments in order to clarify the effect of K+. Elemental analysis showed that the seedlings cultivated for 4 weeks under low-K (K+ = 50 μM) contained higher amount of Cs comparing to the seedlings cultivated under high-K (K+ = 3 mM). Then, the uptake rate of Cs+ and K+ in the seedlings from the solution having 50 μM K+ and 0.1 μM Cs+ was calculated using radioactive 137Cs+ and 42K+ to evaluate the effect of growth condition on the ion uptake mechanism. The interference between Cs+ and K+ at the site of root uptake was also evaluated based on the Cs+ and K+ uptake rates at K+ concentrations of 50 μM, 200 μM, and 3 mM in the seedlings grown under the medium-K (K+ = 200 μM) condition. As a result, the Cs+ uptake rate at 50 μM K+ was not influenced by the growth condition, whereas Cs+ uptake decreased when the uptake solution itself was supplemented with 3 mM K+. In addition, the Cs/K ratio in the seedlings was found to rise to exceed the Cs/K ratio in the culture solution as the rhizospheric K+ concentration increased, which was in contrast with previous findings in herbaceous plants. Our experiments demonstrated the first direct evidence for woody plants that a high K+ concentration can suppress Cs accumulation in Konara oak and that it was derived from competition for uptake between K+ and Cs+ in the rhizosphere, not from the growth K+ condition.

The effects of previous land-use to herbaceous vegetation in Quercus acutissima stands before and after clear-cutting

ABSTRACTIn rural Japan, various types of forest and grassland once used for agroforestry have now been abandoned because of socioeconomic changes associated with the decline in forestry, falling birth rate and aging population. The biodiversity of such secondary forests and grasslands, which had been maintained by routine management, is now in crisis. Among them, Kunugi (Quercus acutissima) forests in Kyushu island were exceptionally maintained by its management with clear-cut every 15–20 years to produce bed logs for shiitake mushroom cultivation. Some of these Kunugi forests have been planted in abandoned cultivated fields and grasslands. To clarify the effect of clear-cutting on the conservation of herbaceous vegetation on the forest floor, the floor vegetation of Kunugi forests in Kumamoto Prefecture with various land-use histories was surveyed before and after clear-cutting. Detrended correspondence analysis showed that some plots that originated from grassland characterized by the dominance of Pleioblastus argenteostriatus before clear-cutting became dominated by Miscanthus sinensis after clear-cutting. After clear-cutting, species of grassland origin emerged and the biodiversity increased. The management of Kunugi forests has facilitated the survival of grassland species such as Solidago virgaurea subsp. asiatica, Eupatorium laciniatum, Adenophora triphylla var. japonica, Desmodium podocarpum subsp. podocarpum, Vincetoxicum amplexicaule and Sanguisorba officinalis. Therefore, the large-scale mosaic landscape of Kunugi patches of various ages within a 15–20-year clear-cutting cycle may have contributed to the maintenance of regional biodiversity.

Quadrat method for measurement of injurious effects of Hypoxylon truncatum on bed logs used for shiitake (Lentinula edodes) cultivation

Quadrat method for measurement of injurious effects of Hypoxylon truncatum on bed logs used for shiitake (Lentinula edodes) cultivation

Characterization of vitamin B12 compounds in the fruiting bodies of shiitake mushroom (Lentinula edodes) and bed logs after fruiting of the mushroom

This study determined the vitamin B12 content in commercially available dried fruiting bodies of shiitake mushroom, Lentinula edodes. The vitamin B12 contents in dried donko-type fruiting bodies with closed caps (5.61 ± 3.90 μg/100 g dry weight), did not significantly differ from those of dried koushin-type fruiting bodies with open caps (4.23 ± 2.42 μg/100 g dry weight). The bed logs after fruiting of the mushroom also contained the vitamin B12 levels similar to that in the dried shiitake fruiting bodies. To determine whether the dried shiitake fruiting bodies and their bed logs contained vitamin B12 or other corrinoid compounds that are inactive in humans, we purified corrinoid compounds using an immunoaffinity column and identified vitamin B12 using vitamin B12-dependent Escherichia coli 215 bioautograms and liquid chromatography-electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) chromatograms. Dried shiitake fruiting bodies rarely contained an unnatural corrinoid vitamin B12[c-lactone] that is inactive in humans. Given that shiitake mushroom lacks the ability to synthesize vitamin B12de novo, the vitamin B12 found in dried shiitake fruiting bodies must have been derived from the bed logs.

Application of attract-and-kill traps and other methods for mitigating damage by the fungus moth, Morophagoides moriutii complex, to bed logs of the mushroom, Lentinula edodes

Application of attract-and-kill traps and other methods for mitigating damage by the fungus moth, Morophagoides moriutii complex, to bed logs of the mushroom, Lentinula edodes

Investigation of on-site biodegradation of thinned cedar wood by cedar-rot fungi, and influence of fungal-induced wood rot on shiitake-mushroom bed logs

Investigation of on-site biodegradation of thinned cedar wood by cedar-rot fungi, and influence of fungal-induced wood rot on shiitake-mushroom bed logs

국내 표고버섯 주요 버섯파리의 분자생물학적 종 동정 및 발생양상

표고버섯 재배지에서 버섯파리는 가장 문제가 되는 주요해충이다. 버섯파리에 의한 피해를 입은 농가는 표고버섯의 생산 뿐만 아니라 상품성이 현저히 떨어져 많은 피해를 입고 있다. 국내 표고버섯 재배양식은 크게 원목과 톱밥배지에 의한 방법으로 나뉘는데 재배양식의 차이 및 지역 간 주요 피해원인이 되는 버섯파리의 종과 분포양상을 조사하기 위해 봄부터 가을까지 경기도와 충청도 지역의 주요 표고버섯 재배지에서 버섯파리를 채집하였다. 채집은 황색 끈끈이트랩(참고, Yellow sticky trap)을 이용하였고 버섯파리의 종 동정은 cytochrome c oxidase subunit I (COI)의 염기서열 분석을 통해 버섯파리류의 다양한 종을 분류하였다. 그 결과, 원목을 이용하는 표고버섯 재배지에서는 Bradysia difformis, B. alpicola가 우점종인것으로 나타났고, 톱밥배지로 표고버섯을 재배하는 농가의 경우, B. difformi와 Scatopsidae sp.의 종이 다량 동정되었다. 그 외에도 B. trispinifera, B. longimentura, B. chlorocornea, B. protohilaris 및 Lycoriella ingenua가 동정되었다. Fungus gnats are usually found in mushroom farm and have recently become important pest because they can cause severe damage and reduce the production on shiitake mushroom. Usually shiitake mushrooms are cultivated on both oak bed logs and in the artificial sawdust beds in greenhouses. Using yellow sticky trap, the dipteran species in shiitake mushroom farm were collected from May to September in Kyonggi-do and Chungcheong-do in 2013. To identify the main species of fungus gnat on the shiitake farm in Korea, the collected samples were determined the sequence of cytochrome c oxidase subunit I (COI) by DNA barcoding. The phylogeny based on maximum likelihood analyses from COI sequence showed that Bradysia difformis and B. alpicola were main species of shiitake bed log and Scatopsidae sp. and B. difformis were dominant species of sawdust beds.

Molecular identification of dipteran pests (Diptera: Sciaroidea) from shiitake mushroom

On shiitake farms, mycophagous maggots can cause serious damage by preventing formation of the fruiting body. Recently, these pests have significantly reduced shiitake production in Korea. However, larvae and female adults cannot be identified due to their lack of morphological characteristics. Therefore, farmers and applied entomologists are unable to determine which species is the primary cause of the shiitake damage. In this study, mycophagous flies (colonized larvae) were collected from damaged shiitake farms and subsequently identified by matching identified males with the cytochrome c oxidase subunit I (COI) sequences from the larvae. Divergences of the COI sequences among the species discriminated the clusters clearly, and the mycophagous pests were identified as Camptomyia corticalis and C. heterobia. Interestingly, these two species coexisted under the bark of shiitake oak bed logs.

Dark winged fungus gnats (Diptera: Sciaridae) collected from shiitake mushroom in Korea

Seven species of sciarid flies were collected in shiitake mushroom farm in Korea. Among them, Lycoriella ingenua (Dufour 1839) and Bradysia difformis Frey 1948 were dominant as possible pests of the shiitake mushroom because the larvae were found on both oak bed logs and in the artificial sawdust beds for shiitake cultivation. Five other species, which were collected in lower numbers, are reported for the first time in Korea: Bradysia longimentula (Sasakawa 1994), Bradysia trispinifera Mohrig & Krivosheina 1979, Leptosciarella ( Leptospina) subdentata (Mohrig and Menzel 1992), Scatopsciara camptospina Mohrig and Mamaev 1990, and Xylosciara inornata Mohrig and Krivosheina 1979.

Artificial diets for the larval oak longicorn beetle, Moechotypa diphysis (Coleoptera: Cerambycidae)

The oak longicorn beetle, Moechotypa diphysis (Pascoe), is a pest of bed logs for shiitake mushroom and an invasive species on Japan’s main islands. I attempted to rear larvae of M. diphysis on two artificial diets consisting of a commercially available diet for silkworm plus dried yeast and sawdust of the sawtooth oak, Quercus acutissima Carruthers, or of Japanese beech, Fagus crenata Blume. Newly hatched larvae were inoculated on these artificial diets and reared at 25°C in the dark. More than 60% of larvae emerged as adults when fed with these diets. The weights of emerged adults fed on the artificial diets were heavier than those emerging from logs of Q. acutissima, their natural diet, in a field cage. These results demonstrate that the two artificial diets are useful for rearing M. diphysis larvae and can assist further studies on the development of this invasive species.

The smell and odorous components of dried shiitake mushroom, Lentinula edodes VI: increase in odorous compounds of dried shiitake mushroom cultivated on bed logs

Odor is one of the most important characteristics affecting consumer preference for dried shiitake mushrooms [Lentinula edodes (Berk.) Pegler]. In our previous studies, we found that the odor content of commercial dried products was too weak for most people, and that the odorous compound content could be increased by adding amino acids to sawdust media. Currently, however, bed-log cultivation is used to produce fruiting bodies for dried products. The purpose of this study was to fi nd a method to increase the content of odorous compounds in dried products cultivated on bed logs. Pressure injection of amino acids from the side of the bed log was the most effi cient method, but it had some problems. Hence, a simpler and less troublesome method was developed, i.e., injecting amino acid solution from small bottles set in deep holes bored in the sides of the bed logs. In fruiting bodies cultivated on bed logs injected with amino acid solution by the improved method, the mean contents of lentinic acid, a precursor of the odorous compound lenthionine, approximately doubled compared to that in the untreated logs, although the infi ltration area of the solution injected by the improved method was smaller than that by the former method.

Uptake of the insecticide, fenitrothion, by fruit bodies of shiitake (Lentinus edodes) from treated bed logs

Uptake of the insecticide, fenitrothion, by fruit bodies of shiitake (Lentinus edodes) from treated bed logs

Cultivation of Lentinus subnudus Berk (Polyporales: Polyporaceae) on woodlogs

Studies were carried out on the cultivability of Lentinus subnudus on woodlogs of various hardwood trees and the effect of chemical treatments of these woodlogs with citric, tartaric, indole-3-acetic (IAA) and gibberellic (GA 3) acids on fruitbody production and yield. Of the four hardwood species of Chlorophora excelsa, Terminalia ivorensis, Terminalia superba and Spondias mombin tried, woodlogs of C. excelsa were the best in supporting L. subnudus fructification, followed by those of S. mombin. On the effect of chemical treatments of C. excelsa and S. mombin woodlogs on L. subnudus' fruitbody production and yield, bed logs treated with 50 ppm indole-3-acetic and gibberellic acids were the best in enhancing fructification and yield with C. excelsa GA 3 and IAA treated bed logs consistently producing more fruitbodies and greater yields than S. mombin bed logs given the same treatments. The implication of these findings in relation to results obtained in previous studies are discussed.

Invasion of bed logs of Shiitake by Armillaria spp.

Invasion of bed logs of Shiitake by Armillaria spp.

Recycling of the waste substrate for mushroom cultivation. II : Cultivation of Pleurotus ostreatus and Flammulina velutipes using the sawdust from waste Shiitake bed logs

Recycling of the waste substrate for mushroom cultivation. II : Cultivation of Pleurotus ostreatus and Flammulina velutipes using the sawdust from waste Shiitake bed logs