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Volume 24
Displaying 1-5 of 5 articles from this issue
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Yasuo SAWADAArticle type: Article
1982 Volume 24 Pages 1-6
Published: December 15, 1982
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSSpecial references to accumulation and distribution of organic matter, differentiation of soil layer, and fungistasis of soil were presented to reach a better understanding on the characteristic microbial environment of grassland. Primary production (including underground parts) of a typical grazing pasture was shown as follows: aboveground biomass was ranged 200-400 g/m^2; standing litter was 30-50% of the total aboveground biomass; surface litter was 40-60 g/m^2; and underground biomass was 400-600 g/m^2. Almost whole biomass was distributed in a surface-3 cm layer of soil. Consequently, different-sized organic residues present in soil were more abundant in grassland than cropland. On the other hand, anaerobic condition of sublayer below 5 cm of soil was progressed by compaction of soil during long-term utilization of grassland. From experimental results of microbial growth on the separated organic residues after incubating in soil, it seemed likely that microbial growth even on the organic matter might be strongly restricted by fungi- and bacteriostasis of natural soil.View full abstractDownload PDF (879K) -
Toshiki MORICHI, Yoshinobu OHYAMAArticle type: Article
1982 Volume 24 Pages 7-15
Published: December 15, 1982
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSTypes of microorganisms in grass and silages, and their changes during ensilage were discussed mainly based upon the authors' experimental results. Lactic acid bacteria, especially lactobacilli, are found in relatively small numbers on fresh herbage. Provided that sealing of silo is perfect and sufficient amounts of water soluble carbohydrates are available, rapid increase in lactobacilli and concomitant decrease in aerobic Gram-negative bacteria take place in a short period after ensiling. The resulting low pH inhibits the growth of clostridia. Invasion of air into a silo for a certain period after ensiling definitely brings about undesirable fermentation according to the following mechanism: Under the aerobic condition thus induced, active multiplication of Gram-negative bacteria is promoted. As a result, growth of lactobacilli is suppressed therefore pH does not fall satisfactorily. Following the sealing of the silo, Gram-negative bacteria rapidly consume the remaining oxygen and brings about anaerobic condition. Thus the combined high pH and anaerobic conditions promote the growth of clostridia, finally producing silage of very poor quality with large amounts of butyric acid. Inoculation of herbage with Lactobacillus plantarum, combined with glucose addition at ensiling, could overcome the adverse effect of the air invasion and produce high quality silage. Types and behaviour of yeasts and fungi, which are responsible for aerobic deterioration of silages after opening silo, were also described.View full abstractDownload PDF (918K) -
Hajime MINATOArticle type: Article
1982 Volume 24 Pages 17-25
Published: December 15, 1982
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSIn this review, the environments in the rumen, kinds of microorganisms living in the rumen, the localization of bacteria in the rumen and the techniques of searching the behavior of bacteria in the rumen are discussed on the basis of my experience and knowledge. The points described here are as follows: 1. The rumen has the environmental features of anaerobiosis, constant volume of the contents regulated by the rumen volume, neutral condition kept by the supply of large amounts of saliva having a high buffering capacity, and a constant temperature maintained by the body temperature. 2. Although there exist many kinds of protozoa, bacteria, fungi and virus, the kinds of bacteria are mainly explained in this review. The bacteria are divided into several groups on the basis of their ability to digest the components of feed. The bacteria are also explained from the angles of their stenotrophic and eurytrophic property. 3. The bacteria are grouped roughly into four groups according to their existing location in the rumen; free living, food-particle-associated, rumen epithelium associated and protozoa associated bacteria. It is described here that the physiological characteristics and kinds of bacteria are different in each group. 4. It is pointed out that the development and employment of the research techniques except culture methods will be important to clarify the behavior of bacteria in the rumen.View full abstractDownload PDF (1173K) -
Hiroyuki NIEDAArticle type: Article
1982 Volume 24 Pages 27-37
Published: December 15, 1982
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSDry rot disease of konnyaku (Amorphophallas konjac C. KOCH) is caused much commonly by plantiong of affected seed corms and rarely by ones infected in soli after planting. When severely affected seed corms were planted, usually their inner tissues were almost completely rotted except their skin. From the results of optical microscopic and scanning electron microscopic observations, it was confirmed that causal fungus (Fusarium solani f. sp. radicicola) overwinters in brown-rotted area of the infected tissues and most commonly in the mannanscells in the state of mycelium or mycelial strands. When such affected seed corms were planted, the fungus get the moisture in soil, soon grows and spreads on the surface of the corms and invades the new corms. As the symptoms of the disease, there are two types; "Samehada" like and "Dry-rot" like symptoms. The former means roughen surface, and appears when the skin of the corms at young stage are invaded, and the latter appears when the fungus invades the new corm through injured parts caused by feeding of soil-inhabiting organisms and brown-rotted areas spread deeply during the periods in drying and storage. When a Konnyaku corm slice, about 5 mm thick, were inoculated with the pathogen and incubated for 3 to 5 days at 28℃, the brown-rotted areas developed in the vicinity of growing mycelia. However, Fusariun sp. except F. solani f. sp. radicicola did't form such a brown-rot symptom in the slice. Thus, the present reported slice method is exceedingly useful as a simple method for an identification of F. solani f. sp. radicicola. Moreover, the method is not only surely able to apply to a simple test of variental resistance but also it is useful for a screening method of chemicals for the seed corm sterilization, by measuring the size of brown-rotted area formed on the treated slices.View full abstractDownload PDF (1098K) -
Kei OGAWA, Hajimu KOMADAArticle type: Article
1982 Volume 24 Pages 39-48
Published: December 15, 1982
Released on J-STAGE: May 31, 2017
JOURNAL FREE ACCESSUnder seven times of continuous cropping of radish (Japanese radish), the incidence of radish yellows, caused by Fusarium oxysporum f. sp. raphani, was constantly high in the field heavily infested with the pathogen, and it increased in slightly infested field. It also was high in the field applied with cereal-straw manure and the field poorly fertilized with synthetic fertilizer. While it was rather low in the field richly fertilized with synthetic one. In the field applied with slaked lime, it converged to a cirtain value lower than that in the former two and higher than that in the latter one. Averaged value of inoculum density of the pathogen approximately correlated with that of the disease incidence, but each value scattered widely. The amount of scattering was relatively small in heavily infested field, but it was very large in slightly infested one. The more frequently radish was cropped, the more the disease occurred even if in the same level of infestation. According as radish was cropped continuously, inoculum density of the pathogen remarkably decreased in heavily infested one: Both value showed a tendency to converged to a certain value. Growth of the healthy plants was better in richly fertilized field and in lime-applied field than in poorly fertilized field and in manure applied field. No distinct correlation was recognized between population of general microorganisms and antagonistic actinomycetes in rhizosphere of radish seedlings and the disease incidence. In richly fertilized field, soil pH was lower, percentage of microconidial germination on glass slide burried in soli was lower, and inoculum density in the rhizospere soil was lower than those in the others. The reason why the disease incidence was less in richly fertilized field than the others was assumed that soil environmental factor(s) was favorable to radish growth, but unfavorable to activity of the pathogen.View full abstractDownload PDF (823K)
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