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51.
Shirota K Katoh H Ito T Otsuki K 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(7):789-791
A total of 4,418 samples of commercial layer feeds obtained in 1998 were investigated for the presence of salmonellae. A total of 146 strains of salmonellae which consisted of 32 serovars, including 20 strains of Salmonella Enteritidis, were isolated from 143 feed samples. 相似文献
52.
Daisuke Yamagishi Hajime Akamatsu Hiroshi Otani Motoichiro Kodama 《Journal of General Plant Pathology》2006,72(5):323-327
Host-specific AAL-toxins and mycotoxin fumonisins are structurally related and were originally isolated from the tomato pathotype
of Alternaria alternata and from Fusarium verticillioides, respectively. Previous reports on the production of fumonisin derivatives by the tomato pathotype suggested a possible involvement
in the pathogenicity of the pathogen. Here, we have evaluated the role of fumonisin in A. alternata–tomato interactions. The results indicate that highly pathogenic isolates of A. alternata tomato pathotype produce AAL-toxin as the sole toxin, strongly implicating it as a pathogenicity factor. The related compound,
fumonisin, is also toxigenic and has infection-inducing activity on susceptible tomato plants. 相似文献
53.
54.
Takao Tsukiboshi Yoshiaki Chikuo Yoko Ito Yosuke Matsushita Koji Kageyama 《Journal of General Plant Pathology》2007,73(4):293-296
Root and stem rot with wilt of above ground parts of cultivated chrysanthemums was first found in Ibaraki, Toyama and Kagawa
prefectures, Japan in 2002 and 2003. Pythium species were isolated from the diseased tissues and identified as P. dissotocum, P. oedochilum, P. sylvaticum, P. ultimum var. ultimum and asexual strains of P. helicoides based on their morphologies and sequences of rDNA-ITS region. All the Pythium species were strongly pathogenic to chrysanthemums in pot conditions and were reisolated from the inoculated plants. Because
Pythium root and stem rot of chrysanthemum has never been reported in Japan, we propose that this is a new disease that can
be caused by the five Pythium species. 相似文献
55.
We investigated the validity and efficiency of a survey using sight per unit effort (SPUE) of sika deer and shrub-layer decline
rank (SDR), which is an index of decline in the physical structure of a whole stand caused by sika deer, based on data collected
on a broad scale. This survey was to be used to manage a deer population in order to conserve a forest ecosystem. First, we
evaluated the spatial and temporal scales of deer density that are most appropriate for predicting decline in the status of
understory vegetation. The model with SPUE calculated in a buffer with a radius of 4.5 km using data for the past 4 years
was found to be the best. We showed that our knowledge of the relationship between deer density and status of shrub-layer
vegetation is improved by identifying the most suitable spatial and temporal scales of SPUE for predicting SDR. Next, we quantified
the effects of SPUE and environmental components on SDR in stands. We found that SPUE had the greatest effect on SDR among
all explanatory variables. Moreover, the area under the curve (AUC) was large in a model that only used SPUE (AUC = 0.718).
This result suggests that the variation in SDR among stands was explained well by SPUE regardless of differences in the forest
environment. Furthermore, we identified the effective values of SPUE for preventing shrub-layer vegetation from declining
through deer density control. We conclude that a management system based on SPUE and SDR is a simple and valid method for
managing deer populations in order to conserve forest ecosystems. 相似文献
56.
Rice plants cope with flash floods using either an ‘escape strategy’ involving rapid shoot elongation or a ‘quiescence strategy’ involving survival underwater with minimal activity. To clarify the differences in the response of leaf photosynthesis properties to conditions during and after submergence, two rice cultivars were compared: a non‐shoot‐elongating cultivar IR 67520‐B‐14‐1‐3‐2‐2 (IR67520) and a shoot‐elongating cultivar IR72442‐6B‐3‐2‐1‐1 (IR72442). Twenty‐three‐day‐old seedlings were submerged in 80‐cm‐deep water for 14 days. During submergence, the chlorophyll contents of the upper fully expanded leaf (5th leaf) and newly developed leaf later (6th leaf) and the maximal quantum yield of photosystem II (Fv/Fm) of the fifth leaf decreased earlier in IR72442 than in IR67520. In the submerged sixth leaf, Fv/Fm was higher in IR72442 than in IR67520 at early measurement. Although Fv/Fm of the sixth leaf in submerged IR67520 increased substantially from 2 days post‐submergence, IR72442 decreased because of leaf chlorosis. Therefore, a non‐shoot‐elongating cultivar coped with submergence by inhibiting photodamage and maintaining high chlorophyll content in the leaves. The shoot‐elongating cultivar was able to maintain the photosynthetic capacity of the newly developed leaf during submergence by prompt reduction of chlorophyll and chlorophyll fluorescence in the leaf that developed before submergence. 相似文献
57.
58.
Riparian forests greatly influence aquatic ecosystems by providing shade cover, which controls water temperature and limits
primary production. We examined the relationship between forest cover and summer stream temperature in northernmost Japan.
Heat budget and statistical analyses were employed and the results were compared. Heat budget analysis revealed that the water
temperature would decrease almost linearly from 29°C to 25°C with an increase in forested reaches along a 3.2 km stretch of
the river. Multiple regression analysis by the stepwise method chose only open channel length as a variable to explain the
variation in maximum stream temperature. A sharp increase in stream temperature was noted when riparian forest cover was removed
in short lengths, of up to 1.0km; this increasing trend gradually flattened as the length of open stretch increased. Thus,
even small openings in the riparian canopy resulted in drastic rises in summer stream temperature. The maximum summer temperatures
estimated by the two methods were coincided, and can therefore be accurately estimated by regression analysis. Retrospective
analysis based on the regression equation showed that the maximum summer temperature in 1947 was 6°C lower than at present,
and that a sharp increase occurred from 1947 to 1960, a period of rapid expansion of agricultural land development in the
watershed. 相似文献
59.
T. Ona T. Sonoda K. Ito M. Shibata Y. Tamai Y. Kojima J. Ohshima S. Yokota N. Yoshizawa 《Wood Science and Technology》2001,35(3):229-243
Relationships between cell and pulp properties were investigated by examining the within-tree property variations in Eucalyptus camaldulensis and Eucalyptus globulus. Properties investigated included proportions of ray and axial parenchyma, thickness of cell walls and cell wall percentages.
The characteristics of the ray and axial parenchyma (their proportions and wall thickness) were found to have a significant
influence on all measured pulp properties, including paper strength properties. Multiple regression of pulp properties in
relation to cell properties revealed that nearly all measured pulp properties were explained by cell properties at the 1%
significance level. It was concluded, therefore, that all cell types are important for predicting pulp properties, and it
is strongly recommended that tree breeding programs for Eucalyptus include the measurement of all cell types.
Received 6 July 1999 相似文献
60.
The effects of shoot size and differences in budburst phenology ofQuercus serrata trees on the spatial patterns of galls were investigated for two cynipid species: the sexual generation ofAndricus moriokae and the agamic generation ofAphelonyx glanduliferae. There were marked differences in budburst phenology, but these did not affect the gall density on the tree. The galls of
both cynipids showed a contagious distribution in their respective trees, but different abundance patterns under high gall
density. The mean number of galls ofA. glanduliferae over a shoot size range was positively correlated with shoot size. More galls ofA. moriokae appeared on larger shoots on trees on which many buds had started growing before oviposition by the agamic adults. In the
case of a tree on which a few buds had burst by the time of oviposition, the mean numbers ofA. moriokae galls on shoots of particular size ranges depended on the frequency of shoots in the size class. These results suggest that,
although these cynipids prefer to attack larger shoots within a host tree, they may exhibit plasticity in their preference
in response to changes in budburst phenology of the host plant relative to the time of oviposition. 相似文献