The growth of <Emphasis Type="Italic">Larix gmelinii</Emphasis> seedlings as affected by charcoal produced at two different temperatures     

Kobayashi Makoto  Dongsu Choi  Yasuyuki Hashidoko  Takayoshi Koike 《Biology and Fertility of Soils》2011,47(4):467-472

Fires burn forest with spatially heterogeneous intensity and charcoals generated at various temperatures during fires exhibit variable physical and chemical characteristics. These variable properties of charcoal may, in turn, influence germination and growth of tree seedlings. To examine the effects of different charcoal properties on the growth of Gmelin larch (Larix gmelinii) seedlings, we conducted an experiment with larch-branch-derived charcoals produced at 400°C (low charcoal) and 800°C (high charcoal); charcoal was combined with sand at three different rates (5%, 20% and 50%, v/v charcoal in sand). The high charcoal had no significant effects on any measured property while the low charcoal application stimulated growth and the effect increased with the addition rate. The low charcoal application resulted in the greater available P content, a lower N/P in needles and the greater growth of seedlings than high charcoal application. The growth of seedlings was not affected by the application of the high charcoal at any rate probably because the high charcoal inhibited the seedling growth due to its high pH. These results indicate that charcoal produced at different temperatures during forest fires can affect the growth of Gmelin larch seedlings differently.  相似文献   

Impact of clod (aggregate) size on evaporation rate and soil moisture profile during the drying process     

Yoshihiro Matsumoto  Shuichiro Yoshida  Akimasa Okabe  Kazuhiro Nishida 《European Journal of Soil Science》2023,74(5):e13420

Large clods (centimetres in size) can be formed by tillage in clayey paddy fields where upland crops are planted. These clods cause early water depletion near the soil surface, which decreases crop germination and emergence rates. Because of the difficulty in reducing clod size, desiccation damage to seeds can be avoided by adjusting the seeding depth based on the clod size-dependent soil moisture profile. This study aimed to clarify the effect of clod size on (1) the evaporation rate (E) and soil moisture profile and (2) the mobility of soil water during the drying process. Evaporation experiments were conducted in an air-conditioned greenhouse with natural light using cylindrical columns filled with artificially made clods 3 (L columns) and 1 cm (S columns) in diameter. We measured E, potential evaporation rate (PE), and total soil moisture content (w_tot) throughout the experiment and the soil moisture profiles at the end of the experiment. The water diffusivity (D_w) and apparent vapour diffusion coefficient (d_vap) were calculated as the mobility of soil water and water vapour, respectively. We found that w_tot was lower in the L column than in the S column, although not at the onset of the experiment. At the end of the experiment, the soil moisture content was lower in the L column than in the S column throughout the soil layer. In contrast, E/PE was higher in the L column than in the S column throughout the experiment and even at the same w_tot. Regarding mobility, D_w was slightly greater in the L column than in the S column in the soil moisture content range, where vapour movement could be greater than liquid water movement. In addition, the ratio of d_vap to the diffusion coefficient of water vapour in soil was higher than unity in both columns and was 2.4–3.2 times higher in the L column than in the S column. In summary, larger clods caused a higher evaporation rate and lower soil moisture content, owing to the increased enhancement of water vapour movement probably induced by wind.  相似文献   

Multiple copies of <Emphasis Type="Italic">AMT2</Emphasis> are prerequisite for the apple pathotype of <Emphasis Type="Italic">Alternaria alternata</Emphasis> to produce enough AM-toxin for expressing pathogenicity     

Yoshiaki Harimoto  Takayoshi Tanaka  Motoichiro Kodama  Mikihiro Yamamoto  Hiroshi Otani  Takashi Tsuge 《Journal of General Plant Pathology》2008,74(3):222-229

The apple pathotype of Alternaria alternata produces the cyclic depsipeptide AM-toxin and causes Alternaria blotch of apple. Previously, we cloned AMT2 from the apple pathotype as an orthologue of AFTS1, which is required for biosynthesis of the decatrienoic acid ester AF-toxin I of the strawberry pathotype. These genes were predicted to encode aldo-keto reductases involved in biosynthesis of a common precursor, 2-hydroxy-isovaleric acid, of AF-toxin I and AM-toxin. In this study, we analyzed the function of AMT2 in AM-toxin biosynthesis in the apple pathotype. DNA gel blot analysis of the apple pathotype strain IFO8984 with five restriction enzymes suggested that this strain has a single copy of AMT2 in the genome. However, gene disruption experiments showed that IFO8984 probably has three copies of AMT2. We made mutants having one or two copies of AMT2 disrupted. The single-copy mutants produced less AM-toxin than did the wild type and were still as pathogenic as the wild type. The two-copy mutants produced trace or undetectable amounts of AM-toxin and were markedly reduced in pathogenicity. Thus, AMT2 was verified to be required for AM-toxin biosynthesis and hence pathogenicity. The fact that the two-copy mutants have a remaining copy of AMT2 suggests that multiple copies of AMT2 are prerequisite for the pathogen to produce enough AM-toxin for full pathogenicity.  相似文献   

Bird responses to broad-leaved forest patch area in a plantation landscape across seasons   总被引：1，自引：0，他引：1  

Yuichi Yamaura  Susumu Ikeno  Makoto Sano  Kimiko Okabe  Kenichi Ozaki   《Biological conservation》2009,142(10):2155-2165

Although plantation forests have widely replaced native forests worldwide, few studies have examined the effects of plantation forestry on organisms at the landscape level. In this study, we examined the effects of broad-leaved forest patch area (1.4–312 ha) on bird assemblages in a conifer plantation-dominated landscape during wintering and breeding seasons. We also surveyed birds in the plantation matrix and treated the patch area of the matrix as 0. We examined whether the detection rates of species changed suddenly across patch area (threshold) using segmented regression. We found that species richness increased with patch area in both seasons. Responses of detection rates to patch area varied and were categorized as follows: insensitive, linear increase and decrease, quadratic increase and decrease, concave and convex. Thresholds indicating that the detection rate suddenly increased above a certain patch area were found for two species only in the winter. Species responses varied more in the winter than in the breeding season. Certain ecological traits of species were consistently associated with the responses to patch area across seasons (migratory strategy, nesting substrate and foraging trait), while body weight was only associated in the winter. Because species richness and detection rates of many species were high in large patches, large broad-leaved forests (especially >40 ha) should be retained and restored with high priority. Additionally, bird responses to patch area in the winter should not be ignored because many species required large patches during the winter season.  相似文献   

Bioassay-guided isolation of a novel chemoattractant for <Emphasis Type="Italic">Ralstonia solanacearum</Emphasis> in tomato root exudates     

Takuya Hasegawa  Atsushi Okabe  Yusuke Kato  Atsushi Ooshiro  Hiroshi Kawaide  Masahiro Natsume 《Journal of General Plant Pathology》2018,84(1):20-26

Tomato root exudates were analyzed using a bioassay to detect the chemoattractant for Ralstonia solanacearum. An activated charcoal-adsorbed fraction of root exudates from tomato cultivar Oogata-fukuju had chemoattractant activity for R. solanacearum strain MAFF 730138. The active component, purified using a Sep-Pak C18 cartridge, an activated charcoal column, diol-modified silica gel, and NH₂-modified silica gel, is a new hydrophobic attractant. The final purified fraction produced a single peak in a diol-modified silica gel HPLC analysis.  相似文献   

SONOGRAPHIC APPEARANCE OF UREMIC GASTROPATHY IN FOUR DOGS     

Amy M.  Grooters  DVM  Takayoshi  Miyabayashi  BVS  MS  David S.  Biller  DVM  Joyce  Merryman  DVM 《Veterinary radiology & ultrasound》1994,35(1):35-40

Gastrointestinal signs are common in dogs with uremia. Structural changes in the stomach associated with uremia in dogs include ulceration, edema, necrosis, gastric wall thickening, submucosal arteriopathy, and mineralization of the gastric mucosa and submucosa. Upon ultrasonographic evaluation of the abdomen in four dogs with severe uremia due to chronic renal disease, a thickened gastric wall, thickened rugal folds, and a hyperechoic line at the mucosal-luminal interface due to mineralization of the gastric mucosa were found. Ultrasonography was more sensitive than survey radiography for the identification of gastric lesions associated with uremia in these dogs.  相似文献   

Desiccation-tolerance ofFagus crenata blume seeds from localities of different snowfall regime in central Japan     

Emiko Maruta  Tomohiko Kamitani  Midori Okabe  Yuji Ide 《Journal of Forest Research》1997,2(1):45-50

In beech (Fagus crenata Blume) forests on the Pacific Ocean side in Central Japan, snowpack depth is little and xeric conditions may prevail in winter, in contrast to heavy snow in beech forests on the Japan Sea side. The effects of such conditions during winter on the viability of beech seeds were studied at a beech forest on the Pacific Ocean side. Thickness and weight ratio of pericarp of beech seeds were significantly greater in populations on the Pacific Ocean side compared to the Japan Sea side, this apparently being related to snowpack depth in winter. During the initial stage of seed drying, the drying rate of seeds from the Fuji population (the Pacific Ocean side) was less than that from the Sumon population (the Japan Sea side), possibly due to the thicker pericarp. Germination percentage of seeds which dried to a water content as low as 7% d.w. did not decrease for either population, indicating desiccation tolerance of beech seeds. In the beech forest (University Forest at Yamanaka) on the Pacific Ocean side, water content of seeds sown below litter from both populations remained sufficient for viability during winter. Germinating seeds from the populations on the Japan Sea side were more desiccation-sensitive in early spring, compared to those from the Fuji population, partially due possibly to differences in pericarp thickness.  相似文献   

便携式测定仪在测定叶片衰老过程中氮和叶绿素含量上的应用   总被引：5，自引：0，他引：5  

王文杰  李雪莹  王慧梅  祖元刚  小池孝良 《林业科学》2006,42(6):20-25

选取哈尔滨地区本地植物华北紫丁香和山槐,以及华北引进种紫穗槐为研究材料,于2003年秋季对3种植物叶片从夏末叶片盛期到秋末叶片脱水变干脱落全过程进行了连续测定.结果表明:1)2种仪器对于表征单位叶面积上叶绿素和N含量的有效性明显高于表征单位鲜质量上叶绿素和N含量.2)尽管PPW-3000和SPAD-502对于表征单位叶面积N含量和各种叶绿素含量具有一定的普适性(R2=0.51～0.65),但不能有效表征不同植物的种间差异性.因此,使用2种便携式测定仪准确估计N和叶绿素含量需要首先确定每种植物的标准校正曲线.3)当表征同一种植物不同生长时期叶绿素和N含量变化时,2种仪器都适用于表征本地种华北紫丁香和山槐叶片衰老过程的变化(R2＞0.82);而对于外地引进种紫穗槐,叶片衰老脱水过程中叶绿素并未同时分解,表征效果欠佳(R2＜0.66),甚至相关性不显著.可见,便携式仪器更适用于适应本地气候的正常衰老种的相关测定.4)2种仪器比较而言,PPW-3000对于表征叶片N含量变化,尤其是对于叶片衰老脱水过程叶绿素并未同时分解的叶片(如紫穗槐),效果较SPAD-502好;而对于叶片衰老过程中叶绿素同时降解的叶片(如华北紫丁香和山槐),2种仪器效果没有明显区别.  相似文献   

Distribution of Frankia, ectomycorrhizal fungi, and bacteria in soil after the eruption of Miyake-Jima (Izu Islands, Japan) in 2000     

Takashi Yamanaka  Hiroaki Okabe 《Journal of Forest Research》2006,11(1):21-26

Miyake-Jima, a round island of about 8 km in diameter, is located about 200 km south of Tokyo, Japan (34°08′ N, 139°53′ E). In July 2000, the central cone of this island collapsed and a new eruption started with the falling of volcanic ash and SO₂ emission. In October 2001, we measured the distribution of bacteria, and Frankia, a symbiotic nitrogen-fixing actinomycete that forms root nodules, and ectomycorrhizal fungi associated with alder in newly deposited ash and its underlying soil by cultivation of Alnus sieboldiana seedlings in these soils. There were fewer bacteria growing on the nutrient broth agar and fewer bacteria growing on 100-fold diluted nutrient broth agar in newly deposited volcanic ash than there were growing in the buried old soil. In four out of five sites, little or no nodulation was observed in newly deposited ash; abundant root nodules were formed in the underlying soil. Ectomycorrhizae formed in the seedlings cultivated in the underlying soil. In May 2003, the distribution of Frankia and ectomycorrhizal fungi in soil at different depths (up to 160 cm) was also investigated. Frankia and ectomycorrhizal fungi were relatively abundant in surface soil layers.  相似文献   

Acclimation of shoot and needle morphology and photosynthesis of two Picea species to differences in soil nutrient availability     

Ishii H  Ooishi M  Maruyama Y  Koike T 《Tree physiology》2003,23(7):453-461

To investigate morphological acclimation to differences in nutrient availability, we compared shoot and needle morphology of Picea glehnii (Friedr. Schmidt) M. T. Mast. and Picea jezoensis (Siebold & Zucc.) Carrière trees growing on nutrient-poor volcanic ash and nutrient-rich, brown forest soil. Trees of both species were shorter and had more open canopies when growing on volcanic ash than when growing on brown forest soil. Nutrient-poor conditions limited height growth less in P. glehnii than in P. jezoensis. In both species, trees growing on volcanic ash had shorter annual increments in the previous year and more needles per shoot length and, hence, a smaller shoot silhouette area (SSA) relative to needle dry mass (NDM) than trees growing on brown forest soil. Soil type had less effect on shoot projected needle area (PNA). Total needle area (TNA) of P. glehnii shoots was similar between soil types, whereas TNA of P. jezoensis was lower in trees growing on volcanic ash than in trees growing on brown forest soil. For both species, low SSA in response to nutrient-poor conditions resulted in low shoot SSA/PNA ratios, indicating high within-shoot self-shading. Shoot SSA/TNA of P. glehnii was lower in trees growing on volcanic ash than in trees growing on brown forest soil, indicating that needles were sun-acclimated. In contrast, shoot SSA/TNA of P. jezoensis was higher in trees growing on volcanic ash than in trees growing on brown forest soil. The contrasting response of TNA to low nutrient availability was associated with species-specific differences in needle morphology. Needles of P. glehnii growing on volcanic ash were slightly shorter, wider, thicker and heavier than those of trees growing on brown forest soil, indicating morphological acclimation to high irradiance. Needles of P. jezoensis growing on volcanic ash were shorter than those of trees growing on brown forest soil, but did not show morphological acclimation to high irradiance in width, thickness or mass. For both species, nutrient-poor conditions decreased maximum photosynthetic rate (Amax) per NDM. However, when expressed per PNA, the decrease in Amax was reduced, and when expressed per SSA, Amax was higher in trees growing on volcanic ash than in trees growing on brown forest soil. On volcanic ash, Amax per NDM was lower for P. glehnii than for P. jezoensis. However, morphological changes at the shoot and needle levels reversed this trend when Amax was expressed per SSA or per PNA. The species-specific differences in morphological response to differences in soil nutrient availability suggest that P. glehnii is more tolerant of nutrient-poor conditions, whereas P. jezoensis is better at exploiting nutrient-rich soils.  相似文献