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排序方式: 共有64条查询结果,搜索用时 15 毫秒
1.
Summary The alder has a perennial nodule cluster. The nodule amount on the roots increases with tree age. The N2-fixing activity of nodules decreases with nodule age. Purple coloured soils with various soil pHs and CaCO3 contents are, in the main, the ones which influence nodulation and N2-fixing. Higher N2-fixing capacity existed in the neutral and low calcium soils. High calcium soils and acid soils can restrain nodulation and
the N2-fixing rate significantly. On the slope, where calcarous light loams are found, the annual nitrogen fixation capacity of
alder and cypress mixed plantations, less than 10 years old, is 16 or 17 kg/ha yr, but in the valley, a pure alder plantation
can reach 40 kg/ha yr. 相似文献
2.
Summary ThreeAlnus glutinosa (L.) Gaertn. clones, obtained byin vitro propagation techniques, were inoculated with four strains ofFrankia. The ability of these clones to nodulate and fix nitrogen was previously reported; this study deals with the performance of 12 different combinations of pairs of symbionts.Shoot fresh weight, shoot height and collar diameter were measured 60 and 82 days after inoculation. Shoot fresh weight seems to be more sensitive and reliable than the other parameters. Nitrogenase activity, measured by the acetylene reduction assay, was assayed 78 days after inoculation and was consistent with the biomass measurements.Better growth was observed when type N strains were used. Significant growth differences were observed between clones AG-2 and AG-8 on the one hand and clone AG-4 on the other. Thus, the use of genetically defined host plants and microsymbionts permitted the demonstration of significant performance variation even among cloned plants from the same provenance (AG-4 and AG-8).The duration of the experiment influenced the results with differences becoming less significant with time. This might be caused by an external limiting factor such as the pot size, competition for light,etc. But it could also be indicative of differences in nodulation speed among the treatments. 相似文献
3.
Peter Schröder 《Trees - Structure and Function》1989,3(1):38-44
Summary A gas transport system based upon the physico-chemical effect of thermo-osmosis of gases in described for the black alder, Alnus glutinosa (L.) Gaertn. Air is transported through the alder's stem to the roots, thus improving O2 supply to respiring tissues of the root system. The gas transport system is investigated by means of a tracer gas technique (11% ethane in air, v/v). Gas transport depends on any source of radiant heat generating a temperature difference between the tree's stems and the atmosphere. The amount of gas transported in leafless trees is four times higher than the amount of gas reaching the roots by gas diffusion. Two-thirds of the gas is transported in the wood, only one-third in the bark. Intercellular spaces inside the porous lenticels of the bark are responsible for this kind of gas transport. Their diameters are estimated by the effusion rates of different tracer gases to be in the range of 1 m. 相似文献
4.
Nitrogen-fixing root nodules of Alnus crispa var. mollis Fern. were studied by transmission electron microscopy and by freeze-etching technique. Ultrathin sectioning of septate vesicles of the actinomycetal endophyte showed an electron transparent zone, the so-called void area, between the vesicle cell wall and its encapsulation material. This void area was not observed in the freeze-etching replicas of cryoprotected nodular tissue. It is suggested that the void area is the result of the coming-off of the vesicle cell wall from the capsule and that its formation reflects difficulty in fixing the voluminous mature vesicle of the root nodule endophyte. 相似文献
5.
A new chiral Lewis acid catalyst 9 was prepared in situ from a 1:2 molar mixture of (R)-3,3'-di(2-mesitylethynyl)binaphthol (6) and titanium(IV) isopropoxide at ambient temperature. The 3- and 3'-substituents on 6 were effective for preventing undesired aggregation between Ti(IV) complexes and increasing the enantioselectivity (up to 82% ee) in the Diels-Alder reaction of methacrolein with cyclopentadiene. 相似文献
6.
Humus bacteria of Norway spruce stands: plant growth promoting properties and birch, red fescue and alder colonizing capacity 总被引:5,自引:0,他引:5
Elo S Maunuksela L Salkinoja-Salonen M Smolander A Haahtela K 《FEMS microbiology ecology》2000,31(2):143-152
We studied the potential of the humus layer of the Norway spruce stands to supply beneficial rhizobacteria to birch (Betula pendula), alder (Alnus incana) and fescue grass (Festuca rubra), representatives of pioneer vegetation after clear-cutting of the coniferous forest. Axenically grown seedlings of these species were inoculated with the acid spruce humus, pH 3.7-5.3. Actinorhizal propagules, capable of nodulating alder, were present in high density (10(3) g(-1)) in humus of long-term limed plots, whereas plots with nitrogen fertilization contained almost none (=10 g(-1)). The genera most frequently found in the humus were Bacillus, Paenibacillus, Arthrobacter, Nocardia, Rhodococcus and Pseudomonas, independently of prior liming or fertilization of the plots. The taxa found in the seedling roots differed from that in humus by the prevalence of the Gram-negative genera Pseudomonas, Alcaligenes and Comamonas. Enrichment cultures of the roots on nitrogen-free media yielded Paenibacillus and Rhodococcus species. Nitrogen-fixing R. erythropolis and a novel Paenibacillus, closest by full sequence of 16S rDNA to P. durus, represented new classes of nitrogen-fixing rhizosphere bacteria. In addition, nitrogen-fixing R. fascians was found in the humus. The rhizoflora and humus contained high proportions of bacteria antagonistic towards plant pathogenic Rhizoctonia sp., Botrytis cinerea and Fusarium culmorum. The antagonistic isolates also commonly produced siderophores and/or cell wall degrading enzymes. 相似文献
7.
Palmer AM Grobbel B Brehm C Zimmermann PJ Buhr W Feth MP Holst HC Simon WA 《Bioorganic & medicinal chemistry》2007,15(24):7647-7660
A series of novel tetrahydroimidazo[2,1-a]isoquinolines was prepared based on a hetero Diels–Alder reaction between an enamine and 1,2,4-triazine as key step. A structure–activity relationship was established focussing on the influence of the substitution pattern in position 3 and 6 of the heterocycle on antisecretory activity, lipophilicity, and pKa value. Potent inhibitors of the gastric acid pump were identified. 相似文献
8.
The optimization of a Diels-Alder reaction to prepare a novel ketone bearing a 2,3-dimethylnorbornyl group is presented together with the structure elucidation of the isomers. Employing this new ketone as starting material, derivatives with new woody odor notes as well as attempts to obtain ambery-musky odorants are reported. 相似文献
9.
Tomoko Negishi 《Landscape and Ecological Engineering》2008,4(2):83-89
The interrelation among size, biomass, and sprouting of alder trees was studied to extract the most important hydrochemistrical
factors controlling the growth of alder forest in Kushiro Mire, northern Japan. The gradient was mostly explained by chemical
variables such as pH, ash content, and P2O5, which showed strong positive correlation with each other, and secondarily by fluctuation of the water table (WL, i.e., water
level range). These variables are more important than other hydrochemical ones, because neutral and turbid flood water replaces
acidic mire water and conveys fine sediment with adsorbed phosphorus, which in turn could regulate the pH and amount of phosphorus.
Also, the number of sprouts showed negative correlation mainly with tree size and redox potential (Eh), which suggested a
flooded environment. Because of this, the size of alder was suppressed by hydrochemical variables; however, alder individuals
producing new sprouts were maintained. We conclude that variation in size, biomass, and sprouting of alder was mainly controlled
by acidity and phosphorus availability, and was significantly influenced by water fluctuation. 相似文献
10.
Response of winter chemical defense in Alaska paper birch and green alder to manipulation of plant carbon/nutrient balance 总被引:5,自引:0,他引:5
Summary Plant carbon/nutrient balance has been implicated as an important factor in plant defensive chemistry and palatability to herbivores. We tested this hypothesis by fertilizing juvenile growth form Alaska paper birch and green alder with N, P and N-plus-P in a balanced 2x2 factorial experiment. Additionally, we shaded unfertilized plants of both species. Fertilization with N and N-plus-P increased growth of Alaska paper birch, reduced the concentration of papyriferic acid in internodes and increased the palatability of birch twigs to snowshoe hares. Shading decreased birch growth, decreased the concentration of papyriferic acid in internodes and increased twig palatability. These results indicate that the defensive chemistry and palatability of winter-dormant juvenile Alaska paper birch are sensitive to soil fertility and shade. Conversely the defensive chemistry and palatability of green alder twigs to snowshoe hares were not significantly affected by soil fertility or shade. The greater sensitivity of Alaska paper birch defensive chemistry and palatability to snowshoe hares in comparison to green alder is in agreement with the hypothesis that early successional woody plants that are adapted to high resource availability are more plastic in their chemical responses to the physical environment than are species from less favorable environments. 相似文献