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1.
Summary Litterfall was collected over 1 year from eight natural stands of red alder growing on different sites in western Washington. The stands occurred at various elevations and on different soils, and differed in age, basal area, and site index. Most litterfall was leaf litter (average 86 percent). Amounts of litterfall and leaf litter varied significantly (P<0.05) among the sites. Average weights of litterfall and leaf litter in kg ha–1 yr–1, were 5150 and 4440, respectively. Weight of leaf litter was not significantly (P<0.05) related to site index, stand age, or basal area. The sites varied significantly (P<0.05) in concentrations of all elements determined in the leaf litter, except Zn. Average chemical concentrations were: N, 1.98 percent; P, 0.09 percent; K, 0.44 percent; Ca, 1.01 percent; Mg, 0.21 percent; S, 0.17 percent; SO4–S, nil; Fe, 324 ppm; Mn, 311 ppm; Zn, 53 ppm; Cu, 13 ppm; and Al, 281 ppm. There were significant correlations between some stand characteristics and concentrations of some elements, and among the different chemical components of the leaf litter. Important correlations were found between stand age and P concentration (r=–0.84,P<0.01); weight of leaf litter and P concentration (r=0.74,P<0.05); weight of leaf litter and K concentration (r=0.71,P<0.05); concentrations of N and S (r=0.81,P<0.05); and concentrations of Fe and Al (r=0.98,P<0.01). Returns of the different elements to the soil by leaf litter varied among the different sites. Average nutrient and Al returns, in kg ha–1 yr–1, were: N, 82; Ca, 41; K, 19; Mg, 8; S, 7; P, 4; Fe, 1; Mn, 1; Al, 1; Zn, 0.2, and Cu, <0.1. 相似文献
2.
Red alder (Alnus rubra Bong.) stands in the Pacific Northwest are the common first stage in succession following disturbance. These stands are highly productive and contribute a large amount of N to the soils as a result of their N2-fixing symbiosis with Frankia. As these alder stands age, the soils not only increase in total N, but concentrations of NO–
3 increase and pH decreases as a result of nitrification. The objective of this study was to determine how the nodulation capacity of Frankia varies as red alder stands age and if differences in nodulation capacity are related to changes in soil properties. Nodulation capacity was determined by a red alder seedling bioassay for soils from red alder stands in the Oregon coast range covering a wide range of ages. Six chronosequences were sampled, each containing a young, an intermediate, and an older alder stand. Soil total N, total C, NO–
3, NH+
4, and pH were measured on the same soil samples. These factors as well as alder stand characteristics were compared with nodulation capacity in an attempt to identify soil characteristics typical in developing alder stands that most strongly affect nodulation capacity. Soil pH and NO–
3 concentration were highly correlated with nodulation capacity and with each other. Cluster analysis of the sites using these two variables identified two groups with distinctly different nodulation capacities. The cluster with the higher nodulation capacity was lower in NO–
3 and higher in pH than the other cluster, which included the majority of sites. There was substantial overlap in the age ranges for the two clusters and there was no significant correlation between age and nodulation capacity. Thus nodulation capacity appears to be most closely related to soil properties than to stand age. 相似文献
3.
Two-year-old coppice of black cottonwood and red alder, grown in pure culture and in mixture, were compared using terminal
twigs and leafless shoots harvested in the winter. Terminal twigs were taken with buds intact; they were about 15 cm long.
Leafless shoot samples included all above-ground components. In pure culture, dry weights of the leafless shoots per plant
were similar for the two species. In mixture with alder, however, weight of the cottonwood plants was enhanced and that of
alder was reduced, but neither response was statistically significant. Nutrient concentration, content per plant, and utilization
varied by the plant tissues analyzed, cultural treatment (purevs. mixed), and species. In general, nutrient concentrations were higher in the terminal twigs than in the leafless shoots of
both species. Cultural treatment did not significantly affect nutrient concentration in cottonwood twigs or in the leafless
shoots of either species. Concentrations of N and Fe were significantly higher and those of Mn were lower in twigs of mixed
alder than in twigs of pure alder. Twigs of cottonwood were significantly higher than those of alder in concentration of P
and Zn, and lower in N, Mn, and Cu. Compared with alder, cottonwood leafless shoots were significantly higher in concentration
of Ca, but lower in N, S, Cu, and Mn. With few exceptions, nutrient content was highest in the shoots of the large plants
of mixed cottonwood, intermediate in medium-sized pure cottonwood and pure alder, and lowest in the small mixed alder. Cottonwood
was significantly more efficient than alder in use of N, S, and Cu, and less efficient in use of Ca. Some of the differences
between cultural treatments and species may be associated directly or indirectly with the N2-fixing ability of red alder. Mixed culture of the two species appears promising because of the increased growth of cottonwood.
Planted separately in pure culture, the choice between cottonwood and alder may be determined, in part, by the nutritional
status of the soil where plantations are established. 相似文献
4.
Summary The inoculation ofAlnus rubra (red alder) withFrankia sp. can lead to a highly efficient symbiosis. Several factors contribute to the successful establishment of nitrogenfixing nodules: (1) quantity and quality ofFrankia inoculant; (2) time and method of inoculation; (3) nutritional status of the host plant.Frankia isolates were screened for their ability to nodulate and promote plant growth of container-grown red alder. Inoculations were performed on seedlings and seeds. Apparent differences in symbiotic performance could be seen when seeds or seedlings were inoculated. Plants inoculated at planting performed significantly better than those inoculated four weeks later in terms of shoot height, nodule number and shoot dry weight. If inoculation was delayed further, reduction in shoot height, nodule number and shoot dry weight resulted. The effect of fertilizer was also investigated with regard to providing optimal plant growth after inoculation. Plants receiving 1/5 Hoagland's solution minus nitrogen showed maximal plant growth with abundant nodulation. Plants receiving 1/5 Hoagland's solution with nitrogen showed excellent plant growth with significantly reduced nodulation. 相似文献
5.
Summary From acetylene reduction assays over a 10-month period starting in April 1979, nodule activities averaged 18.78 (se 4.67) moles C2H4 g nodule dw–1 h–1 forAlnus rubra and 59.95 (se 12.14) moles C2H4 g nodule dw–1 h–1 forCytisus scorparius. Plant rates were 1.91 (se. 47) moles C2H4 plant–1 h–1 forA. rubra and 0.55 (se. 17) moles C2H4 plant–1 h–1 forC. Scoparius. Plant activity and total leaf N were strongly correlated with the dw of other plant parts, but nodule activity and percent leaf N were not. Plant and nodule activities were not associated with temperature, moisture stress, precipitation events or percent light for either species over the growing season nor for 54A. rubra sampled in mid-season 1979 on one replication. After 5 to 6 growing seasons, 14A. rubra on the same site ranged from 30 to 332 cm in height and showed strong correlation between nodule dw, leaf dw, plant size and total leaf N. Results from this study and others indicate logistic equations may be modified to predict the effect of adding a N2 fixing plant to a population of non N2 fixing trees. 相似文献
6.
Investigations on the ecological function of ineffectiveFrankia strains and their behaviour in competition with effectiveFrankia strains indicated an enhanced plant growth upon dual inoculation with increasing amounts of effective (i.e. N2-fixing)Frankia strains and simultaneous inoculation with a constant amount of an ineffectiveFrankia strain. Enhanced plant growth was measured as increase in plant height and total dry weight at constant shoot/root ratio.
The stimulating effect of the ineffective strain was independent of the plant clone and was obtained with bothAlnus glutinosa clones W I and B II, which were resistant and susceptable, respectively, to the ineffective strain. Stimulation was also
independent of the nodulation conditions. Short-term studies (7 weeks) under axenic conditions and greenhouse experiments
during 3 months showed comparable results, not only in plant growth but also in nodule formation. Increment in plant growth
was not necessarily correlated to higher nodule formation with the effectiveFrankia strains. 相似文献
7.
Six mutant strains of Rhizobium were isolated after UV treatment which could exhibit nitrogenase activity in Burk's N-free medium without any supplement. The activity ranged between 99.5 and 113 nmol/mg cell dry weight and hour. Two of the parent strains belonged to soybean, and one each to mungbean and Sesbania sp. Both the parent and mutant strains exhibited nitrogenase activity in CS 7 medium. One of the mutants retained its capacity to produce nodules on soybean roots.List of Abbreviations C.D.
Critical difference
- EMS
ethylmethane sulphonate
- NTG
N-methyl-N-nitro, N-nitrosoguanidine 相似文献
8.
Teaumroong Neung Innok Sasidhorn Chunleuchanon Somporn Boonkerd Nantakorn 《World journal of microbiology & biotechnology》2002,18(7):673-682
The diversity among 853 isolates of nitrogen-fixing cyanobacteria obtained from soil samples collected from different ecosystems including mountainous, forest and cultivated areas in the central, northern and northeastern regions of Thailand was examined. Most isolates showed slow growth rate and had filamentous, heterocystous cells. The percentage of heterocysts in the filaments of different isolates varied from 8.3 to 9.6. Only a few strains showed high nitrogen-fixing potential, while most of the strains exhibited low capacity for nitrogen fixation. Anabaena and Nostoc were the dominant genera among these isolates. One hundred and two isolates were randomly selected from this diverse collection to determine the extent of genetic diversity on the basis of DNA fingerprinting using the PCR method. Based on the PCR products obtained by using a combination of three primers, all strains could be distinguished from one another. When a subset of 45 isolates of Nostoc and a subset of 44 isolates of Anabaena were further analysed by PCR, a wide range of diversity was observed within each of these genera. 相似文献
9.
Autumnal changes in tissue nitrogen of autumn olive,black alder and eastern cottonwood 总被引:5,自引:0,他引:5
Two experiments were conducted to determine patterns of N change in tissues of autumn olive (Elaeagnus umbellata Thunb.) and black alder (Alnus glutinosa [L.] Gaertn.) during autumn in central Illinois, U.S.A. In the first study leaf nitrogen concentrations of autumn olive decreased 40% at an infertile minespoil site and 39% at a fertile prairie site throughout autumn whereas nitrogen concentrations in respective bark samples increased by 39% and 37%. Salt-extractable protein concentrations increased in bark and decreased in leaves over the sampling period. Free amino acid concentrations of autumn olive leaves decreased over the course of the experiment from peak concentrations in August. Asparagine, glutamic acid and proline were major constituents of the free amino acid pools in leaves. Total phosphorus concentrations of autumn olive leaves declined by 40–46% during autumn while bark concentrations of P did not significantly change.In the second experiment non-nodulated seedlings of alder receiving a low level of N-fertilization did not exhibit net resorption of leaf N during autumn whereas foliar N concentration of contrasting nonactinorhizal cottonwood plants (Populus deltoides Bartr. ex. Marsh) under the same fertilization regime decreased by 27% after the first frost. A gradual but significant decrease of 38% in foliar N concentration of nodulated alder seedlings grown under a low N-fertilization regime was associated with the cessation of nitrogenase activity during autumn in nodules. Compared with the low N fertilization regime, the higher level of N-fertilization resulted in smaller autumnal decreases of foliar N concentration in nodulated alder (17%) and in cottonwood (20%); but there was no decrease in foliar N concentration in non-nodulated alder. The higher level of N-fertilization promoted a greater accumulation of N in the roots than in the bark of both tree species after the first frost.Our results suggest that black alder lackingFrankia symbionts does not exhibit net leaf N resorption and that autumnal decreases in leaf N ofFrankia-nodulated black alder result primarily from declining foliar N import relative to export due to low temperature inhibition of N2 fixation. In contrast, autumn olive exhibited greater and more precipitous autumnal declines in foliar N concentration than those of alder, and the pattern of N decline was unaffected by site fertility. 相似文献
10.
Summary Inoculation with root-nodule bacteria had favourable influence on N-uptake and yield of wheat. Since waterlogged root region
of rice permits higher nitrogenase activity a pot culture experiment was conducted using same nine strains of rhizobia,Azotobacter chroococcum and bluegreen algae as inoculants.R. leguminosarum in combination with 50 kg N ha−1;R. japonicum and a strain of rhizobium isolated from moong bean increased the yield of paddy cv. Pusa-33. On the other hand an adverse
effect of bacterial inoculation and of applied N was observed in case of Azotobacter, and rhizobia isolated from green gram,
cicer, soyabean and clover.
The importance of plant type, growth conditions and application of inorganic N in determining the success of plant-rhizobial
associations is emphasised. 相似文献
11.
Oxygen uptake measurements have shown that pressurized gas transport, resulting from the physical effect of thermo-osmosis
of gases, improves oxygen supply to the roots of the seedlings in two alder speciesAlnus japonica (Thunb.) Steud. andAlnus hirsuta (Spach) Rupr., which are both native in Japan. When gas transport conditions were established by irradiation of the tree
stems the internal aeration was increased to a level nearly equal to the oxygen demand of the root system in leafless seedlings
ofA. hirsuta, but was higher inA. japonica so that excess oxygen was excreted into the environment. An increase of superoxide dismutase (SOD) activity, which protects
plants from toxic oxygen radicals and post-anoxic injury, has been observed in root tissues ofA. japonica when the seedlings were flooded for 3 days. The increase of SOD activity, in concert with high gas transport rates, may enable
this tree species to grow in wet sites characterized by low oxygen partial pressure in the soil and by varying water tables.
A less effective gas transport, flood-induced reduction of SOD activity in root tissues, and reduced height growth in waterlogged
soil may be responsible for the fact thatA. hirsuta is unable to inhabit wettland sites. 相似文献
12.
Nitrogen fixation by non-legumes in tropical agriculture with special reference to wetland rice 总被引:3,自引:0,他引:3
I. Watanabe 《Plant and Soil》1986,90(1-3):343-357
Summary Of the 143 million hectares of cultivated rice land in the world, 75% are planted to wetland rice. Wet or flooded conditions favour biological nitrogen fixation by providing (1) photic-oxic floodwater and surface soil for phototrophic, free-living or symbiotic blue-green algae (BGA), and (2) aphotic-anoxic soil for anaerobic or microaerobic, heterotrophic bacteria. TheAzolla-Anabaena symbiosis can accumulate as much as 200 kg N ha–1 in biomass. In tropical flooded fields, biomass production from a singleAzolla crop is about 15 t fresh weight ha–1 or 35 kg N ha–1. Low tolerance for high temperature, insect damage, phosphorus requirement, and maintenance of inoculum, limit application in the tropics. Basic work on taxonomy, sporulation, and breeding ofAzolla is needed. Although there are many reports of the positive effect of BGA inoculation on rice yield, the mechanisms of yield increase are not known. Efficient ways to increase N2-fixation by field-grown BGA are not well exploited. Studies on the ecology of floodwater communities are needed to understand the principles of manipulating BGA. Bacteria associated with rice roots and the basal portion of the shoot also fix nitrogen. The system is known as a rhizocoenosis. N2-fixation in rhizocoenosis in wetland rice is lower than that ofAzolla or BGA. Ways of manipulating this process are not known. Screening rice varieties that greatly stimulate N2-fixation may be the most efficient way of manipulating the rhizocoenosis. Stimulation of N2-fixation by bacterial inoculation needs to be quantified. 相似文献
13.
Nodulation tests onin-vitro propagated clones ofAlnus glutinosa ecotypes (forest ecotype, pioneer ecotype) withFrankia strains originating from both ecotypes indicated differences in host-plant compatibility. Inoculated plants of the pioneer
ecotype clone were not infected by strains, that were unable to fix nitrogen in pure culture. Nodulation could only be induced
on the clone of the forest ecotype, but no nitrogen-fixing activity could be detected. Ultra-structural observations of the
nodules by SEM and TEM indicated that ineffectivity of these strains was correlated with the lack of vesicles in the infected
cells. Cells were only filled with hyphae: neither sporangia nor vesicles could be detected. In contrast, effective nodules
could be obtained on both alder clones after inoculation with an effective strain, showing normal development of vesicle clusters
in infected cells. In pure culture the ineffective strains produced no vesicles; sporangia were found only during early stage
of growth. The results demonstrate the existence ofFrankia strains which were either non-infective or ineffective on different clones ofAlnus glutinosa. 相似文献
14.
Bacteria occurring in high numbers on the rhizoplane of kallar grass grown at a natural site in Pakistan were effective scavengers of traces of combined nitrogen from the atmosphere. Bacteria grew under appropriate conditions in nitrogen-free semi-solid malate medium in the form of a typical subsurface pellicle which resulted in a significant nitrogen gain in the medium within 3 to 4 days of incubation; this could be also measured by15N-dilution. Bacteria grew and incorporated nitrogen under an atmosphere containing NH3 and N2O. A rapid and strong binding of strain W1 to roots of kallar grass grown in hydroponic culture was found by using a32P-tracer technique. We obtained no evidence for diazotrophy of our strains because they failed to grow on nitrogen-free media when gases of high purity were used. No15N2 was incorporated when bacteria were grown on15N2 although a nitrogen gain was found, no acetylene reduction was observed and no homology with DNA containing sequences ofnifHDK structural genes for the nitrogenase components fromKlebsiella pneumoniae were detected. Owing to close contact of these bacteria with roots of kallar grass, utilization of scavenged nitrogen by the plant may have to be taken into account. 相似文献
15.
M. A. Line 《Plant and Soil》1990,125(1):149-152
Nitrogen-fixing enterobacteria (Enterobacter agglomerans and Citrobacter freundii) were commonly found associated with the microflora of stained Sassafras (Atherosperma moschatum Labill.) in forests of SE Tasmania. However, their populations never exceeded 3× 104 cells g−1 dry wood and comprised at most 3% of the total bacterial flora. Bacterial colonization of the wood appeared to coincide with
that by non-hymenocetous fungi: bacteria were never isolated in significant numbers from wood not infected with fungi. The
contribution of the N2-fixing flora to the N economy of the habitat is considered to be negligible. 相似文献
16.
Boreal forests are increasing in age partly due to reduced logging and efficient wildfire control. As a result, they also
stock more carbon. Whether increased forest C stock causes greater production of dissolved organic carbon (DOC) is uncertain.
DOC in bulk precipitation, throughfall and soil water was studied in 10-, 30-, 60- and 120-year-old stands of Norway spruce
(Picea abies (L.) Karst.) DOC concentrations in throughfall and O horizon soil water followed the order 10 < 30 < 60 = 120 and 10 = 30 < 120 < 60,
respectively. DOC fluxes followed the order 10 = 30 < 60 = 120 in throughfall, while no significant difference between stands
was found for O horizon soil water. Above-ground tree litter varied according to 10 < 30 < 60 = 120, a pattern identical to
that for DOC concentrations in throughfall and resembling but not identical to that for DOC concentrations in O horizon soil
water. This indicates additional sources for DOC in soil water. Seasonality in DOC concentrations was observed at the base
of the O horizon, and seasonality in DOC fluxes in both throughfall and O horizon soil water. Our results suggest differences
in the polarity of DOC between the 10-year stand and the others, which we interpret as reflecting the lack of grown trees
and possibly the different vegetation on the 10-year stand. 相似文献
17.
A recently developed oxygen gradient system and a complex medium were used to isolate a microaerobically N2-fixing heterotrophic bacterium from the rhizosphere of a high fixing Sorghum nutans cultivar. The isolate was identified as nif(+) phenotype of Pseudomonas stutzeri on the basis of cultural, physiological and biochemical characteristics, including DNA/DNA hybridization. N2 fixation was demonstrated by assimilation of 15N2 into cellular protein; the physiology of nitrogen fixation was studied. The isolate contains one 30 MD plasmid and can be cured with associated loss of N2 fixation capability.Dedicated to Prof. Dr. W. Nultsch on the occasion of his 60th birthday 相似文献
18.
This study reports the effect of salinity and inoculation on growth, ion uptake and nitrogen fixation byVigna radiata. A soil ECe level of 7.5 dS m−1 was quite detrimental causing about 60% decline in dry matter and grain yield of mungbean plants whereas a soil ECe level of 10.0 dS m−1 was almost toxic. In contrast most of the studied strains of Rhizobium were salt tolerant. Nevertheless, nodulation, nitrogen
fixation and total nitrogen concentration in the plant was drastically affected at high salt concentration. A noticeable decline
in acetylene reduction activity occurred when salinity level increased to 7.5 dS m−1. 相似文献
19.
L. Turbanti M. Bazzicalupo E. Casalone R. Fani E. Gallori M. Polsinelli 《Archives of microbiology》1988,150(5):421-425
One hundred and twenty-nine mutants of Azospirillum brasilense strain Sp6, resistant to methylammonium, were isolated. Three of the mutants were found to be able to reduce acetylene in the presence of 4 mM ammonium or 120mM methylammonium, concentrations which strongly reduced the nitrogenase activity of the parental strain. Under N2-fixing conditions, two mutants failed to switch off nitrogenase when NH4Cl was added. Moreover, the three mutants showed a reduced capacity to incorporate [14C]methylammonium. The level of glutamine synthetase activity found in the mutants was not reduced as compared to that of the parental strain. All of the data indicate an impairement in the mechanism of ammonium uptake by the bacterial cell.Abbreviations MEA
Methylammonium
- MSP
minimal medium (ammonium free)
- PY
complete medium
- GS
glutamine synthetase 相似文献
20.
I. Papastylianou 《Plant and Soil》1987,104(1):23-29
The increasing need for protein at low cost has created a need to evaluate the biological nitrogen fixing potential of legumes
in Cyprus. In field studies which were conducted over the growing years of 1982–3 and 1983–4, legumes which are traditionally
grown in the country were evaluated for dry matter and nitrogen yield and biological nitrogen fixation (BNF). The legumes
studied were medic (Medicago truncatula Gearth), ochrus vetch (Lathyrus ochrus L.), bitter vetch (Vicia ervilia L.) and faba bean (Vicia faba L. var major) in the first year and in addition chickpea (Cicer arietinum L.), woollypod vetch (Vicia dasycarpa Ten.) and tickbean (Vicia faba L. var minor) in the second year.
Using the A-value method with barley and oats as reference crops, nitrogen (N) fixed by the various legumes in the first year
was 30–50% and from 55–67% of total N yield for the two reference crops, respectively. In the second year the estimates of
N fixed ranged from 70 to 80% with similar results obtained for the two reference crops barley and ryegrass. However, in the
second year chickpea, which had limited nodulation, fixed only 40% of its N yield.
Estimates of nitrogen from the atmosphere (Ndfa) obtained by the difference method (DM) were 10 to 14% lower than those from
the A-value method. These results were obtained after correcting for the amount of N derived from the applied fertilizer.
The two methods were highly correlated (r=0.98) for estimates of amount of BNF. The rates of N2 fixation of uninoculated legumes which are nodulated by the indigenous populations of Rhizobium in Cyprus are comparable
to those of legumes inoculated with selected strains of Rhizobium in other countries. An exception was the amount of N fixed
by chickpea. The appearance of the first nodules at late stages of growth may be the reason for the low BNF of this crop. 相似文献