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1.
Thirty-five Azospirillum strains (13 strains from plant roots and 22 strains from soils) were isolated from Ishigaki island, Japan, which has a subtropical
climate. These strains were different from each other according to polymerase-chain-reaction band patterns obtained by using
a random primer (OPT-08). Two Azospirillum strains (AZ43 and AZ92-2) were also examined for use in further experiments. Inoculation of lowland rice with these strains
enhanced early growth of rice to various degrees. Inoculation of strains VIII.P1-2, AZ92-2, V.S2-2, and V.P5 in sterilized
soil yielded higher shoot dry weights than the application of 90 μg N g–1 soil without inoculation. Only inoculation with strains AZ92-2 and VIII.P1-2 caused higher N uptake than the application
of 90 μg N g–1 soil. Three strains were selected for the next experiment based on the results of their effect on the early growth of rice.
An investigation was conducted to determine the ability of two indigenous Azospirillum strains (V.S2-2 and VIII.P1-2) and one stock strain (AZ92-2) to promote growth and nutrient-uptake of lowland rice in unsterilized
soil under several levels of N application (0, 80, 160, and 240 mg N pot–1). Inoculation with these strains without N application increased shoot dry weight by 12–15% compared to the uninoculated
treatment. Inoculation with Azospirillum V.S2-2 together with the application of 160 mg N pot–1 resulted in a shoot dry weight as high as that obtained in the treatment with 240 mg N pot–1 without inoculation. Thus, in this former case, the amount of N applied could be reduced by 80 mg pot–1 due to the effect of the microbial inoculum without a significant change in the high, targeted, yield. 相似文献
2.
Many phosphate solubilizing microorganisms (PSM) require external pyrroloquinoline quinone (PQQ) for strong phosphorus (P)
solubilization in vitro. The objective of this study was to isolate efficient and PQQ-independent PSM. A total of 21 PSM were
isolated from the rhizosphere soil of wheat and maize grown in the pots. Acinetobacter strains were the only PQQ-independent and most effective solubilizers of tricalcium phosphate containing agar. The mean P
dissolved in liquid cultures of Acinetobacter strains in a 5-day incubation ranged from 167 to 888 μg/ml P. The pH dropped to below 4.7 from 7.8 in six isolates, which
produced gluconic acid in concentrations ranging between 27.5 and 37.5 mM. There was a linear regression between soluble P
and gluconic acid concentrations in the bacterial cultures (P < 0.05; R
2 = 0.59). Inoculation with Acinetobacter sp. WR922 significantly (P < 0.05) increased wheat (Triticum aestivum L.) P content by 27% at 15 days after emergence (DAE) and dry matter by 15% at 30 DAE compared to the control. The plant
P content in inoculated plants at 30 DAE was linearly correlated with soluble P of the bacterial cultures (P < 0.05; R
2 = 0.69). Gluconic acid production directly affected phosphate solubilization in vitro, which in turn influenced plant P content
of inoculated plants in PQQ-independent P-solubilizing Acinetobacter strains. 相似文献
3.
Gang Xin Gengyun Zhang Jun Won Kang James T. Staley Sharon L. Doty 《Biology and Fertility of Soils》2009,45(6):669-674
An endophytic bacterium, wild poplar strain B (WPB), isolated from stems of wild cottonwood (Populus trichocarpa) was identified to Burkholderia vietnamiensis by analyzing the recA and rDNA genes. Phylogenetic analysis of the nifHDK cluster indicates that the WPB isolate shares high sequence similarity with known B. vietnamiensis strains. The nitrogenase activity of WPB was determined by a 15N2 incorporation assay and an acetylene reduction assay. WPB was also monitored for production of indole-3-acetic acid (IAA),
a phytohormone which can promote plant growth, when incubated with l-tryptophan. In addition, its plant growth promotion capacity was assessed by inoculating the WPB strain onto Kentucky bluegrass
in nitrogen-free medium. Compared to uninoculated control plants, the plants inoculated with WPB gained more dry weight (42%,
p = 0.01) and more nitrogen content (37%, p = 0.04) in 50 days. 相似文献
4.
We have estimated the production of water-soluble B vitamins by plant growth-promoting rhizobacterium Pseudomonas fluorescens strain 267 in a minimal medium with different C sources and at different pH values. In the minimal medium, strain 267 produced
large amounts of niacin (0.92 μg ml–1) and pantothenic acid (0.75 μg ml–1), but also other vitamins such as biotin, thiamine, cobalamine and pyridoxine. The production of B vitamins was dependent
on the C source and pH of the growth medium. By random Tn5 mutagenesis, thiamine and niacin auxotrophs were isolated from P. fluorescens strain 267 and mutants were used to evaluate the vitamin production on colonization of clover roots under controlled conditions.
Red clover root colonization decreased by about 1 order of magnitude in the case of the niacin auxotroph. The vitamin auxotrophs
of P. fluorescens in a mixed inoculation of clover with R. leguminosarum bv. trifolii strain 24.1 showed no plant growth-promotion activity.
Received: 23 May 2000 相似文献
5.
Allolobophora chlorotica exists as two colour morphs, pink and green. Field observations have indicated that the two morphs have ecological preferences
linked to soil moisture: the green morph dominating in wet soils and the pink morph in dry soils. The aim of this laboratory-based
research was to investigate the potential differences in fitness and adaptation to soil-moisture conditions of the two morphs
measured in terms of growth rate, reproductive output and cocoon viability. An initial experiment maintained hatchlings of
both morphs individually under standard culture conditions. On maturation, these were paired (intra-morph), and cocoon production,
viability and incubation time were determined. The green morph had significantly faster (P < 0.01) growth rates than the pink morph. Cocoon production was also significantly greater in the green compared with the
pink morph (3.2 and 1.5 cocoons worm−1 28 days−1, respectively) with corresponding viabilities of 87 and 58%. In a second experiment, the growth rates of pink and green hatchlings
were assessed under wet and dry soils (29 and 21% soil moisture, respectively). The growth of the pink morph was not influenced
significantly (P > 0.05) by soil moisture. In contrast, lower soil-moisture content significantly (P < 0.05) slowed growth and maturation of the green morph. These results support field observations relating to distribution
of the two A. chlorotica colour morphs. We suggest that soil-moisture content may act to isolate these morphs, providing, in extremes, a barrier to inter-morphic
mating. 相似文献
6.
This study aims to determine leaf litter preference, consumption rate, growth rate, food conversion efficiency, and quality
of fecal pellets of two endemic pill millipedes (Arthrosphaera dalyi and Arthrosphaera davisoni) of the Western Ghats of India by laboratory microcosm experiments. Among seven combinations of three plantation leaf litters
offered in 4-day trial, top three preferred combinations were selected for 4-week trial. In 4-week trial, preference of mixed
litter diet was higher than single litter diet, which resulted in enhanced growth as well as food conversion efficiency of
millipedes. Among Hopea
,
Pongamia
, and Areca litters, A. dalyi preferred Hopea + Pongamia, and its consumption was significantly correlated with contents of organic carbon (P < 0.05; r = –0.97) and nitrogen (P < 0.01; r = 0.99), while growth rate with phosphorus content (P < 0.05; r = 0.97) and food conversion efficiency with contents of organic carbon (P < 0.05; r = 0.98) and calcium (P < 0.01; r = –0.99). Among Areca
,
Elettaria
, and Coffea litters, Areca + Elettaria
+ Coffea was most preferred by A. davisoni, which was significantly correlated with organic carbon content (P < 0.05; r = 0.98) and food conversion efficiency with calcium content (P < 0.0001; r = 0.99). The food conversion efficiency, however, was the highest in millipedes fed with Areca
+
Elettaria. The present study demonstrated increased nitrogen and phosphorus contents and decreased phenolic content and C/N ratio in
fecal pellets of pill millipedes fed with plantation litter, and thus, these millipedes play an important role in leaf litter
mineralization and soil enrichment in plantations Western Ghats. 相似文献
7.
Bradyrhizobium japonicum strain CB 1809 was recently chosen to replace strain WB 1 in commercial soybean [Glycine max (L.) Merr.] inoculants in South Africa, the selection criterion being N2-fixing effectiveness. Nodulation competitiveness is an additional characteristic required of inoculants and was determined
for CB 1809 and WB 1 as well as two other strains, USDA 110 and a Brazilian strain 965, using the gusA marker gene to identify strains. Initial experiments with plants grown in sterile sand showed that the competitive index
of strain WB 1 was less than that of the other strains. Further comparisons used plants grown in five soils containing established
populations of B. japonicum. When strains were applied in peat inoculum to seed at a rate of 1,000 cells per seed in a soil containing 300 rhizobia g–1, significant differences in nodule occupancy were detected and strains ranked in the order 965>CB 1809>USDA 110>WB 1. The
remaining four soils each contained about 106 rhizobia g–1 and 5×106 cells were applied per seed. Nodule occupancy by inoculant strains ranged from 22% to 81% between soils. In this experiment,
WB 1 was consistently the poorest performer and its competitiveness was significantly less than CB 1809. The competition results
supported the recent decision to replace WB 1 with CB 1809 in commercial inoculants. Although WB 1 had been used in inoculants
over a period of 19 years, this strain was detected in only one soil, where it comprised 8% of isolates. In contrast, a substantial
proportion (32–78%) of isolates from the soils corresponded serologically to a former inoculant strain WB 66, which had been
discontinued in 1966. This illustrates the difficulty of replacing a resident population with an introduced strain. The effect
of naturalized populations on the establishment of CB 1809 in South African soils will need monitoring
Received: 23 November 1999 相似文献
8.
V. A. Biradar S. D. Amoji U. M. Shagoti P. M. Biradar 《Biology and Fertility of Soils》1999,28(4):389-392
One-week-old juveniles of Perionyx excavatus were cultured in urine-free cow manure for 16 weeks in three different seasons to find out the influence of environmental
factors on growth and reproduction. The biomass of worms increased gradually until the 16th week in all seasons. There was
no significant (F=2.51) variation in biomass between the three seasons; however, the growth rate varied significantly (F=50.49, P<0.01). During the pre-clitellar period, the growth rate (mg/g) increased steeply (1013.17±41.33 in the monsoon season, 728.64±15.5
in winter and 463.16±22.96 in summer) until the worms attained maturity (5–8 weeks) and from then onwards gradually decreased
after the commencement of cocoon production. Worms attained maturity when the mean weight of each worm ranged from 167.46 mg
to 197.13 mg. The cumulative number of cocoons varied significantly (F=26.07, P<0.01) with season. Similarly, the rate of cocoon production also varied significantly (F=62.06, P<0.01). The average rate of cocoon production was 7.23, 0.99 and 0.53/worm/week in the monsoon season, winter and summer,
respectively. By week 16, the ratio of weight gain to the initial weight of 1-week-old juveniles was 1 : 43.13 in the monsoon
season, 1 : 30.49 in the winter and 1 : 23.69 in the summer. The maximum mass gain, growth rate, and cocoon production and
earliest attainment of maturity were recorded during the monsoon season, and were attributed to the lowest range of fluctuating
temperatures and high humidity compared with during winter and summer. The growth rate of worms in all seasons was inversely
proportional to the number of cocoons produced. Further, the higher the rate of cocoon production, the lower the weight of
individual cocoons.
Received: 1 July 1997 相似文献
9.
Ecological pre-release risk assessment of two genetically engineered, bioluminescent Rhizobium meliloti strains in soil column model systems 总被引:2,自引:0,他引:2
In order to identify potential ecological risks associated with the environmental release of two Rhizobium meliloti strains, genetically engineered with the firefly-derived luciferase gene (luc), a pre-release greenhouse investigation was conducted. The upper 4 cm of soil columns (30 cm diameter; 65 cm depth), which
were filled according to the horizons of an agricultural field (loamy sand), were inoculated with seeds of Medicago sativa (alfalfa) and R. meliloti cells at approximately 5×106 cells·g–1 soil. Four treatments were tested: inoculation with a non-engineered wild type strain (2011), strain L33 (luc
+), strain L1(luc
+, recA–) and non-inoculated controls. The fate of the engineered strains was followed by two methods: (1) selective cultivation and
subsequent detection of bioluminescent colonies and (2) PCR detection of the luc gene in DNA, directly extracted from soil. Strain R. meliloti L33 declined to 9.0×104 cfu·g–1 soil within 24 weeks and to 2.8×103 cfu·g–1 soil within 85 weeks in the upper 25 cm of the soil columns. Decline rates for R. meliloti L1 were not significantly different. Vertical distribution analysis of the recombinant cells after 37 weeks revealed that
in three of four columns tested, the majority of cells (>98%) remained above 10 cm soil depth and no recombinant cells occurred
below 20 cm depth. However, in one column all horizons below 20 cm were colonized with 2.2×104 to 6.8×104 cfu g–1 soil. Ecological monitoring parameters included organic substance, total nitrogen, ammonium and nitrate, microbial biomass,
culturable bacteria on four different growth media and the immediate utilization of 95 carbon sources (BiologGN) by soil-extracted
microbial consortia. None of the parameters was specifically affected by the genetically engineered cells.
Received: 6 December 1996 相似文献
10.
Rooibos (Aspalathus linearis) has been reported to be nodulated by rhizobia belonging to members of the genus Bradyrhizobium but based solely on slow growth rate on growth media in vitro. Because there is very little information about the rhizobia
that nodulate and fix nitrogen in rooibos, the characterization of rhizobial strains and their ability to nodulate A. linearis was investigated in this study. Soils intially collected from the rhizosphere of different Aspalathus populations were used in a baiting experiment to trap rhizobia by rooibos roots. The rhizobia trapped in the nodules were
re-isolated and used in Koch’s postulate experiment using the Leonard jar assembly in the glasshouse. The strains that formed
on the average between five and 12 indeterminate pink nodules per plant resulted in statistically significant (P = 0.05) increase in shoot and root dry weights. Phylogenetic analysis of the 16S ribosomal RNA sequence of the isolates from
the root nodules revealed for the first time that A. linearis is nodulated by different groups of rhizobia belonging to members of both the α-Proteobacteria and the β-Proteobacteria.
It was also found that only 2% of the total rhizobia isolated from the root nodules of rooibos were represented by the genus
Bradyrhizobium. The finding that rooibos is nodulated by different groups of α-rhizobia and β-rhizobia provides valuable information both
in the study of the microbial ecology of rooibos and in the selection of highly efficient nitrogen fixing strains for the
commercial cultivation of this indigenous legume. 相似文献
11.
Mariel Josue Bizarro Adriana Giongo Luciano Kayser Vargas Luiz Fernando Wurdig Roesch Kelsey Annette Gano Enilson Luiz Saccol de Sá Luciane Maria Pereira Passaglia Pedro Alberto Selbach 《Biology and Fertility of Soils》2011,47(3):357-362
Due to their ecologic and economic importance, bradyrhizobia have been extensively studied in recent years. Since 1992, Bradyrhizobium elkanii SEMIA 587 and SEMIA 5019 and Bradyrhizobium japonicum SEMIA 5079 and SEMIA 5080 have been widely used in most Brazilian soybean fields. The objective of this work was to estimate
the genetic variability of bradyrhizobial isolates recovered from soils under rhizobial inoculation and different soil managements.
Only 25% of the isolates demonstrated high similarities to the original strains, and a strong correlation was obtained between
the bradyrhizobial genetic variability and soil management. A high level of genetic diversity was observed both within isolates
(H = 5.46) as well as among the different soil practices. Soil under no-tillage presented a higher bradyrhizobia diversity compared
with bradyrhizobia isolated from soil under conventional tillage. Serological characterization also indicated that B. elkanii strains SEMIA 587 and SEMIA 5019 were more competitive and presented a higher nodular occupancy capacity than strains belonging
to B. japonicum species in Southern Brazilian soils. 相似文献
12.
The effect of soil freeze–thaw cycles on the denitrification potential was examined based on the C2H2 inhibition method. The gross N2O production curve of the soil sample (incubation with C2H2) showed minor changes between the freeze–thaw treatment and the unfrozen control. However, kinetics analysis revealed that
the initial production rate, an indicator of the population density of denitrifying communities, decreased (P = 0.043) and the specific growth rate constant, an indicator of the activity of denitrifying communities, increased (P = 0.039) as a result of the freeze–thaw cycles in five of six soil samples examined. The increase in the specific growth
rate constant suggested the stimulation of the activity of denitrifying communities that survived after the freeze–thaw cycles
and may explain the minor suppression on the gross N2O production in spite of decreasing the population density of denitrifying communities that was suggested by the initial production
rate. The net N2O production curve of the soil sample (incubation without C2H2) showed a remarkable change in one out of six soil samples, and in that one soil sample, N2O release to the atmosphere was largely stimulated (7.6 times) by the freeze–thaw cycles. However, the stimulation of the
N2O release by the freeze–thaw cycles was even observed in two other selected soil samples (4.6 and 1.8 times), suggesting that
an imbalance in the N2O-producing and N2O-reducing activities of denitrifying communities might complementally explain the N2O release stimulated by the freeze–thaw cycles. 相似文献
13.
D. Lippi M.R. De Paolis E. Di Mattia S. Grego T. Pietrosanti I. Cacciari 《Biology and Fertility of Soils》2000,30(4):276-283
The effect of salinity on growth, starvation-survival and recovery from salt stress of a Rhizobium sp. strain isolated from nodules of Acacia tortilis from a soil of Senegal was studied. Growth parameters of C-limited continuous cultures, grown in the presence and the absence
of 342 mM NaCl, decreased in the saline medium and with increasing dilution rates. The survival capacity of starved cultures
depended on the previous growth conditions: culturability of cells grown with salt was inversely related to growth rate, while
culturability increased with increasing dilution rate for cultures grown without salt. Culturability of the cultures subjected
to the double stress of starvation and salinity was reduced and a high percentage of cells entered the viable but nonculturable
state. All the starved cultures were capable of regrowth when nutrients became available, thus showing that this strain can
withstand long periods of nutrient deprivation in soil while maintaining the capacity for an active metabolism and a potential
infectiousness toward an appropriate host.
Received: 14 December 1998 相似文献
14.
Alok Kalra Mahesh Chandra Ashutosh Awasthi Anil K. Singh Suman Preet S. Khanuja 《Biology and Fertility of Soils》2010,46(5):521-524
The present study demonstrates the usefulness of natural microbial growth-promoting compounds for improving the stability
and life of vermicompost-based (both granular and its aqueous extract) bioformulations. Granular vermicompost maintained the
number of cells of Rhizobium meliloti Rmd 201 up to 5.9 × 108 after 180 days at 28°C compared with 2.1 × 108 in charcoal (powdered), while aqueous extract of the vermicompost supported the 5.6 × 107 rhizobia numbers even after 270 days. The addition of 25 μL/mL cow urine and 0.01 mM calliterpinone, a natural plant growth
promoter, increased the rhizobia number significantly in granular vermicompost and its aqueous extract, respectively. 相似文献
15.
The effects of biochar properties on crop growth are little understood. Therefore, biochar was produced from eight feedstocks
and pyrolyzed at four temperatures (300°C, 400°C, 500°C, 600°C) using slow pyrolysis. Corn was grown for 46 days in a greenhouse
pot trial on a temperate and moderately fertile Alfisol amended with the biochar at application rates of 0.0%, 0.2%, 0.5%,
2.0%, and 7.0% (w/w) (equivalent to 0.0, 2.6, 6.5, 26, and 91 t biochar ha−1) and full recommended fertilization. Animal manure biochars increased biomass by up to 43% and corn stover biochar by up
to 30%, while food waste biochar decreased biomass by up to 92% in relation to similarly fertilized controls (all P < 0.05). Increasing the pyrolysis temperature from 300°C to 600°C decreased the negative effect of food waste as well as
paper sludge biochars. On average, plant growth was the highest with additions of biochar produced at a pyrolysis temperature
of 500°C (P < 0.05), but feedstock type caused eight times more variation in growth than pyrolysis temperature. Biochar application rates
above 2.0% (w/w) (equivalent to 26 t ha−1) did generally not improve corn growth and rather decreased growth when biochars produced from dairy manure, paper sludge,
or food waste were applied. Crop N uptake was 15% greater than the fully fertilized control (P < 0.05, average at 300°C) at a biochar application rate of 0.2% but decreased with greater application to 16% below the N
uptake of the control at an application rate of 7%. Volatile matter or ash content in biochar did not correlate with crop
growth or N uptake (P > 0.05), and greater pH had only a weak positive relationship with growth at intermediate application rates. Greater nutrient
contents (N, P, K, Mg) improved growth at low application rates of 0.2% and 0.5%, but Na reduced growth at high application
rates of 2.0% and 7.0% in the studied fertile Alfisol. 相似文献
16.
Shixue Yin Yuanhua Dong Yangchun Xu Qiwei Huang Qirong Shen 《Biology and Fertility of Soils》2011,47(3):303-313
Rice seedling wilt frequently occurs in upland nurseries under well-aerated conditions and causes considerable economic loss.
Whether the wilt is pathogenic or edaphic is not known. We hypothesize the use of composts to alleviate seedling wilt. The
severity level of upland rice seedling wilt was significantly (p < 0.05) positively correlated with soil pH (r = 0.499; n = 19), but negatively correlated with soil organic matter (r = −0.745), microbial biomass C (r = −0.669), activities of dehydrogenase (r = −0.589), arylsulfatase (r = −0.272), fluorescein diacetate hydrolysis (r = −0.466), and β-glucosidase (r = −0.280). Correlations between severity level and soil inorganic N and exchangeable potassium K were not significant. Contents
of Fe, Zn, Cu, and Mn in healthy seedlings were not significantly (p < 0.05) different from those in infected seedlings. These data suggest that seedling wilts are not associated with nutrient
constraints. Compost amendment at the rate of 3% or above in pot experiments significantly improved seedling growth and reduced
the wilt symptoms. Field trials further showed that aboveground weight of seedlings in compost-amended treatment ranged from
11.5 to 14.9 mg per plant, significantly higher than the range from 6.38 to 12.1 mg per plant in the control treatment; in
addition to rice growth compost significantly increased microbial biomass and enzyme activities of soils. Soil fumigation
significantly increased rice growth and alleviation symptoms in 11 out of 19 soils, suggesting the involvement of pathogens.
It is concluded that upland seedling wilt is a pathogen-associated disease. Probably high soil pH and low soil biochemical
activities may favor pathogen activities. 相似文献
17.
Manuel Aira Niall P. McNamara Trevor G. Piearce Jorge Domínguez 《Journal of Soils and Sediments》2009,9(1):54-61
Background, aim, and scope Earthworms make a major contribution to decomposition in ecosystems where they are present, mainly acting in the drilosphere,
that is, galleries, burrows, casts, and middens. Earthworm middens are hot-spots of microbial activity and nutrient dynamics
and represent a suitable model for studying earthworm-mediated influences on soil microbial communities by alteration of the
patch structure of the microbial environment. We studied the structure and activity of the microbial communities in the soil
system formed by middens of Lumbricus terrestris and the soil below and surrounding them and the role of earthworms in maintaining these structures through time.
Material and methods We set up an experiment in which middens were either left (control) or removed from their original place (translocated) and
left in a nearby area free of earthworm activity for 2 months. After 1 and 2 months we sampled middens, soil below them, and
surrounding soil. We analyzed the phospholipid fatty acid (PLFA) profiles and measured respiratory fluxes of CO2 and CH4.
Results Microbial communities of middens clearly differed from those of soil below and surrounding soil samples, showing higher bacterial
and fungal PLFAs (p < 0.0001 and p < 0.01, respectively); furthermore, changes in microbial communities were stronger in control middens than in translocated
middens. Moreover, gram positive and negative bacterial PLFAs were greater in translocated than control middens (p < 0.0001 and p < 0.001, respectively), as well as total organic carbon (p < 0.001). Microbial activity was higher in middens than in soil below and surrounding soil samples both for CO2 (p < 0.0001) and CH4 (p < 0.0001).
Discussion Soil bioturbation by the earthworm L. terrestris was strong in their middens, but there was not any effect on soil below and surrounding soil. Microbial communities of middens
maintain their biomass and activity when earthworms were not present, whereas they decreased their biomass and increased their
activity when earthworms were present.
Conclusions Earthworms strongly enhanced microbial activity measured as CO2 production in middens, which indicates that there are hot spots for soil microbial dynamics and increasing habitat heterogeneity
for soil microorganisms. Moreover, our data strongly support the fact that the impact of this earthworm species in this soil
is restricted to their middens and increasing soil heterogeneity.
Recommendations and perspectives Our data indicate that it is not clear if earthworms enhance or depress microbial communities of middens since the microbial
activity increased, but did not modify their biomass and this was not dependent on soil organic C content. These results indicate
no competence for C pools between this anecic earthworm and microorganisms, which has been found for other earthworm species,
mainly endogeics. Conversely, they suggest some type of facilitation due to the release of additional nutrient pools in middens
when earthworms are present, through the digestion of middens' material or the addition of casts produced from other food
sources. 相似文献
18.
Field experiments were conducted to investigate the performance of three soybean cultivars with five foreign bradyrhizobia
strains in different regions. The experiments at the two sites were designed with soybean (Glycine max L.) cultivars as the main factor and bradyrhizobia strains (USDA 136, TAL 122, USDA 6, TAL 377 and TAL 102) as the sub-factor.
The experiments were arranged in randomised complete block design with four replications. Results show that nodule number,
nodule dry weight and shoot dry weight, total N and seed yield were significantly increased when soybean cultivars were inoculated
with foreign bradyrhizobia in two locations in the south east of Nigeria. At 63 days after planting the percentage increase
in nodule number and dry weight after inoculation of soybean cultivars with bradyrhizobia strains ranged from 71 to 486% and
from 0 to 200%, respectively. The percentage increase in shoot dry matter, %N and total N after bradyrhizobia inoculation
ranged between 2–130%, 18–62% and 35–191%, respectively at Awka, and at the Igbariam site the percentage increase in shoot
dry weight, %N and total N ranged between 3–76%, 0–43% and 19–125%, respectively. Seed yields after bradyrhizobia inoculation
of soybean cultivar TGX 1485–1D at Igbariam ranged between 1.20 and 2.18 t ha–1 against the uninoculated plants, which had seed yields of 1.05 t ha–1. The poorest yield response after inoculation with bradyrhizobia strains was observed in soybean cultivar M-351, with a seed
yield ranging from 0.60 to 0.98 t ha–1. The fact that foreign bradyrhizobia strains were more effective than the indigenous strains for all the parameters studied
suggests that there is a need to use bradyrhizobia inoculants for increased soybean production in Nigeria. The variations
in the strain performance with the different soybean cultivars at the two sites, emphasises the need for careful Bradyrhizobium spp. strain selection. The fact that inoculation response was cultivar- and site-specific suggests that strategies for improving
inoculation response in soybean cultivars should also consider the soil environment where the soybean is to be produced.
Received: 25 May 1999 相似文献
19.
Effect of Inoculation with Plant Growth-Promoting Bacteria on Growth and Copper Uptake by Sunflowers
Daniel Fernando Rojas-Tapias Ruth Rebeca Bonilla Jenny Dussán 《Water, air, and soil pollution》2012,223(2):643-654
The effect of plant growth-promoting bacteria inoculation on Helianthus annuus growth and copper (Cu) uptake was investigated. For this, the strains CC22, CC24, CC30, and CC33 previously isolated from
heavy metal- and hydrocarbon-polluted soil were selected for study. These strains were characterized on the basis of their
16S rDNA sequences and identified as Pseudomonas putida CC22, Enterobacter sakazakii CC24, Acinetobacter sp. CC30, and Acinetobacter sp. CC33. Strains were able to synthesize indole, solubilize phosphorus, and produce siderophores in vitro, which are proper
characteristics of plant growth-promoting (PGP) bacteria. Bacteria were also able to bioaccumulate Cu(II), and most of them
could use aromatic hydrocarbons as a sole carbon source. Furthermore, Acinetobacter sp. CC33 exhibited the greatest extent of Cu(II) accumulation, and CC30 the widest range for degrading hydrocarbons. Acinetobacter sp. CC30 was selected for pot experiments on the basis of its plant growth-promoting properties. Inoculation with CC30 significantly
increased the plant biomass (dry weight and length of root and shoot) and improved the photosynthetic pigment content in non-
and Cu-contaminated soil (p < 0.05). Additionally, plant Cu uptake was improved by CC30 inoculation showing a significantly enhanced root Cu content
(p < 0.05). Our findings evidenced that the strain CC30 protected the plant against the deleterious effect of Cu contamination
and improved the Cu extraction by plant, hence concluding that its inoculation represents an alternative to improve phytoremediation
process of heavy metals, particularly Cu, in contaminated environments. 相似文献
20.
Long-term winter cover cropping effects on corn (Zea mays L.) production and soil nitrogen availability 总被引:1,自引:0,他引:1
This study was conducted to determine effects of long-term winter cover cropping with hairy vetch, cereal rye and annual
ryegrass on soil N availability and corn productivity. From 1987 to 1995, with the exception of the first year of the study,
the cover crops were seeded each year in late September or early October after the corn harvest and incorporated into the
soil in late April or early May. Corn was seeded 10 days to 2 weeks after the cover crop residues had been incorporated, and
N fertilizer was applied as a side-dressing at rates of 0, 67, 134, or 201 kg N ha–1 each year. While the average annual total N input from the above-ground biomass of the cover crops was highest for hairy
vetch (72.4 kg N ha–1), the average annual total C input was highest for cereal rye (1043 kg C ha–1) compared with the other cover crops. Hairy vetch was the only cover crop that significantly increased pre-side-dressed NO3
–-N (Ni) corn biomass and N uptake at 0 N. At an N fertilizer rate of 134 kg N ha–1 or higher, the cover crops had a minimal effect on corn biomass. This indicated that even after 9 years of winter cover cropping,
the effect of the cover crops on corn growth resulted primarily from their influence on soil N availability. The amount of
available N estimated from the cover crops (Nac) was significantly correlated with relative corn biomass production (r
2=0.707, P<0.001). The total amount of available N, comprising Nac and N added from fertilizer (Nf), was strongly correlated (r
2=0.820, P<0.001)) with relative corn biomass production. The correlation was also high for the available N comprising Ni and Nf (r
2=0.775, P<0.001). Although cereal rye and annual ryegrass did not improve corn biomass production in the short term, they benefited
soil organic N accumulation and gradually improved corn biomass production compared with the control over the long term.
Received: 10 August 1999 相似文献