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自生固氮菌活化土壤无机磷研究 总被引:6,自引:1,他引:5
以土壤为磷源,通过液体培养试验研究了5株自生固氮菌(Azotobacter sp.)对土壤无机磷的活化利用.结果表明,自生固氮菌能释放大量的氢离子,使液体培养基的pH大幅度降低,氢离子的浓度至少提高58倍以上.自生固氮菌分泌有机酸的种类与数量因菌株不同而异,这些有机酸包括甲酸、乙酸、草酸、丁二酸、柠檬酸、苹果酸和乳酸等,其中均能分泌草酸和苹果酸.在接种自生固氮菌的液体培养基中,全磷含量显著高于不接种的液体培养基,土壤无机磷总量则显著降低.由于土壤是培养基磷的唯一来源,故自生固氮菌促进了土壤无机磷的溶解释放.相关分析表明,培养基的pH值与土壤无机磷总量呈极显著正相关(r=0.959**,n=6),与液体培养基中的无机磷和全磷呈显著或极显著负相关(r =-0.850*;r=-0.918**,n=6),说明自生固氮菌分泌的氢离子可能是溶解土壤无机磷的原因之一.接种自生固氮菌显著降低土壤钙磷,土壤中的铁磷、铝磷和闭蓄态磷的降幅因菌株不同而异,其原因可能与有机酸分泌的数量和种类有关. 相似文献
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A. Islam 《Plant and Soil》1970,33(1-3):533-544
Summary The concentrations of water soluble and ammonium acetate extractable phosphorus in all the soils under investigation first
increased and then decreased with time of submergence under rice cropping. The increase in soluble phosphorus in the three
acid soils of Luisiana, Casiguran and Guadalupe was related to decrease in the concentration of iron, calcium and reductant
soluble phosphates, while in slightly acidic Maahas clay, the increase was associated with decrease in iron and aluminium
phosphates. But in the calcareous soil, the increase was due to decrease in the concentration of aluminium and reductant soluble
phosphates. The decrease was due to the re-formation of insoluble aluminium, iron and calcium phosphates in Luisiana and Guadalupe
clays, to the formation of aluminium and calcium phosphates in Maahas and to the formation of calcium phosphate only in Casiguran
fine sand. The application of phosphorus at the rate of 100 pounds per acre produced better tillering, more penicles and higher
straw and grain productions in Luisiana, Casiguran and Guadalupe only where the level of soluble phosphate was very low in
pots where no phosphorus was applied. This study, thus, indicated the necessity of phosphorus fertilization in low land rice
for soils which are low in phosphorus and high in active iron and aluminium. 相似文献
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1.?We tested the hypotheses that feeding guild structure of beetle assemblages changed with different arboreal microhabitats and that these differences were consistent across rainforest tree species. 2.?Hand collection and beating techniques were used from the gondola of the Australian Canopy Crane to collect beetles from five microhabitats (mature leaves, flush leaves, flowers, fruit and suspended dead wood) within the rainforest canopy. A simple randomization procedure was implemented to test whether the abundances of each feeding guild on each microhabitat were different from that expected based on a null hypothesis of random distribution of individuals across microhabitats. 3.?Beetles from different feeding guilds were not randomly distributed, but congregated on those microhabitats that are likely to provide the highest concentrations of their preferred food sources. Herbivorous beetles, in particular, were over-represented on flowers and flush foliage and under-represented on mature leaves and dead wood. Proportional numbers of species within each feeding guild were remarkably uniform across tree species for each microhabitat, but proportional abundances of feeding guilds were all significantly non-uniformly distributed between host tree species, regardless of microhabitat, confirming patterns previously found for arthropods in trees in temperate and tropical forests. 4.?These results show that the canopy beetle community is partitioned into discrete assemblages between microhabitats and that this partitioning arises because of differences in feeding guild structure as a function of the diversity and the temporal and spatial availability of resources found on each microhabitat. 相似文献
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Microbial growth under the snow: Implications for nutrient and allelochemical availability in temperate soils 总被引:2,自引:0,他引:2
Plant and Soil - Recent work has shown that plant litter inputs fuel microbial growth in autumn and winter resulting in a large increase of microbial biomass under the snow pack in tundra soils.... 相似文献
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Background and Aims
The formation of root cortical aerenchyma (RCA) reduces root respiration and nutrient content by converting living tissue to air volume. It was hypothesized that RCA increases soil resource acquisition by reducing the metabolic and phosphorus cost of soil exploration.Methods
To test the quantitative logic of the hypothesis, SimRoot, a functional–structural plant model with emphasis on root architecture and nutrient acquisition, was employed. Sensitivity analyses for the effects of RCA on the initial 40 d of growth of maize (Zea mays) and common bean (Phaseolus vulgaris) were conducted in soils with varying degrees of phosphorus availability. With reference to future climates, the benefit of having RCA in high CO2 environments was simulated.Key Results
The model shows that RCA may increase the growth of plants faced with suboptimal phosphorus availability up to 70 % for maize and 14 % for bean after 40 d of growth. Maximum increases were obtained at low phosphorus availability (3 µm). Remobilization of phosphorus from dying cells had a larger effect on plant growth than reduced root respiration. The benefit of both these functions was additive and increased over time. Larger benefits may be expected for mature plants. Sensitivity analysis for light-use efficiency showed that the benefit of having RCA is relatively stable, suggesting that elevated CO2 in future climates will not significantly effect the benefits of having RCA.Conclusions
The results support the hypothesis that RCA is an adaptive trait for phosphorus acquisition by remobilizing phosphorus from the root cortex and reducing the metabolic costs of soil exploration. The benefit of having RCA in low-phosphorus soils is larger for maize than for bean, as maize is more sensitive to low phosphorus availability while it has a more ‘expensive’ root system. Genetic variation in RCA may be useful for breeding phosphorus-efficient crop cultivars, which is important for improving global food security. 相似文献8.
In this article, we develop a simple model to study the effect of stochasticity in pollination on evolutionarily stable (ES) resource allocation within a hermaphrodite flower of animal-pollinating plants. For simplicity, we consider trade-off in resource allocation between attractive structure (petals etc.) and female function (seeds and fruits) with neglecting the amount of resource allocated to male function (pollens and stamens). We show that ES resource allocation does not much depend on the detail of the probability distribution of the number of pollinator visit on a flower, but on the probability that a flower fails to be visited. We also find that: (1) When the flowers are self-incompatible, the ES allocation to the attractive structure monotonically increases as the availability of pollinators in the environment decreases. (2) When there is strong positive correlation among flowers in the number of pollinator visit, the ES allocation is larger than the case without the correlation. (3) When the flowers are self-compatible and engage prior selfing, the ES allocation monotonically increases as the availability of pollinators in the environment decreases to a threshold, under which it suddenly decreases to zero. 相似文献
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Michelle L. McCrackin Tamara K. Harms Nancy B. Grimm Sharon J. Hall Jason P. Kaye 《Biogeochemistry》2008,87(2):143-155
Terrestrial desert ecosystems are strongly structured by the distribution of plants, which concentrate resources and create
islands of fertility relative to interplant spaces. Atmospheric nitrogen (N) deposition resulting from urbanization has the
potential to change those spatial patterns via resource inputs, resulting in more homogeneous soil resource availability.
We sampled soils at 12 desert remnant sites around Phoenix, Arizona along a model-predicted gradient in N deposition to determine
the degree to which deposition has altered spatial patterns in soil resource availability and microbial activity. Soil microbial
biomass and abundance were not influenced by atmospheric N deposition. Instead, plant islands remained strong organizers of
soil microbial processes. These islands of fertility exhibited elevated pools of resources, microbial abundance, and activity
relative to interspaces. In both plant islands and interspaces, soil moisture and soil N concentrations predicted microbial
biomass and abundance. Following experimental wetting, carbon dioxide (CO2) flux from soil of interspaces was positively correlated with N deposition, whereas in plant islands, soil CO2 flux was positively correlated with soil moisture content and soil organic matter. Soil CO2 flux in both patch types showed rapid and short-lived responses to precipitation, demonstrating the brief time scales during
which soil biota may process deposited materials. Although we observed patterns consistent with N limitation of microbes in
interspaces, we conclude that atmospheric N deposition likely accumulates in soils because microbes are primarily limited
by water and secondarily by carbon or nitrogen. Soil microbial uptake of atmospherically deposited N likely occurs only during
sparse and infrequent rainfall. 相似文献
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Seasonal variation in organic and inorganic phosphorus fractions of temperate-climate sandy soils 总被引:3,自引:0,他引:3
Soils from an arable plot, a grassland plot and pasture plot were sampled over an 18-month period. Inorganic (Pi) and organic (Po) soil phosphorus fractions were extracted sequentially with resin, NaHCO3, and NaOH. Soil solution was sampled on the arable plot and pasture plot during 12 months with teflon suction cups, and the contents of Pi and Po were determined.The patterns of the variation for all soil fractions were similar for the three plots. All soil Pi fractions were at minimum in the cool moist winter period. The soil Po fractions varied less systematically than Pi fractions. The sum of Po fractions had a winter maximum and a spring minimum. For all soil P fractions temporal variation was highly significant (p<0.0001). The magnitude of change in Pi and Po soil fractions was 4–40 times greater than what would be expected from the magnitude of new N mineralization.The content of P in the inorganic soil P fractions was negatively correlated with soil moisture. The variation in organic soil P could not be explained by any single factor, but it is suggested that the variation is caused by changes in solubility rather than by biological transformations. Thus, physicochemical processes masked the impact of biological transformations on the temporal variation of soil phosphorus fractions.Both soil solution Pi and Po varied significantly with time on field scale. In contrast to soil Pi fractions, solution Pi was initially low in the early autumn, increased by a factor 4 during the following 6 weeks, and thereafter decreased to a low level by the end of the sampling period. Soil solution Po had several fluctuations during the sampling period. 相似文献
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Chen C. R. Condron L. M. Sinaj S. Davis M. R. Sherlock R. R. Frossard E. 《Plant and Soil》2003,256(1):115-130
Vegetative conversion from grass to forest may influence soil nutrient dynamics and availability. A short-term (40 weeks) glasshouse experiment was carried out to investigate the impacts of ryegrass (Lolium perenne) and radiata pine (Pinus radiata) on soil phosphorus (P) availability in 15 grassland soils collected across New Zealand using 33P isotopic exchange kinetics (IEK) and chemical extraction methods. Results from this study showed that radiata pine took up more P (4.5–33.5 mg P pot–1) than ryegrass (1.1–15.6 mg pot–1) from the soil except in the Temuka soil in which the level of available P (e.g., E
1min Pi, bicarbonate extractable Pi) was very high. Radiata pine tended to be better able to access different forms of soil P, compared with ryegrass. There were no significant differences in the level of water soluble P (Cp, intensity factor) between soils under ryegrass and radiata pine, but the levels of Cp were generally lower compared with original soils due to plant uptake. The growth of both ryegrass and radiata pine resulted in the redistribution of soil P from the slowly exchangeable Pi pool (E
> 10m Pi, reduced by 31.8% on the average) to the rapidly exchangeable Pi (E
1min-1d Pi, E
1d-10m Pi) pools in most soils. The values of R/r
1 (the capacity factor) were also generally greater in most soils under radiata pine compared with ryegrass. Specific P mineralisation rates were significantly greater for soils under radiata pine (8.4–21.9%) compared with ryegrass (0.5–10.8%), indicating that the growth of radiata pine enhanced mineralisation of soil organic P. This may partly be ascribed to greater root phosphatase activity for radiata pine than for ryegrass. Plant species × soil type interactions for most soil variables measured indicate that the impacts of plant species on soil P dynamics was strongly influenced by soil properties. 相似文献
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Background and aims
The combined effects of (1) reduced soil moisture availability, (2) reduced application of inorganic fertilisers while incorporating straw, (3) soil type, and their effects on growth, root system plasticity, phosphorus (P) nutrition of rice, and soil P dynamics are poorly known, but very important when aiming to increase the efficiency of water and P use.Methods
Using large pots a three-factor factorial experiment was conducted with two moisture treatments (i.e. continuous flooding, and draining of top soil after flowering while subsoil was kept moist through capillary action), three fertilisation treatments; with (P1) and without (P0) applications of inorganic P fertilisers, and 25 % of inorganic fertilisers reduced while incorporating straw (5 t ha?1), and soil type (i.e. clay and sandy soils with 15 and 9 mg P kg?1 soil, respectively in P0). Shoot and root growth, root system plasticity, P nutrient status and soil P dynamics were measured.Key results
Straw incorporation with reduced inorganic fertiliser application ensured a higher shoot dry weight and yield only in flooded clay soil as compared with P0 and P1, and a similar shoot dry weight and yield to P1 under drained clay soil. A positive growth response was facilitated by an increased water-use efficiency and rate of photosynthesis in shoots, and increased root system plasticity through the production of greater root length, more roots in deep soil layers, and an increased fraction of fine roots. Straw enhanced P extractability in soil. Drained soil reduced P uptake (15–45 %) and increased P-use efficiency. In addition to the re-translocation of P from senescing leaves and stems under both moisture conditions, the P concentration in green leaves under drained condition was also reduced (41–72 %).Conclusion
Growth benefits of straw incorporation were observed in clay soil under both moisture conditions, and this was facilitated by the improved P availability, increased P uptake, and greater root system plasticity with the production of deeper and finer roots, compared with that in sandy soil, and inorganic fertiliser applications alone. As P uptake was reduced under drained soil, P re-translocation and % P allocated to panicles increased. 相似文献15.
Summary Laboratory experiments were conducted to study the effect of algal growth on the change of (I) pH, (II) available phosphorus and (III) solubility of iron and manganese content in five waterlogged alluvial rice soils of West Bengal, India. The results showed that the algal growth initially caused an increase in the soil pH, which later declined to the original value in some of the soils. The available phosphorus content decreased upto 90 days of their growth and began to increase towards the later period of incubation. The drastic fall of water soluble plus exchaneable manganese content of the soils due to algal growth was accompanied by similar increase in reducible manganese content. No appreciable change in water soluble plus exchangeable ferrous iron content was encountered but theN-NH4OAC(pH 3) extractable iron due to algal growth progressively decreased with the progress of the incubation period. 相似文献
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Yanpeng Li Han Xu Jie Chen Yihua Xiao Yunlong Ni Ruyun Zhang Wanhui Ye Juyu Lian 《Ecology and evolution》2022,12(2)
Identifying patterns and drivers of plant community assembly has long been a central issue in ecology. Many studies have explored the above questions using a trait‐based approach; however, there are still unknowns around how patterns of plant functional traits vary with environmental gradients. In this study, the responses of individual and multivariate trait dispersions of 134 species to soil resource availability were examined based on correlational analysis and torus‐translation tests across four spatial scales in a subtropical forest, China. Results indicated that different degrees of soil resource availability had different effects on trait dispersions. Specifically, limited resource (available phosphorus) showed negative relationships with trait dispersions, non‐limited resource (available potassium) showed positive relationships with trait dispersions, and saturated resource (available nitrogen) had no effect on trait dispersions. Moreover, compared with the stem (wood density) and architectural trait (maximum height), we found that leaf functional traits can well reflect the response of plants to nutrient gradients. Lastly, the spatial scale only affected the magnitude but not the direction of the correlations between trait dispersions and environmental gradients. Overall, the results highlight the importance of soil resource availability and spatial scale in understanding how plant functional traits respond to environmental gradients. 相似文献
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Phosphorus was added to two acidic upland soils (a Cambisol and a Ferralsol) at two rates (9 mg P kg−1 and 145 mg P kg−1) either in an inorganic P form (KH2PO4) or as a green manure (Tithonia diversifolia H. at 2.5 g kg−1 and 40 g kg−1). The effect of P source on the chemical availability of P was assessed in an incubation experiment by measuring resin extractable
P, soluble molybdate reactive (DMR-P) and unreactive P (DMU-P). Soil pH and extractable Al were monitored during the incubation
period of 49 days. Green manure addition caused an immediate and sustained increase in soil pH and an immediate and sustained
decrease in extractable Al. Labile P (resin P + DMR-P + DMU-P) was increased more by P added as a green manure than when added
in inorganic form in one soil (Ferralsol), while it decreased or did not differ in the other one (Cambisol). In both soils,
the concentrations of soluble DMU-P were frequently higher where Tithonia had been added. The effects of green manure amendment on physical factors governing the phosphorus supply through diffusive
transport were also investigated. Aggregate size distribution was substantially changed by green manure amendment due to a
shift in the percentage of microaggregates (<250 μm in diameter) to larger sizes. Changes in soil aggregation as a consequence
of green manure amendment led to a reduction in specific surface area (SSA) of the whole soil. Coupled with the large increase
in effective cation exchange capacity caused by green manure amendment in both soils, and the decrease in SSA, there was an
increase in the net negative surface charge density in both soils. In summary, at a large addition rate – and in addition
to the well-known effect derived from the extra supply in P, green manure amendment may improve the chemical availability
and diffusive supply of P through the following mechanisms: (i) an increase in soil pH increasing the solubility of phosphate
sources; (ii) a decrease in extractable Al reducing the fixation of added P; (iii) increased macro-aggregation and reduced
specific surface area and porosity leading to fewer sorption sites for P and hence enhanced diffusion rates; and (iv) increased
negative charges and reduced positive charges at the soil surface resulting in a net increase in repulsive force for P. The
induced changes in most measured soil properties were smaller in the Ferralsol than in the Cambisol.
This revised version was published online in June 2005 with a corrected article title. 相似文献
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Summary The effects of CO2 enrichment on the growth, biomass partitioning, photosynthetic rates, and leaf nitrogen concentration of a grass, Bromus mollis (C3), were investigated at a favorable and a low level of nitrogen availability. Despite increases in root: shoot ratios, leaf nitrogen concentrations were decreased under CO2 enrichment at both nitrogen levels. For the low-nitrogen treatment, this resulted in lower photosynthetic rates measured at 650 l/l for the CO2-enriched plants, compared to photosynthetic rates measured at 350 l/l for the non-enriched plants. At higher nitrogen availability, photosynthetic rates of plants grown and measured at 650 l/l were greater than photosynthetic rates of the non-enriched plants measured at 350 l/l. Water use efficiency, however, was increased in enriched plants at both nitrogen levels. CO2 enrichment stimulated vegetative growth at both high and low nitrogen during most of the vegetative growth phase but, at the end of the experiment, total biomass of the high and low CO2 treatments did not differ for plants grown at low nitrogen availability. While not statistically significant, CO2 tended to stimulate seed production at high nitrogen and to decrease it at low nitrogen. 相似文献
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A microcolorimetric method for the determination of inorganic phosphorus 总被引:121,自引:0,他引:121
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