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91.
An optimized soy-based medium was developed for ethanol production byEscherichia coli KO11. The medium consists of mineral salts, vitamins, crude enzymatic hydrolysate of soy and fermentable sugar. Ethanol produced after 24 h was used as an endpoint in bioassays to optimize hydrolysate preparation. Although longer fermentation times were required with soy medium than with LB medium, similar final ethanol concentrations were achieved (44–45 g ethanol L–1 from 100 g glucose L–1). The cost of materials for soy medium (excluding sugar) was estimated to be $0.003 L–1 broth, $0.006 L–1 ethanol. 相似文献
92.
Biodiversity of soil biota and plants in abandoned arable fields and grasslands under restoration management 总被引:2,自引:0,他引:2
The currently widespread abandoning of agricultural land use in Western Europe offers new opportunities for ecological restoration and nature conservation. This is illustrated for abandoned arable fields and for permanent grasslands cut for hay after the cessation of fertilizer application. Although initiated by a sudden reduction of nutrient input to the system, the changing nutrient supply from the soil is considered to be the main driving force of succession. The soil nutrient supply is affected by soil organisms, both directly (root symbionts and herbivores) and indirectly (nutrient mineralization from dead organic matter). It is argued that because of the close association of changes in species diversity with changes in the functioning of ecosystems, biodiversity has to be studied in an ecosystem ecology context. 相似文献
93.
Eggplants (Solanum melongena L. cv. Bonica) were grown in a glasshouse during summer under natural light with one unbranched shoot or one shoot with 3
to 4 branches and with or without fruit in quartz sand buffered and not buffered with 0.5% CaCO3 (w : v), respectively. Nutrient solutions supplied contained nitrate or ammonium as the sole nitrogen source.
Compared with nutrient solutions containing nitrate (10 mM), solutions containing ammonium (10 mM) caused a decrease in net photosynthesis of eggplants during early stages of vegetative growth when grown in quartz sand
not buffered with CaCO3. The decrease was not observed before leaves showed interveinal chlorosis. In contrast, net photosynthesis after bloom at
first increased more rapidly in eggplants supplied with ammonium than with nitrate nitrogen. However, even in this case, net
photosynthesis decreased four weeks later when ammonium nutrition was continued. The decrease was accompanied by epinasty
and interveinal chlorosis on the lower leaves and later by severe wilting, leaf drop, stem lesions, and hampered growth of
stems, roots, and fruits. These symptoms appeared later on plants not bearing fruits than on plants bearing fruits. If nutrient
solutions containing increasing concentrations of ammonium (0.5–30 mM) were supplied after the time of first fruit ripening, shoot growth and set of later flowers and fruits were promoted. In
contrast, vegetative growth and reproduction was only slightly affected by increasing the concentration of nitrate in the
nutrient solutions.
In quartz sand buffered with CaCO3 ammonium nutrition caused deleterious effects only under low light conditions (shade) and on young plants during rapid fruit
growth. If eggplants were supplied with ammonium nitrogen before bloom, vegetative growth was promoted, and set of flowers
and fruit occurred earlier than on plants supplied with nitrate. Furthermore, the number of flowers and fruit yield increased.
These effects of ammonium nutrition were more pronounced when plants were grown with branched shoots than with unbranched
shoots.
The results indicate that vegetative and reproductive growth of eggplants may be manipulated without causing injury to the
plants by supplying ammonium nitrogen as long as the age of the plants, carbohydrate reserves of the roots, quantity of ammonium
nitrogen supplied, and pH of the growth medium are favourable. T W Rufty Section editor 相似文献
94.
In a model system using intact spruce trees (Picea abies [L.] Karst.) we followed the path of magnesium, calcium and potassium during uptake into the root and during long-range transport into the shoot, by multiple stable isotope labelling. The roots of two- and three-year-old spruce trees originating from soil culture were removed from the soil and, in part or in toto, exposed to labelling solutions containing the stable isotopes 25Mg or 26Mg, 41K and 42Ca or 44Ca. Optical-emission-spectroscopy (ICP-OES) of plant fractions and labelling solutions was combined with the quantitative analysis of stable isotope ratios in sections of shock frozen, cryosubstituted material using the laser-microprobe-mass-analyser (LAMMA). This combination allowed us to distinguish, both in bulk samples and on the cellular level between (i) the fraction of elements originally present in the plant before the start of the labelling, (ii) the material taken up from the labelling solution into the plant and (iii) any material released by the plant into the labelling solution.In single-root labelling experiments, roots of three-year-old spruce trees, grown in nursery soil, were exposed to various pH conditions. The exchange of Mg and Ca with the labelling solution was nearly 100% in the cell walls of the mycorrhized finest roots. This exchange was only slightly affected by a step down to pH 3.5. The absolute Mg and Ca content in the cell walls was moderately reduced by incubation at pH 3.5 and strongly reduced in the presence of Al at this pH. After a pH 3.5 and 2 mM Al treatment we found Al in the xylem cell walls and the cortex cell lumina at elevated concentrations. To analyse the combined effect of high Al and high proton concentrations on the long-range transport, we used a split-root system. The root mass of an intact two-year-old spruce tree, grown in mineral soil, was divided into even parts and both halves incubated in solutions with two sets of different stable isotopes of Mg and Ca (side A: no Al, 25Mg and 42Ca; side B: +Al, 26Mg and 44Ca) and 41K on both sides. We observed a large uptake of Mg, Ca and K into the plant and a pronounced release. The net uptake of all three elements was lower from the Al-doted solution. In cross-sections of the apical shoot we found after seven-day labelling period about 60–70% of the Mg and Ca and 30% of the K content in the xylem cell walls originating from both labelling solutions. The clear majority of the Mg and Ca label originated from the Al-doted side. 相似文献
95.
The influences of soil surface modification (blade scarification and plastic mulching), fertilization and herbicide application on soil nutrient and organic carbon content and tree growth and foliar nutrient status were examined after seven years in a study located within the Great Lakes-St. Lawrence forest region of Canada. Plots had been planted with white pine (Pinus strobus L.) and white spruce (Picea glauca [Moench] Voss) seedlings. Light (PAR), soil moisture and temperature were monitored and recorded throughout the growing season. Forest floor and soil mineral (0–20 cm layer) samples were collected from all experimental plots, except those which had plastic mulching. Foliar samples were collected in autumn and analysed for N, P and K and storage compounds. Seedling mortality was 20% higher in unscarified plots. Combined silvicultural treatments increased productivity as much as 14 times, but scarification reduced soil carbon and nutrient capital 2–3 fold. Herbicide application reduced soil carbon by at least 20 %. Foliar nutrient, protein, starch and lipid contents in autumn were little affected by treatment. The future management of such stands in Canada probably will include more shelterwood harvesting and crop rotations, silvicultural systems that are more closely aligned with natural forest succession. 相似文献
96.
A five year study was conducted in a 100–120 year old even-aged sugar maple stand in southern Quebec (46°07N 73° 56W; 305 m altitude) to explore the effect of different fertilization formulations aimed at 1) correcting the most common nutrient deficiencies observed in declining maple stands (K and Mg), 2) decreasing soil acidity, and 3) simulating enrichment with atmospheric N. Seven fertilizer mixtures were applied in the spring of 1987: 400 kg ha-1 of K2SO4, CaCO3, CaMg(CO3)2, (NH4)2SO4, complete fertilizer (Maplegro) and 800 kg ha-1 of an equal mixture of K2SO4+CaCO3 or K2SO4+CaMg(CO3)2. The site was divided into twenty-four 25×25 m plots and treatments including control were replicated three times. Leaves and soils (organic and mineral) were sampled in 1987, 1988 and 1991. Trees were cored at 1.2 m to measure their response in diameter growth. The application of K2SO4+CaMg(CO3)2 was the only treatment that significantly increased (+13%) the average growth rate over the five year period after fertilization. The application of (NH4)2SO4, Maplegro, CaMg(CO3)2 and K2SO4 reduced growth relative to the control for the five year period by 29, 24, 20 and 12 %, respectively. Positive and negative effects on growth can be explained mainly in terms of changes in leaf K. Both the application of Maplegro and (NH4)2SO4 increased soil P availability. Overall, the rate of growth showed a cubic pattern of change over the 5 year period with peaks in 1988 and 1991. Trees in control plots went from a limiting foliar status of Ca and Mg, and surplus N in 1987 to a surplus of Ca and Mg, and lower N concentration in 1991. Our results suggest that nutrient deficiencies observed at our site were associated with a disturbance of the biogeochemical cycle of nutrients rather than soil nutrient depletion.Abbreviations BS
base saturation
- CEC
cation exchange capacity
- DRIS
diagnosis and recommendation integrated system 相似文献
97.
The effects of slow and fast-release fertilizers (P, K, Mg) on the movement and availability of nutrients in acid forest soil were studied. Fast-release superphosphate, potassium chloride and magnesium sulphate and slow-release apatite (P) and biotite (K, Mg) were applied alone or together with urea or urea+limestone. The nutrient content in the organic horizon was determined one growing season and three growing seasons after the application, and in the mineral layer after one growing season. The movement of nutrient ions in the organic horizon was studied by an ion exchange resin bag method during a 5-month period following application. The fast-release salts immediately increased the soluble P and exchangeable K and Mg contents in the organic and mineral soils and in the resin bags. After three growing seasons the effect of K application in the organic layer was non-detectable and that of P had clearly diminished. Apatite gradually increased soluble P content in the organic layer, but biotite had only a minor effect on the K and Mg contents. The nutrients from the fast-release fertilizers had clearly become available and mobile in the year of application and were thus susceptible to leaching. The rate of nutrient release from apatite and biotite is slower and the added nutrients are retained in the organic horizon. Slow-release compounds, like apatite and biotite, might be potential fertilizers for counteracting acidic deposition and subsequent nutrient losses. 相似文献
98.
Acid atmospheric deposition can cause losses of metal nutrients from the organic layer of a soil. The size of these losses
depend on the sizes of the different pools in which the metals are present, as these pools differ in mobility. The metal pools
in an organic soil layer of a Douglas fir forest in the Netherlands subjected to acid deposition were determined by means
of extractions and percolations. Na was mainly dissolved and exchangeably adsorbed, K dissolved, exchangeably adsorbed and
present in the soil microbial biomass, Ca exchangeably adsorbed and present in organic precipitates, Mg exchangeably adsorbed
and present in the soil biomass, and Mn exchangeably adsorbed and present in inorganic precipitates. The main part of the
metals was exchangeably adsorbed. The adsorption affinity increased in the order Na < K < Mg < Mn ≈ Ca. The vertical distribution
of the metals in the organic layer showed that all metals were continuously lost from the organic layer. The differences between
the metals in retention and vertical distribution patterns were in agreement with their differences in deposition rate, pool
distribution, and exchange affinity. Since the metals were mainly exchangeably adsorbed, and the acidifying cations dominated
the atmospheric deposition, acid deposition and cation exchange must be processes that strongly affect the losses of metals
from this organic soil layer. R F Huettl Section editor 相似文献
99.
The paper contains a discussion of the interrelations between the sciences used by managers of forest land to improve their management, in particular with respect to the plant nutrient economy of the forest ecosystems. Both site studies and studies of nutrient cycling have been carried out for long periods without proper consideration of tree nutrition. Therefore these studies contributed less to the understanding of the role of nutrients as regulators of processes in ecosystems than might have been expected. This situation has improved, especially within the last decade. In addition the necessity to manage forest land for environmental values as well as for forest yield requires new interdisciplinary approaches in the study of the roles of plant nutrients in the forest. Even more branches of biological and environmental sciences than those just mentioned must be involved. 相似文献
100.
Phosphorus limitation of forest leaf area and net primary production on a highly weathered soil 总被引:11,自引:0,他引:11
We tested the hypothesis that P was the nutrient limiting net primary production of a nativeMetrosideros polymorpha forest on a highly weathered montane tropical soil in Hawaii. A factorial experiment used all combinations of three fertilizer treatments: nitrogen (N), phosphorus (P) and a mix of other essential nutrients (OE), consisting primarily of mineral derived cations and excluding N and P. P addition, but not N or OE, increased leaf area index within 12 months, foliar P concentration measured at 18 months, and stem diameter increment within 18 months. Stem growth at 18 months was even greater when trees fertilized with P also received the OE treatment. N and P additions increased leaf litterfall and N and P in combination further increased litterfall. The sequence of responses suggests that increased available P promoted an increase in photosynthetic area which led to increased wood production. P was the essential element most limiting to primary production on old volcanic soil in contrast to the N limitation found on young volcanic soils. 相似文献