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21.
DIFFERENTIAL EXPRESSION OF DIEL ACID METABOLISM IN TWO LIFE FORMS OF LITTORELLA UNIFLORA (L.) ASCHERS 总被引:1,自引:0,他引:1
K. AULIO 《The New phytologist》1985,100(4):533-536
22.
Huijuan Xia Weijing Kong Lusan Liu Hongli Li Kuixuan Lin 《Global Change Biology Bioenergy》2020,12(8):636-647
Converting feedstocks of invasive plants into biochar is a new and cost‐effective measure for their control, and benefits for the sustainable development of native ecosystems. Spartina alterniflora, an invasive plant widely distributed in coastal wetlands of China, was used to produce biochar. We aimed to analyze how S. alterniflora biochar properties changed with desalination of feedstocks, pyrolysis temperature, and residence time. Results showed that desalting feedstocks increased biochar pH, stability, porosity, and surface area, but diminished biochar yield and polarity. Pyrolysis temperature positively affected biochar pH, surface area, and pore volume, while it had negative effects on biochar yield, oxygen and hydrogen contents, hydrogen/carbon and oxygen/carbon ratios, pore size, and function groups. However, residence time of pyrolysis had slight effects on biochar properties. The results are valuable for optimizing pyrolysis temperature and pretreatment measure of feedstocks, to tune S. alterniflora biochar properties for specific environmental usage. 相似文献
23.
Summary The VA-infected wheat varieties showed an increase of total (Lozano var.) and reducing (Lozano and Pane vars.) sugars in their root extracts. However, no clear relationship between sugar concentration in the root and VA mycorrhizal infection level could be established.In addition, the VA mycorrhizal hosts sorghum, alfalfa, sunflower and maize, and non-host radish and cabbage plants were tested for sugar content in their root extracts after fifteen days of growth. Sugars present in the root extracts of these plants did not seem to be a decisive factor in plant susceptibility to VA infection. 相似文献
24.
M. Sazima S. Vogel A. L. do Prado D. M. de Oliveira G. Franz I. Sazima 《Plant Systematics and Evolution》2001,227(3-4):195-208
The pollination biology of the neotropical scandent shrub Combretum lanceolatum was studied in the seasonally-flooded Pantanal region in western Brazil. This plant bears horizontally oriented inflorescences,
whose yellowish green flowers begin to expand at dusk and are fully open at dawn. Instead of fluid nectar the flowers produce
sweet gelatinous secretion in form of pellets. The glandular complex of the flower is composed of the inner wall of the receptacle
and its tubular extension, being equivalent to the nectariferous disk of the nectar-producing species within the genus. The
jelly is produced at night, contains mannan and is imbibed by free hexoses. It originates by swelling and disintegration of
the inner wall, after contact with the nectar generated concomitantly in the mesophyll. Combretum lanceolatum is unique within the genus in its production of jelly pellets instead of liquid nectar. A new term, the jelly-flower, is
proposed for flowers with this kind of reward. The pellet is not replaced once removed by a bird, and thus resembles a fruit
in its availability to consumers, another unique feature that distinguishes this species within the genus. The jelly pellets
offered by the many flowered branches attract a great diversity of bird visitors (28 species from eight families), which feed
on this copious food resource and pollinate the flowers. The most effective pollinators probably are thrushes, tanagers, and
orioles. Flocking parakeets and macaws sometimes feed on the petals, thus acting as flower plunderers. Combretum lanceolatum presents a high fruit set under natural conditions, which likely favours its spreading and becoming a weed species.
Received July 11, 2000 Accepted November 18, 2000 相似文献
25.
Biosynthesis and Genetic Engineering of Lignin 总被引:1,自引:0,他引:1
Lignin, a complex heteropolymer of cinnamyl alcohols, is, second to cellulose, the most abundant biopolymer on Earth. Lignification has played a determining role in the adaptation of plants to terrestrial life. As all extracellular polymers, lignin confers rheological properties to plant tissues and participates probably in many other functions in cell and tissue physiology orin cell-to-cell communication. Economically, lignin is very important because it determines wood quality and it affects the pulp and paper-making processes as well as the digestibility of forage crops. For all these reasons the lignin biosynthesis pathway has been the subject of many studies. At present, most genes encoding the enzymes involved in the biosynthesis of lignin have been cloned and characterized. Various recent studies report on the alteration of the expression of these genes by genetic engineering, yielding plants with modified lignin. In addition, several mutants have been analyzed with changes in lignin content or lignin composition resulting in altered properties. Thanks to these studies, progress in the knowledge of the lignin biosynthesis pathway has been obtained. It is now clear that the pathway is more complex than initially thought and there is evidence for alternative pathways. A fine manipulation of the lignin content and/or composition in plants is now achievable and could have important economical and environmental benefits. 相似文献
26.
27.
Michael Kleyer 《植被学杂志》1999,10(5):697-708
Abstract. In this study, plant functional types are understood as groups of plants with similar biological traits displaying significant optima or maxima on a gradient plane of resource supply and disturbance intensity. The biological traits refer to expansion, vegetative regeneration, generative reproduction, dispersal and seed bank longevity. 129 vegetation samples were taken in an agricultural landscape in southwestern Germany, covering a wide range of terrestrial vegetation types – but with the exception of forests and wetlands. For each site, also soil data were recorded. Mean daily soil moisture was estimated with a simple model. Soil moisture, balanced nitrogen supply and available phosphorus were combined into a factor ‘resource supply’. In addition, disturbance intensity was estimated for each site. This factor was based on (1) frequency of disturbance, (2) disturbance depth below or above the soil surface, and (3) proportion of the area affected by a discrete disturbance event. 30 plant groups with similar biological characteristics resulted from a cluster analysis, based on a compilation of 19 biological traits for a regional species pool. Logistic regression on a gradient plane of disturbance intensity and resource supply yielded response curves for 28 groups. The dependent variable was defined as the probability of encountering all members of a group in a sample. 17 groups display a significant response curve on the gradient plane. Plants with a potential for long- range dispersal are concentrated on sites with low or high disturbance intensities (e.g. fallow land, fields, lawns). On sites with medium disturbance intensity (e.g. meadows) and low to medium resource supply, small-range dispersal predominates. There are no distinct trends concerning seed bank longevity. The potential for vertical and lateral expansion increases with decreasing disturbance intensity. Only at medium disturbance intensities does vertical expansion correlate positively with resource supply. Rapid detachment of daughter individuals occurs more often on productive sites than on less productive sites. Diversity of groups with similar biological traits is highest on sites with medium disturbance intensities. 相似文献
28.
29.
The parsimony and bootstrap branching pattern of major groups of land plants derived from relevant 5S rRNA sequence trees
have been discussed in the light of paleobotanical and morphological evidences. Although 5S rRNA sequence information is not
useful for dileneating angiosperm relationships, it does capture the earlier phase of land plant evolution. The consensus
branching pattern indicates an ancient split of bryophytes and vascular plants from the charophycean algal stem. Among the
bryophytes,Marchantia andLophocolea appear to be phylogenetically close and together withPlagiomnium form a monophyletic group.Lycopodium andPsilotum arose early in vascular land plant evolution, independent of fem-sphenopsid branch. Gymnosperms are polyphyletic; conifers,
Gnetales and cycads emerge in that order with ginkgo joiningCycas. Among the conifers,Metasequoia,Juniperus andTaxus emerge as a branch independent ofPinus which joins Gnetales.
The phylogeny derived from the available ss-RNA sequences shows that angiosperms are monophyletic with monocots and dicots
diverging from a common stem. The nucleotide replacements during angiosperm descent from the gymnosperm ancestor which presumably
arose around 370 my ago indicates that monocots and dicots diverged around 180 my ago, which is compatible with the reported
divergence estimate of around 200 my ago deduced from chloroplast DNA sequences.
Since deceased. 相似文献
30.
Photosynthesis and root growth in Spartina alterniflora in relation to root zone aeration 总被引:1,自引:0,他引:1
S.R. Pezeshki 《Photosynthetica》1997,34(1):107-114
Spartina alterniflora Lois. is a dominant species growing in intermediate and saline marshes of the US Gulf coast and Atlantic
coastal marshes. S. alterniflora plants were subjected to a range of soil redox potential (Eh) conditions representing a well
aerated to reduced conditions in a rhizotron system under controlled environmental conditions. The low soil Eh resulted in
inhibition of root elongation shortly after treatment initiation. Root elongation was reduced as soil Eh approached values
below ca. +350 mV. Substantial decrease in root elongation was noted when soil Eh fell below +200 mV. Generally, net photosynthetic
rate (PN) decreased as soil Eh was reduced, with substantial reductions in PN found when Eh approached negative values. Average
PN was reduced to 87, 64, and 44% of control under +340, +245, and -180 mV treatments, respectively. The reductions in root
elongation and PN in response to low soil Eh indicated the adverse effects of low soil Eh on plant functioning and the need
for periods of soil aeration that allow plants to resume normal functioning. Thus periods of drainage allowing soil aeration
during the growing season appear to be critical to S. alterniflora by providing favorable conditions for root growth and gas
exchange with important implications for plant carbon fixation.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献