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1.
This review compares new developmental models on flowering andother vascular plants with evolutionary hypotheses formulatedby Agnes Arber (18791960) and like-minded botanists.Special emphasis is laid on philosophical basics such as perspectivism,pluralism about evolutionary modelling, continuum way of thinking,and fuzzy logic. Arber's perspective is best labelled as F uzzyA rberian M orphology (FAM Approach). Its proponents (FAMmers)treat structural categories (e.g. roots, shoots,stems, leaves, stipules)in vascular plants as concepts with fuzzy borderlines allowingintermediates (including transitional forms, developmental mosaics).The FAM Approach complements Cla ssical Plant M orphology (ClaMApproach), which is the traditional approach in botany. ClaMproponents (ClaMmers) postulate that the structuralcategories of vascular plants are regarded as concepts withclear-cut borderlines and without intermediates. However, duringthe evolution of vascular plants, the root-shoot distinctionand the stem-leaf distinction have become blurred several timesdue to developmental changes, resulting in organs with uniquecombinations of features. This happened, for example, in thebladderworts (Utricularia, Lentibulariaceae). When focusingon the leaf, the FAM Approach is identical toArber's partial-shoot theory of the leaf and Sinha'sleaf shoot continuum model. A compound leaf canrepeat the developmental pathway of the whole shoot, at leastto some degree. For example, compound leaves of Chisocheton(Meliaceae)with indeterminate apical growth and three-dimensional branchingmay be seen as developmental mosaics sharing some growth processeswith whole shoots! We focus here on the FAM Approach becausethis perspective is especially promising for developmental geneticistsstudying flowering and other vascular plants. Copyright 2001Annals of Botany Company Review, body plan, developmental mosaics, leaf development, history of botany, homeosis, homeotic genes, Lentibulariaceae, morphological evolution, process morphology, stipules, Utricularia, flowering plants 相似文献
2.
Potted plants of three types of cacao (Theobroma cacao) knownin St. Thomé Islands as Laranja Amarelo(LA), Amelonado Vermelho (AV), and AmelonadoAmarelo (AA) were submitted to artificial drought, andtheir drought resistance evaluated. The AV type proved to bethe most resistant one. According to the results obtained itshigher drought resistance may be interpreted in terms of stomatalbehaviour and transpiration rate 相似文献
3.
KANAMORI-FUKUDA IKUKO; ASHIHARA HIROSHI; KOMAMINE ATSUSHI 《Journal of experimental botany》1981,32(1):69-78
Marked changes in the activity of the de novoand salvage pathways of pyrimidine biosynthesisduring growth of Vinca rosea cells in a batch suspension culturewere observed. The activity of these pathways was investigated by determiningthe contribution of 14C of [2-14Cluracil, 12-14Cluridine. and[6-14Clorotate to the cell constituents and by measuring theactivity of the several enzymes of these pathways. During the lag phase of the culture, uracil- anduridine-salvage pathways made the predominantcontribution to nucleotide biosynthesis, but, following theinitiation of cell division, the de novo pathwayfor nucleotide biosynthesis operated appreciably. These results suggest that nucleotide synthesis during cellgrowth in a suspension culture can be divided into two stages:a turnover stage, during the lag phase of cellgrowth, and a true biosynthetic stage, which isinitiated in the cell division phase. 相似文献
4.
Diurnal Changes in Stem Diameter Depend Upon Variations in Water Content: Direct Evidence in Peach Trees 总被引:14,自引:4,他引:10
SIMONNEAU T.; HABIB R.; GOUTOULY J.-P.; HUGUET J.-G. 《Journal of experimental botany》1993,44(3):615-621
Three to five-year-old peach trees (Prunus persica (L.) Batschcv. Maycrest) grafted on P. Damas 1869grown in a sand trench were removed in the spring and grownhydroponically for several months. The system comprised twobalances continuously recording the mass of the nutrient solutionand that of the tree, so as to estimate transpiration and wateruptake rates separately. Diurnal variation in plant water content(transpiration minus water uptake) was observed, with rapidlydecreasing values when the solar radiation increased, whilethe reverse occurred when radiation decreased. Changes in stemdiameter were continuously recorded using linear variable differentialtransducers. Data collected over several days of contrastingclimatic conditions revealed that rapid changes in the stemdiameter occurred throughout the day and were closely relatedto plant water content. A lag-time not exceeding 10 min wasfound between changes in stem diameter and plant water content.These results are discussed in relation to the use of micromorphometricmethods to control irrigation in fruit trees. Moreover, we givevalues for the water stored in the shoots which may contributeto the transpiration stream. Key words: Prunus persica, stem shrinkage, plant water storage, water uptake, transpiration 相似文献
5.
The Nitrogen Content of Plants and the Self-thinning Rule of Plant Ecology: A Test of the Core-skin Hypothesis 总被引:3,自引:0,他引:3
The core-skin hypothesis postulates that secondarilythickened plants behave energetically as an inert corecovered by an active skin, the skinbeing two-imensional, the core three-dimensional.This would explain the self-thinning or3/2 rule of plant ecology, that is, the tendencyfor log (dry weight per plant) and log (number of plants perunit area) to progress along a straight line relationship, withslope = 3/2. The hypothesis was tested as follows. Plant nitrogen contentwas used as an estimate of the mass of skin perplant, and dry weight as an estimate of the mass of the core.As plants mature the slope of the relationship between y = log(mass of nitrogen per plant) and x = log (mass of dry matterper plant) is expected to decline from an initial value of 1.0towards a final value of 0.66. The intercept of the relationshipis expected to reflect the intrinsic content of skinper unit of core. Genotypic variation in thisparameter should cause genotypic differences in the maximumattainable yield of biomass per unit area. The expectations were investigated by fitting the function y= p+qx+r exp x to 30 sets of data on plant nitrogencontent, plant weight and time in 18 different vegetables. Simplelinear regressions of y on x were fitted to more limited setsof data on weights and nitrogen contents of mature trees. Theexpectations were, with some minor exceptions, confirmed. Nitrogen, yield, plant competition, self-thinning 相似文献
6.
《Journal of Molluscan Studies》1953,29(6):258
Part 1, under the frontispiece portrait of Dr. N. B. Eales,the words President 19481951 should havebeen added. Page 103, line 49, for Newton Collection readNorman Collection (Canon Norman). 185, line 37, for capillaris read capillacca. 188, Table 1, for bemoralis. read nemoralis. 188, Table 2, for Cochlicella acuta (Müll)? ventrosa(Fér.) read Cochlicella ventrosa (Fér.). 191, line 24, for araheo- read archeo-. 相似文献
7.
The maceration medium comprised a basal nutrient medium (BM)containing an optimum concentration of 3% (w/v) sucrose. Mannitoland sorbitol were inferior osmotica. Addition of potassium dextransulphate adversely affected maceration. Macerozymewas not as effective as Macerase in the productionof single cells. The optimal concentration of Macerasewas found to be 23% (w/v). Single cells obtained by filtering the macerate were rinsedwith BM and cultured in, and on, agar media comprising: BM;BM + 500 mg 11 malt extract (ME); and BM + 10% (v/v)coconut milk (CM). No growth or organization was observed incultures where cells were mixed in with warm medium prior togelling. When spread on the surface of gelled media supplementedwith ME and CM, proliferation and organization occurred. Manymicroscopic globular proembryoids developed within 3 weeks onthe supplemented media. Microscopic torpedo-shaped embryoidswere frequently observed on BM + CM, rarely on BM + ME, andnot at all on unsupplemented BM. The high frequency of microscopic globular proembryoids, andlater of macroscopic pseudo-bulbils, formed on BM + ME leadsus to postulate that pseudobulbils are derived from globularproembryoids in which polarity is not established by the 16to 32-cell stage. Microscopic torpedo-shaped embryoids probablygive rise to macroscopic heart-shaped embryoids which developinto plantlets. The technique reported in this article provides an ideal systemfor examining embryogenesis per se and for studying the effectsof various treatments on embryogenesis and organ differentiationin vitro. It also affords excellent opportunities for the breedingof solid mutant plants. 相似文献
8.
Simulated swards of each of two selection lines of Lolium perennecv. S23 with fast and slow ratesof mature tissue respiration were establishedin growth rooms at 20/15 °C day/night temperatures and studiedover four successive regrowth periods of 46, 30, 26 and 53 daysduration. The slow line outyielded the fast,both in harvestable shoot (above a 5 cm cut) and in root andstubble. Its advantage increased over successive regrowth periodsto 23 per cent (total biomass). Gas analysis measurements onthe entire communities (including roots), during the final regrowthperiod, showed that the slow line had a 2234per cent lower rate of dark respiration per unit dry weight.This enabled it to maintain its greater mass of tissue for thesame cost in terms of CO2 efflux per unit ground area. Halfthe extra dry weight produced by the slow line,relative to the fast, could be attributed to itsmore economic use of carbon. The rest could be traced to a 25per cent greater tiller number which enabled the slowline to expand leaf area faster (though not at a greater rateper tiller), intercept more light and fix more carbon, earlyin the regrowth period. Lolium perenne L., ryegrass, respiration, maintenance respiration, tiller production, simulated swards, canopy photosynthesis, carbon economy 相似文献
9.
In nodulated common bean (Phaseolus vulgaris L.), there is typicallya period of N stress between 15 and 20 d after emergence (DAE),due to a lack of synchronization between the depletion of Nin the cotyledons and the beginning of N2 fixation and transport.Screening trials identified some Rhizobium leguminosarum bv.phaseoli strains with which symptoms of N deficiency were notvisible (precocious strains). Cultivar Negro Argelwas then inoculated with two traditional strains(C-05 and CIAT 727) and two precocious strains(CNPAF 146 and CNPAF 512), and plants were harvested from 8to 30 DAE. There were no differences between the two groupsof strains in nodule dry weight or in the acetylene reductionrates between 8 and 16 DAE. However, nodules induced by theprecocious strains showed earlier onset of glutaminesynthetase (GS) (EC 6.3.1.2
[EC]
) and glutamate synthase (GOGAT)(EC 1.4.1.14
[EC]
) activities, and ureide synthesis. The N concentrationin the nodules formed by precocious strains variedfrom 4.2 to 4.5%, whereas with the traditionalstrains, it increased from 3.2% at 8 DAE to 65% at 18 DAE, atwhich time plants exhibited N-deficiency symptoms. By 21 DAE,GS and GOGAT activities in traditional noduleswere increased, as well as the ureide-N-concentration in thexylem sap, nodule N content declined to 4.5% and the leavesbecame green. These results suggest that the N stress with traditionalstrains is not a limitation in early N2 fixation activity butrather in the rates of expression of the processes of N assimilationand transport. Key words: Glutamate synthase, glutamine synthetase, nitrogen fixation, Phaseolus vulgaris, Rhizobium 相似文献
10.
Histochemical investigations on the Prosopis juliflora seedcoat indicate the occurrence of a hydrophobic stripas the primary water barrier. Its position and the structureand histochemistry of the palisade cells of the seed coat differaccording to their location on the seed. These differences maybe responsible for differences in the water permeability ofvarious parts of the seed coat. In particular, parts of theseed coat in which the hydrophobic strip is locatedmore superficially tend to be more water impermeable than partslike the chalaza, in which the strip is more deeplylocated within the palisade cells. Prosopis juliflora, seed coat impermeability, palisade cells, hydrophobic strip 相似文献
11.
A survey of pollen- and stigma-dimorphism and monomorphism inthe genus Limonium (as understood at present) reveals considerableheterogeneity which is useful for the solution of taxonomic,phylogenetic, and phytogeographic problems. Two main pollen types (A and B) and two main stigma types (coband papillate) occur in the genus. Capitate stigmata also occur. Type A pollen has frequently been found in conjunctionwith papillate stigmata as a secondarily monomorphic(self-compatible) combination and this must have arisen at leastfour times in the genus as well as in Armeria. Type Bpollen and cob stigmata are recorded togetherfor the first time (also as a secondarily monomorphic, self-compatiblecombination) in L. echioides. Apomixis, already discovered insubsections Densiflorae and Dissitiflorae, has been found inL. cosyrense of the subsection Steirocladae. The taxonomic and phylogenetic significance of the facts indiscussed. 相似文献
12.
A general modelling approach was used to predict the changesresulting from dehydration in the Young's modulus (E) of a tereteorgan with a simple anatomy (e.g. hypodermis of thick-walledtissue surrounding a parenchymatous core of ground tissue).Two general anatomical models were investigated: (1) an apoplastmodel in which each cross section through the organ wasconsidered as a composite elastic material consisting of a solid(cell wall) and liquid (protoplasm) phase; and (2) a core-rindmodel in which the organ consisted of a thick-walledand a thin-walled tissue. For each of these two anatomical models,two composite material models were considered, i.e. a Voigtor Reuss equation was used to predict the changes in E attendingdehydration. The predictions from the variants of the generalmodel were evaluated on the basis of observed changes in E ascylindrical segments of the pseudopetioles of Spathiphyllumwere allowed to desiccate at room temperature. Statistical comparisonsbetween predicted and observed values of E revealed that oneof the simple variants of the model, the Voigt apoplastmodel, was the most successful in predicting the observedtrend seen in the changes in E. However, when the Voigt andReuss apoplast models were combined, the hybridmodel provided estimates of changes in E that were statisticallyindistinguishable from those observed. Based on the hybrid model,it was estimated that roughly 76.7% of the tissues with a representativeSpathiphyllum pscudopetiole operated according to a Voigt apoplastmodel. Young's modulus, dehydration, plant tissues 相似文献
13.
Crop phenology is one of the most important characters influencingproductivity in a given environment. Narrow-leafed lupin (Lupinusangustifolius L.) is a major grain legume crop in southern Australiawith general phenological adaptation to this Mediterranean-typeenvironment. However, it is an indeterminate crop with severalassociated limitations to productivity, such as overlappingvegetative and reproductive growth, late grain filling and sometimesexcessive vegetative growth. Here we studied two novel typesof narrow-leafed lupin with restricted branching, which mightbe useful for overcoming these problems. These restricted branchinglupins arose spontaneously within a breeding population, inthe case of Tallerack, and within a farmer's cropin the case of Hurst and we compared them withthe Merrit, which is widely grown and has thenormal indeterminate branching habit. The morphology and developmentof the main shoot of these genotypes were similar. However,Hurst had much larger leaves. There were alsostriking differences in the lateral branches of the restrictedbranching types; they had fewer leaves than Merritand flowered earlier. These differences were most marked in Hurst, where the upper main stem branches werereduced to a single floret in the axil of main stem leaves,and these flowers often exhibited abnormal morphology. Copyright2000 Annals of Botany Company Lupinus angustifolius L., narrow-leafed lupin, adaptation, development, morphology, branching, leaves, mutant, plastochron, phyllochron, floral initiation, flowering. 相似文献
14.
Recalling Taste Intensities in Sweetened and Salted Liquids 总被引:2,自引:1,他引:1
The effect of training on recalling taste intensities over 6weeks was studied using an ad libitum mixing procedure. Subjectstasted sweet and salty standards labeled as weakand strong (3 and 8% sucrose in redcurrant juice;0.4 and 1.2% NaCl in beef broth). They subsequently mixed unsweetenedand sweetened juice, and unsalted and salted broth, to producetaste intensities that corresponded to the standards. A minimumtraining (MT) group (n = 13) produced comparison stimuli bytasting and directly comparing with standards in one sessiononly; an extensive training (ET) group (n = 13) did this insix sessions before producing comparison stimuli based on memoryonly at 1 h, 1 day, 1 week and 6 weeks. An upward bias (chemicallydetermined concentrations of comparison stimuli exceeding thoseof standards) occurred at 1 day or 1 week in MT subjects forweak and strong sweetness, and forstrong saltiness, and sustained thereafter. Theupward tendency was also observed in ET subjects but was significantonly for strong sweetness. It is important torecognize memory effects such as the one described, as theyaffect food perceptions and can be a major source of bias insensory food research. Chem. Senses 21: 2934, 1996.
3Current address: Psychonomics Department, Utrecht University,Heidelberglaan 2, 3584 CS Utrecht, The Netherlands 相似文献
15.
Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of B extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of Bin lupin pods was 5001,500 times more potent than thatof inhibitor ß in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of A of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of B. Mature podsof virus-infected plants again yielded moreA,but also 2? times more B than pods of healthyplants. Healthy pods yielded more A than virus-infectedpods, and there was no difference in X. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. A accelerated abscission when applied proximally,and delayed or prevented it when applied distally. Bstrongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances A and B. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism. 相似文献
16.
As the first step in an investigation of the life-history ofPorphyra umbilicalis (L.) Kütz. var. laciniata (Lightf.)J. Ag., spores which have originated as a result of the repeateddivision of the mother-cells have been germinated. When grownon glass their method of germination and growth agrees withthat described by previous investigators, but when germinatedon sterile shell the germ-tubes penetrate the shell and developinto growths identical with Conchocelis rosea Batters. Thisspecies, therefore, is a phase in the life-historyof P. umbilicalis var. laciniata and not an autonomous species.The development of the Conchocelis-phase in cultureis described and also the formation of fertile cell-rows andplantlets. Until the significance of these structuresis understood and a cytological investigation completed, therelationship of the intertidal leafy Porphyra-thallua to thefilamentous, shell-inhabiting, deep-water Conchocelis cannotbe expressed in the terms usually employed to denote the variousphases of the life-histories of algae. 相似文献
17.
The effects of the foliar application of phytocidal concentrationsof 2-methyl-4-chlorophenoxyacetic acid (MCPA) on change in totaldry weight, and in available carbohydrate (starch,total and reducing sugars), totalnitrogen, phosphorus, potassium, calcium, and magnesium of topsand roots of tomato plants have been followed over a periodof 14 days following spraying. There were two main treatmentsnutrient(nutrient supply to roots continued after spraying) and water(distilled water only supplied to roots after spraying) andwater (distilled water only supplied to rootsafter spraying)the sub-treatments consisting of MCPAversus no-MCPA for each of the main treatments.Twelve different times of sampling were used. In analysing the present data, the quantity residualdry weight (total dry weight less available carbohydrate),which was originally introduced by Mason and Maskell as a basisof reference for analyses of plant organs in short-period experimentsnot involving appreciable growth, has been used as an estimateof the permanent structure of plant growth. This new use ofthe residual dry weight basis has brought outimportant features which were obscured when the data were leftin their primary form (as percentages of total dry weight oramounts per plant). Growth, as measured by increase in residual dry weight,was greatly inhibited by 2-methyl-4-chlorophenoxyacetic acidshortly after spraying, in both the presence and the absenceof nutrient. In the presence of 2-methyl-4-chlorophenoxyacetic acid, netassimilation rate (estimated as rate of increase in total dryweight per gram residual dry weight of the tops)was greatly diminished while uptake of total nitrogen and ofP2O5 (estimated as increase in total nitrogen or of P2O5 ofthe whole plant per day per 1 g. residual dry weightof the roots) appeared to undergo a similar but much smallerdiminution. It seemed probable, however, that in the presenceof MCPA a larger proportion of the carbohydrate actually formedwas utilized for synthesis of aminoacids and protein. In the plant as a whole there was no evidence of actual depletionof available carbohydrate as a result of MCPAtreatment, this fraction showing a steady increase in all treatmentsthroughout the experiment. The rate of increase was, however,much reduced by MCPA treatment. The tops presentedmuch the same picture as the whole plant, but for the rootsthe situation was quite different. While the roots of the no-MCPAplants and also of the MCPA-water plants showeda steady increase in available carbohydrate, those of the MCPA-nutrientplants rose only very slightly (from the initial value of 8mg. per plant to about 10 mg.) during the first 2 days, andthen in the next 2 days declined to a value (about 6 mg.) belowthe initial and remained at this low level for the rest of theexperiment. It is suggested that the phytocidal effect of 2-methyl-4-chlorophenoxyaceticacid in the presence of nutrient may be due to depletion ofthe available carbohydrate supplies in the roots,which is shown to be brought about, in part, by reduced transportfrom the tops, and partly by the relatively greater utilizationof the carbohydrate present. These results offer an explanationfor the facts that plants showing vigorous growth are more easilykilled by MCPA and that perennial plants, particularly thosewith storage tissues in their roots, are more resistant. Further,they suggest the useful practical application that MCPA treatmentshould be given when the carbohydrate reserves of the rootsare at a minimum. For perennial plants, conditions might beexpected to be optimal for the application of MCPA in late spring,at a time when the first flush of growth is slowingdown and before any appreciable new reserves of carbohydratehave been accumulated. It was also shown that 2-methyl-4-chlorophenoxyacetic acid preventedthe net synthesis of starch, but still permitted an appreciablenet formation of sucrose. 2-methyl-4-chlorophenoxyacetic acid appeared to have no effecton the uptake of potassium, calcium, or of magnesium. The lackof effect on potassium is contrasted with the previous observationby Rhodes, Templeman, and Thruston (1950) that sub-lethal concentrationsof MCPA, applied over a relatively long period to the rootsof tomato plants, specifically depressed the uptake of potassium. 相似文献
18.
19.
When nitrate, ammonium, or urea were the sole nitrogen sourcesfor the growth of Platymonas striata there was a short initiallag period, after which uptake/assimilation occurred at a constantrate. Glycine uptake was however non-linear withtime. Addition of ammonium or urea markedly inhibited nitrateuptake whereas although glycine was initiallytotally inhibitory, nitrate uptake recommencedabout 1 h after addition, but at a greatly reduced rate. Ammoniumtotally inhibited urea uptake, but did not inhibitglycine uptake. When ammonium, urea, or glycinewere present at the same time as nitrate the total rate of nitrogen'uptake/assimilation was within 40% (or closer) of that of nitratenitrogen uptake alone. In the first two casesthis reflected a total switching off of nitrate uptakewhilst the new substrate was assimilated at a rate similar tothe initial nitrate rate, whereas in the case of glycine, bothsubstrates were used simultaneously. Once the concentrationof any of the inhibitory nitrogen sources had been reduced toa low level the uptake/assimilation of nitraterecommenced. It is suggested that the ability of P. striatato maintain a more or less constant rate total nitrogen uptake/assimilationirrespective of the mixture of utilizable nitrogen sources presentedto it, is not due to controls at the level of the entry of substrateinto the cell, but to intracellular actions at the enzyme level.The relative constancy of, and high rate of uptake,irrespective of nitrogen source and over a wide range of extracellularconcentrations, is tentatively considered to be due to saturationof the assimilatory mechanisms under the conditions employed;all the sources lead, either directly or indirectly, to theproduction of amino groupings for entry into nitrogenous metabolism.This homeostasis of nitrogen uptake/assimilationwould clearly be of considerable benefit to the alga in nature,enabling it to maximize growth in changing environmental conditions. Platymonas striata, nitrogen update, nitrogen assimilation 相似文献
20.
Haploids (2n =24) of the common tetraploid (2n=48) potato (SolanumtuberosumL.) provide promising material for attacking many problemsconcerned with the genetics, cytogenetics and breeding of thisspecies. Interspecific 4xx2xcrosses betweenSolanum tuberosumgp.Andigenaorgp.Tuberosumcultivars as pistillate parents andSolanum tuberosumgp.Phurejaassource of pollen (hereafter pollinator) have beenused to produce maternally derived haploids through parthenogenesis.This paper discusses the nature of the pollinatoreffect in haploid extraction. The pollinator hada significant effect on haploid frequencies following 4xx2xcrosses.The pollinator effect seems to operate via theendosperm, in which haploid (n=2x) embryos are associated withhexaploid endosperm. A superior pollinator appearsto have its effect by contributing two haploid (n) gametes tothe central cell. 2n pollen; double fertilization; endosperm; ploidy manipulations; Solanum tuberosum 相似文献