共查询到20条相似文献,搜索用时 31 毫秒
1.
Four-year-old seedlings of Nothofagus procera were grown outof doors in pots while subjected to two levels of shading (mediumand dense shades) and to full light. Shoot morphological andwood anatomical studies showed that growing N. procera in mediumlight, rather than in full light, can result in fewer leaves,but higher shoot growth, a greater amount of fibres, a widerwood growth increment and thicker fibre walls. Significant positivecorrelations were found between the rate of shoot extensionand the rate of wood production. Conversely, significant negativecorrelations were obtained between fibre lumen diameter andfibre wall thickness. The significance of these findings isdiscussed. Southern beech, Nothofagus procera, shading, shoot morphology, wood production, wood anatomy 相似文献
2.
FENNING T. M.; GARTLAND K. M. A.; BRASIER C. M. 《Journal of experimental botany》1993,44(7):1211-1217
Rapidly elongating shoot tips from a clone of the English elm,Ulmus procera SR4, were taken in early summer and sterilizedby sodium hypochlorite treatment before transfer to three differentproliferation media. Proliferating shoot cultures readily establishedon Driver and Kuniyuki Walnut medium (DKW), but failed to establishon either Murashige and Skoog-based medium, or Woody Plant medium.On DKW medium 35 shoots were produced per 3 week subcultureperiod or up to 20 more shoots from the stem base callus, ifthis was subcultured separately. Excised leaves regeneratedshoots readily from the petiole region on standard DKW mediumafter 34 weeks, and this was unaffected by the antibioticcefotaxime, but prevented by concentrations of kanamycin above50 mg dm3. U. procera SR4, a well characterized clonaltree of known habit and high timber quality is, therefore, amenableto the procedures necessary for genetic manipulation. Key words: English elm, Ulmus procera, micropropagation, regeneration 相似文献
3.
The Effect of Wind and a Reduced Supply of Water on the Growth and Water Relations of Festuca arundinacea Schreb 总被引:1,自引:0,他引:1
Festuca arundinacea was grown at high and low wind-speeds attwo levels of soil water. Transpiration was increased at highwind-speed and accompanied by leaf water stress. Growth of leafarea was progressively reduced according to the severity ofthe experimental treatments in the sequence: wet soil and lowwind; dry soil and low wind; wet soil and high wind; dry soiland high wind. The leaf water potential was also reduced inthis sequence. Festuca arundinacea Schreb., transpiration, water stress, wind, water potential 相似文献
4.
Sagebrush (Artemisia tridentata Nutt.) roots maintain nutrient uptake capacity under water stress 总被引:2,自引:0,他引:2
Phosphorus and nitrogen uptake capacities were assessed during3658 d drying cycles to determine whether the abilityof sagebrush (Artemisia tridentata Nutt.) to absorb these nutrientschanged as the roots were subjected to increasing levels ofwater stress. Water was withheld from mature plants in large(6 I) containers and the uptake capacity of excised roots insolution was determined as soil water potentials decreased from0.03 MPa to 5.0 MPa. Phosphorus uptake rates of excised roots at given substrateconcentrations increased as preharvest soil water potentialsdecreased to 5.0 MPa. Vmax and Km also increased as soilwater potentials declined. Declining soil water potentials depressednitrogen uptake at set substrate concentrations, but uptakecapacity, calculated as the sum Vmax for both NH+4+NO3,did not change significantly with drying. The sum Vmax correlatedwith root nitrogen concentration. Root uptake capacity for nitrogen and phosphorus was extremelystable under severe water stress in this aridland shrub. Maintenanceof uptake capacity, coupled with a previously demonstrated abilityto conduct hydraulic lift, may enable A. tridentata better tomaintain nitrogen and phosphorus uptake as soil water availabilitydeclines. These mechanisms may be important in the ability ofA. tridentata to maintain growth, complete reproduction, andgain an advantage against competitors late in the season whenthe soil layers with higher nutrient availability are dry. Key words: Kinetics, nitrogen, phosphorus, roots, water stress 相似文献
5.
Festuca arundinaceae was grown at high and low wind-speed attwo levels of either soil phosphorus or soil nitrogen. At increasedwind-speed, mean relative growth rate and leaf extension ratewere reduced when plants were grown with high nutrient concentrationsand further reduced when phosphorus or nitrogen stress was imposedon the plants. Transpiration was increased at high wind-speedexcept under conditions of phosphorus stress, where the ratewas actually decreased. Relationships between water stress,wind and nutrient status are discussed, especially in relationto the possible role of phosphorus stress in causing sclerophylly. Festuca arundinacea Schreb., relative growth rate, water stress, wind, nitrogen, phosphorus, sclerophylly 相似文献
6.
Photosynthesis and Transpiration in Rice as Influenced by Soil Moisture and Air Humidity 总被引:4,自引:0,他引:4
The paper describes the effect of soil moisture content andair humidity on CO2 exchange (PN), CO2 diffusion resistance(Cr) and transpiration (E) in four varieties of japonica rice(Oryza sativa L.). A decrease in soil moisture content reducedthe rate of photosynthesis to a varying degree in the varieties.Reduction in photosynthesis was attributed to increase in Cr.The effect of low soil moisture on photosynthesis and CO2 diffusionwas further intensified by decrease in air humidity. By maintaininga high humidity in the air around the leaves however, the effectof soil moisture deficiency was reduced considerably, exceptin Rikuto Norin 21 which was very sensitive to soil-moisturedeficiency alone. Dryness of the air enhanced the transpirationrate, although the increase was relatively less in the plantsfacing a simultaneous water crisis at the root surface. In plantsgrowing under flooded conditions, a decrease in air humiditycaused a slight depression in PN despite the simultaneous decreasein Cr. Oryza sativa L., rice, photosynthesis, transpiration, diffusion resistance, soil moisture, air humidity 相似文献
7.
Plants of 24 genotypes of fourBrassicaspecies (B. campestris,B.carinata,B. juncea,B. napus) were grown on stored soil waterin a sandy loam soil under field conditions. Water use was recordedthroughout the growing season. Leaf water potential ( 相似文献
8.
Water Relations of Red Clover Trifolium pratense L. as Affected by VA Mycorrhizal Infection and Phosphorus Supply Before and During Drought 总被引:6,自引:0,他引:6
Red clover Trifolium pratense L. plants were grown in a factorialdesign with four levels of added P and with and without a mycorrhizalinoculum, to test the separate effects of P nutrition and infectionon plant water relations. Under well-watered conditions, onlyuninfected plants on very low P soil showed reduced stomatalconductance and these had the lowest leaf P concentrations.During droughting, only plants with very high leaf P concentrationsmaintained high conductance. There was no evidence of increasedwater uptake by mycorrhizal plants. This and other evidencesuggests that mycorrhizal effects on water relations are secondaryconsequences of changes in P nutrition which are, in any case,inconsistent. Key words: Trifolium pratense, VAM, water relations, concentration, drought 相似文献
9.
Veronica spicata and Phleum phleoides are calcicole plants,mainly occurring on neutral or alkaline soil. An experimentof 16 weeks duration was performed in a glasshouse with theobjective of elucidating the influence of soil moisture levelon soil solution chemistry, and biomass concentrations and uptakeof mineral nutrients by the plants. Seven levels of moisture,corresponding to 3585% of the water holding capacity(WHC) of the soil, were tested. Soil solution HCO3, P and Mnconcentrations, and pH, increased, whereas Ca, Mg and Zn concentrationsdecreased, with increasing soil moisture. Concentrations ofK were highest at 5070% WHC. Concentrations and amountsof P, Zn and Mn in the two species were usually related to soilsolution concentrations; these are elements with low solubilityand availability in calcareous soils. Concentrations of nutrientsin biomass were more influenced by soil moisture in V. spicatathan inP. phleoides . This indicates that P. phleoides is morecapable of controlling its uptake of mineral nutrients, whereasV. spicata is sensitive to variations in soil moisture. It isconcluded that variation in soil moisture regime may greatlyinfluence concentrations of mineral nutrients in calcareoussoil solutions and their uptake by plants. Species able to utilizethese solubility fluctuations may have an advantage in competitionfor nutrients. Variation in soil moisture content might evenbe a prerequisite for adequate acquisition of mineral nutrientsand growth of plants on limestone soils, thereby influencingthe field distribution of native plants among habitats. Copyright1999 Annals of Botany Company Calcareous, calcicole, concentration, mineral, moisture, nutrient, Phleum phleoides, soil, soil solution, uptake, Veronica spicata, water. 相似文献
10.
PREMACHANDRA GNANASIRI S.; SANEOKA HIROHUMI; FUJITA KOUNOSUKE; OGATA SHOITSU 《Journal of experimental botany》1992,43(11):1451-1456
A pot experiment was carried out using five maize {Zea maysL.) cultivars under three soil moisture levels (MPa 0 to 0.05,0.3 to 0.9 and 1.2 to 1.5) to investigatethe effects of water deficits on osmotic adjustment and stomatalconductance. The degree of leaf rolling and the sugar and nutrientconcentrations in leaf cell sap were measured. Leaf water potential and osmotic potential decreased and stomatalconductance decreased with increasing water deficits. Stomatalconductance correlated positively with leaf water potentialand osmotic potential. Degree of leaf rolling was lower in cultivarswhich maintained higher turgor. Osmotic adjustment of 0.08 to0.43 MPa was found under the lowest soil moisture level in fivecultivars used. Sugar and K were the major osmotic substancesin the maize plant. Sugar, K and Mg concentrations increasedunder water deficit, and correlated negatively with a decreasein osmotic potential. Key words: Zea mays L., leaf water relations, leaf rolling, osmotic adjustment, stomatal conductance, water deficit 相似文献
11.
Hydraulic Conductances of the Soil, the Root-Soil Air Gap, and the Root: Changes for Desert Succulents in Drying Soil 总被引:5,自引:0,他引:5
Water movement to and from a root depends on the soil hydraulicconductivity coefficient (Lsoil), the distance across any root-soilair gap, and the hydraulic conductivity coefficient of the root(LP). After analytical equations for the effective conductanceof each part of the pathway are developed, the influences ofsoil drying on the soil water potential and Lsoil are describedduring a 30 d period for a loamy sand in the field. The influencesof soil drying on LP for three desert succulents, Agave deserti,Ferocactus acanthodes, and Opuntia ficus-indica, are also describedfor a 30 d period. To quantify the effects of soil drying onthe development of a root-soil air gap, diameters of 6-week-oldroots of the three species were determined at constant watervapour potentials of 1.0 MPa and 10 MPa as wellas with the water vapour potential decreasing at the same rateas soil drying during a 30 d period. The shrinkage observedfor roots initially 2·0 mm in diameter averaged 19% duringthe 30d period. The predominant limiting factor for water movementwas LP of the root for the first 7 d of soil drying, the root-soilair gap for the next 13 d, and Lsoil thereafter. Compared withthe ease of water uptake from a wet soil, the decrease in conductancesduring soil drying, especially the decrease in Lsoil causedthe overall conductance to decrease by 3 x 103-fold during the30 d period for the three species considered, so relativelylittle water was lost to the dry soil. Such rectifier-like behaviourof water movement in the soil-root system resulted primarilyfrom changes in Lsoil and, presumably, is a general phenomenonamong plants, preventing water loss during drought but facilitatingwater uptake after rainfall. Key words: Agave deserti, Ferocactus acanthodes, Opuntia ficus-indica, rectification, soil water potential, water movement 相似文献
12.
A Two-dimensional Model for Water Uptake by Desert Succulents: Implications of Root Distribution 总被引:3,自引:0,他引:3
Water uptake by Agave deserti and Ferocatus acanthodes was predictedusing a two-dimensional simulation model in which the soil arounda plant was divided into a series of layers and concentric cylindricalshells. Root lengths in 0.05 m thick soil layers were determinedfor both species in the field, where mean root depths were only0.11 m for A. deserti and 0.10 m for F. acanthodes. For a yearwith average precipitation (159 mm), 42 per cent of the annualprecipitation could be taken up by A. deserti and 25 per centby F. acanthodes. Predicted water uptake by both species wasgreater from the upper soil layers (above 0.15 m) for averageand dry years, but was greater from the deeper layers for awet year. The actual root distribution for both species ledto more water uptake than when all of the roots were in a singlelayer. The large number of days per year when the soil temperaturesexceeded 57 °C (the temperature for 50 per cent inhibitionof uptake of a vital stain by root cells) may exclude rootsfrom the 0.000.05 m soil layer, even though water uptakewhen all roots were located there was predicted to be maximal.Therefore, the observed root distribution of A. deserti andF. acanthodes may be limited near the soil surface by high temperaturesand at maximum depths by water availability for all but wetyears. Agave deserti, Ferocactus acanthodes, desert succulents, root system, root distribution, soil temperature, water uptake 相似文献
13.
Cultures of Calotropis procera were maintained on MS mediumsupplemented with 4·6 µM FAP and 3 µM NAA.Laticifer initials were observed in 2-week-old cultures whichwere converted into matured, branched, non-articulated laticifersin 4 weeks. It was observed that laticifer differentiation increasedwith the age of cultures, from 2·78% (in the second passage)to 15·11% (in the 12th passage). It has been establishedthat laticifer differentiation in vitro is a cytokinin-dependentprocess and among the cytokinins, FAP was more effective thanBA and 2-iP. But the type of auxin and its concentration alsoplay an important role in modifying the effect of cytokinin.Among the different auxins used IAA was more effective for laticiferdifferentiation than IBA and NAA, while 2,4D was inhibitory.Maximum laticifer differentiation (17·01% was observedon MS medium supplemented with 4·6 µM FAP and 1µM IAA.Copyright 1995, 1999 Academic Press Calotropis procera, callus culture, laticifer, differentiation, hormonal regulation 相似文献
14.
Water uptake resumption following soil drought: a comparison among four barley genotypes 总被引:4,自引:0,他引:4
Soil water resulting from episodic growing season rainfall evaporatesrapidly in semi-arid regions. Plants may mnot benefit from suchwater additions if near-surface roots are unable to resume wateruptake rapidly following periods of soil water deficit. Ourobjectives were to develop a means of quantifying root uptakeresponses in the upper soil layer following rewetting aftersoil water deficit, and to evaluate the existence of genotypicdifferences among four diverse barley (Hordeum vulgare L.) genotypesin this regard. Plants were grown in replicate soil columnshaving hydraulically isolated surface and subsoil layers, andinstrumented with time-domain reflectometry (TDR) waveguides.The upper 0.05 m soil layer was allowed to dry to 1.8to 3.0 MPa for 10-14 d, during which time subsoil wetnesswas maintained at about 0.6 to 0.7 MPa. The time-courseof soil water uptake was monitored at 0.5 h intervals followingrewetting of the surface layer. Substantial water uptake began1 d after rewetting following 10 d, and 2-3 d after rewettingfollowing 14 d of water deficit. Rate of water uptake was morerapid in response to a second rewetting 5-7 d later. Consistentgenotypic responses in terms of cumulative water uptake on awhole plant and leaf area-specific basis were observed duringeach trial. These results have application to evaluating droughthardiness and interspecific competitive ability under semi-aridconditions, and to investigations of root physiological andmorphological changes that contribute to recovery from waterdeficit Key words: Hordeum vulgare, root water uptake, soil water deficit, time-domain reflectometry 相似文献
15.
The response of leaf area expansion to atmospheric saturationdeficit (SD) and soil moisture deficit was examined in termsof leaf water potential (1) and turgor potential (p), as partof a wider study of the effects of SD on groundnut growth. Standsof plants were grown at four levels of SD and without irrigationin controlled environment glasshouses. A fifth stand was grownat low SD on soil kept irrigated to field capacity. Large saturation deficits accelerated the depletion of soilmoisture reserves in the unirrigated stands and greatly reducedleaf area index, particularly in the driest treatment. Leafnumber per plant and leaf size both decreased as SD increased,but the effect on leaf size was greater than on number. SD hadless effect than soil water deficit on leaf production. Turgorpotential and leaf extension rate (R) were both reduced at highsaturation deficits and R was linearly related to p between0900 and 1600 h. However, leaf extension rate and turgor potentialwere poorly correlated between 0400 and 0700 h in the driesttreatment. Arachis hypogaea L., groundnut, saturation deficit, leaf growth, canopy development 相似文献
16.
Aug Robert M.; Stodola Ann J.W.; Ebel Robert C.; Duan Xiangrong 《Journal of experimental botany》1995,46(3):297-307
Arbuscular mycorrhizal symbiosis has previously been shown toalter the response of sorghum leaves to probable non-hydraulicsignals of soil drying. Our objectives here were to determine:(1) how changes in phosphorus nutrition affect this root-to-shootsignalling in sorghum, (2) if mycorrhizal symbiosis can affectthe signalling process independently of effects on host P nutrition,and (3) how two Glomus species compare in their influence onsignalling. Sorghum bicolor (L.) Moench G1990A plants weregrown with root systems split between two pots. The 332 experimentaldesign included three levels of mycorrhizae (Glomus intraradicesSchenck & Smith, Glomus etunicatum Becker & Gerd., non-mycorrhizal),three levels of phosphorus fertilization and two levels of water(fully watered, half-dried). Declines in leaf elongation with soil drying were more consistentin non-mycorrhizal than mycorrhizal plants. Relative growthrate (RGR) of both mycorrhizal and non-mycorrhizal plants initiallydeclined when water was withheld from about half of the rootsystem. With further soil drying, RGR of mycorrhizal plantseventually returned to control levels, while RGR of non-mycorrhizalplants remained depressed throughout the drying episode. Bythe end of the drying episode, mycorrhizal symbiosis had eliminateddrying-induced declines in total plant leaf length. Shoot androot dry weight declines of half-dried plants were not affectedby mycorrhizae. Declines in stomatal conductance with soil dryingwere larger and more frequent in non-mycorrhizal than mycorrhizalplants. Leaf osmotic potential and relative water content remainedsimilar in control and half-dried plants during drying, suggestingthat altered leaf behaviour of half-dried plants was due tosome non-hydraulic factor. The two fungi did not differ substantiallyin their influence on leaf behaviour. The applied phosphorustreatments did not affect either growth or stomatal responseof halfdried plants to the root-to-shoot signal, but lengthdeclines were related to actual leaf phosphorus concentrations.Rate of soil drying did not appear to influence ultimate growthreductions. We conclude that mycorrhizal fungi can modify leaf growth responseto the root-to-shoot signal of soil drying, and that this mycorrhizaleffect can occur independently of mycorrhizal effects on plantsize or phosphorus nutrition. However, plant size and nutrition,which are commonly affected by mycorrhizal symbiosis, can alsomodify the signalling process. Key words: Drought, nutrition, root signal, Sorghum bicolor, vesicular-arbuscular 相似文献
17.
Gabriella Frosi Marciel Teixeira Oliveira Jarcilene Almeida-Cortez Mauro Guida Santos 《Acta Physiologiae Plantarum》2013,35(2):335-344
To better understand the proliferation of Calotropis procera in a semi-arid region of northeastern Brazil (Caatinga), we designed two experiments to determine which ecophysiological characteristics contribute to the species adaptive success. The first experiment was conducted with young plants under greenhouse conditions and three water regimes. The second experiment was conducted with adult plants under field conditions subject to regional seasonality. Young plants exhibited a high tolerance to water deficits, mainly because of their strong stomatal control, which was observed before any biochemical alterations in leaf metabolism. Only under full suspension of irrigation did the plants show a reduction in relative water content. Under field conditions, adult plants showed a high resilience to the semi-arid environment with respect to gas exchange and other measured biochemical parameters, including photosynthetic pigment, soluble sugars, amino acids and protein content, even under the low soil water availability of the dry season. This season featured high photosynthetically active radiation, low relative humidity and high temperatures, and thus exposed plants to extreme differences between leaf and air temperatures. Calotropis procera remains green throughout the year, indicating that it has developed several means of tolerating the semi-arid climate. Furthermore, this species maintains a high photosynthetic rate despite reduced stomatal conductance, which increases its water use efficiency, a fundamental characteristic for survival in this ecosystem. 相似文献
18.
From a consideration of the possible relationships between thelevel of a nutrient in the soil, the depletion due to a competitor,and the response of a test plant, it is argued that a validcriterion for the implication of a nutrient factor in root competitionis that some growth response of the test plant to competitionshould be less at higher levels of supply of that nutrient thanat lower levels. Young test plants of Impatiens parviflora were transplantedinto pans of soil in which stands of Agropyron repens were growing.Two levels of nitgrogen and gtwo rates of watering were appliedin a multifactorial design, and from half of the test plantsroot competition was excluded, so that their responses to rootcompetition could be measured under the various nitrogen andwatering treatments. A preliminary experiment hadf shown, and the competition experimentconfirmed, that the optimum nitrogen level for root growth andNet Assimilation Rate was less than the higher level employed,whereas this level was not sufficient for maximum leaf-growth.In agreement with this, the depressions of relative root growth-rateand Net Assimilation Rate caused by competition at the lowernitrogen level were significantly reduced at the higher level,but for relative leaf-growth this reduction did not reach significance.The effects of competition were reduced by the higher rate ofwstering, and for relative leaf growth-rate this interactionwas highly significant. It is deduced that competition from A. repensfinvolves bothnitrogen and water, and that water is probably the more importantfactor under normal conditions. There is no need to postulkateany toxic root product to account for the experimentalo results.Compared with competition above ground, it appeared that rootcompetition could have an effect on the relative growth-rateof I. parviflora about as great as a reduction of light intensityfrom full to 510 per cent. of summer daylight. 相似文献
19.
The role of abscisic acid and water relations in drought responses of subterranean clover 总被引:6,自引:1,他引:5
The role of water relations and abscisic acid (ABA) in the responsesto drought were studied in a mediterranean forage crop, Trifoliumsubterraneum L. under field conditions. Soil and plant waterstatus, leaf gas exchange parameters, and xylem sap ABA contentwere determined at different times during a long-term soil dryingepisode in irrigated and droughted plants. The diurnal time-coursesof these parameters were also measured at the end of a droughtperiod. In response to soil drying stomatal conductance (g) was reducedearly to 50% that of irrigated plants before any substantialchange in water potential was detected. A close logarithmicregression between photosynthesis rate (A) and g was present.For the first weeks of drought the decline in A was less pronouncedthan in g, thus increasing water use efficiency. Stomatal conductanceduring diurnal time-courses showed no consistent relationshipswith respect to etther ABA or leaf water potential. Throughoutthe experimental period dependence of g on leaf water statuswas evident from the tight correlation (r2=0.88, P<0.01)achieved between stomatal conductance and midday water potential,but the correlation was also high when comparing g with respectto ABA content in xylem sap (r=0.83, P<0.001). However, thestomata from drought acclimated plants were apparently moresensitive to xylem ABA content. For similar xylem ABA concentrationsstomatal conductance was significantly higher in irrigated thanin waterstressed plants. Key words: Drought, stomatal conductance, water potential, abscisic acid 相似文献
20.
Water Use Efficiency and Biomass Partitioning of Three Different Miscanthus Genotypes with Limited and Unlimited Water Supply 总被引:5,自引:0,他引:5
Miscanthus species, which are C4perennial grasses, have a highbiomass potential but yields at many sites in Europe can belimited by insufficient water supply and plant survival is endangeredunder extreme summer drought. A pot experiment was conductedto measure the influence of reduced water supply on the wateruse efficiency (WUE) and biomass partitioning of three Miscanthusgenotypes (M. x giganteus, M. sacchariflorus, and a M. sinensishybrid) in a controlled environment. The experiment consistedof three phases (phase 1 = 020 d; phase 2 = 2139d; phase 3 = 4054 d) punctuated by destructive harvests.In phase 1, soil moisture was non-limiting. In the second andthird phases, lowered soil moisture contents induced water deficits.Air vapour pressure deficit (VPD) was 0.49 ± 0.05 kPa.Water deficits caused leaf senescence in M. x giganteus andM. sacchariflorus, but not in the M. sinensis hybrid. Greenleaf conductances were lowest in M. sinensis under water deficit,indicating stomatal regulation. Water use efficiency for wholeplants of each genotype ranged from 11.5 to 14.2 g dry matter(DM) kg-1H2O but did not differ significantly between genotypesor water treatments under the conditions of this experiment.However, differences in dry matter partitioning to the shoot(the harvestable component) resulted in genotypic differencesin WUE, calculated on a harvestable dry matter basis, whichranged from 4.1 g DM kg-1H2O for M. sacchariflorus to 2.2 gDM kg-1H2O for M. x giganteus. Copyright 2000 Annals of BotanyCompany Miscanthus sinensis, Miscanthus sacchariflorus, Miscanthus x giganteus, water use efficiency, biomass, C4plants, drought 相似文献