共查询到20条相似文献,搜索用时 15 毫秒
1.
On the causes of interspecific differences in the growth-irradiance relationship for phytoplankton. II. A general review 总被引:5,自引:0,他引:5
The causes of interspecific differences in the µ-l relationshipare examined in the context of a mechanistic model which relatesµ to irradiance in terms of six factors:, kc photosyntheticquotient (PQ), Chl a:C, respiration and excretion. The effectof cell size on the light saturated growth rate is also considered.It is shown that photosynthetic efficiency and PQ exhibit remarkablylittle interspecific variability, and average 0.024 ±0.005 µg C(µg Chl a)1 h1 (µEm2 s1)1 and 1.5 ± 0.2 mol 02 molC1 (when NO3 is the nitrogen source) respectively.Two useful relationships were derived: (i) between growth efficiency,g and Chl a:C at µ. = 0; (ii) between the compensationintensity, Ic and the Chl a-specific maintenance respirationrate. Both relationships were independent of temperature anddaylength. Species best adapted to growth at low light werefound to exhibit high Chl a:C ratios and low maintenance respirationrates. As a group, diatoms were consistently the best adaptedfor growth at low irradiance. Chiorophytes, haptophytes, chrysophytesand cryptophytes were intermediate in their performance at lowirradiance. Dinoflagellates exhibited extreme diversity, withspecies spanning the spectrum from very good performance atlow irradiance to very poor. A new µmax-cell carbon relationshipis given based on growth rates normalized to 15°C. Evidenceis presented to show that noise in this relationship can besignificantly reduced by using only carbon-specific growth ratesand using only data for species grown at the same daylength. 相似文献
2.
In situ light measurements were used to obtain information oninherent and apparent optical properties. The average verticalattenuation coefficient Kd(ave) varied from 1.1 to 4.6 In unitsm1 During three periods the variation in Kd(ave) correlatedwith changes in chlorophyll a concentration and specific attenuationcoefficients Ks, of 0.013, 0.014 and 0.022 m2 mg Chl a1were calculated. Chlorophyll-specific diffuse absorption coefficients(A,) for these periods were 0.012. 0.013 and 0.017 m2 mg Chla1 and only varied significantly from estimates of Ksin the period when scattering was intense. Absorption coefficientsa(zmid) and scattering coefficients b(zmid) calculated for themid-point of the euphotic zone ranged between 0.45 and 2.9 mand 3.552.0 m respectively. Chlorophyll-specific absorptioncoefficients Ka, of 0.005, 0.006 and 0.007 m2 mg Chl a1and scattering coefficients Kb of 0.05. 0.09 and 0.191 m2 mgChl a1 were measured during the three periods. The highKb value occurred when gas-vacuolate cyanobactena were dominant.Algal photosynthesis and light absorption were related throughthe maximum quantum yield m which varied between 0.019 and 0.11mol C Einstein1 while average quantum yields a, variedbetween 0.006 and 0.024 with a mean of 0.013 mol C Einstein1A comparison of changes in the mean irradiance of the mixedzone and chlorophyll concentration indicated that growth waslight limited below 0.040.05 Einsteins absorbed mg Chla1 day1. 相似文献
3.
The relationship between chlorophyll a (Chl a) and primary productivity(PP) in the uppermost water layer and the water column-based(015 m) integral values of those variables were examinedusing measurements taken in Lake Kinneret (Israel) from 1990to 2003. In 81% of all Chl a profiles examined, the distributionwas fairly uniform within the entire 015 m water column,and 12.3% of instances showed a prominent subsurface maximum,when the lake phytoplankton was dominated by the dinoflagellatePeridinium gatunense. Chl a can be reliably estimated by remotesensing techniques in the productive and turbid water of LakeKinneret, since Chl a concentration at surface layers can beextrapolated to the entire water column. Light vertical attenuationcoefficient average for wavelengths from 400 to 700 nm, Kd,ranged from 0.203 to 1.954 m1 and showed high degreeof temporal variation. The maximal rate of photosynthetic efficiency,PBopt [average 3.16 (±1.50)], ranged from 0.25 to 8.85mg C m3 h1 mg Chl a1. Using measured dataof Chl a, PBopt, and light as an input, a simple depth-integratedPP model allowed plausible simulation of PP. However, a lackof correlation between photosynthetic activity and temperature(or other variable with remotely sensed potential) renders theuse of models that require input of photosynthetic efficiencyto calculate integrated PP of little value in the case of productiveand turbid Lake Kinneret. 相似文献
4.
In situ growth and development of Neocalanus flemingeri/plumchrusstage C1C4 copepodites were estimated by both the artificial-cohortand the single-stage incubation methods in March, April andMay of 20012005 at 56°C. Results from thesetwo methods were comparable and consistent. In the field, C1C4stage durations ranged from 7 to >100 days, dependent ontemperature and chlorophyll a (Chl a) concentration. Averagestage durations were 12.414.1 days, yielding an averageof 56 days to reach C5, but under optimal conditions stage durationswere closer to 10 days, shortening the time to reach C5 (fromC1) to 46 days. Generally, growth rates decreased with increasingstage, ranging from 0.28 day1 to close to zero but weretypically between 0.20 and 0.05 day1, averaging 0.110± 0.006 day1 (mean ± SE) for single-stageand 0.107 ± 0.005 day1 (mean ± SE) forartificial-cohort methods. Growth was well described by equationsof MichaelisMenten form, with maximum growth rates (Gmax)of 0.170.18 day1 and half saturation Chl a concentrations(Kchl) of 0.450.46 mg m3 for combined C13,while Gmax dropped to 0.080.09 day1 but Kchl remainedat 0.380.93 mg m3 for C4. In this study, in situgrowth of N. flemingeri/plumchrus was frequently food limitedto some degree, particularly during March. A comparison withglobal models of copepod growth rates suggests that these modelsstill require considerable refinement. We suggest that the artificial-cohortmethod is the most practical approach to generating the multispeciesdata required to address these deficiencies. 相似文献
5.
Responses of CO2 assimilation to changes in irradiance: laboratory and field data and a model for beans (Phaseolus vulgaris L.) 总被引:1,自引:0,他引:1
The responses of net CO2 assimilation to sudden changes in irradiancewere studied in Phaseolus vulgaris L. in the laboratory andthe field. For irradiance changes between 50 µmol m2s1 to 350 µmol m2 s1 in the laboratory,assimilation rate increased with half-times of 2.7 and 4.1 minin well-watered and water-stressed plants, respectively. Ina field experiment with a change in irradiance from 400 to 1200µmol m2 s1 the response was faster (half-time=c.1.2 min). In all cases when irradiance was returned to a lowvalue, assimilation declined rapidly with a half-time of approximately1 min, which approached the time resolution of the gas-exchangesystem. The corresponding changes in stomatal conductance in responseto both increasing and decreasing irradiance were much slowerthan the assimilation responses, indicating that biochemicalprocesses, rather than CO2 supply, primarily determined theactual rate of assimilation in these experiments. The conceptof stomatal limitation to photosynthesis is discussed in relationto these results. A simple model for assimilation in a fluctuating light environmentis proposed that depends on a steadystate light response curve,an induction lag on increasing irradiance, andan induction-state memory. The likely importance of taking accountof such induction lags in natural canopy microclimates is considered. Key words: Models, Phaseolus vulgaris, photosynthetic induction, CO2 assimilation, stomatal limitation, sunflecks, water stress 相似文献
6.
Mistletoes usually have slower rates of photosynthesis thantheir hosts. This study examines CO2assimilation, chlorophyllfluorescence and the chlorophyll content of temperate hostparasitepairs (nine hosts parasitized by Ileostylus micranthus and Carpodetusserratus parasitized by Tupeia antarctica). The hosts of I.micranthus had higher mean annual CO2assimilation (3.59 ±0.41 µmol m-2 s-1) than I. micranthus(2.42 ± 0.20µmol m-2 s-1), and C. serratus(2.41 ± 0.43 µmolm-2 s-1) showed higher CO2assimilation than T. antarctica(0.67± 0.64 µmol m-2 s-1). Hosts saturated at significantlyhigher electron transport rates (ETR) and light levels thanmistletoes. The positive relationship between CO2assimilationand electron transport suggests that the lower CO2assimilationrates in mistletoes are a consequence of lower electron transportrates. When photosynthetic rates, ETR and chlorophyll a /b ratioswere adjusted for photosynthetically active radiation, hostsdid not have significantly higher CO2assimilation (3.21 ±0.37 µmol m-2 s-1) than mistletoes (2.54 ± 0.41µmol m-2 s-1), but still had significantly higher ETRand chlorophyll a / b ratios. The electron transport rates,saturating light and chlorophyll a / b ratios of sun leavesfrom mistletoes were similar to host shade leaves. These responsesindicate that in comparison with their hosts, mistletoe leaveshave the photosynthetic characteristics of the leaves of shadeplants. Copyright 2000 Annals of Botany Company CO2assimilation, photosynthetic active radiation (PAR), chlorophyll fluorescence, electron transport rate (ETR), photochemical quenching (qp), non-photochemical quenching (qn), sun and shade leaves, chlorophyll content, Ileostylus micranthus, Tupeia antarctica, New Zealand 相似文献
7.
Single clonal plants of white clover (Trifolium repens L) grownfrom explants in a Perlite rooting medium, and dependent fornitrogen on N2 fixation in root nodules, were grown for severalweeks in controlled environments which provided two regimesof CO2, and temperature 23/18 °C day/night temperaturesat 680 µmol mol1 CO2, (C680), and 20/15 °Cday/night temperatures at 340 µmol mol1 CO2 (C340)After 34 weeks of growth, when the plants were acclimatedto the environmental regimes, leaf and whole-plant photosynthesisand respiration were measured using conventional infra-red gasanalysis techniques Elevated CO2 and temperature increased ratesof photosynthesis of young, fully expanded leaves at the growthirradiance by 1729%, despite decreased stomatal conductancesand transpiration rates Water use efficiency (mol CO2 mol H2O1)was also significantly increased Plants acclimated to elevatedCO2, and temperature exhibited rates of leaf photosynthesisvery similar to those of C340 leaves instantaneouslyexposed to the C680 regime However, leaves developed in theC680 regime photosynthesised less rapidly than C340 leaves whenboth were exposed to a normal CO2, and temperature environmentIn measurements where irradiance was varied, the enhancementof photosynthesis in elevated CO2 at 23 °C increased graduallyfrom approx 10 % at 100 µmol m1 s1 to >27 % at 1170 µmol m2 s1 In parallel, wateruse efficiency increased by 2040 % at 315 µmolm2 s1 In parallel, water use efficiency increasedby 2040 % at 315 µmol m2 s1 In parallel,water use efficiency increased by 2040 % at 315 µmolm2 s1 In parallel, water use efficiency increasedby 2040 % at 315 µmol m2 s1 to approx100 % at the highest irradiance Elevated CO2, and temperatureincreased whole-plant photosynthesis by > 40 %, when expressedin terms of shoot surface area or shoot weight No effects ofelevated CO2 and temperature on rate of tissue respiration,either during growth or measurement, were established for singleleaves or for whole plants Dependence on N2, fixation in rootnodules appeared to have no detrimental effect on photosyntheticperformance in elevated CO2, and temperature Trifolium repens, white clover, photosynthesis, respiration, elevated CO2, elevated temperature, water use efficiency, N2 fixation 相似文献
8.
Planktonic primary production in the German Wadden Sea 总被引:8,自引:0,他引:8
By combining weekly data of irradiance, attenuation and chlorophylla concentrations with photosynthesis (P) versus light intensity(E) curve characteristics, the annual cycle of planktonic primaryproduction in the estuarine part of the Northfrisian WaddenSea was computed for a 2 year period. Daily water column particulategross production ranged from 5 to 2200 mg C m2 day1and showed a seasonal pattern similar to chlorophyll a. Budgetcalculation yielded annual gross particulate primary productionsof 124 and 176 g C m2 year1 in 1995 and 1996,respectively. Annual amounts of phytoplankton respiration, calculatedaccording to a two-compartment model of Langdon [in Li,W.K.W.and Maestrini,S.Y. (eds), Measurement of Primary Productionfrom the Molecular to the Global Scale. International Councilfor the Exploration of the Sea, Copenhagen, 1993, pp. 2036],and dissolved production in 1996, were both in the range of2439 g C m2 year1. Annual total net productionwas thus very similar to particulate gross production (127 and177 g C m2 year1 in 1995 and 1996, respectively).Phytoplankton growth was low or even negative in winter. Inspring and summer, production/biomass (Pr/B) ratios varied from0.2 up to 1.7. Phytoplankton growth during the growth seasonalways surpassed average flushing time in the area, thus underliningthe potential of local phytoplankton bloom development in thispart of the Wadden Sea. The chlorophyll-specific maximum photosyntheticrate (PBmax) ranged from 0.8 to 9.9 mg C mg1 Chl h1and was strongly correlated with water temperature (r2 = 0.67).By contrast, there was no clear seasonal cycle in B, which rangedfrom 0.007 to 0.039 mg C mg1 Chl h1 (µmolphotons m2 s1)1. Its variability was muchless than PBmax and independent of temperature. The magnitudeand part of the variability of PBmax and B are presumably causedby changes in species composition, as evidenced from the rangeof these parameters found among 10 predominant diatom speciesisolated from the Wadden Sea. The ratio of average light conditionsin the water column (Eav) to the light saturation parameterEk indicates that primary production in the Wadden Sea regionunder study is predominantly controlled by light limitationand that nutrient limitation was likely to occur for a few hoursper day only during 5 (dissolved inorganic nitrogen) to 10 (PO4,Si) weeks in the 2 year period investigated. 相似文献
9.
Yield stress threshold (Y) and volumetric extensibility () arethe rheological properties that appear to control root growth.In this study they were measured in wheat roots by means ofparallel measurement of the growth rate (r) of intact wheatroots and of the turgor pressures (P) of individual cells withinthe expansion zone. Growth and turgor pressure were manipulatedby immersion in graded osmoticum (mannitol) solutions. Turgorwas measured with a pressure probe and growth rate by visualobservation. The influence of various growth conditions on Yand was investigated; (a) At 27 °C.In 0.5 mol m3 CaCl2 r, P, Y and were20.7±4.6 µm min1, 0.77±0.05 MPa,0.07±0.03 MPa and 26±1.9 µm min1MPa1 (expressed as increase in length), respectively.Following 24 h growth in 10 mol m3 KC1 these parametersbecame 12.3±3.5 µm min1, 0.72±0.04MPa, 0.13±0.01 MPa and 21±0.7 µm min1MPa1. After 24 h osmotic adjustment in 150 mol m3mannitol/0.5 mol m3 CaCl2 r= 19.6±4.2 µmmin1, P = 0.68±0.05 MPa and Y and were 0.07±0.04MPa and 30±0.2 µm min1 MPa01, respectively.After 24 h growth in 350 mol m3 mannitol/0.5 mol m3CaCl2 r= 13.3±4.1 µm min1, P= 0.58±0.07MPa, Y=0.12±0.01 MPa and ø 32±0.2 tim min1MPa1. During osmotic adjustment in 200 mol m3mannitol/0.5 mol m3 CaCl2, with or without KCl, the recoveryof growth rate corresponded to turgor pressure recovery (t1/2approximately 3 h). (b) At 15 °C. Lowered temperature dramatically influencedthe growth parameters which became r= 8.3±2.8 um min1,P=0.78 MPa, r=<0.2 MPa and =15±0.1 µm min1MPa1. Therefore, Y and are influenced by 10 mol m3 K+ ionsand low temperature. In each case the effective pressure forgrowth (P-Y) was large indicating that small fluctuations ofsoil water potential will not stop root elongation. Key words: Yield threshold, cell wall extensibility, wheat root growth, temperature, turgor pressur 相似文献
10.
Hogan K.P.; Fleck I.; Bungard R.; Cheeseman J.M.; Whitehead D. 《Journal of experimental botany》1997,48(6):1289-1297
Red beech (Nothofagus fusca (Hook. F.) Oerst.; Fagaceae) andradiata pine (Pinus radiata D. Don; Pinaceae) were grown for16 months in large open-top chambers at ambient (37 Pa) andelevated (66 Pa) atmospheric partial pressure of CO2, and incontrol plots (no chamber). Summer-time measurements showedthat photosynthetic capacity was similar at elevated CO2 (lightand CO2-saturated value of 17.2 µmol m2 s1for beech, 13.5 µmol m2 s1 for pine), plantsgrown at ambient CO2 (beech 21.0 µmol2 s1,pine 14.9 µmol m2s1) or control plants grownwithout chambers (beech 23.2 µmol m2 s1,pine 12.9 µmol m2 s1). However, the higherCO2 partial pressure had a direct effect on photosynthetic rate,such that under their respective growth conditions, photosynthesisfor the elevated CO2 treatment (measured at 70 Pa CO2 partialpressure: beech 14.1 µmol m2 s1 pine 10.3)was greater than in ambient (measured at 35 Pa CO2: beech 9.7µmol m2 s1, pine 7.0 µmol m2s1) or control plants (beech 10.8 µmol m2s1, pine 7.2 µmol m2 s1). Measurementsof chlorophyll fluorescence revealed no evidence of photodamagein any treatment for either species. The quantity of the photoprotectivexanthophyll cycle pigments and their degree of de-epoxidationat midday did not differ among treatments for either species.The photochemical efficiency of photosystem II (yield) was lowerin control plants than in chamber-grown plants, and was higherin chamber plants at ambient than at elevated CO2. These resultssuggest that at lower (ambient) CO2 partial pressure, beechplants may have dissipated excess energy by a mechanism thatdoes not involve the xanthophyll cycle pigments. Key words: Carotenoids, chlorophyll fluorescence, photosynthesis, photoinhibition, photoprotection, xanthophyll cycle 相似文献
11.
For Gyrodinium aureolum significant irradiance and daylengtheffects were found on the division rate and on the growth-relevantChla-normalized photosynthetic rate (gPB). Optimum conditionsof irradiance and daylength were found at 230 µmol m2s1 and 14 h for the division rate, and at >260 µmolm2 s1 and <6 h for gPB.gPB showed no photoinhibition,while the division rate decreased markedly at irradiances abovesaturation. This difference and the difference in optimum irradiancebetween the division rate and gPB are explained by a decreasein cellular Chla/carbon ratio with increasing irradiance. Thecellular content of carbon and nitrogen decreased significantlywith increasing irradiance. Total phosphorus was independentof irradiance and daylength. Below the saturation irradiancefor gPB the daily Chla-normalized carbon yield may be describedas an exponential function of the daily irradiance (irradiancex daylength). 相似文献
12.
Biochemical Limitations to Carbon Assimilation in C3 Plants--A Retrospective Analysis of the A/Ci Curves from 109 Species 总被引:9,自引:0,他引:9
Species-specific differences in the assimilation of atmosphericCO2 depends upon differences in the capacities for the biochemicalreactions that regulate the gas-exchange process. Quantifyingthese differences for more than a few species, however, hasproven difficult. Therefore, to understand better how speciesdiffer in their capacity for CO2 assimilation, a widely usedmodel, capable of partitioning limitations to the activity ofribulose-1,5-bisphosphate carboxylase-oxygenase, to the rateof ribulose 1,5-bisphosphate regeneration via electron transport,and to the rate of triose phosphate utilization was used toanalyse 164 previously published A/Ci, curves for 109 C3 plantspecies. Based on this analysis, the maximum rate of carboxylation,Vcmax, ranged from 6µmol m2 s1 for the coniferousspecies Picea abies to 194µmol m2 s1 forthe agricultural species Beta vulgaris, and averaged 64µmolm2 s1 across all species. The maximum rate ofelectron transport, Jmax, ranged from 17µmol m2s1 again for Picea abies to 372µmol m2 s1for the desert annual Malvastrum rotundifolium, and averaged134µmol m2 s1 across all species. A strongpositive correlation between Vcmax and Jmax indicated that theassimilation of CO2 was regulated in a co-ordinated manner bythese two component processes. Of the A/Ci curves analysed,23 showed either an insensitivity or reversed-sensitivity toincreasing CO2 concentration, indicating that CO2 assimilationwas limited by the utilization of triose phosphates. The rateof triose phosphate utilization ranged from 4·9 µmolm2 s1 for the tropical perennial Tabebuia roseato 20·1 µmol m2 s1 for the weedyannual Xanthium strumarium, and averaged 10·1 µmolm2 s1 across all species. Despite what at first glance would appear to be a wide rangeof estimates for the biochemical capacities that regulate CO2assimilation, separating these species-specific results intothose of broad plant categories revealed that Vcmax and Jmaxwere in general higher for herbaceous annuals than they werefor woody perennials. For annuals, Vcmax and Jmax averaged 75and 154 µmol m2 s1, while for perennialsthese same two parameters averaged only 44 and 97 µmolm2 s1, respectively. Although these differencesbetween groups may be coincidental, such an observation pointsto differences between annuals and perennials in either theavailability or allocation of resources to the gas-exchangeprocess. Key words: A/Ci curve, CO2 assimilation, internal CO2 partial pressure, photosynthesis 相似文献
13.
Cobelas M.Alvarez; Haering F.J.; Velasco J.L.; Rubio A. 《Journal of plankton research》1992,14(7):979-996
The seasonal time course of phytoplankton primary productivitywas studied weekly in a hypertrophic, gravel-pit lake closeto Madrid, Spain. Chlorophyll a ranged 22445 mg m2.Gross primary productivity attained 0.28±0.14 g C m2h1 (range: 0.060.60), its yearly value being 900g C m2, but the shallow euphotic depths and the highplankton respiration ensured that net productivity was generallylow. Respiration losses amounted to 0.31±0.24 g O2 m2h1, with phytoplankton respiration roughly attainingone-half of overall plankton respiration. Areal phytoplanktonproductivity and plankton respiration followed a seasonal trendbut this was not the case for photosynthetic capacity. Surfacephotoinhibition was evenly distributed throughout the study.Quantum yields showed an increasing depth trend, but no seasonaltrend. Both Pmax and Ik were both temperature- and irradiance-dependent.As compared with lakes of lesser trophic degree, phytoplanktonprimary production in hypertrophic lakes might be increasednot only by higher nutrient contents but also by low chlorophyll-specificattenuation coefficients and low background, non-algal attenuation,thereby allowing for higher areal chlorophyll contents and hencehigher areal productivity. Our study suggests that physical(irradiance and water column stability) as well as chemicalfeatures (dissolved inorganic carbon and soluble reactive phosphorus)may control seasonality of phytoplankton primary productionin this lake despite recent claims that only physical factorsare of significance in hypertrophic lakes. However, this doesnot explain all the variability observed and so a food web controlis also likely to be operating. 相似文献
14.
The relationships between photosynthesis and photosyntheticphoton flux densities (PPFD, P-l) were studied during a red-tideof Dinophysis norvegica (July-August 1990) in Bedford Basin.Dinophysis norvegica, together with other dinoflagellates suchas Gonyaulax digitate, Ceratium tripos, contributed {small tilde}50%of the phytoplankton biomass that attained a maximum of 16.7µg Chla 1 and 11.93 106 total cells I1.The atomic ratios of carbon to nitrogen for D.norvegica rangedfrom 8.7 to 10.0. The photosynthetic characteristics of fractionatedphytoplankton (>30 µm) dominated by D.norvegica weresimilar to natural bloom assemblages: o (the initial slope ofthe P-l curves) ranged between 0.013 and 0.047 µg C [µgChla]1 h1 [µmol m s1]1the maximum photosynthetic rate, pBm, between 0.66 and 1.85µg C [µghla]1 h1; lk (the photoadaptationindex) from 14 to 69 µ,mol m2 s1. Carbonuptake rates of the isolated cells of D.norvegica (at 780 µmolm2 s1) ranged from 16 to 25 pg C cell1h and were lower than those for C.tripos, G.digitaleand some other dinoflagellates. The variation in carbon uptakerates of isolated cells of D.norvegica corresponded with PBmof the red-tide phytoplankton assemblages in the P-l experiments.Our study showed that D.norvegica, a toxigenic dinoflagellate,was the main contributor to the primary production in the bloom. 相似文献
15.
Leaf Development in Lolium temulentum: Photosynthesis and Photosynthetic Proteins in Leaves Senescing under Different Irradiances 总被引:3,自引:0,他引:3
Mae Tadahiko; Thomas Howard; Gay Alan P.; Makino Amane; Hidema Jun 《Plant & cell physiology》1993,34(3):391-399
Changes in carbon fixation rate and the levels of photosyntheticproteins were measured in fourth leaves of Lolium temulentumgrown until full expansion at 360 µmol quanta m2s1 and subsequently at the same irradiance or shadedto 90 µmol m2 s1. Ribulose-1,5-bisphosphatecarboxylase/oxygenase (Rubisco), light-harvesting chlorophylla/b protein of photosystem II (LHCII), 65 kDa protein of photosystemI (PSI), cytochrome f (Cytf) and coupling factor 1 (CF1) declinedsteadily in amount throughout senescence in unshaded leaves.In shaded leaves, however, the decrease in LHCII and the 65kDa protein was delayed until later in senescence whereas theamount of Cyt f protein decreased rapidly following transferto shade and was lower than that of unshaded leaves at the earlyand middle stages of senescence. Decreases in the Rubisco andCF1 of shaded leaves occurred at slightly reduced rates comparedwith unshaded leaves. These results indicate that chloroplastproteins in fully-expanded leaves are controlled individually,in a direction appropriate to acclimate photosynthesis to agiven irradiance during senescence. (Received August 20, 1992; Accepted January 5, 1993) 相似文献
16.
Community structure, biomass and productivity of size-fractionated summer phytoplankton populations in lower Narragansett Bay, Rhode Island 总被引:1,自引:0,他引:1
Seventeen size-fractionation experiments were carried out duringthe summer of 1979 to compare biomass and productivity in the< 10, <8 and <5 µm size fractions with that ofthe total phytoplankton community in surface waters of NarragansettBay. Flagellates and non-motile ultra-plankton passing 8 µmpolycarbonate filters dominated early summer phytoplankton populations,while diatoms and dinoflagellates retained by 10 µm nylonnetting dominated during the late summer. A significant numberof small diatoms and dinoflagellates were found in the 108µm size fraction. The > 10 µm size fraction accountedfor 50% of the chlorophyll a standing crop and 38% of surfaceproduction. The <8 µm fraction accounted for 39 and18% of the surface biomass and production. Production by the< 8 µm fraction exceeded half of the total communityproduction only during a mid-summer bloom of microflagellates.Mean assimilation numbers and calculated carbon doubling ratesin the <8 µm (2.8 g C g Chl a1 h1; 0.9day1)and<5 µm(1.7 g C g Chl a1h1; 0.5day1)size fractions were consistently lower than those of the totalpopulation (4.8 g C g Chl a1 h1; 1.3 day1)and the <10 µm size fraction (5.8 g C g Chl a1h1; 1.4 day 1). The results indicate that smalldiatoms and dinoflagellates in fractionated phytoplankton populationscan influence productivity out of proportion to their numbersor biomass.
1Present address: Australian Institute of Marine Science, P.M.B.No. 3, Townsville M.S.O., Qld. 4810, Australia. 相似文献
17.
Acclimation of single plants of Lolium temulentum to changing[CO2] was studied on plants grown in controlled environmentsat 20°C with an 8 h photoperiod. In the first experimentplants were grown at 135 µ;mol m2 s1 photosyntheticphoton flux density (PPFD) at 415µl l1 or 550µll1 [CO2] with some plants transferred from the lowerto the higher [CO2] at emergence of leaf 4. In the second experimentplants were grown at 135 and 500 µmol m2 s1PPFD at 345 and 575 µl l1 [CO2]. High [CO2] during growth had little effect on stomatal density,total soluble proteins, chlorophyll a content, amount of Rubiscoor cytochrome f. However, increasing [CO2] during measurementincreased photosynthetic rates, particularly in high light.Plants grown in the higher [CO2] had greater leaf extension,leaf and plant growth rates in low but not in high light. Theresults are discussed in relation to the limitation of growthby sink capacity and the modifications in the plant which allowthe storage of extra assimilates at high [CO2]. Key words: Lolium, carbon dioxide, photosynthesis, growth, stomatal density 相似文献
18.
Ecological studies on the phytoplankton of Boknafjorden, western Norway. II. Environmental control of photosynthesis 总被引:2,自引:0,他引:2
Both predicted (incubator) and measured (in situ) 14C-assimilationrates were studied from February to November 1981 at three stationsin Boknafjorden, a deep silled fjord of western Norway. Sampleswere taken from different light depths within the euphotic zone.A high degree of conformity was found between the two approaches.Daily values of carbon assimilation integrated over the euphoticzone varied between 0.05 and 1.4 g C m2. Yearly primaryproduction varied between stations from 82 to 112 g C m2(120148 g C m2 when based on average light conditions).The light-saturation curve parameters B and PBmax ranged from0.0056 to 0.0537 mg C mg Chla1 h1 µE1m2 and from 0.7 to 8.5 mg C mg Chla1 h2 (in situassimilation numbers ranged from 0.9 to 9.3 mg C mg Chla1h1) respectively, which compare well with those publishedfrom the northwestern side of the Atlantic. The overall importanceof light in controlling photosynthesis throughout the year wasrevealed by the light utilization index , estimated to be 0.43mg C mg Chla1 E1 m2. The maximum quantum yieldwas encountered on August 17, with 0.089 mol CE1. Chla/Cratios above and below 0.010 were found to be typical for shade-and light-adapted cells respectively. Assimilation numbers andgrowth rates were linearly related only when considering light-adaptedcells. Consistent with the findings of this study, the applicabilityof IK, B and PBmax as indicators of light-shade adaptation propertiesshould be questioned. Maximum growth rates were encounteredduring an autumn bloom of the dinoflagellate Gyrodinium aureolum(1.0 doublings day1), while 0.70.8 doublings day1were found for a winter bloom (water temperature of 2°C)of the diatom Skeletonema costatum. No unambiguous temperatureeffect on assimilation number and growth of phytoplankton couldbe recognized in Boknafjorden. A tendency towards increasedassimilation numbers coinciding with increased water columnstability was revealed. The highest PBmax values were oftenencountered at almost undetectable nutrient concentrations.At least during summer this could be attributed to recyclingof nutrients by macro- and/or microzooplankton, responsiblefor a greater part of the primary production now being grazeddown. This study supports the convention that the depth of theeuphotic zone may extend considerably below the 1% light depth. 相似文献
19.
The stomatal response of seedlings grown in 360 or 720 µmolmol1 to irradiance and leaf-to-air vapour pressure deficit(VPD) at both 360 and 720 µmol mol1 to CO2 wasmeasured to determine how environmental factors interact withCO2 enrichment to affect stomatal conductance. Seedlings offour species with different conductances and life histories,Cercis canadensis (L.), Quercus rubra (L.), Populus deltoides(Bartr. ex Marsh.) P. nigra (L.), and Pinus taeda (L.), weremeasured in hopes of identifying general responses. Conductanceof seedlings grown at 360 and 720 µmol mol1 CO2were similar and responded in the same manner to measurementCO2 concentration, irradiance and VPD. Conductance was lowerfor all species when measured at 720 than when measured at 360µmol mol1 CO2 at both VPDs ({small tilde}1.5 and{small tilde}2.5 kPa) and all measured irradiances greater thanzero (100, 300, 600,>1600 µmol m2 S2)The average decrease in conductance due to measurement in elevatedCO2 concentration was 32% for Cercis, 29% for Quercus, 26% forPopulus, and 11% for Pinus. For alt species, the absolute decreasein conductance due to measurement in CO2 enrichment decreasedas irradiance decreased or VPD increased. The proportional decreasedue to measurement in CO2 enrichment decreased in three of eightcases: from 0.46 to 0.10 in Populus and from 0.18 to 0.07 inPinus as irradiance decreased from>1600 to 100 µmolm2 s1 and from 0.35 to 0.24 in Cercis as VPD increasedfrom 1.3 to 2.6 kPa. Key words: Stomatal conductance, CO2 enrichment, irradiance, vapour pressure deficit 相似文献
20.
Ramirez Teodoro; Liger Esperanza; Mercado Jesus M.; Cortes Dolores; Vargas-Yanez Manuel; Sebastian Marta; Reul Andreas; Aguilera Jose; Bautista Begona 《Journal of plankton research》2006,28(7):629-641
Respiratory electron transport system (ETS) activity was measuredin plankton samples (<200 µm) collected in the NW AlboranSea. Sampling was carried out during seasonal cruises (summerand autumn 2003 and winter and spring 2004) in 12 stations locatedin transects off the coast of Malaga (southern Spain). Thiswork reports for the first time seasonal variations of the Arrheniusactivation energy (Ea) as well as being the first study to addressCO2 balance in the NW Alboran Sea. These variations were relatedto changes in the phytoplankton community assemblage, whichcould ultimately be caused by the seasonal variability of hydrologicalconditions. ETS activity was significantly higher in summer,coinciding with a higher chlorophyll a (Chl a) concentrationand relatively high levels of particulate organic matter. TheETS:Chl atotal ratios were low during the four seasons, suggestinga high contribution of autotrophic phytoplankton to the respiratoryactivity of planktonic community. Respiratory CO2 production(RCP) calculated from ETS activity ranged from 4.6 to 28.1 mgC m3 day1 during the four cruises. Chl a-specificRCP was lower than the maximum photosynthetic rates reportedin the literature for the studied area, suggesting that primaryproduction (PP) and respiration in the water column might beunbalanced. 相似文献