共查询到20条相似文献,搜索用时 31 毫秒
1.
Jouko Silvola 《Ecography》1990,13(3):224-228
The photosynthesis of Spagnum fuscum (Schimp.) Klinggr. at different water contents and CO2 concentrations was measured in the laboratory. The optimal water content for photosynthesis near the current atmospheric CO2 concentration is 600–800% (percentage of dry weight). The decrease in photosynthesis is very steep towards lower water contents and less steep towards higher water contents. The optimal water content range moves higher and becomes wider with increasing CO2 concentration. At 3000 ppm there is no longer any decrease in photosynthesis with increasing water content. The water content of S. fuscum has a considerable effect on the response of photosynthesis to CO2 concentration. In a moss saturated with water, photosynthesis increases gradually until 8000 ppm CO2 , but this saturation concentration becomes lower with decreasing water content, being c. 1500 ppm at a water content of 700–800%. An increase in CO2 concentration over 300 ppm will raise photosynthesis very little in dry moss with a water content of only 300–400%. 相似文献
2.
Three soybean ( Glycine max L. Merr.) cultivars (Maple Glen, Clark and CNS) were exposed to three CO2 concentrations (370, 555 and 740 μmol mol−1 ) and three growth temperatures (20/15°, 25/20° and 31/26°C, day/night) to determine intraspecific differences in single leaf/whole plant photosynthesis, growth and partitioning, phenology and final biomass. Based on known carboxylation kinetics, a synergistic effect between temperature and CO2 on growth and photosynthesis was predicted since elevated CO2 increases photosynthesis by reducing photorespiration and photorespiration increases with temperature. Increasing CO2 concentrations resulted in a stimulation of single leaf photosynthesis for 40–60 days after emergence (DAE) at 20/15°C in all cultivars and for Maple Glen and CNS at all temperatures. For Clark, however, the onset of flowering at warmer temperatures coincided with the loss of stimulation in single leaf photosynthesis at elevated CO2 concentrations. Despite the season-long stimulation of single leaf photosynthesis, elevated CO2 concentrations did not increase whole plant photosynthesis except at the highest growth temperature in Maple Glen and CNS, and there was no synergistic effect on final biomass. Instead, the stimulatory effect of CO2 on growth was delayed by higher temperatures. Data from this experiment suggest that: (1) intraspecific variation could be used to select for optimum soybean cultivars with future climate change; and (2) the relationship between temperature and CO2 concentration may be expressed differently at the leaf and whole plant levels and may not solely reflect known changes in carboxylation kinetics. 相似文献
3.
Abstract. A mechanistic model of photosynthesis is developed based on the characteristics of ribulose 1,5-bisphosphate (RuBP) carboxylase and the assimilation of CO2 as an ordered reaction with RuBP binding before CO2 . An equation is derived which considers the effects of light (for regeneration of RuBP) and CO2 . Taking values for the maximum turnover of RuBP carboxylase at substrate saturation, the maximum carboxylation efficiency (maximum increase in rate per increase in CO2 concentration) and the minimum quantum requirement for the C3 pathway, photosynthesis in the absence of photorespiration is simulated. In the model, at varying concentrations of CO2 , the efficiency of light utilization approaches a maximum value as photon flux density decreases. Similarly, with a given maximum carboxyation capacity, at varying photon flux densities the carboxylation efficiency approaches a constant maximum value (equal to V max / K m CO2 ) as CO2 is decreased. However, a decrease in the state of activation of RuBP carboxylase under low light results in a lower carboxylation efficiency. Limits on the rate of photosynthesis, as the maximum capacity for regeneration of RuBP is reduced relative to carboxylation potential, or as the maximum capacity of the carboxylase varies, are considered. 相似文献
4.
Abstract. A model is developed for photosynthesis and photorespiration in C3 plants, using an equation for the multisubslrate ordered reaction of ribulose 1,5-bisphosphalc carboxylase-oxygenase (Farazdaghi & Edwards, 1988). The model examines net CO2 fixation with O2 inhibition, and mutual inhibition when equilibrium exists between carboxylation and oxygenation (at the CO2 compensation point). It is based on the stoichiometry of energy requirements and O2 , and CO2 exchange in the cycles, the quantum efficiency for RuBP generation, the maximum capacity for RuBP generation, the carboxylation efficiency with respect to [CO2 ], and the oxygenation efficiency with respect to [O2 ]. With increasing concentrations of CO2 above the CO2 compensation point, decreasing quantum flux density, or decreasing O2 , simulations show that the rate of photorespiration progressively decreases. The two components of O2 inhibition of photosynthesis change disproportionately with increasing CO2 concentration. According to the model, the energy utilized during photosynthesis at the CO2 compensation point is about half that under atmospheric conditions. 相似文献
5.
The role of mitochondrial respiration in optimizing photosynthesis was assessed in mesophyll protoplasts of pea ( Pisum sativum L., cv. Arkel) by using low concentrations of oligomycin (an inhibitor of oxidative phosphorylation), antimycin A (inhibits cytochrome pathway of electron transport) and salicylhydroxamic acid (SHAM, an inhibitor of alternative oxidase). All three compounds decreased the rate of photosynthetic O2 evolution in mesophyll protoplasts, but did not affect chloroplast photosynthesis. The inhibition of photosynthesis by these mitochondrial inhibitors was stronger at optimal CO2 (1.0 m M NaHCO3 ) than that at limiting CO2 (0.1 m M NaHCO3 ). We conclude that mitochondrial metabolism through both cytochrome and alternative pathways is essential for optimizing photosynthesis at limiting as well as at optimal CO2 . The ratios of ATP to ADP in whole protoplast extracts were hardly affected, despite the marked decrease in their photosynthetic rates by SHAM. Similarly, the decrease in the ATP/ADP ratio by oligomycin or antimycin A was more pronounced at limiting CO2 than at optimal CO2 . The mitochondrial oxidative electron transport, through both cytochrome and alternative pathways, therefore akppears to be more important than oxidative phosphorylation in optimizing photosynthesis, particularly at limiting CO2 (when ATP demand is expected to be low). Our results also confirm that the alternative pathway has a significant role in contributing to the cellular ATP, when the cytochrome pathway is limited. 相似文献
6.
Abstract: The concentration dependency of the impact of elevated atmospheric CO2 concentrations on Arabidopsis thaliana L. was studied. Plants were exposed to nearly ambient (390), 560, 810, 1240 and 1680 μl I-1 CO2 during the vegetative growth phase for 8 days. Shoot biomass production and dry matter content were increased upon exposure to elevated CO2 . Maximal increase in shoot fresh and dry weight was obtained at 560 μl I-1 CU2 , which was due to a transient stimulation of the relative growth rate for up to 3 days. The shoot starch content increased with increasing CO2 concentrations up to two-fold at 1680 μl I-1 CO2 , whereas the contents of soluble sugars and phenolic compounds were hardly affected by elevated CO2 . The chlorophyll and carotenoid contents were not substantially affected at elevated CO2 and the chlorophyll a/b ratio remained unaltered. There was no acclimation of photosynthesis at elevated CO2 ; the photosynthetic capacity of leaves, which had completely developed at elevated CO2 was similar to that of leaves developed in ambient air. The possible consequences of an elevated atmospheric CO2 concentration to Arabidopsis thaliana in its natural habitat is discussed. 相似文献
7.
Carbon dioxide exchange in lichens: Estimation of internal thallus CO2 transport resistances 总被引:1,自引:0,他引:1
The gaseous exchange pathways of Sticla latifrons Rich. and Pseudocyphellaria amphisticta Kremp. were examined using both light and scanning electron microscopes. The size and frequency of the pores in the gas exchange structures (cyphellae and pseudocyphellae) and in the medulla were measured and from these CO2 diffusion resistances were calculated. Pseudocyphellae were found to be smaller and more widely spaced than cyphellae, consequently the resistance of the pseudocyphellae, was much greater than that of the cyphellae. Medulla resistances were low in both lichens and are probably unimportant, even at high water contents. No evidence of hyphal swelling was found. Gas exchange structure resistances were more than five fold greater than medulla resistances. It is suggested that this arrangement of resistances may simultaneously encourage refixation of respired CO2 and maintain a non desiccating environment for the lichen algae. The internal transport resistances calculated in this work approximate experimentally obtained values. 相似文献
8.
Plant responses to elevated CO2 can be modified by many environmental factors, but very little attention has been paid to the interaction between CO2 and changes in vapour pressure deficit (VPD). Thirty-day-old alfalfa plants ( Medicago sativa L. cv. Aragón), which were inoculated with Sinorhizobium meliloti 102F78 strain, were grown for 1 month in controlled environment chambers at 25/15°C, 14 h photoperiod, and 600 µmol m−2 s−1 photosynthetic photon flux (PPF), using a factorial combination of CO2 concentration (400 µmol mol−1 or 700 µmol mol−1 ) and vapour pressure deficit (0.48 kPa or 1.74 kPa, which corresponded to relative humidities of 85% and 45% at 25°C, respectively). Elevated CO2 strongly stimulated plant growth under high VPD conditions, but this beneficial effect was not observed under low VPD. Under low VPD, elevated CO2 also did not enhance plant photosynthesis, and plant water stress was greatest for plants grown at elevated CO2 and low VPD. Moreover, plants grown under elevated CO2 and low VPD had a lower leaf soluble protein and photosynthetic activity (photosynthetic rate and carboxylation efficiency) than plants grown under elevated CO2 and high VPD. Elevated CO2 significantly increased leaf adaxial and abaxial temperatures. Because the effects of elevated CO2 were dependent on vapour pressure deficit, VPD needs to be controlled in experiments studying the effect of elevated CO2 as well as considered in the extrapolations of results to a warmer, high-CO2 world. 相似文献
9.
Seedlings of two tree species from the Atlantic lowlands of Costa Rica, Ochroma la-gopus Swartz, a fast-growing pioneer species, and Pentaclethra macroloba (Willd.) Kuntze, a slower-growing climax species, were grown under enriched atmospheric CO2 in controlled environment chambers. Carbon dioxide concentrations were maintained at 350 and 675 μl 1−1 under photosynthetic photon flux densities of 500 μol m−2 s−1 and temperatures of 26°C day and 20°C night. Total biomass of both species increased significantly in the elevated CO2 treatment; the increase in biomass was greatest for the pioneer species, O. lagopus . Both species had greater leaf areas and specific leaf weights with increased atmospheric CO2 . However, the ratio of non-pho-tosynthetic tissue to leaf area also increased in both species leading to decreased leaf area ratios. Plants of both species grown at 675 μl 1−1 CO2 had lower chlorophyll contents and photosynthesis on a leaf area basis than those grown at 350 μl 1−1 . Reductions in net photosynthesis occurred despite increased internal CO2 concentrations in the CO2 -enriched treatment. Stomatal conductances of both species decreased with CO2 -enrichment resulting in significant increases in water use efficiency. 相似文献
10.
Physiological effects of sulphur dioxide. 1. The effect of SO2 on photosynthesis and stomatal regulation of Vicia faba L. 总被引:2,自引:0,他引:2
M. J. KROPFF 《Plant, cell & environment》1987,10(9):753-760
Abstract. The effect of short-term SO2 fumigation on photosynthesis and transpiration of Vicia faba L. was measured at different irradiances and SO2 concentrations. At high irradiances photosynthetic rates were reduced when leaves were exposed to SO2 and the magnitude of the reduction was linearly related to the rate of SO2 uptake through the stomata. Photosynthetic rates stabilized within 2 h after the start of fumigation.
The effect of SO2 on photosynthesis was measured at different CO2 concentrations to analyse the contribution of stomatal and non-stomatal factors to photosynthetic inhibition. Mesophyll resistance to CO2 diffusion increased as a result of SO2 exposure and caused a rapid reduction in photosynthesis after the start of fumigation. Stomatal resistance was not affected directly by SO2 fumigation, but indirectly as a result of a feedback loop between net photosynthesis and internal CO2 concentration.
Analysis of gas-exchange measurements in biochemical terms indicated that photosynthetic inhibition during SO2 exposure can be explained by a stronger reduction in the affinity of RBP carboxylase/oxygenase for CO2 than for O2 . 相似文献
The effect of SO
Analysis of gas-exchange measurements in biochemical terms indicated that photosynthetic inhibition during SO
11.
L. Blaschke M. Schulte A. Raschi N. Slee H. Rennenberg A. Polle 《Plant biology (Stuttgart, Germany)》2001,3(3):288-298
Abstract: To study physiological responses of mature forest trees to elevated CO2 after lifetime growth under elevated atmospheric CO2 concentrations ( p CO2 ), photosynthesis, Rubisco content, foliar concentrations of soluble sugars and starch, sugar concentrations in transport tissues (phloem and xylem), structural biomass, and lignin in leaves and branches were investigated in 30- to 50-year-old Quercus pubescens and Q. ilex trees grown at two naturally elevated CO2 springs in Italy. Ribulose-1,5-bisphosphate carboxylase/oxygenase content was decreased in Q. pubescens grown under elevated CO2 concentrations, but not in Q. ilex. Photosynthesis was consistently higher in Q. pubescens grown at elevated CO2 as compared with "control" sites, whereas the response in Q. ilex was less pronounced. Stomatal conductance was lower in both species leading to decreased transpiration and increased instantaneous water use efficiency in Q. pubescens. Overall mean sugar + starch concentrations of the leaves were not affected by elevated p CO2 , but phloem exudates contained higher concentrations of soluble sugars. This finding suggests increased transport to sinks. Qualitative changes in major carbon-bearing compounds, such as structural biomass and lignins, were only found in bark but not in other tissues. These results support the concept that the maintenance of increased rates of photosynthesis after long-term acclimation to elevated p CO2 provides a means of optimization of water relations under arid climatic conditions but does not cause an increase in aboveground carbon sequestration per unit of tissue in Mediterranean oak species. 相似文献
12.
1. The affinity of photosynthesis for CO2 is calculated here as the initial slope of net-photosynthetic rate against concentration of CO2 . The affinity for CO2 for pairs of freshwater macrophytes with similar leaf morphology but able or unable to use HCO– 3 as a carbon source was compared.
2. Species restricted to CO2 had a higher affinity for CO2 than species that were also able to use HCO– 3 when rates were expressed on the basis of area, dry mass and content of chlorophyll a .
3. Published values for the affinity for CO2 and the concentration of CO2 which half-saturated rate of photosynthesis were compiled and compared. Despite a large range of values, affinity for CO2 was greater for species restricted to CO2 than for those also able to use HCO– 3 and statistically different when the slope was expressed on the basis of dry mass and chlorophyll a content.
4. The difference in affinity is consistent with predicted benefits of a high permeability to CO2 for species relying on passive diffusion of CO2 and a lower permeability for species able to use HCO– 3 in order to reduce efflux of CO2 from a high internal concentration generated by active transport.
5. The implications of the different affinities are discussed in terms of species distribution. 相似文献
2. Species restricted to CO
3. Published values for the affinity for CO
4. The difference in affinity is consistent with predicted benefits of a high permeability to CO
5. The implications of the different affinities are discussed in terms of species distribution. 相似文献
13.
1. We report changes in photosynthetic capacity of leaves developed in varying photon flux density (PFD), nitrogen supply and CO2 concentration. We determined the relative effect of these environmental factors on photosynthetic capacity per unit leaf volume as well as the volume of tissue per unit leaf area. We calculated resource-use efficiencies from the photosynthetic capacities and measurements of leaf dry mass, carbohydrates and nitrogen content.
2. There were clear differences between the mechanisms of photosynthetic acclimation to PFD, nitrogen supply and CO2 . PFD primarily affected volume of tissue per unit area whereas nitrogen supply primarily affected photosynthetic capacity per unit volume. CO2 concentration affected both of these parameters and interacted strongly with the PFD and nitrogen treatments.
3. Photosynthetic capacity per unit carbon invested in leaves increased in the low PFD, high nitrogen and low CO2 treatments. Photosynthetic capacity per unit nitrogen was significantly affected only by nitrogen supply.
4. The responses to low PFD and low nitrogen appear to function to increase the efficiency of utilization of the limiting resource. However, the responses to elevated CO2 in the high PFD and high nitrogen treatments suggest that high CO2 can result in a situation where growth is not limited by either carbon or nitrogen supply. Limitation of growth at elevated CO2 appears to result from internal plant factors that limit utilization of carbohydrates at sinks and/or transport of carbohydrates to sinks. 相似文献
2. There were clear differences between the mechanisms of photosynthetic acclimation to PFD, nitrogen supply and CO
3. Photosynthetic capacity per unit carbon invested in leaves increased in the low PFD, high nitrogen and low CO
4. The responses to low PFD and low nitrogen appear to function to increase the efficiency of utilization of the limiting resource. However, the responses to elevated CO
14.
Interactions between elevated CO2 concentration, nitrogen and water: effects on growth and water use of six perennial plant species 总被引:2,自引:1,他引:1
Two experiments are described in which plants of six species were grown for one full season in greenhouse compartments with 350 or 560 μ mol mol–1 CO2 . In the first experiment two levels of nitrogen supply were applied to study the interaction between CO2 and nitrogen. In the second experiment two levels of water supply were added to the experimental set-up to investigate the three-way interaction between CO2 , nitrogen and water. Biomass and biomass distribution were determined at harvests, while water use and soil moisture were monitored throughout the experiments. In both experiments a positive effect of CO2 on growth was found at high nitrogen concentrations but not at low nitrogen concentrations. However, plants used much less water in the presence of low nitrogen concentrations. Drought stress increased the relative effect of elevated CO2 on growth. Available soil moisture was used more slowly at high CO2 during drought or at high nitrogen concentrations, while at low nitrogen concentrations decreased water use resulted in an increase in soil moisture. The response to the treatments was similar in all the species used. Although potentially faster growing species appeared to respond better to high CO2 when supplied with a high level of nitrogen, inherently slow-growing species were more successful at low nitrogen concentrations. 相似文献
15.
Abstract. Boundary-layer resistances of aquatic bryophytes for CO2 diffusion in water were estimated from wind tunnel measurements of evaporation of aniline in air, using the principle of dynamic similarity. The results indicated resistances at water velocities between 0.02 and 0.2 m s −1 ranging from about 35 to 5 s mm−1 and 70 to 9 s mm−1 , respectively, for the mat-forming liverworts Nardia compressa and Scapania undulata , measured on a projected area (canopy) basis. Over a range of velocities from 0.01 to 0.2 m s−1 the estimated CO2 boundary-layer resistance of the streamer-like shoots of the moss Fontinalis antipyretica is between about 180 and 15 s mm−1 . Comparison with experiments on photosynthetic 14 CO2 -uptake at a range of water velocities suggests that boundary-layer resistance limits photosynthesis at velocities below about 0.01 m s−l in Fontinalis and below about 0.1 m s−1 in the mat-forming species. It is suggested that high leaf-area index allows the mat growth form more effectively to exploit the low boundary-layer resistance at high velocities while remaining relatively invulnerable to drag. By contrast, the streamer form allows Fontinalis to maximize surface area under conditions where boundary-layer resistance is limiting. 相似文献
16.
Changes in the temperature dependence of the photosynthetic rate depending on growth temperature were investigated for a temperate evergreen tree, Quercus myrsinaefolia . Plants were grown at 250 μ mol quanta m–2 s–1 under two temperature conditions, 15 and 30 °C. The optimal temperature that maximizes the light-saturated rate of photosynthesis at 350 μ L L–1 CO2 was found to be 20–25 and 30–35 °C for leaves grown at 15 and 30 °C, respectively. We focused on two processes, carboxylation and regeneration of ribulose-1,5-bisphosphate (RuBP), which potentially limit photosynthetic rates. Because the former process is known to limit photosynthesis at lower CO2 concentrations while the latter limits it at higher CO2 concentrations, we determined the temperature dependence of the photosynthetic rate at 200 and 1000 μ L L–1 CO2 under saturated light. It was revealed that the temperature dependence of both processes varied depending on the growth temperature. Using a biochemical model, we estimated the capacity of the two processes at various temperatures under ambient CO2 concentration. It was suggested that, in leaves grown at low temperature (15 °C), the photosynthetic rate was limited solely by RuBP carboxylation under any temperature. On the other hand, it was suggested that, in leaves grown at high temperature (30 °C), the photosynthetic rate was limited by RuBP regeneration below 22 °C, but limited by RuBP carboxylation above 22 °C. We concluded that: (1) the changes in the temperature dependence of carboxylation and regeneration of RuBP and (2) the changes in the balance of these two processes altered the temperature dependence of the photosynthetic rate. 相似文献
17.
Iker Aranjuelo Pilar Pérez Libia Hernández Juan José Irigoyen Gloria Zita Rafael Martínez-Carrasco Manuel Sánchez-Díaz 《Physiologia plantarum》2005,123(3):348-358
Plants grown in an environment of elevated CO2 and temperature often show reduced CO2 assimilation capacity, providing evidence of photosynthetic downregulation. The aim of this study was to analyse the downregulation of photosynthesis in elevated CO2 (700 µmol mol−1 ) in nodulated alfalfa plants grown at different temperatures (ambient and ambient + 4°C) and water availability regimes in temperature gradient tunnels. When the measurements were taken in growth conditions, a combination of elevated CO2 and temperature enhanced the photosynthetic rate; however, when they were carried out at the same CO2 concentration (350 and 700 µmol mol−1 ), elevated CO2 induced photosynthetic downregulation, regardless of temperature and drought. Intercellular CO2 concentration measurements revealed that photosynthetic acclimation could not be accounted for by stomatal limitations. Downregulation of plants grown in elevated CO2 was a consequence of decreased carboxylation efficiency as a result of reduced rubisco activity and protein content; in plants grown at ambient temperature, downregulation was also induced by decreased quantum efficiency. The decrease in rubisco activity was associated with carbohydrate accumulation and depleted nitrogen availability. The root nodules were not sufficiently effective to balance the source–sink relation in elevated CO2 treatments and to provide the required nitrogen to counteract photosynthetic acclimation. 相似文献
18.
In the CAM plants, Kalanchoë tubiflora (Harvey) Hasset, Sedum morganianum E. Walth and Sedum rubrotinctum R. T. Clausen, the effects of CO2 concentrations on the light-dependent 14 C transfer from the nocturnally synthetized [14C]-malic acid to starch have been studied. CO2 concentrations up to 5 × 103 μ1 1–1 did not inhibit this carbon transfer. Higher CO2 concentrations, however, were increasingly inhibitory. At 104 μl 1–1 CO2 , the carbon transfer was practically prevented.
The malic acid consumption in the light showed the same response to CO2 concentrations as the [l4 C]-transfer. Photosynthesis itself was not inhibited by the CO2 concentrations applied. It is assumed that, during phase III of CAM, light controls the internal CO2 concentration via photosynthesis; and that the internal CO2 concentration then controls the rate of malate decarboxylation. 相似文献
The malic acid consumption in the light showed the same response to CO
19.
Michael Knee 《Physiologia plantarum》1995,95(2):211-216
I considered the possibility that changes in fruit photosynthesis obscure the occurrence of the climacteric rise in respiration in tomato fruits attached to the plant. Internal CO2 and ethylene concentrations in tomatoes ( Lycopersicon esculentum Mill. cv. OH 7814) were analyzed after direct sampling through polyethylene tubes implanted in the external pericarp. Fruits which were shaded with aluminium foil contained up to 60 ml 1−1 CO2 , until the internal ethylene concentration exceeded 1 μl l−1 , when CO2 concentration declined to below 40 ml l−1 ; the CO2 concentration in fruits exposed to light only occasionally exceeded 40 ml 1−1 . The internal CO2 concentration of detached fruits first declined and then increased along with ethylene concentration, as expected for the climacteric. Detached green fruits under continuous low photosynthetic photon flux density (100 μmol m−2 s−1 ) contained almost no internal CO2 and produced no CO2 . Changes in photosynthesis and an associated CO2 -generating system in green fruits are thought to obscure the climacteric rise in tomato fruits developing on the plant. 相似文献
20.
Xavier Aranda Cristina Agustí Richard Joffre Isabel Fleck 《Physiologia plantarum》2006,128(2):302-312
The physiological characteristics of holm oak ( Quercus ilex L.) resprouts originated from plants grown under current CO2 concentration (350 μl l−1 ) (A-resprouts) were compared with those of resprouts originated from plants grown under elevated CO2 (750 μl l−1 ) (E-resprouts). At their respective CO2 growth concentration, no differences were observed in photosynthesis and chlorophyll fluorescence parameters between the two kinds of resprout. E-resprouts appeared earlier and showed lower stomatal conductance, higher water-use efficiency and increased growth (higher leaf, stem and root biomass and increased height). Analyses of leaf chemical composition showed the effect of elevated [CO2 ] on structural polysaccharide (higher cellulose content), but no accumulation of total non-structural carbohydrate on area or dry weight basis was seen. Four months after appearance, downregulation of photosynthesis and electron transport components was observed in E-resprouts: lower photosynthetic capacity, photosystem II quantum efficiency, photochemical quenching of fluorescence and relative electron transport rate. Reduction in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) activity, deduced from the maximum carboxylation velocity of RuBisCo, accounts for the observed acclimation. Increased susceptibility of photosynthetic apparatus to increasing irradiance was detected in E-resprouts. 相似文献