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1.
UV‐B dose responses of two lines of pea were quantified at 2.3, 4.6, 6.9 and 9.2 kJ m−2 day−1 UV‐B (weighted according to Caldwell's generalised plant action spectrum) in controlled environments providing near‐field doses of photosynthetic radiation. Increasing UV‐B significantly increased UV‐B absorbing compounds in both lines. In the UV‐B sensitive line, JI1389, increasing UV‐B significantly inhibited most aspects of plant morphology and biomass. In the more UV‐B‐tolerant line, Scout, increasing UV‐B significantly reduced foliage area but had no effect on above‐ground biomass, although root biomass was significantly increased. Reduced plant height in JI1389 was caused by shorter internodes, in turn due to reduced cell number but not cell length. UV‐B had no significant effects on photosynthesis in either line. Significant dose responses were linear for the growth of the main stem in JI1389 but remaining significant dose responses were better fitted by quadratics with maximum UV‐B effects occurring in the range 5–7 kJ m−2 day−1 PAS300, due to stimulation of branch growth at the highest dose. However, growth stimulation by UV‐B was confined to PAS300 doses which at temperate latitudes would result only from rather extreme ozone depletions. We conclude that investigations using relatively low UV‐B doses, rather than those well above the current maximum, may be the best approach to both understanding of the fundamental mechanisms of plant responses to UV‐B and quantifying the magnitude of responses to stratospheric ozone depletion. 相似文献
2.
Peter von Ballmoos Markus Ammann Alfred Egger Marianne Suter Christian Brunold 《Physiologia plantarum》1998,102(4):596-604
The induction of activity of the enzyme nitrate reductase (NR, EC 1.6.6.1, 1.6.6.2) in needles of Norway spruce ( Picea abies [L.] Karst.) by nitrogen dioxide (NO2 ) was studied under laboratory and field conditions. In fumigation chambers an increase in nitrate reductase activity (NRA) was detected 4 h after the start of the NO2 treatment. During the first 2 days with 100 µg NO2 m−3 , NRA reached a constant level and did not change during the following 4 days. At the same level of NO2 , NRA was lower in needles from trees grown on NPK‐fertilized soil than on non‐fertilized soil. After the transfer of spruce trees from fertilized soil to NPK‐rich nutrient solution, NRA was transiently increased. This effect was assigned to root injuries causing nitrate transport to the shoot and subsequent induction of NRA. Neither trees on fertilized soil nor trees transferred to NPK‐poor nutrient solution had increased NRA unless NO2 was provided. The NO2 gradient in the vicinity of a highway was used to test the long‐term effect of elevated levels of NO2 on needle NRA of potted and field‐grown spruce trees. Compared with less polluted sites, permanently increased NRAs were detected when NO2 concentrations were above 20 µg m−3 . Controls of field measurements some 10 years after the introduction of catalytic converters in cars showed no significant change neither in NO2 levels nor in the decreasing NRA of spruce needles with the distance from the highway. 相似文献
3.
4.
Metabolism of a desert stream 总被引:8,自引:0,他引:8
SUMMARY. Rates of photosynthesis and community respiration were determined for benthic assemblages in Sycamore Creek, a Sonoran Desert stream in Arizona. Benthos in this stream can be separated into (1) mats of Cladophora glomerata and associated epiphytes and (2) assemblages of epipelic diatoms and blue-green algae. Community respiration and net photosynthesis were measured for these assemblages using submerged light-dark chambers in situ . Multiple regression analysis was used to predict (1) gross photosynthesis as a function of photosynthetically active radiation, temperature and chlorophyll-α concentration; and (2) community respiration as a function of temperature and biomass.
Calculations suggest that Sycamore Creek is autotrophic during the summer ( P/R = 1.7) and that the rates of gross photosynthesis ( P =8.5 g O2 m−2 day−1 ) and community respiration ( R = 5.1 g O2 m−2 day−1 ) are high for a small stream. Considerable difference exists between the Cladophora mat assemblages, in which mean P is 12.5gO2 m−2 day−1 and the P/R ratio is 2.3, and the epipelic assemblages in which mean P is 4.4 g O2 m−2 day−1 and P/R is 0.96. The high rate of gross photosynthesis, low litter inputs, high biomass of algae and the intermittent but severe floods that characterize Sycamore Creek indicate that this stream and other similar desert streams are net exporters of organic matter and are, thereby, truly autotrophic stream ecosystems. 相似文献
Calculations suggest that Sycamore Creek is autotrophic during the summer ( P/R = 1.7) and that the rates of gross photosynthesis ( P =8.5 g O
5.
Effect of atmospheric ammonia on the nitrogen metabolism of Scots pine (Pinus sylvestris) needles 总被引:5,自引:0,他引:5
Four-year-old seedlings of Scots pine ( Pinus sylvestris L.) were exposed to filtered air (FA), and to FA supplemented with NH3 (60 and 240 μg m−3 ) in controlled-environment chambers for 14 weeks. Exposure to the higher NH3 concentration resulted in an increased activity of glutamine synthetase (GS, EC 6.3.1.2), and an increase in the concentrations of soluble proteins, total nitrogen, free amino acids and leaf pigments in the needles. The GS activity (μmol g−1 fresh weight h−1 ) in the needle extract increased to levels 69% higher than in FA and the soluble protein concentration to levels 22% higher. Total nitrogen concentration in the needles was 42% higher than in FA, while the free amino acid concentration was 300% higher, which was caused by an increase in arginine, glutamate, aspartate and glutamine. Chlorophyll a , chlorophyll b and carotenoid concentrations were 29, 38 and 11% higher, respectively. Neither the glutamate dehydrogenase (GDH, EC 1.4.1.2) activity nor the concentrations of free NH4 + and glucose in the needles were affected by exposure to NH3 . After NH3 fumigation at 240 μg m−3 the starch concentration decreased by 39% relative to the FA. The results indicate that the metabolism of Scots pine acclimates to concentrations of NH3 which are 3 to 10 times higher than the average concentration in areas with intensive stock farming. The possible mechanisms underlying acclimation to NH3 are discussed. 相似文献
6.
Stefano Predieri Donald T. Krizek Chien Y. Wang Roman M. Mirecki Richard H. Zimmerman 《Physiologia plantarum》1993,87(2):109-117
In vitro shoots of cv. Doyenne ďHiver pear ( Pyrus communis L.) were irradiated under controlled environments for 6 h per day at 5 different levels of biologically effective UV-B radiation (UV-BBE ). UV-B exposure caused a progressive increase in apical necrosis above background levels and stimulated leaf abscission. Shoots grown for 2 weeks at 7. 8 mol m−2 day −1 of photosynthetic photon flux (PPF) and treated with 8. 4 or 12. 0 kJ m−2 day −1 UV-BBE produced up to 4 times more ethylene than those given 2. 2 or 5. 1 kJ m−2 day−1 UV-BBE or untreated controls. Exposure of shoots to 12 kJ m−2 day −1 of UV-BBE caused an increase in free putreseine content after 4 to 14 days of irradiation. Shoots showed a decrease in CO2 uptake after 3 days of UV-B: thereafter, they appeared to recover their photosynthetic capacity. Under typical PPF conditions used in micropropagation (90 μmol m−2 S−1 ). 8. 4 kJ m−2 day −1 of UV-B radiation was injurious to realatively tender tissues of in vitro pear shoots: increasing the level of UV-BBE to 12 kJ m−2 day−1 produced even more adverse effects. 相似文献
7.
Peter Van Gestelen Han Asard Nele Horemans Roland J. Caubergs 《Physiologia plantarum》1998,104(4):653-660
Higher plants produce active oxygen species (AOS) that regulate their defence responses against pathogenic elicitation. Etiolated bean seedlings ( Phaseolus vulgaris L. cv. Limburgse vroege) were used to measure the in vivo‐induced AOS production and to search for plasma membrane bound NAD(P)H‐dependent oxidases producing AOS. Immersed bean plants showed a substantial production of H2 O2 , as determined by the peroxidase (EC 1.11.1.7)‐dependent oxidation of 3,5‐dichloro‐2‐hydroxybenzenesulfonic acid (DHBS). Addition of the elicitor polygalacturonase (PGase, EC 3.2.1.15) from Aspergillus japonicus or the phosphatase inhibitor, cantharidin, resulted in a transient increase of AOS synthesis. Plasma membrane vesicles, purified from etiolated bean seedlings, showed an NAD(P)H‐dependent superoxide (O2 − ) production that was highly stimulated with naphthoquinones. Protein solubilisation and anion exchange chromatography resolved a basal and three naphthoquinone‐stimulated NAD(P)H‐dependent O2 − oxidase fractions. The natural phenol, apigenin, was also a strong inducer of the naphthoquinone‐dependent enzymes, when it was used in the presence of peroxidase. Although, the relation of these different in vitro‐determined plasma membrane NAD(P)H‐dependent O2 − oxidases to the in vivo elicitation of H 2 O2 has not been elucidated so far. 相似文献
8.
Photosynthetically active radiation (PhAR) is apparently the environmental factor having the greatest influence on leaf thickness for Plectranthus parviflorus Henckel (Labiatae). A four-fold increase in leaf thickness from 280 to 1170 μm occurred as the PhAR was raised from 1.3 to 32.5 mol m−2 day−1 . Compared to a constant PhAR of 2.5 mol m−2 day−1 , a PhAR of 32.5 mol m−2 day−1 for one week during the first week (with return to 2.5 mol m−2 day−1 during the second and third weeks) led to an increase in final leaf thickness by 323 μm (to 802 μm). When increased PhAR was applied during the second week the increase in final thickness over the control was 217 μm, and when increased PhAR was applied during the third week it was 99 μm. However, leaf thickness was not simply responding to total daily PhAR, since a leaf 450 μm thick could occur at a low instantaneous PhAR for a long daytime (total daily PhAR of 1.5 mol m−2 day−1 ) and at a high PhAR for a short daytime (4.5 mol m−2 day−1 ). Total daily CO2 uptake (net photosynthesis) was approximately the same in the two cases, suggesting that this is an important factor underlying the differences in leaf thickness. Leaf thickness is physiologically important, since thicker leaves tend to have greater mesophyll surface area per unit leaf area ( A mes / A ) and hence higher photosynthetic rates. 相似文献
9.
Usue Pérez-López Anabel Robredo Maite Lacuesta Cristina Sgherri Alberto Muñoz-Rueda Flavia Navari-Izzo Amaia Mena-Petite 《Physiologia plantarum》2009,135(1):29-42
Changes in antioxidant metabolism because of the effect of salinity stress (0, 80, 160 or 240 m M NaCl) on protective enzyme activities under ambient (350 μmol mol−1 ) and elevated (700 μmol mol−1 ) CO2 concentrations were investigated in two barley cultivars ( Hordeum vulgare L., cvs Alpha and Iranis). Electrolyte leakage, peroxidation, antioxidant enzyme activities [superoxide dismutase (SOD), EC 1.15.1.1; ascorbate peroxidase (APX), EC 1.11.1.11; catalase (CAT), EC 1.11.1.6; dehydroascorbate reductase (DHAR), EC 1.8.5.1; monodehydroascorbate reductase (MDHAR), EC 1.6.5.4; glutathione reductase (GR), EC 1.6.4.2] and their isoenzymatic profiles were determined. Under salinity and ambient CO2 , upregulation of antioxidant enzymes such as SOD, APX, CAT, DHAR and GR occurred. However, this upregulation was not enough to counteract all ROS formation as both ion leakage and lipid peroxidation came into play. The higher constitutive SOD and CAT activities together with a higher contribution of Cu,Zn-SOD 1 detected in Iranis might possibly contribute and make this cultivar more salt-tolerant than Alpha. Elevated CO2 alone had no effect on the constitutive levels of antioxidant enzymes in Iranis, whereas in Alpha it induced an increase in SOD, CAT and MDHAR together with a decrease of DHAR and GR. Under combined conditions of elevated CO2 and salinity the oxidative damage recorded was lower, above all in Alpha, together with a lower upregulation of the antioxidant system. So it can be concluded that elevated CO2 mitigates the oxidative stress caused by salinity, involving lower ROS generation and a better maintenance of redox homeostasis as a consequence of higher assimilation rates and lower photorespiration, being the response dependent on the cultivar analysed. 相似文献
10.
Stanislaw Maleszewski Zofia Kamiska Agnieszka Kondracka Maria Mikulska 《Physiologia plantarum》1988,74(2):221-224
Bean ( Phaseolus vulgaris L. cv. Golden Saxa) plants were grown under low artificial light or under natural daylight. The rate of net photosynthesis (PN ) was measured at: CO2 partial pressure, p(CO2 ), of 0.03, 0.09 or 0.15 kPa; O2 partial pressure, p(O2 ), of 2, 21 or 31 kPa and at light intensities of 350 or 1000 μmol m−2 s−1 (photosynthetically active radiation). In plants which had been grown under natural light, stimulation of PN at 21 kPa p(O2 ) was found only at elevated p(CO2 ) and high light. It is proposed that this phenomenon is dependent on a high capacity of the photosynthetic apparatus to regenerate ribulose 1.5-bisphosphate. 相似文献
11.
The aim of this work was to examine the correspondence between apoplastic/symplastic antioxidant status and previously reported plant age-related shifts in the ozone (O3 ) resistance of Plantago major L. Seed-grown plants were fumigated in duplicate controlled environment chambers with charcoal/Purafil®-filtered air (CFA) or CFA plus 70 nmol mol−1 O3 for 7 h d−1 over a 42 d period. Measurements of stomatal conductance and antioxidants were made after 14, 28 and 42 d fumigation, on leaves at an equivalent stage of development (youngest fully expanded leaf, measured c . 9 d after emergence). Ozone exposure resulted in a similar decline in stomatal conductance across plant ages, indicating that increases in O3 resistance with plant age were mediated through changes in the tolerance of leaf tissue rather than enhanced pollutant exclusion. Leaf apoplastic washing fluid was found to contain 'unspecific' peroxidase, ascorbate peroxidase, superoxide dismutase and ascorbate, but not glutathione and the enzymes required to facilitate the regeneration of ascorbate from its oxidized forms. A weak induction in the activity of certain symplastic antioxidants was found after 14 d O3 fumigation, despite a lack of visible symptoms of injury, but shifts in symplastic antioxidant enzyme activity were not consistent with previously observed increases in resistance to O3 with plant age. By contrast, changes in 'unspecific' peroxidase activity and in the small pool of ascorbate in the leaf apoplast were found to accompany age-related shifts in O3 resistance. It is concluded that constituents of the leaf apoplast may constitute a potentially important front line defence against O3 . 相似文献
12.
Gian Franco Soldatini Giacomo Lorenzini Ferruccio Filippi Cristina Nali Lucia Guidi 《Physiologia plantarum》1998,104(4):707-712
The photosynthetic response was studied in two clones ( Populus deltoides × maximowiczii Eridano and Populus × euramericana I‐214), known for their differential response to ozone (O3 ) in terms of visible symptoms, when exposed to O3 (60 nl l−1 5 h day−1 , 7 and 15 days). The photosynthetic ability was tested using gas exchange and chlorophyll fluorescence analysis. O3 caused a decrease in the CO2 assimilation rate at light saturation level in mature leaves of both clones. Alterations of Chl fluorescence parameters, in particular the Fv /Fm ratio and non‐photochemical quenching were also observed. The effects were similar for both clones and it could not be concluded that differential effects on electron transport capacity were responsible for the observed reduction in photosynthesis. The reduction of photosynthetic rate in Eridano was due mainly to a reduced mesophyll activity, as evidenced by the increase in intercellular CO2 concentration and the minimal changes in stomatal conductance. In contrast, in I‐214, stomatal effects were primarily responsible, although effects on the mesophyll cannot be excluded. Data obtained indicate that the effects observed at the mesophyll level may be attributed to indirect effects caused by membrane disorders. 相似文献
13.
A comparative study of the effects of NaCl salinity on respiration, photosynthesis, and leaf extension growth in Beta vulgaris L. (sugar beet) 总被引:1,自引:1,他引:0
Abstract. Three parameters influencing the capacity for carbon accumulation, i.e. photosynthesis, respiration, and leaf extension growth, were studied in Beta vulgaris L. (sugar beet) cultured in nutrient solution containing 0.5 to 500 mol m−3 NaCl. Leaf extension growth was the parameter most sensitive to salinity: the initial rate of leaf extension and final leaf length each declined linearly with increase in external NaCl concentration. Photosynthetic O2 evolution of thin leaf slices did not decline until salinity levels reached 350 to 500 mol m−3 NaCl, while respiratory O2 consumption was not affected by salinity throughout the range. The results suggest that the influence of salinity on the capacity for carbon accumulation in B. vulgaris occurs primarily through reduction in the area of photosynthetic surface. 相似文献
14.
On the response of pigments and antioxidants of Pinus halepensis seedlings to Mediterranean climatic factors and long-term ozone exposure 总被引:3,自引:0,他引:3
SUSANA ELVIRA ROCÍO ALONSO FEDERICO J. CASTILLO & BENJAMÍN S. GIMENO 《The New phytologist》1998,138(3):419-432
An experiment was carried out in open-top chambers located in eastern Spain. One-yr-old Pinus halepensis Mill. seedlings were exposed during three consecutive summers to the following ozone (O3 ) treatments: charcoal-filtered air (CFA), non-filtered air (NFA) or non-filtered air plus 40 nl l−1 O3 , 9 h d−1 , 5 d wk−1 (NFA+40). Seasonal variations in Aleppo pine performance were observed since reductions in chlorophyll and cellular peroxidase levels associated with increases in superoxide dismutase activity, were recorded during the summer. Similarly, a reduction in epoxidation state was found at midday during the summer, derived from an activation of the xanthophyll cycle associated to an increment in radiation and temperature levels.
The first O3 -induced effects were recorded in previous-year needles (1991) during the first summer exposure as an increase in extracellular and total peroxidase activities and in zeaxanthin levels in the NFA+40 treatment along with a trend to a higher SOD activity in this treatment. A carry-over effect was detected since a lower winter recovery of chlorophyll levels was found in the NFA+40 seedlings along with a reduction of xanthophyll levels. A reduction in chlorophyll levels was observed in the previous-year needles (1992) from the NFA+40 treatment at the end of the second fumigation period. Realistic ozone exposures induced alterations in plant antioxidative systems and plant pigments as shown in this paper. These observations together with the reductions in stomatal conductance and net photosynthesis recorded in the same experiment, indicate that Aleppo pine is a species sensitive to ozone. 相似文献
The first O
15.
SUMMARY. Oxygen consumption of P. zietziana was measured monthly in two saline (>60‰ salinity) lakes from November 1973 to November 1975 with short (<2 h) in situ incubations in BOD bottles. Tests in which oxygen decline was monitored continuously showed that there was no handling effect and respiratory rate was constant down to 1.8–1.9 mg O2 1−1 , about 40% of the usual initial concentration. Incubations over 24 h demonstrated no diurnal fluctuations in oxygen consumption. Multiple regression analysis indicated that 90% of the variance in respiratory rate ( R in mg O2 x10−4 h−1 individual−1 ) was accounted for by changes in salinity (3%; S in ‰), temperature (7%; T in °C) and dry weight (8%; W in mg × 10−3 ): log R =−1.123+0.0025+0.021 T+ 0.756 log W. From this equation and data on population density, population respiration was calculated: 91864.5 mg O2 m−2 year−1 in Pink Lake and 12367.5 mg O2 m−2 year−1 in Lake Cundare. 相似文献
16.
Inter‐individual differences in rates of routine (non‐feeding) metabolism and growth were evaluated in young‐of‐the‐year (YOY) juvenile Atlantic cod Gadus morhua . Rates of O2 consumption, CO2 production and ammonia (TAN) excretion were measured in 64, 25–43 mm standard length ( L S ) YOY growing at different rates (0·27–0·47 mm day−1 ) in a common rearing tank. Parameter rates ( y ) increased allometrically ( y = a·Mb ) with increasing body mass ( M ) with b ‐values for O2 production, CO2 consumption and TAN excretion equal to 0·81, 0·89 and 0·56, respectively. In some cases, residuals from these regressions were significantly negatively correlated to fish growth rate. In no cases did residuals of parameter rates increase with increasing growth rate. These data suggest that, during unfed periods, relatively fast‐growing fish were more metabolically efficient than slower‐growing fish from the same cohort. The fish condition factor, derived from , also significantly decreased with increasing growth rate. Results indicated differences in both the rates of routine energy loss and the patterns of growth allocation among YOY Atlantic cod. Since these physiological attributes were positively correlated with growth rate, they may be indicative of 'survivors' in field populations. 相似文献
17.
Abstract A diatom biofilm was grown in a chamber developed for culture of biofilms in chemical gradients. The diatoms grew on a polycarbonate membrane filter which separated a sterile reservoir, with added phosphate, from a reservoir without phosphate. Within 3 weeks of inoculation, a thick biofilm developed on the surface of the filter. The biofilms were homogeneous and therefore suitable for calculations of O2 diffusion fluxes from concentration profiles of O2 . Profiles of O2 , pH, and gross photosynthesis at different light intensities and liquid medium concentrations of dissolved inorganic carbon and O2 were measured with microelectrodes. Respiratory activity in a layer of the biofilm was determined as the difference between gross photosynthesis and outflux of O2 from that layer. The photosynthetic activity in a well-developed biofilm grown at 360 μEinst m−2 s−1 and 2.4 mM HCO3 − was limited by the supply of inorganic carbon. Exposure to light above 360 μEinst m−2 s−1 stimulated gross photosynthesis as well as respiratory processes without affecting net outflux of O2 . Higher concentrations of inorganic carbon, on the other hand, enhanced gross photosynthesis without concurrent increase in respiratory rate, resulting in an increased outflux of O2 . High concentrations of O2 in the liquid medium decreased the net outflux of O2 with little effect on the gross photosynthesis. The effects of inorganic carbon and O2 on the metabolic activities of the biofilm were consistent with the presence of photorespiratory activity. 相似文献
18.
Net CO2 exchange rates (CERs) were measured in seedlings of two loblotly pine ( Pinus taeda L.) families following 6- or 13-week exposures to ozone (charcoalfiltered or ambient air + O3 ) and acid rain treatments (pH 3.3, 4.5 and 5.2). Ozone exposures (14 or 170 nl l−1 ) were made in open-top chambers, and in continously stirred tank reactors (14, 160 or 320 nl l−1 ) located in the field and laboratory, respectively. The CERs of whole shoots were measured in an open infrared gas analysis system at 6 levels of photosynthetic photon flux density (0, 33, 60, 410, 800 and 1660 μmol m−2 s−1 ). Treatment effects were not consistent between field- and laboratory-exposed seedlings. Ozone-treated field seedlings exhibited statistically significant reductions in light-saturated CER of 12.5 and 25% when measured at 6 and 13 weeks, respectively. Laboratory seedlings exhibited mixed responses to O3 , with one family showing reduced CER only after 6 weeks of O3 exposure and the other only after 13 weeks (O3 >160 nl l−1 for both). After 13 weeks of exposure, pH 3.3, and 4.5 rain treatments enhanced light-saturated CER by an average of 52% over that observed in seedlings exposed to the pH 5.2 treatment. Enhanced CERs due to acid rain were of the same magnitude (3–5 μmol CO2 g−1 s−1 ) as ozone-induced CER reductions. No differences in dark respiration were detected between treatments. Although ozone and acid rain treatments altered seedling CER, the differences were not translated into altered final plant dry weights over the 13-week exposure period. 相似文献
19.
Effect of organic loading on nitrification and denitrification in a marine sediment microcosm 总被引:3,自引:0,他引:3
Abstract The effects of organic additions on nitrification and dentrification were examined in sediment microcosms. The organic material, heat killed yeast, had a C/N ratio of 7.5 and was added to sieved, homogenized sediments. Four treatments were compared: no addition (control), 30 g dry weight (dw) m−2 mixed throughout the 10 cm sediment column (30M), 100 g dw m−2 mixed throughout sediments (100M), and 100 g dw m−2 mixed into top 1 cm (100S). After the microcosms had been established for 7–11 days, depth of O2 penetration, sediment-water fluxes and nitrification rates were measured. Nitrification rates were measured using three different techniques: N-serve and acetylene inhibition in intact cores, and nitrification potentials in slurris. Increased organic additions decreased O2 penetration from 2.7 to 0.2 mm while increasing both O2 consumption, from 30 to 70 mmol O2 m−2 d−1 , and NO3 − flux into sediments. Nitrification rates in intact cores were similar for the two methods. Highest rates occurred in the 30M treatment, while the lowest rate was measured in the 100S treatment. Total denitrification rates (estimated from nitrification and nitrate fluxes) increased with increased organic addition, because of the high concentrations of NO3 − (40 μM) in the overlaying water. The ratio of nitrification: denitrification was used as an indication of the importance of nitrification as the NO3 − supply for denitrificaion. This ratio decreased from 1.55 to 0.05 iwth increase organic addition. 相似文献
20.
Oxygen-dependent stomatal opening in Zea mays leaves. Effect of Light and carbon dioxide 总被引:2,自引:0,他引:2
The oxygen requirement for stomatal opening in maize plants ( Zea mays L. hybrid INRA 508) was studied at different CO2 concentrations and light intensities. In the absence of CO2 , stomatal opening always required O2 , but this requirement decreased with increasing light intensity. In darkness, the lowest O2 partial pressure needed to obtain a weak stomatal movement was about 50 Pa. This value was lowered to ca 10 Pa in light (320 μmol m−2 s−1 ).
On the other hand. in the absence of O2 , CO2 enabled stomatal opening to occur in the light, presumably due to the evolved photosynthetic O2 . Thus, CO2 , which generally reduced stomatal aperture, could induce stomatal movement in anoxia and light. The effect of CO2 on stomatal opening was closely dependent on O2 concentration and light intensity. Stomatal aperture appeared CO2 -independent at an O2 partial pressure which was dependent on light intensity and was about 25 Pa at 320 umol m−2 s−1 .
The presence of a plasmalemma oxidase, in addition to mitochondrial oxidase, might explain the differences in the O2 requirement at various light intensities. The possible involvement of such a system in relation to the effect of CO2 is discussed. 相似文献
On the other hand. in the absence of O
The presence of a plasmalemma oxidase, in addition to mitochondrial oxidase, might explain the differences in the O