首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Harnos  N.  Tuba  Z.  Szente  K. 《Photosynthetica》2002,40(2):293-300
Winter wheat plants were grown in open top chambers either at 365 µmol mol–1 (AC) or at 700 µmol mol–1 (EC) air CO2 concentrations. The photosynthetic response of flag leaves at the beginning of flowering and on four vertical leaf levels at the beginning of grain filling were measured. Net photosynthetic rates (P N) were higher at both developmental phases in plants grown at EC coupled with larger leaf area and photosynthetic pigment contents. The widely accepted Farquhar net photosynthesis model was parameterised and tested using several observed data. After parameterisation the test results corresponded satisfactorily with observed values under several environmental conditions.  相似文献   

2.
We investigated net photosynthetic rate (PN) of ear and two uppermost (flag and penultimate) leaves of wheat cultivars Hongmangmai (drought resistant) and Haruhikari (drought sensitive) during post-anthesis under irrigated and non-irrigated field conditions. The PNof ear and flag leaf were significantly higher and less affected by drought in Hongmangmai than in Haruhikari. The rate of reduction in stomatal conductance (gs) was similar for the two cultivars, but intercellular CO2concentration (Ci) in the flag leaf of Hongmangmai was lower than that of Haruhikari in non-irrigated treatment. No differences were observed in leaf water potential (1) and osmotic adjustment of the flag leaf of the cultivars. These results imply that differences in photosynthetic inhibition on the flag leaf at low leaf 1between the cultivars were primarily due to non-stomatal effects. Hence the main physiological factor associated with yield stability of Hongmangmai under drought stress may be attributed to the capacity for chloroplast activity in the flag leaf, which apparently allows sustained PNof flag leaf during grain filling under drought stress. The higher PNof ear in Hongmangmai under drought could also be related to its drought resistance.This revised version was published online in March 2005 with corrections to the page numbers.  相似文献   

3.
Bunce  J.A.  Sicher  R.C. 《Photosynthetica》2001,39(1):95-101
Midday measurements of single leaf gas exchange rates of upper canopy leaves of soybeans grown in the field at 350 (AC) and 700 (EC) µmol(CO2) mol–1 in open topped chambers sometimes indicated up to 50 % higher net photosynthetic rates (P N) measured at EC in plants grown at AC compared to EC. On other days mean P N were nearly identical in the two growth [CO2] treatments. There was no seasonal pattern to the variable photosynthetic responses of soybean to growth [CO2]. Even on days with significantly lower P N in the plants grown at EC, there was no reduction in ribulose-1,5-bisphosphate carboxylase/oxygenase, chlorophyll, or soluble protein contents per unit of leaf area. Over three years, gas exchange evidence of acclimation occurred on days when either soil was dry or the water vapor pressure deficit was high (n = 12 d) and did not occur on days after rain or on days with low water vapor pressure deficit (n = 9 d). On days when photosynthetic acclimation was evident, midday leaf water potentials were consistently 0.2 to 0.3 MPa lower for the plants grown at EC than at AC. This suggested that greater susceptibility to water stress in plants grown at EC cause the apparent photosynthetic acclimation. In other experiments, plants were grown in well-watered pots in field chambers and removed to the laboratory early in the morning for gas exchange measurements. In these experiments, the amount of photosynthetic acclimation evident in the gas exchange measurements increased with the maximum water vapor pressure deficit on the day prior to the measurements, indicating a lag in the recovery of photosynthesis from water stress. The apparent increase in susceptibility to water stress in soybean plants grown at EC is opposite to that observed in some other species, where photosynthetic acclimation was evident under wet but not dry conditions, and may be related to the observation that hydraulic conductance is reduced in soybeans when grown at EC. The day-to-day variation in photosynthetic acclimation observed here may account for some of the conflicting results in the literature concerning the existence of acclimation to EC in field-grown plants.  相似文献   

4.
Wang  Zhi-Min  Wei  Ai-Li  Zheng  Dan-Man 《Photosynthetica》2001,39(2):239-244
Chlorophyll content, photosystem 2 functioning (Fv/Fm, Fv/F0), activity of ribulose-1,5-bisphosphate carboxylase/oxygenase, and net photosynthetic rates (P N) of flag leaf blade, sheath, peduncle, and ear organs were assessed in large-ear type (Pin 7) and small-ear type (ND93) wheat cultivars. Some differences were found in photosynthetic properties between different green plant parts, the values of all studied parameters in ear parts being higher in Pin7 than in ND93. Furthermore, ear surface areas and ear P N in 26 wheat genotypes measured at anthesis showed highly significant positive correlation with grain mass per ear. Hence a greater capability of ear photosynthesis may result in a greater grain yield in large-ear type cultivars.  相似文献   

5.
Sánchez-Díaz  M.  García  J.L.  Antolín  M.C.  Araus  J.L. 《Photosynthetica》2002,40(3):415-421
The combined effects of water status, vapour pressure deficit (VPD), and elevated temperature from heading to maturity were studied in barley. Plants growing at high VPD, either under well-watered or water deficit conditions, had higher grain yield and grain filling rate than plants growing at low VPD. By contrast, water stress decreased grain yield and individual grain dry matter at any VPD. Water regime and to a lesser extent VPD affected 13C of plant parts sampled at mid-grain filling and maturity. The differences between treatments were maximal in mature grains, where high VPD increased 13C for both water regimes. However, the total amount of water used by the plant during grain filling did not change as response to a higher VPD whereas transpiration efficiency (TE) decreased. The net photosynthetic rate (P N) of the flag leaves decreased significantly under water stress at both VPD regimes. However, P N of the ears was higher at high VPD than at low VPD, and did not decrease as response to water stress. The higher correlation of grain yield with P N of the ear compared with that of the flag leaf support the role of ear as the main photosynthetic organ during grain filling under water deficit and high VPD. The deleterious effects of combined moderately high temperature and drought on yield were attenuated at high VPD.  相似文献   

6.
We investigated net photosynthetic rate (PN) of ear and two uppermost (flag and penultimate) leaves of wheat cultivars Hongmangmai (drought resistant) and Haruhikari (drought sensitive) during post-anthesis under irrigated and non-irrigated field conditions. The PNof ear and flag leaf were significantly higher and less affected by drought in Hongmangmai than in Haruhikari. The rate of reduction in stomatal conductance (gs) was similar for the two cultivars, but intercellular CO2concentration (Ci) in the flag leaf of Hongmangmai was lower than that of Haruhikari in non-irrigated treatment. No differences were observed in leaf water potential (ψ1) and osmotic adjustment of the flag leaf of the cultivars. These results imply that differences in photosynthetic inhibition on the flag leaf at low leaf ψ1between the cultivars were primarily due to non-stomatal effects. Hence the main physiological factor associated with yield stability of Hongmangmai under drought stress may be attributed to the capacity for chloroplast activity in the flag leaf, which apparently allows sustained PNof flag leaf during grain filling under drought stress. The higher PNof ear in Hongmangmai under drought could also be related to its drought resistance.  相似文献   

7.
Barták  M.  Raschi  A.  Tognetti  R. 《Photosynthetica》1999,37(1):1-16
Photosynthetic parameters were studied in Arbutus unedo L. trees growing at either ambient (AC) or elevated EC (mean 465 μmol mol-1) CO2 concentration near a natural CO2 vent in Orciatico, Italy Diurnal courses of net photosynthetic rate (P N), ratio of variable to maximum chlorophyll fluorescence (Fv/Fm), and quantum yield of electron transport through photosystem 2 (Φ2) were measured on sun and shade leaves. The contents of N, C, Ca, K, P, and chlorophyll (Chl) and specific leaf area (SLA) in these leaf categories were also determined. A morning peak and midday depression of P N were found for both AC and EC sun leaves. Long-term EC caused little or no down-acclimation of P N in sum leaves. The estimate of total daily CO2 uptake was lower in AC leaves than in EC leaves. In shade leaves, it reached up to 70 % of the value of sun leaves. The Fv/Fm ratio showed decreasing trend in the morning, reached a minimum at midday (90 % of dawn value), and then increased in the afternoon. The EC had no effect on Fv/Fm either in sun or shade leaves. Plants grown near the CO2 spring had lower Chl content, higher SLA, and higher Ca and K contents than plants grown under AC. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

8.
Water status parameters, flag leaf photosynthetic activity, abscisic acid (ABA) levels, grain yield, and storage protein contents were investigated in two drought-tolerant (Triticum aestivum L. cv. MV Emese and cv. Plainsman V) and two drought-sensitive (cvs. GK élet and Cappelle Desprez) wheat genotypes subjected to soil water deficit during grain filling to characterize physiological traits related to yield. The leaf water potential decreased earlier and at a higher rate in the sensitive than in the tolerant cultivars. The net CO2 assimilation rate (P N) in flag leaves during water deficit did not display a strict correlation with the drought sensitivity of the genotypes. The photosynthetic activity terminated earliest in the tolerant cv. Emese, and the senescence of flag leaves lasted 7 days longer in the sensitive Cappelle Desprez. Soil drought did not induce characteristic differences between sensitive and tolerant cultivars in chlorophyll a fluorescence parameters of flag leaves during post-anthesis. Changes in the effective quantum yield of PSII (ΦPSII) and the photochemical quenching (qP) depended on the genotypes and not on the sensitivity of cultivars. In contrast, the levels of ABA in the kernels displayed typical fluctuations in the tolerant and in the sensitive cultivars. Tolerant genotypes exhibited an early maximum in the grain ABA content during drought and the sensitive cultivars maintained high ABA levels in the later stages of grain filling. In contrast with other genotypes, the grain number per ear did not decrease in Plainsman and the gliadin/glutenin ratio was higher than in the control in Emese during drought stress. A possible causal relationship between high ABA levels in the kernels during late stages of grain filling and a decreased grain yield was found in the sensitive cultivars during drought stress.  相似文献   

9.
The role of ear photosynthesis in grain filling was studied in a number of durum wheat (Triticum turgidum var durum L.) landraces and varieties from the Middle East, North Africa, and from the collections of ‘Institut National de la Recherche Agronomique’ (INRA, France) and ‘Centro International de Mejora de Maiz y Trigo’ (CIMMYT, Mexico). Plants were grown in the field in a Mediterranean climate. Flag leaves (blade plus sheath) and ears were kept in the dark from 1 week after anthesis to maturity which reduced grain weight by 22.4% and 59.0%, respectively. In a further experiment, the carbon isotope discrimination ratio (Δ) of ear bracts, awns and flag leaves was measured on samples taken at anthesis and on mature kernels. The mean value of Δ for the water soluble fraction of bracts (17.0‰) and awns (17.7‰) were lower than those of leaves (19.5‰) and fairly similar to those of kernels (17.4‰) averaged across all genotypes. Data indicate that most of the photosynthates in the grain come from ear parts and not from flag leaves. In addition, a higher water use efficiency (WUE) of ear parts than of the flag leaf is suggested by their lower Δ values. Gas exchange in ears and flag leaves was measured during grain filling. Averaged over all genotypes, CO2 diffusive conductance was about five times higher in the flag leaf than in the spike (with distal portions of awns outside the photosynthetic chamber) 2 weeks after anthesis. In absolute terms, the dark respiration rate (Rd) was greater than the net photosynthesis rate (Pn) by a factor of 1.74 in the spike, whereas Rd was much smaller, only 22.1, 65.7 and 24.8% of Pn in blade, sheath and awns, respectively. Data indicate that photosynthesis, and hence the water use efficiency (photosynthesis/transpiration), is greatly underestimated in ears because of the high rates of respiration which diminish the measured rates of net CO2 exchange. Results of 13C discrimination and gas exchange show that genotypes from North Africa have higher WUE than those from the Middle East. The high Rd values of ears as well as their low diffusive conductance suggest that CO2 from respiration may be used as source of carbon for ear photosynthesis. In the same way, the anatomy of glumes, for example, supports the role of bracts using internal CO2 as source of photosynthesis. In the first experiment, the Δ in mature grains from culms with darkened ears compared with control culms provided further evidence in support of this hypothesis. Thus, the Δ from kernels of control plants was 0.40 higher than that from ear-darkened plants, probably because of some degree of refixation (recycling) of respired CO2 in the grains.  相似文献   

10.
Nakamura  T.  Koike  T.  Lei  T.  Ohashi  K.  Shinano  T.  Tadano  T. 《Photosynthetica》1999,37(1):61-70
To find the effects of CO2 enrichment on plant development and photosynthetic capacity of nodulated (line A62-1) and non-nodulated (line A62-2) isogenic lines of soybean (Glycine max Merr.), we examined the interactions among two CO2 treatments (36±3 Pa = AC and 70±5 Pa = EC), and two nitrogen concentrations [0 g(N) m−2(land area) = 0N; 30 g(N) m−2(land area) = 30N]. Nodules were found in both CO2 treatments in 0N of A62-1 where the number and dry mass of nodules increased from AC to EC. While the allocation of dry mass to root and shoot and the amount of N in each organ did not differ between the growth CO2 concentrations, there was larger N allocation to roots in 0N than in 30N for A62-2. The CO2-dependence of net photosynthetic rate (P N) for A62-1 was unaffected by both CO2 and N treatments. In contrast, the CO2-dependence of P N was lower in 0N than in 30N for A62-2, but it was independent of CO2 treatment. P N per unit N content was unaffected by CO2 concentrations. The leaf area of both soybean lines grown in 30N increased in EC. But in 0N, only the nodulated A62-1 showed an increase in leaf area in EC. Nitrogen use efficiency of plants, NUE [(total dry mass of the plant)/(amount of N accumulated in the plant)] in 30N was unaffected by CO2 treatments. In 0N, NUE in EC was lower than in AC in A62-1, and was higher than that at AC in A62-2. Hence, the larger amount and/or rate of N fixation with the increase of the sink-size of symbiotic microorganisms supplied adequate N to the plant under EC. In EC, N deficiency caused the down-regulation of the soybean plant. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

11.
Jiang  D.  Dai  T.  Jing  Q.  Cao  W.  Zhou  Q.  Zhao  H.  Fan  X. 《Photosynthetica》2004,42(3):439-446
Based on a 20-year fertilization experiment with wheat-maize double cropping system, the effects of different long-term fertilization treatments on leaf photosynthetic characteristics and grain yield in different winter wheat (Triticum aestivum L.) cultivars were studied in the growing seasons of 2000–2001 and 2001–2002. A total of nine fertilization treatments were implemented, i.e. no fertilizer (CK), N fertilizer (N), N and P fertilizers (NP), N and K fertilizers (NK), N, P, and K fertilizers (NPK), only organic manure (M), organic manure and N fertilizer (MN), organic manure and N and P fertilizers (MNP), and organic manure and N, P, and K fertilizers (MNPK). With the treatments of combined organic manure and inorganic fertilizers (TMI), net photosynthetic rate (P N), maximal activity of photosystem 2, PS2 (Fv/Fm), and chlorophyll content (SPAD value) of flag leaves and leaf area index (LAI) were much higher at the mid grain filling stage (20 or 23 d post anthesis, DPA), and exhibited slower declines at the late grain filling stage (30 DPA), compared with the treatments of only inorganic fertilizers (TI). The maximal canopy photosynthetic traits expressed as P N×LAI and SPAD×LAI at the mid grain filling stage were also higher in TMI than those in TI, which resulted in different grain yields in TMI and TI. Among the treatments of TMI or among the treatments of TI, both flag leaf and canopy photosynthetic abilities and yield levels increased with the supplement of inorganic nutrients (N, P, and K fertilizers), except for the treatment of NK. Under NK, soil contents of N and K increased while that of P decreased. Hence the unbalanced nutrients in soil from the improper input of nutrients in NK treatment were probably responsible for the reduced flag leaf and canopy photosynthetic characteristics and LAI, and for the fast declining of flag leaf photosynthetic traits during grain filling, resulting in the reduced yield of NK similar to the level of CK.  相似文献   

12.
Singh  Preety  Srivastava  N.K.  Mishra  A.  Sharma  S. 《Photosynthetica》2000,37(4):509-517
Controlled environment chamber and glasshouse studies were conducted on six herbaceous annual species grown at 350 (AC) and 700 (EC) mol(CO2) mol-1 to determine whether growth at EC resulted in acclimation of the apparent quantum yield of photosynthesis (QY) measured at limiting photosynthetic photon flux density (PPFD), or in acclimation of net photosynthetic rate (P N) measured at saturating PPFD. It was also determined whether acclimation in P N at limiting PPFD was correlated with acclimation of carboxylation efficiency or ribulose-1,5-bisphosphate (RuBP) regeneration rate measured at saturating PPFD. Growth at EC reduced both the QY and P N at limiting PPFD in three of the six species. The occurrence of photosynthetic acclimation measured at a rate limiting PPFD was independent of whether photosynthetic acclimation was apparent at saturating measurement PPFD. At saturating measurement PPFD, acclimation to EC in the apparent carboxylation efficiency and RuBP regeneration capacity also occurred independently. Thus at least three components of the photosynthetic system may adjust independently when leaves are grown at EC. Estimates of photosynthetic acclimation at both high and low PPFD are necessary to accurately predict photosynthesis at the whole plant or canopy level as [CO2] increases.  相似文献   

13.
The effects of nitrogen [75 and 150 kg (N) ha−1] and elevated CO2 on growth, photosynthetic rate, contents of soluble leaf proteins and activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and nitrate reductase (NR) were studied on wheat (Triticum aestivum L. cv. HD-2285) grown in open top chambers under either ambient (AC) or elevated (EC) CO2 concentration (350 ± 50, 600 ± 50 μmol mol−1) and analyzed at 40, 60 and 90 d after sowing. Plants grown under EC showed greater photosynthetic rate and were taller and attained greater leaf area along with higher total plant dry mass at all growth stages than those grown under AC. Total soluble and Rubisco protein contents decreased under EC but the activation of Rubisco was higher at EC with higher N supply. Nitrogen increased the NR activity whereas EC reduced it. Thus, EC causes increased growth and PN ability per unit uptake of N in wheat plants, even if N is limiting.  相似文献   

14.
This review concerns ear photosynthesis and its contribution to grain filling in C3 cereals. Ear photosynthesis is quantitatively important to grain filling, particularly in dry areas where source (i.e., assimilate) limitations can occur. Compared to the flag leaf, ear photosynthesis exhibits higher water stress tolerance. Several factors could be involved in the ear's “drought tolerance.” First, although degree of C4 metabolism in ear parts has been reported, current evidence supports only typical C3 metabolism. Second, recycling of respired CO2 (i.e., refixation) could have considerable impact on final crop yield by preventing loss of CO2. Because refixation of CO2 is independent of atmospheric conditions, water use efficiency (measured as total ear photosynthesis divided by transpiration) could be higher in the ear than in the flag leaf. Moreover, ear parts (in particular awns) show higher relative water content and better osmotic adjustment under water stress compared to the flag leaf. This capacity, in addition to persistence of photosynthetic components under drought (delayed senescence), might help the ear to continue to fix CO2 late in the grain filling period.  相似文献   

15.
Drought is a normal, recurrent feature of climate. In order to understand the potential effect of increasing atmospheric CO2 concentration (C a) on ecosystems, it is essential to determine the combined effects of drought and elevated C a (EC) under field conditions. A severe drought occurred in Central Florida in 1998 when precipitation was 88 % less than the average between 1984 and 2002. We determined daytime net ecosystem CO2 exchange (NEE) before, during, and after the drought in the Florida scrub-oak ecosystem exposed to doubled C a in open-top chamber since May 1996. We measured diurnal leaf net photosynthetic rate (P N) of Quercus myrtifolia Willd, the dominant species, during and after the drought. Drought caused a midday depression in NEE and P N at ambient CO2 concentration (AC) and EC. EC mitigated the midday depression in NEE by about 60 % compared to AC and the effect of EC on leaf P N was similar to its effect on NEE. Growth in EC lowered the sensitivity of NEE to air vapor pressure deficit under drought. Thus EC would help the scrub-oak ecosystem to survive the consequences of the effects of rising atmospheric CO2 on climate change, including increased frequency of drought, while simultaneously sequestering more anthropogenic carbon.  相似文献   

16.
Liu  H.Q.  Jiang  G.M.  Zhang  Q.D.  Sun  J.Z.  Guo  R.J.  Gao  L.M.  Bai  K.Z.  Kuang  T.Y. 《Photosynthetica》2002,40(2):237-242
Three winter wheat (Triticum aestivum L.) cultivars, representatives of those widely cultivated in Beijing over the past six decades, were grown in the same environmental conditions. Net photosynthetic rate (P N) per unit leaf area and instantaneous water use efficiency (WUE) of flag leaves increased with elevated CO2 concentration. With an increase in CO2 concentration from 360 to 720 µmol mol–1, P N and WUE of Jingdong 8 (released in 1990s and having the highest yield) increased by 173 and 81 %, while those of Nongda 139 (released in 1970s) increased by 88 and 66 %, and Yanda 1817 (released in 1945, with lowest yield) by 76 and 65 %. Jingdong 8 had the highest P N and WUE values under high CO2 concentration, but Yanda 1817 showed the lowest P N. Stomatal conductance (g s) of Nongda 139 and Yanda 1817 declined with increasing CO2 concentration, but g s of Jingdong 8 firstly went down and then up as the CO2 concentration further increased. Intercellular CO2 concentration (C i) of Jingdong 8 and Nongda 139 increased when CO2 concentration elevated, while that of Yanda 139 increased at the first stage and then declined. Jingdong 8 had the lowest C i of the three wheat cultivars, and Yanda 1817 had the highest C i value under lower CO2 concentrations. However, Jingdong 8 had the highest P N and lowest C i at the highest CO2 concentration which indicates that its photosynthetic potential may be high.  相似文献   

17.
There is continuing controversy over whether a degree of C4 photosynthetic metabolism exists in ears of C3 cereals. In this context, CO2 exchange and the initial products of photosynthesis were examined in flag leaf blades and various ear parts of two durum wheat (Triticum durum Desf.) and two six-rowed barley (Hordeum vulgare L.) cultivars. Three weeks after anthesis, the CO2 compensation concentration at 210 mmol mol?1 O2 in durum wheat and barley ear parts was similar to or greater than that in flag leaves. The O2 dependence of the CO2 compensation concentration in durum wheat ear parts, as well as in the flag leaf blade, was linear, as expected for C3 photosynthesis. In a complementary experiment, intact and attached ears and flag leaf blades of barley and durum wheat were radio-labelled with 14CO2 during a 10s pulse, and the initial products of fixation were studied in various parts of the ears (awns, glumes, inner bracts and grains) and in the flag leaf blade. All tissues assimilated CO2 mainly by the Calvin (C3) cycle, with little fixation of 14CO2 into the C4 acids malate and aspartate (about 10% or less). These collective data support the conclusion that in the ear parts of these C3 cereals C4 photosynthetic metabolism is nil.  相似文献   

18.
Net photosynthetic rate (P N) measured at the same CO2 concentration, the maximum in vivo carboxylation rate, and contents of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (RuBPCO) and RuBPCO activase were significantly decreased, but the maximum in vivo electron transport rate and RuBP content had no significant change in CO2-enriched [EC, about 200 μmol mol−1 above the ambient CO2 concentration (AC)] wheat leaves compared with those in AC grown wheat leaves. Hence photosynthetic acclimation in wheat leaves to EC is largely due to RuBP carboxylation limitation.  相似文献   

19.
The CO2- and H2O-exchanges in the flag leaf and the ear of a spring wheat cultivar (Triticum aestivum L. cv. Arkas) were measured at CO2 partial pressures, pi(CO2), between 8 and 400 Pa under high photosynthetic photon flux densities (2000 μmol m?2 s?1). The experiments were carried out on each organ separately while attached to the intact plant, from the time of ear emergence through senescence. To study the contribution of the kernels to the gas exchange of ears, experiments were also carried out on sterilized ears (treatment A), and on ears from which the kernels were removed (treatment B). Flag leaves and ears differed considerably with regard to CO2-dependence of assimilation, response of stomata to varying pa(CO2), CO2 compensation point (and its temperature dependence), dark respiration, and dissimilation in the light (i.e. CO2 production which is not due to oxygenation of ribulose 1,5-bisphosphate). The higher dark respiration of the ear originated mainly from the kernels and continued to some extent in the light. Thus, the CO2 compensation point was attained at higher CO2 partial pressures for the ear than for the flag leaf. The CO2 uptake of the ear was not saturated at intercellular CO2 partial pressures below 180 Pa CO2, while that of the flag leaf reached saturation at about 80 Pa CO2. CO2-saturated rates of CO2 uptake were 2.5 and 1.5 times the rates at natural CO2 partial pressure for ear and flag leaf, respectively. The stomatal conductance decreased with rising CO2 partial pressure above 35 Pa, in a more pronounced manner for the flag leaf than for the ear.  相似文献   

20.
Increase in both atmospheric CO2 concentration [CO2] and associated warming are likely to alter Earths’ carbon balance and photosynthetic carbon fixation of dominant plant species in a given biome. An experiment was conducted in sunlit, controlled environment chambers to determine effects of atmospheric [CO2] and temperature on net photosynthetic rate (P N) and fluorescence (F) in response to internal CO2 concentration (C i) and photosynthetically active radiation (PAR) of the C4 species, big bluestem (Andropogon gerardii Vitman). Ten treatments were comprised of two [CO2] of 360 (ambient, AC) and 720 (elevated, EC) μmol mol−1 and five day/night temperature of 20/12, 25/17, 30/22, 35/27 and 40/32 °C. Treatments were imposed from 15 d after sowing (DAS) through 130 DAS. Both F-P N/C i and F-P N/PAR response curves were measured on top most fully expanded leaves between 55 and 75 DAS. Plants grown in EC exhibited significantly higher CO2-saturated net photosynthesis (P sat), phosphoenolpyruvate carboxylase (PEPC) efficiency, and electron transport rate (ETR). At a given [CO2], increase in temperature increased P sat, PEPC efficiency, and ETR. Plants grown at EC did not differ for dark respiration rate (R D), but had significantly higher maximum photosynthesis (P max) than plants grown in AC. Increase in temperature increased Pmax, R D, and ETR, irrespective of the [CO2]. The ability of PEPC, ribulose-1,5-bisphosphate carboxylase/oxygenase, and photosystem components, derived from response curves to tolerate higher temperatures (>35 °C), particularly under EC, indicates the ability of C4 species to sustain photosynthetic capacity in future climates.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号