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1.
CO 2 concentrations of 1000 compared to 350 microliters per liter in controlled environment chambers did not increase total fruit weight or number in a monoecious cucumber ( Cucumis sativus L. cv Chipper) nor did it increase biomass, leaf area, or relative growth rates beyond the first 16 days after seeding. Average fruit weight was slightly, but not significantly greater in the 1000 microliters per liter CO 2 treatment because fruit numbers were changed more than total weight. Plants grown at 1000 and 350 microliters per liter CO 2 were similar in distribution of dry matter and leaf area between mainstem, axillary, and subaxillary branches. Early flower production was greater in 1000 microliters per liter plants. Subsequent flower numbers were either lower in enriched plants or similar in the two treatments, except for the harvest at fruiting when enriched plants produced many more male flowers than the 350 microliters per liter treatments. 相似文献
2.
The effect of sink strength on photosynthetic rates under conditions of long-term exposure to high CO 2 has been investigated in soybean. Soybean plants (Merr. cv. Fiskeby V) were grown in growth chambers containing 350 microliters CO 2 per liter air until pod set. At that time, plants were trimmed to three trifoliolate leaves and either 21 pods (high sink treatment) or 6 pods (low sink treatment). Trimmed plants were either left in 350 microliters CO 2 per liter of air or placed in 1000 microliters CO 2 per liter of air (high CO 2 treatment) until pod maturity. Whole plant net photosynthetic rates of all plants were measured twice weekly, both at 350 microliters CO 2 per liter of air and 1000 microliters CO 2 per liter of air. Plants were also harvested at this time for dry weight measurements. Photosynthetic rates of high sink plants at both measurement CO 2 concentrations were consistently higher than those of low sink plants, and those of plants given the 350 microliter CO 2 per liter of air treatment were higher at both measurement CO 2 concentrations than those of plants given the 1000 microliters CO 2 per liter of air treatment. When plants were measured under treatment CO 2 levels, however, rates were higher in 1,000 microliter plants than 350 microliter CO 2 plants. Dry weights of all plant parts were higher in the 1,000 microliters CO 2 per liter air treatment than in the 350 microliters CO 2 per liter air treatment, and were higher in the low sink than in the high sink treatments. 相似文献
3.
Carbon exchange capacity of cucumber ( Cucumis sativus L.) germinated and grown in controlled environment chambers at 1000 microliters per liter CO 2 decreased from the vegetative growth stage to the fruiting stage, during which time capacity of plants grown at 350 microliters per liter increased. Carbon exchange rates (CERs) measured under growth conditions during the fruiting period were, in fact, lower in plants grown at 1000 microliters per liter CO 2 than those grown at 350. Progressive decreases in CERs in 1000 microliters per liter plants were associated with decreasing stomatal conductances and activities of ribulose bisphosphate carboxylase and carbonic anhydrase. Leaf starch concentrations were higher in 1000 microliters per liter CO 2 grown-plants than in 350 microliters per liter grown plants but calcium and nitrogen concentrations were lower, the greatest difference occurring at flowering. Sucrose synthase and sucrose-P-synthase activities were similar in 1000 microliters per liter compared to 350 microliters per liter plants during vegetative growth and flowering but higher in 350 microliters per liter plants at fruiting. The decreased carbon exchange rates observed in this cultivar at 1000 microliters per liter CO 2 could explain the lack of any yield increase (MM Peet 1986 Plant Physiol 80: 59-62) when compared with plants grown at 350 microliters per liter. 相似文献
4.
For the leaf succulent Agave deserti and the stem succulent Ferocactus acanthodes, increasing the ambient CO 2 level from 350 microliters per liter to 650 microliters per liter immediately increased daytime net CO 2 uptake about 30% while leaving nighttime net CO 2 uptake of these Crassulacean acid metabolism (CAM) plants approximately unchanged. A similar enhancement of about 30% was found in dry weight gain over 1 year when the plants were grown at 650 microliters CO 2 per liter compared with 350 microliters per liter. Based on these results plus those at 500 microliters per liter, net CO 2 uptake over 24-hour periods and dry weight productivity of these two CAM succulents is predicted to increase an average of about 1% for each 10 microliters per liter rise in ambient CO 2 level up to 650 microliters per liter. 相似文献
5.
The response of whole-canopy net CO 2 exchange rate (CER) and canopy architecture to CO 2 enrichment and N stress during 1996 and 1997 for open-field-grown wheat ecosystem ( Triticum aestivum L. cv. Yecora Rojo) are described. Every Control (C) and FACE (F) CO 2 treatment (defined as ambient and ambient +200 μmol mol −1, respectively) contained a Low- and High-N treatment. Low-N treatments constituted initial soil content amended with supplemental
nitrogen applied at a rate of 70 kg N ha −1 (1996) and 15 kg N ha −1 (1997), whereas High-N treatments were supplemented with 350 kg N ha −1 (1996 and 1997). Elevated CO 2 enhanced season-long carbon accumulation by 8% and 16% under Low-N and High-N, respectively. N-stress reduced season-long
carbon accumulation 14% under ambient CO 2, but by as much as 22% under CO 2 enrichment. Averaging both years, green plant area index (GPAI) peaked approximately 76 days after planting at 7.13 for FH,
6.00 for CH, 3.89 for FL, and 3.89 for CL treatments. Leaf tip angle distribution (LTA) indicated that Low-N canopies were
more erectophile than those of High-N canopies: 48° for FH, 52° for CH, and 58° for both FL and CL treatments. Temporal trends
in canopy greenness indicated a decrease in leaf chlorophyll content from the flag to flag-2 leaves of 25% for FH, 28% for
CH, 17% for CL, and 33% for FL during 1997. These results indicate that significant modifications of canopy architecture occurs
in response to both CO 2 and N-stress. Optimization of canopy architecture may serve as a mechanism to diminish CO 2 and N-stress effects on CER.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Numerous net photosynthetic and dark respiratory measurements were made over a period of 4 years on leaves of 24 sour orange ( Citrus aurantium) trees; 8 of them growing in ambient air at a mean CO 2 concentration of 400 microliters per liter, and 16 growing in air enriched with CO 2 to concentrations approaching 1000 microliters per liter. Over this CO 2 concentration range, net photosynthesis increased linearly with CO 2 by more than 200%, whereas dark respiration decreased linearly to only 20% of its initial value. These results, together with those of a comprehensive fine-root biomass determination and two independent aboveground trunk and branch volume inventories, suggest that a doubling of the air's current mean CO 2 concentration of 360 microliters per liter would enhance the growth of the trees by a factor of 3.8. 相似文献
7.
Growth at an elevated CO 2 concentration resulted in an enhanced capacity for soybean ( Glycine max L. Merr. cv Bragg) leaflet photosynthesis. Plants were grown from seed in outdoor controlled-environment chambers under natural solar irradiance. Photosynthetic rates, measured during the seed filling stage, were up to 150% greater with leaflets grown at 660 compared to 330 microliters of CO 2 per liter when measured across a range of intercellular CO 2 concentrations and irradiance. Soybean plants grown at elevated CO 2 concentrations had heavier pod weights per plant, 44% heavier with 660 compared to 330 microliters of CO 2 per liter grown plants, and also greater specific leaf weights. Ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) activity showed no response (mean activity of 96 micromoles of CO 2 per square meter per second expressed on a leaflet area basis) to short-term (~1 hour) exposures to a range of CO 2 concentrations (110-880 microliters per liter), nor was a response of activity (mean activity of 1.01 micromoles of CO 2 per minute per milligram of protein) to growth CO 2 concentration (160-990 microliters per liter) observed. The amount of rubisco protein was constant, as growth CO 2 concentration was varied, and averaged 55% of the total leaflet soluble protein. Although CO 2 is required for activation of rubisco, results indicated that within the range of CO 2 concentrations used (110-990 microliters per liter), rubisco activity in soybean leaflets, in the light, was not regulated by CO 2. 相似文献
8.
The relationship between net photosynthesis and CO 2 concentration was investigated for four species of lichen using an infrared gas analyzer operating in a closed loop system. All species showed a linear relationship at low CO 2 levels (100 microliters per liter) with CO 2 saturation levels being in excess of 400 microliters per liter. Detailed studies of Sticta latifrons showed a strong influence of thallus water content which resulted in the net photosynthetic response at high water contents still being nearly linear at 1000 microliters per liter CO 2. Very low CO 2 compensation values (5 microliters per liter) were obtained under some conditions but the value varied between thalli and with thallus water content. The results differ from previous studies which reported low CO 2 saturation levels (200 microliters per liter) and no apparent effect of water content. It is suggested that some of these differences may result from the use of a discrete sampling injection infrared gas analyzer system in the earlier studies and an assessment is made of the influence of nonsaturating CO 2 levels, lack of cuvette ventilation, and data presentation for this technique. 相似文献
9.
One-year-old dormant white oak ( Quercus alba L.) seedlings were planted in a nutrient-deficient forest soil and grown for 40 weeks in growth chambers at ambient (362 microliters per liter) or elevated (690 microliters per liter) levels of CO 2. Although all of the seedlings became severely N deficient, CO 2 enrichment enhanced growth by 85%, with the greatest enhancement in root systems. The growth enhancement did not increase the total water use per plant, so water-use efficiency was significantly greater in elevated CO 2. Total uptake of N, S, and B was not affected by CO 2, therefore, tissue concentrations of these nutrients were significantly lower in elevated CO 2. An increase in nutrient-use efficiency with respect to N was apparent in that a greater proportion of the limited N pool in the CO 2-enriched plants was in fine roots and leaves. The uptake of other nutrients increased with CO 2 concentration, and P and K uptake increased in proportion to growth. Increased uptake of P by plants in elevated CO 2 may have been a result of greater proliferation of fine roots and associated mycorrhizae and rhizosphere bacteria stimulating P mineralization. The results demonstrate that a growth response to CO 2 enrichment is possible in nutrient-limited systems, and that the mechanisms of response may include either increased nutrient supply or decreased physiological demand. 相似文献
10.
Greenhouse-grown plants of Xanthium strumarium L. were exposed in a growth cabinet to 10 C during days and 5 C during nights for periods of up to 120 hours. Subsequently, CO 2 exchange, transpiration, and leaf temperature were measured on attached leaves and in leaf sections at 25 or 30 C, 19 C dew point of the air, 61 milliwatts per square centimeter irradiance, and CO 2 concentrations between 0 and 1000 microliters per liter ambient air. Net photosynthesis and stomatal conductance decreased and dark respiration increased with increasing duration of prechilling. The reduction in net photosynthesis was not a consequence of decreased stomatal conductance because the intercellular CO 2 concentration in prechilled leaves was equal to or greater than that in greenhouse-grown controls. The intercellular CO 2 concentration at which one-half maximum net photosynthesis occurred remained the same in prechilled leaves and controls (175 to 190 microliters per liter). Stomata of the control plants responded to changes in the CO 2 concentration of the air only slightly. Prechilling for 24 hours or more sensitized stomata to CO 2; they responded to changes in CO 2 concentration in the range from 100 to 1000 microliters per liter. 相似文献
11.
Young bean plants ( Phaseolus vulgaris L. cv Seafarer) grew faster in air enriched with CO 2 (1200 microliters per liter) than in ambient CO 2 (330 microliters per liter). However, by 7 days when increases in overall growth (dry weight, leaf area) were visible, there was a significant decline (about 25%) in the leaf mineral content (N, P, K, Ca, Mg) and a drop in the activity of two enzymes of carbon fixation, carbonic anhydrase and ribulose 1,5-bisphosphate (RuBP) carboxylase under high CO 2. Although the activity of neither enzyme was altered in young, expanding leaves during the acclimation period, in mature leaves the activity of carbonic anhydrase was reduced 95% compared with a decline of 50% in ambient CO 2. The drop in RuBP carboxylase was less extreme with 40% of the initial activity retained in the high CO 2 compared with 50% in the ambient atmosphere. While CO 2 enrichment might alter the flow of carbon into the glycolate pathway by modifying the activities of carbonic anhydrase or RuBP carboxylase, there is no early change in the ability of photosynthetic tissue to oxidize glycolate to CO 2. 相似文献
12.
Water hyacinth ( Eichhornia crassipes [Mart.] Solms) plants were grown in environmental chambers at ambient and enriched CO 2 levels (330 and 600 microliters CO 2 per liter). Daughter plants (ramets) produced in the enriched CO 2 gained 39% greater dry weight than those at ambient CO 2, but the original mother plants did not. The CO 2 enrichment increased the number of leaves per ramet and leaf area index, but did not significantly increase leaf size or the number of ramets formed. Flower production was increased 147%. The elevated CO 2 increased the net photosynthetic rate of the mother plants by 40%, but this was not maintained as the plants acclimated to the higher CO 2 level. After 14 days at the elevated CO 2, leaf resistance increased and transpiration decreased, especially from the adaxial leaf surface. After 4 weeks in elevated as compared to ambient CO 2, ribulose bisphosphate carboxylase activity was 40% less, soluble protein content 49% less, and chlorophyll content 26% less; whereas starch content was 40% greater. Although at a given CO 2 level the enriched CO 2 plants had only half the net photosynthetic rate of their counterparts grown at ambient CO 2, they showed similar internal CO 2 concentrations. This suggested that the decreased supply of CO 2 to the mesophyll, as a result of the increased stomatal resistance, was counterbalanced by a decreased utilization of CO 2. Photorespiration and dark respiration were lower, such that the CO 2 compensation point was not altered. The photosynthetic light and CO 2 saturation points were not greatly changed, nor was the O 2 inhibition of photosynthesis (measured at 330 microliters CO 2 per liter). It appears that with CO 2 enrichment the temporary increase in net photosynthesis produced larger ramets. After acclimation, the greater total ramet leaf area more than compensated for the lower net photosynthetic rate on a unit leaf area basis, and resulted in a sustained improvement in dry weight gain. 相似文献
13.
Numerous photosynthesis and growth measurements of sour orange ( Citrus aurantium L.) trees maintained in ambient air and air enriched with an extra 300 microliters per liter of CO 2 have revealed the CO 2-enriched trees to have consistently sequestered approximately 2.8 times more carbon than the control trees over a period of three full years. Under field conditions in the natural environment, plants may not experience the downward regulation of photosynthetic capacity typically observed in long-term CO 2 enrichment experiments with plants growing in pots. 相似文献
14.
The combined effects of inorganic phosphate (Pi) insufficiency and CO 2 enrichment on metabolite levels and carbon partitioning were studied using roots of 9-, 13- and 17-day-old barley seedlings ( Hordeum vulgare L. cv. Brant). Plants were grown from seed in controlled environment chambers providing 36 ± 1 Pa (ambient) or 100 ± 2 Pa (elevated) CO 2 and either 1.0 m M (Pi sufficient) or 0.05 m M (Pi insufficient) Pi. When values were combined for both Pi treatments, plants grown under enhanced CO 2 showed increased root dry matter, adenylates (ATP + ADP), glutamine and non- structural carbohydrates other than starch. In contrast with shoots, enhanced CO 2 partially reversed the inhibition of root dry matter formation imposed by Pi insufficiency. The Pi-insufficient treatment also increased sucrose, glucose and fructose levels in barley roots. The Pi and CO 2 treatments were additive, so that the highest soluble carbohydrate levels were observed in roots of Pi-insufficient plants from the elevated CO 2 treatment. Pi limitation decreased dry matter formation, acid-extractable Pi, nitrate, hexose-phosphates, glutamate, glutamine and acid invertase activity of barley roots in plants grown in both ambient and elevated CO 2. Adenylate levels in roots were unaffected by the moderate Pi insufficiency described here. Thus, the reduced hexose-phosphate levels of Pi-insufficient roots were not likely to be the result of low adenylate concentrations. The above results suggest that the capacity of barley roots to utilize carbohydrates from the shoot is inadequate under both Pi-insufficient and CO 2-enriched treatments. In addition, the Pi and CO 2 treatments used here alter the nitrogen metabolism of barley roots. These findings further emphasize the importance of avoiding nutrient stress during CO 2 enrichment experiments. 相似文献
15.
Experiments are described further indicating that O 2-resistant photosynthesis observed in a tobacco ( Nicotiana tabacum) mutant with enhanced catalase activity is associated with decreased photorespiration under conditions of high photorespiration relative to net photosynthesis. The effects on net photosynthesis of (a) increasing O 2 concentrations from 1% to 42% at low CO 2 (250 microliters CO 2 per liter), and (b) of increasing O 2 concentrations from 21% to 42% at high CO 2 (500 microliters CO 2 per liter) were investigated in M 6 progeny of mutant and wild-type leaf discs. The mutant displayed a progressive increase in net photosynthesis relative to wild type with increasing O 2 and the faster rate at 42% O 2 was completely reversed on returning to 21% O 2. The photosynthetic rate by the mutant was similar to wild type in 21% and 42% O 2 at 500 microliters CO 2 per liter, and a faster rate by the mutant was restored on returning to 250 microliters CO 2 per liter. The results are consistent with a lowered release of photorespiratory CO 2 by the mutant because greater catalase activity inhibits the chemical decarboxylation of α-keto acids by peroxisomal H 2O 2. Higher catalase activity was observed in the tip and middle regions of expanding leaves than in the basal area. On successive selfing of mutant plants with enhanced catalase activity, the percent of plants with this phenotype increased from 60% in M 4 progeny to 85% in M 6 progeny. An increase was also observed in the percent of plants with especially high catalase activity (averaging 1.54 times wild type) on successive selfings suggesting that homozygosity for enhanced catalase activity was being approached. 相似文献
16.
Cotton ( Gossypium hirsutum L. cv Stoneville 213) was grown at 350 and 1000 microliters per liter CO 2. The plants grown at elevated CO 2 concentrations contained large starch pools and showed initial symptoms of visible physical damage. Photosynthetic rates were lower than expected based on instantaneous exposure to high CO 2. A group of plants grown at 1000 microliters per liter CO2 was switched to 350 microliters per liter CO2. Starch pools and photosynthetic rates were monitored in the switched plants and in the two unswitched control groups. Photosynthetic rates per unit leaf area recovered to the level of the 350 microliters per liter CO2 grown control group within four to five days. To assess only nonstomatal limitations to photosynthesis, a measure of photosynthetic efficiencies was calculated (moles CO2 fixed per square meter per second per mole intercellular CO2). Photosynthetic efficiency also recovered to the levels of the 350 microliters per liter CO2 grown controls within three to four days. Recovery was correlated to a rapid depletion of the starch pool, indicating that the inhibition of photosynthesis is primarily a result of feedback inhibition. However, complete recovery may involve the repair of damage to the chloroplasts caused by excessive starch accumulation. The rapid and complete reversal of photosynthetic inhibition suggests that the appearance of large, strong sinks at certain developmental stages could result in reduction of the large starch accumulations and that photosynthetic rates could recover to near the theoretical capacity during periods of high photosynthate demand. 相似文献
17.
A technique is described for the measurement of total dissolved inorganic carbon by acid release as CO 2 followed by its conversion to methane and detection by flame ionization in a modified gas chromatograph. This method was used to determine the dissolved inorganic carbon concentration reached at compensation point when algae were allowed to photosynthesize in a closed system in a buffer at known pH, and the CO 2 compensation point was calculated from this concentration. The CO 2 compensation points of 16 freshwater algae were measured at acid and alkaline pH in air-saturated medium: at acid pH the CO 2 compensation points ranged from 4.8 to 41.5 microliters per liter while at alkaline pH they ranged from 0.2 to 7.2 microliters per liter. Removal of O 2 from the medium caused a slight lowering of compensation point at acid pH but had little effect at alkaline pH. These low, O 2-insensitive compensation points are characteristic of C 4 plants. It is suggested that these low CO 2 compensation points are maintained by an active bicarbonate uptake by algae especially at alkaline pH. 相似文献
18.
Unidirectional O 2 fluxes were measured with 18O 2 in a whole plant of wheat cultivated in a controlled environment. At 2 or 21% O 2, O 2 uptake was maximum at 60 microliters per liter CO 2. At lower CO 2 concentrations, it was strongly inhibited, as was photosynthetic O 2 evolution. At 2% O 2, there remained a substantial O 2 uptake, even at high CO 2 level; the O 2 evolution was inhibited at CO 2 concentrations under 330 microliters per liter. The O 2 uptake increased linearly with light intensity, starting from the level of dark respiration. No saturation was observed at high light intensities. No significant change in the gas-exchange patterns occurred during a long period of the plant life. An adaptation to low light intensities was observed after 3 hours illumination. These results are interpreted in relation to the functioning of the photosynthetic apparatus and point to a regulation by the electron acceptors and a specific action of CO 2. The behavior of the O 2 uptake and the study of the CO 2 compensation point seem to indicate the persistence of mitochondrial respiration during photosynthesis. 相似文献
19.
The effects of water stress and CO 2 enrichment on photosynthesis, assimilate export, and sucrose-P synthase activity were examined in field grown soybean plants. In general, leaves of plants grown in CO 2-enriched atmospheres (300 microliters per liter above unenriched control, which was 349 ± 12 microliters per liter between 0500 and 1900 hours EST over the entire season) had higher carbon exchange rates (CER) compared to plants grown at ambient CO 2, but similar rates of export and similar activities of sucrose-P synthase. On most sample dates, essentially all of the extra carbon fixed as a result of CO 2 enrichment was partitioned into starch. CO 2-enriched plants had lower transpiration rates and therefore had a higher water use efficiency (milligrams CO 2 fixed per gram H 2O transpired) per unit leaf area compared to nonenriched plants. Water stress reduced CER in nonenriched plants to a greater extent than in CO 2-enriched plants. As CER declined, stomatal resistance increased, but this was not the primary cause of the decrease in assimilation because internal CO 2 concentration remained relatively constant. Export of assimilates was less affected by water stress than was CER. When CERs were low as a result of the imposed stress, export was supported by mobilization of reserves (mainly starch). Export rate and leaf sucrose concentration were related in a curvilinear manner. When sucrose concentration was above about 12 milligrams per square decimeter, obtained with nonstressed plants at high CO 2, there was no significant increase in export rate. Assimilate export rate was also correlated positively with SPS activity and the quantitative relationship varied with CER. Thus, export rate was a function of both CER and carbon partitioning. 相似文献
20.
Carbon and nitrogen limitations on symbiotically grown soybean seedlings ( Glycine max [L.] Merr.) were assessed by providing 0.0, 1.0, or 8.0 millimolar NH 4NO 3 and 320 or 1,000 microliters CO 2/liter for 22 days after planting. Maximum development of the Rhizobium-soybean symbiosis, as determined by acetylene reduction, was measured in the presence of 1.0 millimolar NH 4NO 3 under both levels of CO 2. Raising NH 4NO 3 from 0.0 to 8.0 millimolar under 320 microliters CO 2/liter increased plant dry weight by 251% and Kjeldahl N content by 287% at 22 days after planting. Increasing NH 4NO 3 from 1.0 to 8.0 millimolar under 320 microliters CO 2/liter increased total dry weight and Kjeldahl N by 100 and 168%, respectively, on day 22. Raising CO 2 from 320 to 1,000 microliters CO 2/liter during the same period had no significant effect on Kjeldahl N content of plants grown with 0.0 or 1.0 millimolar NH 4NO 3. The maximum CO 2 treatment effects were observed in plants supplied with 8.0 millimolar NH 4NO 3, where dry weight and Kjeldahl N content were increased 64% and 20%, respectively. An increase in shoot CO 2-exchange rate associated with the CO 2-enrichment treatment was reflected in a significant increase in leaf dry weight and starch content for plants grown with 1,000 microliters CO 2/liter under all combined N treatments. These data show directly that seedling growth in symbiotically grown soybeans was limited primarily by N availability. The failure of the CO 2-enrichment treatment to increase total plant N significantly in Rhizobium-dependent plants indicates that root nodule development and functioning in such plants was not limited by photosynthate production. 相似文献
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