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1.
《Journal of Asia》2022,25(3):101963
Biological control of larval mosquitoes is in great demand due to the development of resistance against synthetic insecticides, environmental toxicity and the inability to protect habitats from further oviposition. In the present study, three botanical essential oils (BEOs) – citronella, eucalyptus, and pine oils – were formulated for the assessment of larvicidal and oviposition repellent efficacies against Culex quinquefasciatus Say, the filaria vector. The GC–MS profiling of BEOs showed the presence of 16 – 19 compounds covering 87.7–93% of oil composition. The resistance status of Culex quinquefasciatus population was evaluated with temephos (LC50 = 0.001 ppm, LC90 = 0.01 ppm). Larval bioassay of emulsifiable concentrate (EC) formulations prepared from eucalyptus and pine oils showed promising efficacy (LC50 = 22.7 and 23.2 ppm) and LC90 (63.8 and 62.4 ppm) compared to citronella oil EC (LC50 = 43.4 ppm and LC90 = 199.0 ppm). The field trials of eucalyptus + pine (1:1 ratio) EC showed 100% larval mortality for 3 weeks at 300 ppm compared to 2 weeks of individual oils. Further, the oviposition attraction index (OAI) for ECs of eucalyptus, pine, and their combination showed complete protection of breeding habitats from oviposition at 1st week and ?0.9 to ?1.0 OAI at 2nd week with slight reduction to ?0.5 at 3rd week. Citronella EC provided shortest larvicidal and oviposition repellent efficacy under the field conditions. The promising mosquitocidal activities of EC formulations of eucalyptus and pine or their combination suggest them as potential biocontrol vector control candidates over citronella oil. 相似文献
2.
科尔沁沙地草地营造樟子松人工林对土壤化学和生物学性状的影响 总被引:3,自引:1,他引:2
以科尔沁沙地东南缘沙质草地和不同年龄樟子松(Pinus sylvestris var. mongolica)人工林(15、24和30年生)为对象,研究草地造林对土壤pH,土壤C、N、P含量,无机N(铵态氮、硝态氮)含量,C、N矿化速率,微生物生物量C含量以及土壤酶(脲酶、转化酶和过氧化氢酶)活性的影响.结果表明:草地造林初期,林地土壤C、N、P含量逐渐降低,随着林龄增加而逐渐恢复;与草地相比,24年生樟子松人工林土壤C、N、P含量最低,分别下降29%、34%和33%,而30年生樟子松人工林土壤C和N含量与草地差异不显著.草地造林能够影响土壤无机N存在形式,使土壤铵态氮含量逐渐增加,硝态氮含量下降.草地造林对土壤潜在N矿化速率和硝化速率影响不显著,但能够改变土壤C矿化速率,不同林龄樟子松人工林土壤C矿化速率依次为:24年生>30年生>草地>15年生.草地造林初期,土壤微生物生物量C含量和土壤转化酶活性明显降低,随着林龄的增加又逐渐增加;草地造林对土壤脲酶活性影响不显著,而使土壤过氧化氢酶活性逐渐增加.科尔沁沙地草地造林能够显著改变土壤化学和生物学性状,且随着林龄的变化而有所差异. 相似文献
3.
Zheng Shi Yiqing Li Shaojun Wang Guobing Wang Honghua Ruan Rong He Yanfei Tang Zengxin Zhang 《Ecological Research》2009,24(6):1257-1265
Soil respiration (R
s) is an important component of the carbon cycle in terrestrial ecosystems, and changes in soil respiration with land cover
alteration can have important implications for regional carbon balances. In southeastern China (Xiashu Experimental Forest,
Jiangsu Province), we used an automated LI-8100 soil CO2 flux system to quantify diurnal variation of soil respiration in a secondary oak forest and a pine plantation. We found that
soil respiration in the pine plantation was significantly higher than that in the secondary oak forest. There were similar
patterns of soil respiration throughout the day in both the secondary oak forest and the pine plantation during our 7-month
study (March–September 2005). The maximum of R
s occurred between 4:00 pm and 7:00 pm. The diurnal variations of R
s were usually out of phase with soil surface (0.5 cm) temperature (T
g). However, annual variation in R
s correlated with surface soil temperature. Soil respiration reached to a maximum in June, and decreased thereafter. The Q10 of R
s in the secondary oak forest was significantly higher than that in the pine plantation. The higher Q10 value in the secondary oak forest implied that it might release more CO2 than the pine plantation under a global-warming scenario. Our results indicated that land-use change from secondary forest
to plantation may cause a significant increase in CO2 emission, and reduce the temperature sensitivity of soil respiration in southeastern China. 相似文献
4.
Aluminum and iron chemistry in the O horizon changed by a shift in tree species composition 总被引:2,自引:0,他引:2
In the present study we characterized the buffering system including aluminum in the organic surface horizon (O) of field experiments with replicated plots of pure Norway spruce (Picea abies (L.) Karst) and replicated plots of spruce with a birch (Betula pendula Roth and B. pubescens Ehrh.) admixture. Our results show that a change in tree species composition may have a rather large, short-term (12 years) effect on the concentration of organically bound aluminum in the humus layer (H) of the O horizon. The pure spruce plots had a significantly higher concentration of exchangeable aluminum (Ale) and organically bound (pyrophosphate extractable) aluminum (AlP) in the H layer and a lower concentration of each base cation. Furthermore, our results confirm earlier findings that aluminum has base cation properties in acidic organic horizons. Thus, the change in tree species composition did not affect the pH in spite of a change in base saturation, because base cations were mainly compensated for by aluminum. The change in organically bound aluminum was accompanied by a similar change in organically bound pyrophosphate extractable iron (FeP). The observed differences between the mixed and pure spruce plots in the amounts of AlP and FeP in the H layer could not be explained by estimated differences in biocycling of Al and Fe either by above-ground litterfall or by root turnover. 相似文献
5.
Seedlings of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, and ponderosa pine, Pinus ponderosa Dougl. ex Laws., were grown in a controlled environment and fertilized with nutrient solutions containing 150 ppm (+N), or
0 ppm nitrogen (−N). These treatments greatly altered seedling growth, and the concentrations of N and carbohydrates in their
tissues. Metabolically active tissues, such as roots, incubated with a limited supply of O2 became hypoxic faster and synthesized more ethanol than less active tissues, such as needles. All tissues that were incubated
for 4 h in N2 synthesized ethanol. Needles incubated in N2 and light had much lower quantities of ethanol than needles in N2 and dark, suggesting that O2 from photosynthetsis limited internal anoxia. Most tissues from +N seedlings synthesized greater quantities of ethanol in
N2 anoxia than tissues from −N seedlings, probably because they were able to produce more enzymes with a greater availability
of N. However, this increase in ethanol synthesis between N treatments was most pronounced in the phloem. Ethanol and soluble
sugar concentrations were negatively related in needles and positively related in roots of N+ seedlings, but not −N seedlings.
Starch concentrations had no effect on the amount of ethanol produced by any tissue. Regardless of N treatments, all tissues
from ponderosa pine produced more N2-induced ethanol than Douglas-fir, in part because its tissues contained different concentrations of soluble sugars and N
as a consequence of phenological differences between the species. However, ponderosa pine tissues may also maintain greater
quantities of anaerobic enzymes, or their isozymes than Douglas-fir.
Received: 22 February 1998 / Accepted 23 June 1998 相似文献
6.
《Phytochemistry》1987,26(6):1627-1630
Biosynthesis of polar lipids (phospho- and glycolipids) from [1-14C]acetate was observed in mature needles from hydroponically grown jack pine seedlings. Treatment of the seedlings with vanadium (V) or nickel (Ni) produced marked concentration-dependent inhibitions in the biosynthesis of all polar lipids. Nickel appeared to be more inhibitory than V at 10 ppm. Fumigation of seedlings with gaseous SO2 (0.34 ppm) also resulted in reduced biosynthesis of polar lipids. Combined treatment of plant seedlings with metal (V or Ni) and SO2 produced inhibitory effects that were very similar to those produced by metal alone; however, SO2 did produce an additive inhibitory effect at 10 ppm V. 相似文献
7.
George Nakos 《Plant and Soil》1979,53(4):427-443
Summary Chemical analysis of samples of needles of Aleppo pine (Pinus halepensis), humus and mineral soil collected in the vicinity of the Pb-smelter in Lavrion, Attica, showed that an area of about 2 km around the smelter is heavily polluted primarily with Pb and also with Zn, S and F–. Most of the Pb was found accumulated in the humus and the top layer of the mineral soil.About 50% of the Pb found in the samples of Aleppo pine needles could be removed by washing them in a dilute detergent solution. One and 15% of the total Pb from Pb-polluted soil and humus samples, respectively, was extracted with normal ammonium acetate solution. No Pb or a very small amount was extracted with distilled H2O from humus and soil samples treated with concentrations of Pb as high as 3000 ppm and incubated in the laboratory for 30 days.Humus samples treated with up to 1500 ppm Pb or Pb-polluted humus samples collected from points leeward of the smelter had no adverse effects on the germination of Aleppo pine seeds. When the germination experiment was conducted on Pb-polluted humus samples from points windward of the smelter, where a temporary pine needle death had been observed, the percentage seed germination, for two years, was found reduced and negatively correlated to the distance of the humus sampling point from the Pb-smelter.In nursery experiments Pb concentrations of up to 2000 ppm, added to a calcareous soil, had no adverse effect on height increase of Aleppo pine seedlings. Very little Pb was transported from the roots to the needles after seven months growth of the seedlings on either Pb-amended soil or on Pb-polluted soil from Lavrion. Concentrations of Pb in the roots of the seedlings, however, were found high in both cases and almost proportional to concentrations of Pb in the soil. 相似文献
8.
Morphology and tissue quality of seedling root systems of Pinus taeda and Pinus ponderosa as affected by varying CO2, temperature,and nitrogen 总被引:2,自引:0,他引:2
Rising atmospheric carbon dioxide, nitrogen deposition and warmer temperatures may alter the quantity and quality of plant-derived organic matter available to soil biota, potentially altering rates of belowground herbivory and decomposition. Our objective was to simulate future growth conditions for an early successional (loblolly) and late successional (ponderosa) species of pine to determine if the physical and chemical properties of the root systems would change. Seedlings were grown for 160 days in greenhouses at the Duke University Phytotron at 35 or 70 Pa CO2 partial pressure, ambient or ambient + 5 °C temperature, and 1 or 5 mMNH4O3. Roots from harvested seedlings were analyzed for changes in surface area, specific root length, mass, total nonstructural carbohydrates (TNC), and concentrations of macro-nutrients. Surface area increased in both species under elevated CO2, due primarily to increases in root length, and this response was greatest (+138%) in loblolly pine at high temperature. Specific root length decreased in loblolly pine at elevated CO2 but increases in mass more than compensated for this, resulting in net increases in total length. TNC was unaffected and nutrient concentrations decreased only slightly at elevated CO2, possibly from anatomical changes to the root tissues. We conclude that future growth conditions will enhance soil exploration by some species of pine, but root carbohydrate levels and nutrient concentrations will not be greatly affected, leaving rates of root herbivory and decomposition unaltered. 相似文献
9.
Effects of elevated atmospheric carbon dioxide (CO2) levels on the production and spread of ectomycorrhizal fungal mycelium from colonised Scots pine roots were investigated. Pinus sylvestris (L.) Karst. seedlings inoculated with either Hebeloma crustuliniforme (Bull:Fr.) Quél. or Paxillus involutus (Fr.) Fr. were grown at either ambient (350 ppm) or elevated (700 ppm) levels of CO2. Mycelial production was measured after 6 weeks in pots, and mycelial spread from inoculated seedlings was studied after 4 months growth in perlite in shallow boxes containing uncolonised bait seedlings. Plant and fungal biomass were analysed, as well as carbon and nitrogen content of seedling shoots. Mycelial biomass production by H. crustuliniforme was significantly greater under elevated CO2 (up to a 3-fold increase was observed). Significantly lower concentrations and total amounts of N were found in plants exposed to elevated CO2. 相似文献
10.
Hypocotyl segments, 5 to 8 mm length from 4 to 7 day old seedlings, callused on B5 medium supplemented with Kn (0.5 ppm) and NAA (0.1 ppm). Even without transfer, shoots were formed in such cultures. About 20% of the cultures produced multiple shoots. In medium with 1 ppm each of Kn and NAA direct shoots were formed at one end of the hypocotyl segment and callusing was initiated at the other end. The plants obtained in either medium formed roots and could be transferred to soil for further growth.Abbreviations BA
benzyladenine
- 2,4-D
2,4-dichlorophenoxy acetic acid
- GA3
gibberellic acid
- Kn
Kinetin
- NAA
naphthalene acetic acid 相似文献
11.
Induction of nitrate uptake and nitrate reductase activity in trembling aspen and lodgepole pine 总被引:3,自引:0,他引:3
X. Min M. Y. Siddiqi R. D. Guy A. D. M. Glass & H. J. Kronzucker 《Plant, cell & environment》1998,21(10):1039-1046
13NO3– influx into the roots and in vivo nitrate reductase activity (NRA) in the roots and leaves have been measured in trembling aspen (Populus tremuloides Michx.) and lodgepole pine (Pinus contorta Dougl.) seedlings after exposure to either 0·1 or 1·5 mol m–3 NO3– for varying periods up to 20 d. Both NO3– influx and NRA were inducible in these species and, in trembling aspen, peak induction of nitrate influx and NRA were achieved within 12 h, compared to 2–4 d for influx and 4–12 d for NRA in lodgepole pine. In trembling aspen, ≈ 30% of the total 13N absorbed during a 10 min influx period followed by 2 min of desorption was translocated to the shoot. In lodgepole pine, by contrast, translocation of 13N to the shoot was undetectable during the same time period. Root NRA as well as NO3– influx from 0·1 mol m–3 NO3– were substantially higher in trembling aspen than in lodgepole pine at all stages of NO3– exposure, i.e. during the uninduced, the peak induction, and steady-state stages. In order to examine whether the lower rates of NO3– influx and NRA were related to proportionately fewer young (unsuberized) roots in lodgepole pine, we determined these parameters in young and old (suberized) roots of this species separately. Induction of influx and NRA were initially greater in young roots but at steady-state there were only minor differences between the young and the old roots. However, even the elevated initial rates in the young roots of lodgepole pine were substantially lower than those of aspen. In pine, influx at 1·5 mol m–3 NO3– was ~ 6-fold higher than at 0·1 mol m–3 NO3– and appeared to be mostly via a constitutive system. By contrast, in aspen, steady-state influxes at 0·1 and 1·5 mol m–3 were not significantly different, being similar to the rate attained by pine at only the higher [NO3–]. In aspen, leaf NRA was ~ 2-fold higher than that of roots. In lodgepole pine NRA of the needles was below the detection limit. These results show that trembling aspen seedlings are better adapted for NO3– acquisition and utilization than lodgepole pine seedlings. 相似文献
12.
G. Nakos 《Plant and Soil》1982,66(2):271-277
Summary The Thriasian Plain near Athens in Greece is a site of concentrated industrial development. Total concentrations of Pb, Cd and extractable SO4
2– in surface soil samples collected from this area, were found to be, respectively, 2–7, 6–34 and 2–20 times higher than those in similar soil samples from parts of the country remote from industrial activity.Total concentrations of Pb, Cd, Zn, Cr and S in samples of olive leaves from the same area were found to be, respectively, 4–40, 3–10, 3–9, 2–6 and 17–21 times higher than those found in samples of olive leaves from rural sites. Leaves of cabbages growing in the area contained between 0.82 and 40 g/g (wet weight) of Pb.Addition of Cd, Ni and Cu to a calcareous potted soil at concentrations of 100, 200 and 200 ppm increased the concentrations of the metals in the needles of Aleppo pine (Pinus halepensis) seedlings to 4.5, 3.5 and 10 ppm, respectively, after 7 months growth in the nursey. 相似文献
13.
Our objective was to evaluate the ability of an ectomycorrhizal fungus to alter the competitive interaction of pine seedlings
growing with grass, and to determine whether the interaction was modified by soil-phosphorus (P) concentration. Slash pine
(Pinus elliottii), inoculated with the ectomycorrhizal fungus Pisolithus arhizus or fortuitously colonized by Thelephora terrestris, and a native grass (Panicum chamaelonche) were grown in a greenhouse at three P levels (0.32, 3.22, 32.26 μM H3PO4). Pine inoculated with P. arhizus took up more P when competing with the nonmycorrhizal grass than when competing with another pine (irrespective of pine mycorrhizal
status). Phosphorus uptake kinetics (Cmin, the minimum concentration at which P can be absorbed from a solution; Imax, the maximum uptake rate) for pine and grass were also determined under hydroponic conditions. Pine had a higher Imax than grass but grass had a lower Cmin, suggesting that pine is more competitive at higher nutrient concentrations while grass is more competitive at lower nutrient
concentrations. The controlled conditions used in these experiments allowed us to evaluate specific parameters (P uptake and
absorbing surface area) affecting plant competition.
Accepted: 7 August 1999 相似文献
14.
JohN. V. H. Constable Marcy E. Litvak James P. Greenberg† Russell K. Monson 《Global Change Biology》1999,5(3):252-267
It was hypothesized that high CO2 availability would increase monoterpene emission to the atmosphere. This hypothesis was based on resource allocation theory which predicts increased production of plant secondary compounds when carbon is in excess of that required for growth. Monoterpene emission rates were measured from needles of (a) Ponderosa pine grown at different CO2 concentrations and soil nitrogen levels, and (b) Douglas fir grown at different CO2 concentrations. Ponderosa pine grown at 700 μmol mol–1 CO2 exhibited increased photosynthetic rates and needle starch to nitrogen (N) ratios when compared to trees grown at 350 μmol mol–1 CO2. Nitrogen availability had no consistent effect on photosynthesis. Douglas fir grown at 550 μmol mol–1 CO2 exhibited increased photosynthetic rates as compared to growth at 350 μmol mol–1 CO2 in old, but not young needles, and there was no influence on the starch/N ratio. In neither species was there a significant effect of elevated growth CO2 on needle monoterpene concentration or emission rate. The influence of climate warming and leaf area index (LAI) on monoterpene emission were also investigated. Douglas fir grown at elevated CO2 plus a 4 °C increase in growth temperature exhibited no change in needle monoterpene concentration, despite a predicted 50% increase in emission rate. At elevated CO2 concentration the LAI increased in Ponderosa pine, but not Douglas fir. The combination of increased LAI and climate warming are predicted to cause an 80% increase in monoterpene emissions from Ponderosa pine forests and a 50% increase in emissions from Douglas fir forests. This study demonstrates that although growth at elevated CO2 may not affect the rate of monoterpene emission per unit biomass, the effect of elevated CO2 on LAI, and the effect of climate warming on monoterpene biosynthesis and volatilization, could increase canopy monoterpene emission rate. 相似文献
15.
EMT6 fibrosarcoma cells were grown to the exponential phase in tissue culture and incubated at 37°C under hypoxic conditions. Buoyant density was determined as a function of the time in hypoxia. Hypoxia was produced in two ways. The first involved incubation of the cells in sealed aluminum chambers containing 95% N2, 5% CO2 gas, and <10 ppm oxygen, resulting in the cells rapidly becoming exposed to the hypoxic environment. After incubation at 37°C, they were centrifuged in linear Ficoll gradients to their isopycnic density. A significant decrease in density was found after 4 h, and prolonged incubation up to 24 h did not result in further change. This density change was reversible on transfer back to aerobic conditions, with the hypoxic cells reverting to their aerobic density after about 10 h reincubation in air. The second method of producing hypoxia involved growing about 8×106 cells in a medium-filled air-tight container. Hypoxia was produced gradually as the oxygen in the medium was consumed by cellular respiration. Similar results were obtained; that is, hypoxic cells became significnatly less dense. However, when the level of hypoxia was varied between 4000 and <10 ppm at 2-h intervals after the cells had depleted all of the original oxygen, no significant difference in density was found between hypoxic and aerobic cells. 相似文献
16.
Studies on sulphur in vertisols 总被引:1,自引:0,他引:1
Summary Some soil and plant test methods were evaluated for predicting response of soybean crop (Glycine max (L.) Merr.) to S application in vertisols. Morgan's reagent, 500 ppm P containing Ca(H2PO4)2.H2O and KH2PO4 solutions, 0.5N NH4OAc+0.25N HOAc and 0.15% CaCl2 were found to be suitable extractants for measuring available soil S. The critical limits of extractable S were 9.0 ppm by
Morgan's reagent, 10.0 ppm by phosphate solutions, 8.0 ppm by 0.5N NH4OAc +0.25N HOAc and 14.0 ppm by 0.15% CaCl2. Morgan's reagent was regarded as superior to other soil test methods in view of its high relationship with S uptake by plants,
A values and relative yield. Critical S concentration in soybean plants varied with age. It was 0.15% and 0.185% for 36 and
60 days old plants, respectively. The critical N/S ratio on the other hand appeared to be constant at about 16.5 during vegetative
growth period. Constancy of critical N/S ratio in plants was attributed to the near constancy of N/S ratio in plant proteins.
There was highly significant relationship between response of soybean to S and to N, supporting the conclusion of some earlier
workers that any soil showing large responses to N may not be supplying adequate S from the mineralization of soil organic
matter. 相似文献
17.
Oscillatoria anguistissima could tolerate 50 ppm ZnSO4.7H2O, and a zinc-tolerant strain with maximum tolerance concentration (MTC) of 100 ppm ZnSO4.7H2O was obtained by stepwise transfer to higher concentrations. The adaptation was irreversible even after three generations
in metal-free medium. In the presence of metal, the tolerant strain grew with a shorter lag period of 4 days as against 6
days in the case of the wild strain. The tolerant strain had higher MTC than that of the wild strain for other metals also,
viz., Ni2+, Co2+, Cu2+ and Cd2+. The zinc resistance in the tolerant strain was a result of reduced uptake, since around 42% of the total metal was present
on the surface as against only 30% in the wild strain. The calcium-stimulated uptake, as observed in the wild strain, was
absent in the tolerant strain. Ultrastructural comparisons revealed no structural change in the tolerant strain on exposure
to zinc, whereas in the wild strain a thick extracellular matrix was observed.
Received: 25 January 2001 / Accepted: 9 March 2001 相似文献
18.
We (3,4) previously observed the reduction of 21-dehydrocorticosteroids in the presence of 20β-hydroxysteroid dehydrogenase proceeded at a faster rate than the reduction of the corresponding corticosteroids. The presence of adjacent carbonyl groups suggested the possibility that the increased rate of reduction of the 20-one,21-a1 steroid analogs resulted from a lack of specificity of the enzyme 20β-hydroxysteroid dehydrogenase for either the aldehyde or ketone group. Nuclear magnetic resonance spectroscopy indicated that the angular methyl groups of the steroid were sensitive probes for the constituents on the basic steroid skeleton. The C18 methyl resonance of 17,21-dihydroxy-4-pregnene-3,20-dione and 17-hydroxy-3,20-dioxo-4-pregnene-21-a1 were 0.722 ppm and 0.728 ppm respectively. The magnitude and sign of the change in chemical shift of the C18 methyl resonance for the enzymatic products of 17,21-dihydroxy-4-pregnene-3,20-dione and 17-hydroxy-3,20-dioxo-4-pregnene-21-a1 (+0.135 ppm and +0.144 ppm respectively) were consistent with a stereochemical assignment of 20β-hydroxyl. 相似文献
19.
Z.-J. Mao Y.-J. Wang X.-W. Wang P. Yu. Voronin 《Russian Journal of Plant Physiology》2005,52(2):171-175
Two-year old birch (Betula platyphylla Suk.) seedlings were grown in climatic chambers for 7 weeks under various conditions: (1) ambient CO2 concentration (350 ppm) and an ordinary nitrogen content in soil (2 mM NH4NO3); (2) ambient CO2 concentration and a high nitrogen rate (16 mM NH4NO3); (3) doubled CO2 concentration (700 ppm) and ordinary nitrogen content, and (4) doubled CO2 concentration and a high nitrogen rate. Doubled CO2 concentration in combination with the high nitrogen rate activated mostly seedling growth, e.g., stem thickening and leaf initiation. In this treatment, the maximum rate of apparent photosynthesis (A
max) was twice as high as in control seedlings. At doubled CO2 concentration and ordinary nitrogen content, we observed the phenomenon of stomata absence from the upper leaf surface and doubling their number on the lower surface, whereas, at doubled CO2 concentration and a high nitrogen rate, stomata partition was essentially similar as in control leaves. The conclusion is that, when the balance between CO2 concentration and nitrogen rate is shifted, doubled CO2 concentration exerts a morphotropic effect on differentiation of young epidermal tissue.Translated from Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 198–202.Original Russian Text Copyright © 2005 by Mao, Y.-J. Wang, X.-W. Wang, Voronin.This revised version was published online in April 2005 with a corrected cover date. 相似文献
20.
Marielle Gattmann Scott A M McAdam Benjamin Birami Roman Link Daniel Nadal-Sala Bernhard Schuldt Dan Yakir Nadine K Ruehr 《Plant physiology》2023,191(1):252
The cause of reduced leaf-level transpiration under elevated CO2 remains largely elusive. Here, we assessed stomatal, hydraulic, and morphological adjustments in a long-term experiment on Aleppo pine (Pinus halepensis) seedlings germinated and grown for 22–40 months under elevated (eCO2; c. 860 ppm) or ambient (aCO2; c. 410 ppm) CO2. We assessed if eCO2-triggered reductions in canopy conductance (gc) alter the response to soil or atmospheric drought and are reversible or lasting due to anatomical adjustments by exposing eCO2 seedlings to decreasing [CO2]. To quantify underlying mechanisms, we analyzed leaf abscisic acid (ABA) level, stomatal and leaf morphology, xylem structure, hydraulic efficiency, and hydraulic safety. Effects of eCO2 manifested in a strong reduction in leaf-level gc (−55%) not caused by ABA and not reversible under low CO2 (c. 200 ppm). Stomatal development and size were unchanged, while stomatal density increased (+18%). An increased vein-to-epidermis distance (+65%) suggested a larger leaf resistance to water flow. This was supported by anatomical adjustments of branch xylem having smaller conduits (−8%) and lower conduit lumen fraction (−11%), which resulted in a lower specific conductivity (−19%) and leaf-specific conductivity (−34%). These adaptations to CO2 did not change stomatal sensitivity to soil or atmospheric drought, consistent with similar xylem safety thresholds. In summary, we found reductions of gc under elevated CO2 to be reflected in anatomical adjustments and decreases in hydraulic conductivity. As these water savings were largely annulled by increases in leaf biomass, we do not expect alleviation of drought stress in a high CO2 atmosphere.Increases in atmospheric CO2 can trigger structural modifications in leaves and branches, which contribute to lower leaf-level water loss, but do not affect the drought sensitivity in Aleppo pine. 相似文献