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1.
The response of rice toAzolla caroliniana, newly introduced in India, was compared with the reponse to the local isolate ofAzolla pinnata at varying rates of phosphate fertilizer (4.4–8.8 kg P ha–1) during a wet and a dry season.Fresh weight, dry weight and fixed N were more for both species 21 DAI (days after inoculation) than 14 DAI, but acetylene reduction activity (ARA) was higher 14 DAI than 21 DAI. Dry weight of Azolla and fixed N were less 14 DAI forA. caroliniana than forA. pinnata during the wet season. Twenty-one DAI, fresh weight ofA. caroliniana was 62.1 and 27.6% higher than that ofA. pinnata during the wet and dry season, respectively. However, dry weight and fixed N were more 21 DAI inA. caroliniana than inA. pinnata during only the wet season. The ARA was higher inA. caroliniana both 14 and 21 DAI, irrespective of season. The presence of either species in the rice field increased grain yield, straw yield, number of panicles m–2, number of grains per panicle and reduced percentage sterility during both the wet and the dry season. Phosphate application significantly increased fresh weight, dry weight, ARA and fixed N for both species as well as grain and straw yields of rice. The responses to phosphate fertilizer were similar for both Azolla species and for rice grown with either one of the Azolla species. 相似文献
2.
The growth of 22 strains of Azolla pinnata R. Br., 3 strains of A. filiculoides Lam. and one strain each of A. mexicana Presl and A. caroliniana Willd. was tested separately in liquid culture media kept in controlled, artificial light (30 klux) growth cabinets. Three temperature levels were used: 33°C (37/29°C day/night), 29°C (33/25°C) and 22°C (26/18°C)/ Photoperiod was 12 h a day.For most A. pinnata strains (except three) and an A. mexicana strain the maximum weekly relative growth rate was higher at 33°C than at 22°C, but not for A. filiculoides and A. caroliniana. The highest value of maximum relative growth rate corresponded to 1.9 doubling days and in most strains this occurred in the first week. As the plants grew, the growth rate slowed down more severely at higher temperatures. The maximum biomass was higher at 22°C than at 33°C in all strains. At 22°C, it took 30–50 days to attain maximum biomass and the highest value was 14 g N m?2 or 320 g dry m?2 by A. caroliniana, followed by 12 g N m?2 or 290 g dry wt. m?2 by one strain of A. filiculoides. At 29°C, the maximum biomass was attained in 20–35 days. The highest value was 6.3 g N m?2 or 154 g dry wt. m?2 by A. caroliniana. At 33°C, most A. pinnata strains gave a maximum biomass of less than 4 g N m?2 after 13–23 days, while some strains grew up to 30 days, resulting in a higher maximum biomass. The highest maximum biomass at 33°C was 5.5 g N m?2 or 140 g m?2 dry wt. by A. pinnata from Cheng Mai while the maximum biomass of A. filiculoides and A. caroliniana was much less. Azolla filiculoides requires lower temperature than other species for its growth. Azolla pinnata has the best tolerance to high temperatures among the four species. Azolla mexicana could not be discriminated from A. pinnata in its response to temperature. Azolla caroliniana may keep an intermediate position between A. filiculoides and A. pinnata in temperature response.The formation of ammonia in the medium was examined and it occurred mostly under stationary growth conditions, but, at 33°C, some strains of A. pinnata and A. mexicana released or formed ammonia at 0.3–0.8 μg N ml?1 per week during their initial exponential growth stage. 相似文献
3.
Summary From acetylene reduction assays over a 10-month period starting in April 1979, nodule activities averaged 18.78 (se 4.67) moles C2H4 g nodule dw–1 h–1 forAlnus rubra and 59.95 (se 12.14) moles C2H4 g nodule dw–1 h–1 forCytisus scorparius. Plant rates were 1.91 (se. 47) moles C2H4 plant–1 h–1 forA. rubra and 0.55 (se. 17) moles C2H4 plant–1 h–1 forC. Scoparius. Plant activity and total leaf N were strongly correlated with the dw of other plant parts, but nodule activity and percent leaf N were not. Plant and nodule activities were not associated with temperature, moisture stress, precipitation events or percent light for either species over the growing season nor for 54A. rubra sampled in mid-season 1979 on one replication. After 5 to 6 growing seasons, 14A. rubra on the same site ranged from 30 to 332 cm in height and showed strong correlation between nodule dw, leaf dw, plant size and total leaf N. Results from this study and others indicate logistic equations may be modified to predict the effect of adding a N2 fixing plant to a population of non N2 fixing trees. 相似文献
4.
There are seven known species of Azolla, two of which have been used in cultivated systems, the tropical speciesA. pinnata, and the temperate speciesA. filiculoides. OnlyA. pinnata is indigenous in Thailand. In this study the two exotic species,A. caroliniana andA. microphylla, were evaluated under the various tropical field conditions in Thailand. When compared with seven selected strains ofA. pinnata under three field conditions,A. caroliniana andA. microphylla were similar to the indigenous species, in terms of growth performance, N2 fixation, and yield. This study suggests thatA. caroliniana andA. microphylla can be successfully cultivated as a nitrogen fixing green manure for rice production in the tropics. 相似文献
5.
Nitrogen fixation was measured in four subarctic streams substantially modified by beaver (Castor canadensis) in Quebec. Acetylene-ethylene (C2H2 C2H4) reduction techniques were used during the 1982 ice-free period (May–October) to estimate nitrogen fixation by microorganisms colonizing wood and sediment. Mean seasonal fixation rates were low and patchy, ranging from zero to 2.3 × 10–3 µmol C2H4 · cm–2 · h–1 for wood, and from zero to 7.0 × 10–3 µmol C2H4 · g AFDM–1 · h–1 for sediment; 77% of all wood and 63% of all sediment measurements showed no C2H2 reduction. Nonparametric statistical tests were unable to show a significant difference (p > 0.05) in C2H2 reduction rates between or within sites for wood species or by sediment depth.Nitrogen contributed by microorganisms colonizing wood in riffles of beaver influenced watersheds was small (e.g., 0.207 g N · m–2 · y–1) but greater than that for wood in beaver ponds (e.g., 0.008 g N · m–2 · y–1) or for streams without beaver (e.g., 0.003 g N · m–2 · y–1). Although mass specific nitrogen fixation rates did not change significantly as beaver transform riffles into ponds, the nitrogen fixed by organisms colonizing sediment in pond areas (e.g., 5.1 g N · m–2 · y–1) was greater than that in riffles (e.g., 0.42 g N · m–2 · y–1). The annual nitrogen contribution is proportional to the amount of sediment available for microbial colonization. We estimate that total nitrogen accumulation in sediment, per unit area, is enhanced 9 to 44 fold by beaver damming a section of stream. 相似文献
6.
The problem of optimising agitation and aeration in a given fermenter is addressed. The objective function is total electric power consumed for agitation, compression and refrigeration. The major constraint considered is to ensure that the dissolved oxygen concentration is above the critical value. It is shown that it is possible to analytically calculate the optimal pair (air flowrate, stirrer speed) and that, at least for the industrial antibiotics fermentation used as case-study, the optimum lies within a window for satisfactory operation, limited by other possible constraints to the problem. Savings achievable by optimal operation as compared with current industrial procedure were found to be around 10% at pilot plant scale (0.26 m3) and 20% at full scale (85 m3).List of Symbols
A
fermenter cross sectional area (m2)
-
C
dissolved oxygen concentration (mole m–3)
-
C
*
DO concentration in equilibrium with the gas (mole m–3)
-
C
crit
critical DO concentration (mole m–3)
-
C
p
specific heat of air at constant pressure (J kg–1 K–1)
-
C
sp
dissolved oxygen set point (mole m–3)
-
C
v
specific heat of air at constant volume (J kg–1 K–1)
-
D
agitator diameter (m)
-
f
pressure correction of air flow-rate
-
(Fl
g)F
aeration number at flooding
-
(Fr
g)F
froude number at flooding
-
k
coefficient in expression for mass transfer coefficient
-
K
La
volumetric oxygen transfer coefficient (s–1)
-
m
power exponent in expression for mass transfer coefficient
-
n
gas flow rate exponent in expression for mass transfer coefficient
-
n
*
number of impellers
-
N
rotation speed (s–1)
-
N
F
rotation speed at flooding (s–1)
-
N
p
unaerated power number
-
N
pg
aerated power number
-
OUR
Oxygen Uptake Rate (mole m–3 s–1)
-
p
0
atmospheric pressure (N m–2)
-
p
1
compressor exit pressure (N m–2)
-
p
2
pressure at the bottom of the fermenter (N m–2)
-
p
3
pressure at the top of the fermenter (N m–2)
-
P
c
compression power (W)
-
P
d
power added by expansion (W)
-
P
ev
power removed by evaporation (W)
-
P
g
agitation power (W)
-
P
m
power added by metabolism (W)
-
P
r
power removed by refrigeration (W)
-
P
t
total power (W)
-
Q
air flow-rate at atmospheric conditions (m3 s–1)
-
Q
f
air flow-rate at average fermenter conditions (m3 s–1)
-
s
0
absolute humidity at atmospheric conditions
-
s
3
absolute humidity at fermenter exit
-
T
tank diameter (m)
-
V
liquid volume (m3)
-
v
s
gas superficial velocity (m s–1)
-
i
parameter defined in the text
-
safety margin for dissolved oxygen (mole m–3)
-
ratio of specific heats of air
-
g
agitation efficiency
-
c
compression efficiency
-
r
refrigeration efficiency
-
liquid density (kg m–3)
-
g
air density (kg m–3)
-
latent heat of vaporisation of water (J kg–1)
The authors are grateful to Elsa Silva, Carlos Lopes, Carlos Aguiar, Fernando Mendes, and Alexandre Cardoso, who helped with parts of this work, and to CIPAN for permission to publish these data. 相似文献
7.
Russell K. Monson Robert O. Littlejohn Jr. George J. Williams III 《Photosynthesis research》1982,3(2):153-159
The quantum yield for CO2 uptake was measured in C3 and C4 monocot species from several different grassland habitats. When the quantum yield was measured in the presence of 21% O2 and 340 cm3 m-3 CO2, values were very similar in C3 monocots, C3 dicots, and C4 monocots (0.045–0.056 mole CO2 · mole-1 quanta absorbed). In the presence of 2% O2 and 800 cm3 m-3 CO2, enhancements of the quantum yield values occurred for the C3 plants (both monocots and dicots), but not for C4 monocots. A dependence of the quantum yield on leaf temperature was observed in the C3 grass, Agropyron smithii, but not in the C4 grass, Bouteloua gracilis, in 21% O2 and 340 cm3 m-3 CO2. At leaf temperatures between 22–25°C the quantum yield values were approximately equal in the two species. 相似文献
8.
We measured F420-dependent N5,N10-methylenetetrahydro-methanopterin dehydrogenase, N5, N10-methenyltetrahydro-methanopterin cyclohydrolase, and F420-reducing hydrogenase levels in Methanosarcina barkeri grown on various substrates. Variation in dehydrogenase levels during growth on a specific substrate was usually <3-fold, and much less for cyclohydrolase. H2–CO2-, methanol-, and H2–CO2+ methanol-grown cells had roughly equivalent levels of dehydrogenase and cyclohydrolase. In acetate-grown cells cyclohydrolase level was lowered 2 to 3-fold and dehydrogenase 10 to 80-fold; this was not due to repression by acetate, since, if cultures growing on acetate were supplemented with methanol or H2–CO2, dehydrogenase levels increased 14 to 19-fold, and cyclohydrolase levels by 3 to 4-fold. Compared to H2–CO2- or methanol-grown cells, acetate-or H2–CO2 + methanol-grown cells had lower levels of and less growth phase-dependent variation in hydrogenase activity. Our data are consistent with the following hypotheses: 1. M. barkeri oxidizes methanol via a portion of the CO2-reduction pathway operated in the reverse direction. 2. When steps from CO2 to CH3-S-CoM in the CO2-reduction pathway (in either direction) are not used for methanogenesis, hydrogenase activity is lowered.Abbreviations MF
methanofuran
- H4MPT
5,6,7,8-tetrahydromethanopterin
- HS-HTP
7-mercaptoheptanoylthreonine phosphate
- CoM-S-S-HTP
heterodisulfide of HS-CoM and HS-HTP
- F420
coenzyme F420 (a 7,8-didemethyl-8-hydroxy-5-deaza-riboflavin derivative)
- H2F420
reduced coenzyme F420
- HC+=H4MPT
N5,N10-methenyl-H4MPT
- H2C=H4MPT
N5,N10-methylene-H4MPT
- H3C=H4MPT
N5-methyl-H4MPT
- BES
2-bromoethanesulfonic acid 相似文献
9.
Summary The symbiotic heterocystous cyanobacteriumAnabaena azollae present in the leaf cavities of the water fernAzolla spp. was studied. The cyanobacteria extracted from the leaf cavities showed differences in pigment composition in three species ofAzolla, i.e A.pinnata var.pinnata, A.caroliniana and A.filiculoides, as observed by pigment absorption and epifluorescence tests. These differences suggest that of these species the cyanobiont ofA. pinnata is the most actively nitrogenfixing form. This has been confirmed by nitrogen fixation (acetylene reduction) tests. Heterocysts of the symbiont ofA. pinnata were characterized by high chlorophylla and low phycocyanin content, a low fluorescence yield of chlorophyll in the heterocysts compared to vegetative cells and a gradient of phycocyanin concentration in the vegetative cells adjacent to heterocysts. This indicates that only photosystem I is present in the heterocyst. In the two otherAzolla species quantitative shifts in the pigment composition occurred suggesting a lower nitrogen fixation activity.In the cyanobiontAnabaena azollae the heterocyst frequency could reach a value of 44–45%. It is argued that there are two generations of heterocysts in a matureAzolla plant, which are concomitant with two peaks of nitrogen fixation activity correlated with leaf age,i.e. leaf number along the main axis of the plant. At both peaks of maximal N2-ase activity, only 20–25% of the heterocysts present are metabolically active as demonstrated by the reduction of Neotetrazolium chloride (NTC) in the heterocysts and darkening of nuclear emulsions by silver salt reduction. Vegetative cells of the cyanobiont reduce Neotetrazolium chloride (NTC) to formazan more rapidly than has been observed in the free-living heterocystous cyanobacteriumAnabaena cylindrica tested in parallel experiments. This feature may be due to a more permeable cell wall of the vegetative cells of the cyanobiont compared to the free-living form, since the vegetative cells of the symbiont play a role in cross-feeding of the host (Azolla).Evidence is obtained that only the heterocysts of the cyanobiont ofAzolla are involved in the nitrogen fixation process as in free-living heterocystous cyanobacterium species. This situation is different from other cyanobacterial symbioses such as inGunnera, Blasia andAnthoceros, where physiological modifications are reported in the symbiosis with another photosynthetic partner such as the absence of O2 evolution and the absence of photo-fixation of CO2 in the cyanobionts.Pigment composition and N2-ase activity in the symbiotic cyanobacteria of three Azolla species have indicated the superiority of theA. pinnata symbiont.A. pinnata var.pinnata is a semidomesticated form used in S.E. Asia for agricultural purposes (irrigated rice culture) to increase soil fertility.It is suggested that by selection (domestication) more efficient strains (clones) can be obtained, and further that with more advanced techniques such as gene mutation and genetic manipulation even more efficient and for agriculture more beneficial clones can be obtained. 相似文献
10.
A vertical flat-plate photobioreactor was developed for the outdoor culture of microalgae using sunlight as the light source. The ability for biomass production and CO2 fixation was evaluated by using a cyanobacterium, Synechocystis aquatilis SI-2. The average areal productivity was 31 g biomass m–2 d–1, which corresponded to a CO2 fixation rate of 51 g CO2 m–2 d–1, sustainable in the northern region of Japan during the winter time (January and February). The relationships between the efficiency of solar energy utilization of the reactor and its effect factors (cell concentration and irradiation) were investigated. 相似文献
11.
In Ochroma pyramidale (Cav. ex Lam.) Urb., photon-saturated photosynthetic capacity (P
Nmax) was 13 mol(CO2) m–2 s–1. Average stomatal conductance (g
s) and water-use efficiency (WUE) were greater at high irradiance, about 260 mmol(H2O) m–2 s–1 and 2.15 g(C) kg–1(H2O), respectively. In the dark, g
s values were about 30% of maximum g
s. Leaf nutrient contents on a leaf area basis were 131, 15, 36, 21, and 12 mmol m–2 for N, P, K, Ca, and Mg, respectively. Ochroma also accumulated a greater amount of soluble saccharides than starch, 128 versus 90 g kg–1 (DM). The availability of N and Mg, but not P, Ca, or K, may limit photosynthetic rates of Ochroma in this site. 相似文献
12.
Synechocystis aquatilis SI-2 was grown outdoors in a 12.5cm diam. tubular photobioreactor equipped with static mixers. The static mixers ensured that cells were efficiently circulated between the upper (illuminated) and lower (dark) sections of the tubes. The biomass productivity varied from 22 to 45g m–2d–1, with an average of 35g m–2d–1, etc which corresponded to average CO2 fixation rate of about 57 g CO2 m–2 d–1. The static mixers not only helped in improving the biomass productivities but also have a high potential to lower the photoinhibitory effect of light during the outdoor cultures of algae.
Revisions requested 27 July 2004; Revisions received 12 November 2004 相似文献
13.
Photosynthetic acclimation to reduced growth irradiances (650 and 200 µmol m–2 s–1) in Eleusine coracana (L.) Garten, a nicotinamide adenine dinucleotide-malic enzyme (NAD-ME) C4 species and Gomphrena globosa L., a nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) C4 species were investigated. E. coracana plants acclimated in 4 and 8 d to 650 and 200 µmol m–2 s–1, respectively, whereas G. globosa plants took 8 and 10 d, respectively, to acclimate to the same irradiances. The acclimation to reduced irradiance was achieved in both species by greater partitioning of chlorophyll towards the light-harvesting antennae at the expense of functional components. However, magnitude of increase in the light-harvesting antenna was higher in E. coracana as compared to G. globosa. Superior photosynthetic acclimation to reduced irradiance in G. globosa was due to the smaller change in functions of the cytochrome b
6/f complex, photosystem (PS) 1 and PS2 leading to the higher carbon fixation rates compared to E. coracana. 相似文献
14.
Rhodospirillum rubrum was grown continuously and photoheterotrophically under light limitation using a cylindrical photobioreactor in which the steady state biomass concentration was varied between 0.4 to 4 kg m–3 at a constant radiant incident flux of 100 W m–2. Kinetic and stoichiometric models for the growth are proposed. The biomass productivities, acetate consumption rate and the CO2 production rate can be quantitatively predicted to a high level of accuracy by the proposed model calculations.
Nomenclature:
C
X, biomass concentration (kg m–3) D, dilution rate (h–1) Ea, mean mass absorption coefficient (m2 kg–1) I
, total available radiant light energy (W m–2) K, half saturation constant for light (W m–2) R
W, boundary radius defining the working illuminated volume (m) r
X, local biomass volumetric rate (kg m–3 h–1) <r
X>, mean volumetric growth rate (kg m–3 h–1) V
W, illuminated working volume in the PBR (m–3).
Greek letters:
, working illuminated fraction (–) M, maximum quantum yield (–) bar, mean energetic yield (kg J–1). 相似文献
15.
A model system is described where Azospirillum and germinated wheat seeds were grown in association for a week and then assayed for nitrogen fixation (C2H2-reduction) and denitrification (N2O-formation) activities. The association performed C2H2-reduction and N2O-formation under microaerobic conditions. Both activities were measurable after already 3–5 h of incubation with substantial rates and were strictly dependent on the presence of both plants and bacteria. During the week of the growth of the association, the bacteria had lived exclusively from the carbon compounds supplied by the roots of the plants. C2H2-reduction activity by the association was more or less the same with all the Azospirillum brasilense strains, but lower with A. lipoferum and with the A. amazonense strains tested. Two nitrogenase negative mutants of Azospirillum brasilense showed virtually no activity in the association. C2H2-reduction activity was strongly dependent on the growth temperature of the association. Denitrification (N2O-formation) was high also at higher temperatures and at pH-values in the medium around 7.8 but not at neutrality and was strictly dependent on nitrate. The Azospirillum strain used strongly determined the rate of the N2O-formation in the association. It is suggested that Azospirillum may be beneficial to crops particularly under tropical conditions.Dedicated to Professor Dr. Gerhart Drews, Freiburg, on the occasion of his 60th birthday 相似文献
16.
Gas Exchange and Epidermal Characteristics of Miscanthus Populations in Taiwan Varying with Habitats and Nitrogen Application 总被引:1,自引:0,他引:1
Seventeen clones of C4 grass Miscanthus spp. collected from different climatic regions and elevations of Taiwan were transplanted in pots. 15–16 months after collection the plants received 0, 1, and 2 g of nitrogen fertiliser (N0, N1, and N2, respectively) per pot. All the measurements were done 10–12 d after N application. The relationships between net photosynthetic rate (P
N) and photon flux density (PFD) showed a saturated curve, with PFD saturation at about 1 000 µmol m–2 s–1. The ranges of PFD saturated P
N (P
sat) for all the tested clones with N0, N1, and N2 were 8–16, 11–18, and 12–21 µmol m–2 s–1, respectively. The clones from southern Taiwan, a tropical region, showed the highest P
sat, followed by the clones from northern Taiwan, a subtropical region, while those from mountainous area showed the lowest P
sat. The clones collected from southern Taiwan showed the highest frequency of stomata on the adaxial surface, and those collected from the high mountainous area showed the lowest frequency. Also the adaxial surface of leaves from the higher mountainous area had more wax deposited than the leaves from the lowland. Thus the low P
sat in mountain clones is limited by both stomatal and non-stomatal factors. Further, the lower leaf conductance and different epidermal characteristics of mountain clones might prevent excessive loss of heat through transpiration and provide production against ultraviolet-B radiation. 相似文献
17.
Joann P. Roskoski 《Microbial ecology》1980,6(4):349-355
Nitrogen fixation (C2H2 reduction) by epiphylls on coffee,Coffea arabica, grown in sites with different degrees of shade, was determined. Coffee leaves with nitrogen-fixing epiphylls were found in all sites in approximately equal numbers. Rates of C2H2 reduction were similar for all sites and throughout the year, averaging 3.21 nmoles C2H2 reduced leaf with epiphylls–1 day–1. Apparently, neither rates of activity nor abundance of leaves with nitrogen-fixing epiphylls is related to the degree of shade in a site. No correlation was found between percent epiphyll cover and the presence or magnitude of nitrogen-fixing activity. Calculated annual fixation by epiphylls on coffee was low, ranging from 0.7 g N2 ha–1 year–1 for the shadeless site to 1.4 g N2 ha–1 year–1 for the site withIngajinicuil shade trees. These results suggest that epiphyll fixation is not an important source of nitrogen for the coffee ecosystem studied. 相似文献
18.
Pond cultivation of the subtropical, euryhaline macroscopic red algaGracilaria tenuisipitata var.liui Zhanget Xia was carried out in brackish seawater (6–7) in the Gryt archipelago on the east coast of Sweden, using four outdoor tanks of 30–40 m3. Growth rate and nutrient uptake in batch culture were measured with the aim of estimating the water purification capacity ofG. tenuisipitata in outdoor conditions. Its ability to withstand epiphytic infections was also studied. An average growth rate of 4 biomass increase per day was recorded during two seasons with a maximum growth rate of 9 d–1. The initial biomass was usually 1 kgFW m–3 (FW, fresh weight). The nutrient uptake capacity was on average ca. 1 g Ni kgFW–1 d–1 and 0.08 g Pi kgFW–1 d–1 and the uptake rates for NH4
+-N were higher than those for NO3
–-N. Both the growth rate and the nutrient uptake rate were highest at the highest water temperature. Co-cultivation with rainbow trout (Oncorhynchus mykiss) was tested: with trout fodder as the only nutrient inputG. tenuistipitata could grow and maintain low levels of Ni and Pi with optimum efficiency at a trout: alga ratio of 1:1 (w:w). Epiphytic growth of filamentous green and brown algae was limited, probably as a result of the high pH values caused by inorganic carbon uptake byG. tenuistipitata. The growth ofEnteromorpha intestinalis, the only significant epiphyte, was completely inhibited and the majority of plants died by a few days treatment with 100 µg 1–1 Cu2+, a concentration that did not severely affectG. tenuistipitata. We conclude thatG. tenuistipitata can be cultivated in outdoor ponds in southern Sweden during 5–6 months of the year using aerated or unaerated batch cultures and that wastewater from trout cultivation may be used as a nutrient source, resulting in purification with respect to N and P. 相似文献
19.
In bean (Phaseolus vulgaris L.) seedlings well supplied with water, rates of transpiration (E) and CO2 assimilation (P
N) of the primary leaves were measured under blue (BR) or red (RR) irradiance of 150 µmol(photon) m–2 s–1. The leaf conductance to H2O vapour transfer (g
H2O), as well as the intercellular concentrations of H2O vapour (e
i) and of CO2 (C
i) were calculated. Under BR, g
H2O was significantly greater, but P
N was lower, and E similar as compared with corresponding values found under RR. The increase of stomata aperture under BR was evident although C
i was higher and e
i was lower than under RR. Results agree with the suggestion that BR directly activates guard cell metabolism and in well watered plants determines mainly the stomata aperture. 相似文献
20.
Interrelationships Between Nitrogen Supply and Photosynthetic Parameters in Vicia faba L. 总被引:2,自引:2,他引:0
We determined for Vicia faba L the influence of nitrogen uptake and accumulation on the values of photon saturated net photosynthetic rate (P
Nmax), quantum yield efficiency (), intercellular CO2 concentration (C
i), and carboxylation efficiency (C
e). As leaf nitrogen content (NL) increased, the converged onto a maximum asymptotic value of 0.0664±0.0049 mol(CO2) mol(quantum)–1. Also, as NL increased the C
i value fell to an asymptotic minimum of 115.80±1.59 mol mol–1, and C
e converged onto a maximum asymptotic value of 1.645±0.054 mol(CO2) m–2 s–1 Pa–1 and declined to zero at a NL-intercept equal to 0.596±0.096 g(N) m–2. fell to zero for an NL-intercept of 0.660±0.052 g(N) m–2. As NL increased, the value of P
Nmax converged onto a maximum asymptotic value of 33.400±2.563 mol(CO2) m–2 s–1. P
N fell to zero for an NL-intercept of 0.710±0.035 g(N) m–2. Under variable daily meteorological conditions the values for NL, specific leaf area (L), root mass fraction (Rf), P
Nmax, and remained constant for a given N supply. A monotonic decline in the steady-state value of Rf occurred with increasing N supply. L increased with increasing N supply or with increasing NL. 相似文献