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1.
To examine the hypothesis that stomatal behavior of plants in dry soil is influenced by a slow recovery from daytime water
deficit, we studied the effect of repeated wetting of leaves during evening and night in Cryptomeria japonica seedlings grown in dry soil. After 7 and 10 days of leaf wetting treatment the midday leaf water potential decreased and
the transpiration rate increased, respectively. Therefore, we suggest that rapid recovery from daytime water deficit could
weaken the water conserving stomatal behavior that adapts to drought conditions in the roots. 相似文献
2.
Photosynthetic parameters and leaf water potential of five common bean genotypes under mild water deficit 总被引:2,自引:0,他引:2
The leaf water potential, gas exchange and chlorophyll fluorescence were evaluated in five common bean (Phaseolus vulgaris) genotypes A222, A320, BAT477, Carioca and Ouro Negro subjected to moderate water deficit. At the maximum water deficit (10
d of water withholding), the leaf water potential of genotypes A320 and A222 was higher (−0.35 and −0.50 MPa) when compared
to the other genotypes (−0.67 to −0.77 MPa). The stomatal conductance and net photosynthetic rate were significantly reduced
in all genotypes due to the water deficit. The greater reduction in stomatal conductance of A320 under drought resulted in
high intrinsic water use efficiency. Mild water deficit affected the photochemical apparatus in bean genotypes probably by
down-regulation since plants did not show photoinhibition. The photochemical apparatus of A222 and A320 genotypes was more
sensitive to drought stress, showing reduced apparent electron transport even after the recovery of plant water status. On
the other hand, even after 10 d of water withholding, the maximum efficiency of photosystem 2 was not affected, what suggest
efficiency of the photoprotection mechanisms. 相似文献
3.
The aim of this study was to evaluate how the summer and winter conditions affect the photosynthesis and water relations of
well-watered orange trees, considering the diurnal changes in leaf gas exchange, chlorophyll (Chl) fluorescence, and leaf
water potential (Ψ) of potted-plants growing in a subtropical climate. The diurnal pattern of photosynthesis in young citrus
trees was not significantly affected by the environmental changes when compared the summer and winter seasons. However, citrus
plants showed higher photosynthetic performance in summer, when plants fixed 2.9 times more CO2 during the diurnal period than in the winter season. Curiously, the winter conditions were more favorable to photosynthesis
of citrus plants, when considering the air temperature (< 29 °C), leaf-to-air vapor pressure difference (< 2.4 kPa) and photon
flux density (maximum values near light saturation) during the diurnal period. Therefore, low night temperature was the main
environmental element changing the photosynthetic performance and water relations of well-watered plants during winter. Lower
whole-plant hydraulic conductance, lower shoot hydration and lower stomatal conductance were noticed during winter when compared
to the summer season. In winter, higher ratio between the apparent electron transport rate and leaf CO2 assimilation was verified in afternoon, indicating reduction in electron use efficiency by photosynthesis. The high radiation
loading in the summer season did not impair the citrus photochemistry, being photoprotective mechanisms active. Such mechanisms
were related to increases in the heat dissipation of excessive light energy at the PSII level and to other metabolic processes
consuming electrons, which impede the citrus photoinhibition under high light conditions. 相似文献
4.
Tropospheric ozone (O3) decreases photosynthesis, growth, and yield of crop plants, while elevated carbon dioxide (CO2) has the opposite effect. The net photosynthetic rate (P
N), dark respiration rate (R
D), and ascorbic acid content of rice leaves were examined under combinations of O3 (0, 0.1, or 0.3 cm3 m−3, expressed as O0, O0.1, O0.3, respectively) and CO2 (400 or 800 cm3 m−3, expressed as C400 or C800, respectively). The P
N declined immediately after O3 fumigation, and was larger under O0.3 than under O0.1. When C800 was combined with the O3, P
N was unaffected by O0.1 and there was an approximately 20 % decrease when the rice leaves were exposed to O0.3 for 3 h. The depression of stomatal conductance (g
s) observed under O0.1 was accelerated by C800, and that under O0.3 did not change because the decline under O0.3 was too large. Excluding the stomatal effect, the mesophyll P
N was suppressed only by O0.3, but was substantially ameliorated when C800 was combined. Ozone fumigation boosted the R
D value, whereas C800 suppressed it. An appreciable reduction of ascorbic acid occurred when the leaves were fumigated with O0.3, but the reduction was partially ameliorated by C800. The degree of visible leaf symptoms coincided with the effect of the interaction between O3 and CO2 on P
N. The amelioration of O3 injury by elevated CO2 was largely attributed to the restriction of O3 intake by the leaves with stomatal closure, and partly to the maintenance of the scavenge system for reactive oxygen species
that entered the leaf mesophyll, as well as the promotion of the P
N. 相似文献
5.
Under non-stressed conditions the net photosynthetic rate (P
N) of the mutant plants cbp20 of Arabidopsis was similar to that of the wild type (WT). In response to water deprivation, however, P
N started to decrease later in the mutants and remained substantially higher. Thermoluminescence measurements showed that the
lipid peroxidation induced by severe water stress was also less pronounced in the mutant than in the WT. Both soil gravimetric
and plant water potential data showed that cbp20 mutants lose water more slowly than the WT plants. The drought-induced decline in Fv/Fm, the quantum efficiency of photosystem 2, and photochemical quenching parameters also started later in the cbp20 mutants than in the WT plants. Thus the restricted gas exchange in the cbp20 mutants does not impair the photosynthetic performance of the plant; however, under drought improved water retention provides
significant protection for the photosynthetic apparatus. 相似文献
6.
G. Jyothsnakumari M. Thippeswamy G. Veeranagamallaiah C. Sudhakar 《Biologia Plantarum》2009,53(1):145-150
The relative water content (RWC), cell membrane integrity, protein pattern and the expression of late embryogenesis abundant
proteins (LEA; group 1, 2, 3 and 4) under different levels of salt stress (0, 1.0, 1.5 and 2.0 % NaCl) were investigated in
mulberry (Morus alba L.) cultivars (S1 and ATP) with contrasting salt tolerance. RWC and membrane integrity decreased with increase in NaCl concentration
more in cv. ATP than in cv. S1. SDS-PAGE protein profile of mulberry leaves after the NaCl treatments showed a significant
increase in 35, 41, 45 and 70 kDa proteins and significant decrease in 14.3, 18, 23, 28, 30, 42, 47 and 65 kDa proteins. Exposure
of plants to NaCl resulted in higher accumulation of LEA proteins in S1 than ATP. The maximum content of LEA (group 3 and
4) was detected in S1 at 2.0 % NaCl, which correlates with its salt tolerance. 相似文献
7.
We investigated the effects of long-term acclimation of Eucalyptus nitens seedlings to ultraviolet-A (UV-A) irradiation (320–400 nm) on phenolic compounds (gallotannins, stilbenes, and flavonols),
photochemical efficiency, and chlorophyll and carotenoid contents. Seedlings were raised under four nutrient regimes, ranging
from low to high application rates, in an environment that included or excluded UV-A irradiance. Our aims were: to classify
phenolic compounds that absorb in the UV-A and their relative contribution to total UV-A absorption; to identify how phenolic
compounds respond to UV-A exposure and exclusion, and to determine how plant nutrient status affects acclimation of photo-and
pigment-chemistry to UV-A exposure and exclusion. Gallotannins contributed to only a minor fraction of total absorption within
the lower range (320–360 nm) of the UV-A spectrum. Stilbene and flavonol compounds dominated absorption within the 320–360
and 360–400 nm ranges, respectively. Contents of gallotannin were generally high in UV-A-exposed seedlings. Although there
was a significant effect of UV-A on contents of stilbenes, a general response (across nutrient treatment comparisons) was
not evident. Contents of flavonols were not affected by UV-A exposure. Contents of gallotannin, stilbene, and flavonols decreased
from low to high nutrient-application treatments. There were no effects of UV-A on photochemical efficiency or pigment-chemistry. 相似文献
8.
Leaf area prediction model for sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.) cultivars 总被引:4,自引:4,他引:0
In two successive years (2003 and 2004), a set of 16 commercial sugar beet cultivars was established in Randomized Complete
Block experiments at two sites in central Greece. Cultivar combination was different between years, but not between sites.
Leaf sampling took place once during the growing season and leaf area, LA [cm2], leaf midvein length, L [cm] and maximum leaf width, W [cm] were determined using an image analysis system. Leaf parameters
were mainly affected by cultivars. Leaf dimensions and their squares (L2, W2) did not provide an accurate model for LA predictions. Using L×W as an independent variable, a quadratic model (y = 0.003
x2 − 1.3027 x + 296.84, r
2 = 0.970, p<0.001, n = 32) provided the most accurate estimation of LA. With compromises in accuracy, the linear relationship between L×W and
LA (y = 0.5083 x + 31.928, r
2 = 0.948, p<0.001, n = 32) could be used as a prediction model thanks to its simplicity. 相似文献
9.
Sugar beet cv. Rizor was grown for five growing seasons (2002–2006) in field conditions in Thessaly, central Greece. A total
of 55 samplings took place during the growing seasons and allometric growth of the leaves was monitored. Highly significant
(p<0.001) quadratic relationships were found between individual leaf mass (LM), individual leaf area (LA), aboveground dry biomass
(ADB), and leaf area index (LAI). Only the LM-LA relationship (LA = 43.444 LM2 − 10.693 LM + 118.34) showed a relatively high r
2 (0.63) and thus could be used for prediction of LA. Specific leaf area (SLA) was significantly related with leaf water content
(LWC) (SLA = 26 279 LWC2 − 44 498 LWC + 18 951, r
2 = 0.91, p<0.001) and thus LWC could be a good indirect predictor of SLA in this cultivar. 相似文献
10.
Modelling the dynamics of the electron transport rate measured by PAM fluorimetry during Rapid Light Curve experiments 总被引:1,自引:0,他引:1
We propose a dynamic model specifically designed to simulate changes in the photosynthetic electron transport rate, which
is calculated from fluorescence measurements when plants are exposed, for a short time, to a series of increasing photon flux
densities. This model simulates the dynamics of the effective yield of photochemical energy conversion from the maximum and
natural chlorophyll fluorescence yields, taking into account a cumulative effect of successive irradiations on photosystems.
To estimate a characteristic time of this effect on photosystems, two series of experiments were performed on two benthic
diatom culture concentrations. For each concentration, two different series of irradiations were applied. Simplified formulations
of the model were established based on the observed fluorescence curves. The simplified versions of the model streamlined
the parameters estimation procedure. For the most simplified version of the model (only 4 parameters) the order of magnitude
of the characteristic time of the residual effect of irradiation was about 38 s (within a confidence interval between 20 and
252 s). The model and an appropriate calibration procedure may be used to assess the physiological condition of plants experiencing
short time-scale irradiance changes in experimental or field conditions. 相似文献
11.
Hydrated thalli of the lichen Lobaria pulmonaria were either preconditioned to dim irradiance (DI, 5 μmol m−2 s−1) or medium irradiance (MI, 200 μmol m−2 s−1) for 6 h. After this 6 h period, the thalli were allowed to desiccate under the two respective irradiances. Thereafter, these
dry lichens were exposed to high irradiance (HI, 1 000 μmol m−2 s−1) for 60 h. After this HI treatment, the maximal photochemical quantum yield (FV/FM) and the de-epoxidation state of xanthophyll cycle pigments (DEPS) were highest in thalli preconditioned to MI. Hence irradiance
in the last hydrated period before sampling is significant for the physiological state of lichens. A standardized irradiance
pre-treatment before start of experiments is recommended. 相似文献
12.
Proline accumulation was studied in the leaves of Glycine max (L.) Merr. subjected to salt stress in the presence of aminoguanidine (AG, a specific inhibitor of diamine oxidase, DAO)
and exogenous putrescine (Put). Both DAO activity and proline content were increased while endogenous Put content was decreased
in soybean leaves under 50 to 150 mM NaCl. There was a negative correlation between proline accumulation and endogenous Put
content. The addition of AG during NaCl stress inhibited DAO activity, caused Put accumulation and a 15 to 20 % decrease in
proline content. Application of 1 mM Put to NaCl solution markedly increased proline content. The promotive effect of Put
application could be alleviated by the treatment with Put plus AG. Moreover an application of AG had no effect on proline
accumulation in soybean seedlings grown under normal condition. These results indicate that the quantitative contribution
of Put degradation to proline formation is 15 to 20 %. 相似文献
13.
To determine what factors limit the growth of wild Fritillaria cirrhosa and Fritillaria delavayi in field conditions, we investigated diurnal changes of the net photosynthetic rate (P
N) and the correlation between P
N and various environmental factors. Parameters of chlorophyll (Chl) fluorescence were evaluated to test whether ecological
fragility caused the extinction of wild F. cirrhosa and F. delavayi. Our study reveals for the first time that F. cirrhosa and F. delavayi did not encounter significant stress under field conditions. A small reduction in maximum photochemical efficiency was observed
under high irradiance. The maximum P
N of F. cirrhosa was 30 % higher than F. delavayi (p<0.05), and a similar difference was observed for apparent quantum yield (27.3 %, p<0.01). F. delavayi was better adapted to a wide range of irradiances and high environmental temperature. Correlation between P
N and environmental factors (without considering the effects of interactions among environmental factors on P
N) using leaves of F. cirrhosa revealed that the three primary influencing factors were air pressure (p<0.01), relative humidity (p<0.01), and soil temperature (p<0.05). In F. delavayi, the influencing factors were relative humidity (p<0.01), soil temperature (p<0.05), CO2 concentration (p<0.05), and air pressure (p<0.05). Path analysis (considering effects among environmental factors on P
N) showed that air temperature (negative correlation), photosynthetic photon flux density (PPFD) and relative humidity were
the three primary limiting factors influencing the growth of F. cirrhosa. For this species, relative humidity reacted indirectly with air pressure, which was reported singularly in other species.
Limiting growth factors for F. delavayi were PPFD, air pressure (negative correlation), soil temperature (negative correlation) and air temperature (negative correlation). 相似文献
14.
Effect of osmotic stress on transpiration and absorption rates in triticale and its parental species
In triticale and its parental species, the application of a root osmotic stress induced either a transient increase or an
immediate decrease in transpiration rate. The response of wheat (Trticum dicoccum farrum) proved to depend on relative humidity of air. In rye (Secale cerealecv. Petkus) and triticale (T. 300) the effect of NaCl stress was less expressive, than the effect of PEG. 相似文献
15.
Sulfur (S) is an essential nutrient element required in a large quantity by mustard. S regulates photosynthesis and plant
growth through improving nitrogen (N) acquisition. Mustard cultivars Alankar, Varuna, Pusa Jai Kisan, and SS2 differing in
S accumulation capacity calculated as sulfate transport index (STI) were tested for ATP-sulfurylase activity, S and N accumulation,
photosynthesis, and shoot dry mass (DM) at 30 and 60 d after sowing (DAS). The activity of ATP-sulfurylase, shoot N content,
net photosynthetic rate (P
N), leaf area, and shoot DM of the cultivars were in the order: Pusa Jai Kisan>Alankar>Varuna>SS2. ATP-sulfurylase activity
was strongly and positively correlated with P
N and shoot DM in all the cultivars. Hence ATP-sulfurylase activity may be used as a physiological trait for augmenting photosynthesis
and shoot DM. 相似文献
16.
Y. Yasumura 《Photosynthetica》2009,47(2):263-270
Annual plants transport a large portion of carbohydrates and nitrogenous compounds from leaves to seeds during the phase of
reproductive growth. This study aimed to clarify how reproductive growth affects photosynthetic traits in leaves and matter
transport within the plant in the annual herb Chenopodium album L. Plants were grown in pots and either reproductive tissues or axillary leaves were removed at anthesis. Matter transport
was evaluated as temporal changes in dry mass (as a substitute of carbohydrates) and nitrogen content of aboveground organs:
leaves, axillary leaves, stems and reproductive tissues. Photosynthetic capacity (light-saturated photosynthetic rate under
ambient CO2 concentration), nitrogen, chlorophyll and soluble protein content were followed in the 20th leaf that was mature at the start of the experiment. Removal of reproductive tissues resulted in accumulation of dry mass
in leaves and axillary leaves, and accumulation of nitrogen in stem as nitrogen resorption from leaves and axillary leaves
proceeded with time. Removal of axillary leaves proportionally reduced dry mass and nitrogen allocation to reproductive tissues,
thus affecting the quantity but not quality of seeds. Removal treatments did not alter the time course of photosynthetic capacity,
nitrogen, chlorophyll or soluble protein content during senescence in the 20th leaf, but changed the photosynthetic capacity per unit of leaf nitrogen according to demand from reproductive tissues. Together,
the results indicate that reproductive tissues affected carbon and nitrogen economy separately. The amount of carbon was adjusted
in leaves through photosynthetic capacity and carbohydrate export from them, and the amount of nitrogen was adjusted by transport
from stem to reproductive tissues. The plant’s ability to independently regulate carbon and nitrogen economy should be important
in natural habitats where the plant carbon-nitrogen balance can easily be disturbed by external factors. 相似文献
17.
Independent short-term effects of photosynthetic photon flux density (PPFD) of 50–400 μmol m−2 s−1, external CO2 concentration (C
a) of 85–850 cm3 m−3, and vapor pressure deficit (VPD) of 0.9–2.2 kPa on net photosynthetic rate (P
N), stomatal conductance (g
s), leaf internal CO2 concentration (C
i), and transpiration rates (E) were investigated in three cacao genotypes. In all these genotypes, increasing PPFD from 50 to 400 μmol m−2 s−1 increased P
N by about 50 %, but further increases in PPFD up to 1 500 μmol m−2 s−1 had no effect on P
N. Increasing C
a significantly increased P
N and C
i while g
s and E decreased more strongly than in most trees that have been studied. In all genotypes, increasing VPD reduced P
N, but the slight decrease in g
s and the slight increase in C
i with increasing VPD were non-significant. Increasing VPD significantly increased E and this may have caused the reduction in P
N. The unusually small response of g
s to VPD could limit the ability of cacao to grow where VPD is high. There were no significant differences in gas exchange
characteristics (g
s, C
i, E) among the three cacao genotypes under any measurement conditions. 相似文献
18.
To determine the effects of phosphorus nutrition on chilling tolerance of photosynthetic apparatus, tomato (Lycopersicon esculentum Mill. cv. Kenfengxin 2002) plants were raised under different P contents and subjected to 7 d of chilling at 9/7 °C. After
chilling (2 h or 7 d) plant growth, P content in tissue, gas exchange and chlorophyll fluorescence were measured. Decreasing
P concentration [P] in the nutrient solution markedly reduced plant growth and the chilled plants exhibiting higher optimum
[P] than the unchilled plants. Decreasing [P] significantly decreased light saturated net photosynthetic rate (PNsat), maximum carboxylation velocity of Rubisco (Vcmax), maximum potential rate of electron transport contributed to Rubisco regeneration (Jmax), quantum efficiency of photosystem (PS) 2 (ΠPS2) and O2 sensitivity of PNsat (PSO2) and this trend was especially apparent in chilled plants. 相似文献
19.
The common bean (Phaseolus vulgaris L.) is sensitive to high temperature, while an ecologically contrasting species (Phaseolus acutifolius A. Gray) is cultivated successfully in hot environments. In this study, the two bean species were respectively acclimated
to a control temperature of 25 °C and a moderately elevated temperature of 35 °C in order to compare the thermotolerance capabilities
of their photosynthetic light reactions. Growth at 35 °C appeared to have no obvious adverse effect on the photosynthetic
activities of the two beans, but changed their thermotolerance. After a short period of heat shock (40 °C for up to 4 h),
the photosynthetic activities of 25 °C-grown P. vulgaris declined more severely than those of P. acutifolius grown at 25 °C, implying that the basal thermotolerance of P. vulgaris is inferior to that of P. acutifolius. But after acclimating to 35 °C, the thermotolerances of the two species were both greatly enhanced to about the same level,
clearly demonstrating the induction of acquired thermotolerance in their chloroplasts, and P. vulgaris could be as good as P. acutifolius. Temperature acclimation also changed plants’ resistance to photoinhibition in a manner similar to those toward heat stress.
In addition, acquisition of tolerance to heat and strong irradiance would reduce the dependency of the two beans on xanthophyll
pigments to dissipate heat, and also seemed irrelevant to the agents with antioxidant activities such as SOD. 相似文献
20.
Leaf area estimation by simple measurements and evaluation of leaf area prediction models in Cabernet-Sauvignon grapevine leaves 总被引:2,自引:0,他引:2
For two growing seasons (2005 and 2006), leaves of grapevine cv. Cabernet-Sauvignon were collected at three growth stages
(bunch closure, veraison, and ripeness) from 10-year-old vines grafted on 1103 Paulsen and SO4 rootstocks and subjected to
three watering regimes in a commercial vineyard in central Greece. Leaf shape parameters (leaf area-LA, perimeter-Per, maximum
midvein length-L, maximum width-W, and average radial-AR) were determined using an image analysis system. Leaf morphology
was affected by sampling time but not by year, rootstock, or irrigation treatment. The rootstock×irrigation×sampling time
interaction was significant for all the leaf shape parameters (LA, Per, L, W, and AR) and the means of the interaction were
used to establish relationships between them. A highly significant linear function between L and LA could be used as a non-destructive
LA prediction model for Cabernet-Sauvignon. Eleven models proposed for the non-destructive LA estimation in various grapevine
cultivars were evaluated for their accuracy in predicting LA in this cultivar. For all the models, highly significant linear
functions were found between calculated and measured LA. Based on r
2 and the mean square deviation (MSD), the model proposed for LA estimation in cv. Cencibel [LA = 0.587(L×W)] was the most
appropriate. 相似文献