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1.
We analysed plant growth, ion accumulation, leaf water relations, and gas exchange of Avicennia germinans (L.) L. subjected to a long-term, controlled salinity gradient from 0 to 55 ‰. Growth and leaf area were affected by salinity
higher than 10 ‰. As salinity increased, the predawn leaf water potential (Ψw) and leaf osmotic potential (Ψs) decreased. Leaf Ψw was at least −0.32 MPa lower than the Ψw of solution. Na+ and K+ ions explained about 78 % of decrease in Ψs. K+ tissue water concentration decreased by more than 60 % in all salinity treatments as compared with those grown at 0 ‰. Inversely,
Na+ concentration in tissue water increased with nutrient solution salinity. The maximum net photosynthetic rate (P
N) and stomatal conductance (g
s) decreased by 68 and 82 %, respectively, as salinity increased from 0 to 55 ‰; the intercellular CO2 concentration (C
i) followed the same trend. The P
N as a function of C
i showed that both the initial linear slope and upper plateau of the P
N
vs. C
i curve were markedly affected by high salinity (40 and 55 ‰). 相似文献
2.
In sunflower (Helianthus annuus L.) grown under controlled conditions and subjected to drought by withholding watering, net photosynthetic rate (P
N) and stomatal conductance (g
s) of attached leaves decreased as leaf water potential (Ψw) declined from −0.3 to −2.9 MPa. Although g
s decreased over the whole range of Ψw, nearly constant values in the intercellular CO2 concentrations (C
i) were observed as Ψw decreased to −1.8 MPa, but C
i increased as Ψw decreased further. Relative quantum yield, photochemical quenching, and the apparent quantum yield of photosynthesis decreased
with water deficit, whereas non-photochemical quenching (qNP) increased progressively. A highly significant negative relationship between qNP and ATP content was observed. Water deficit did not alter the pyridine nucleotide concentration but decreased ATP content
suggesting metabolic impairment. At a photon flux density of 550 μmol m−2 s−1, the allocation of electrons from photosystem (PS) 2 to O2 reduction was increased by 51 %, while the allocation to CO2 assimilation was diminished by 32 %, as Ψw declined from −0.3 to −2.9 MPa. A significant linear relationship between mean P
N and the rate of total linear electron transport was observed in well watered plants, the correlation becoming curvilinear
when water deficit increased. The maximum quantum yield of PS2 was not affected by water deficit, whereas qP declined only at very severe stress and the excess photon energy was dissipated by increasing qNP indicating that a greater proportion of the energy was thermally dissipated. This accounted for the apparent down-regulation
of PS2 and supported the protective role of qNP against photoinhibition in sunflower. 相似文献
3.
J. Čatský D. K. Velichkov Jana Pospísilová Jarmila Solárová Ingrid Tichá 《Biologia Plantarum》1987,29(5):355-364
The carbon balances of whole, 21-d old French bean plants (Phaseolus vulgaris L.) grown in standard nutrient solution (1K) and its modifications without (OK) or surplus (2K) potassium were calculated
from the daily photosynthetic carbon inputs of individual leaves, and the daily respiratory carbon losses by individual leaves,
stalks and petioles, and roots. Under the three K concentrations, maximum net photosynthetic rates (Pn) were found in the 2nd or in the 3rd trifoliate leaves, maximum respiratory rates (Rd) in the youngest, 4th trifoliate leaves; the Pn/Rd ratio decreased with leaf age. In all leaves of 2K plants, leaf dry masses and thicknesses, Pn, Pn/Pd ratios, and stomatal and intracellular conductances were lower than in OK and IK plants. Daily whole-plant net carbon gain
was highest in IK plants, whereas in OK and 2K plants it was 98.0 and 81.3 % of IK, respectively. Similar values were found
in the parameters of growth analysis, namely in net assimilation rates and relative growth rates.
No differences were found in water potential (Ψ
w
) or water saturation deficit (Wsat) in the OK, 1K and 2K plants sufficiently supplied with water or during wilting and resaturation. The decrease in Ψw to −0.97 MPa was associated with a 19.9 %, 31.4 % and 23.4 % decrease in Pn of OK, 1K and 2K plants, respectively, but no effect on Rd was found. In the three variants, the short-time effect of mild water stress was fully reversible. 相似文献
4.
Water potential and sap flow rate in adult trees with moist and dry soil as used for the assessment of root system depth 总被引:4,自引:0,他引:4
Sap flow rate (Qw) and leaf water potential (Ψw.leaf) in adult specimens of birch (Betula) and oak (Quercus) were measured under contrasting soil moisture conditions (Ψw.sofl). With sufficient soil moisture Qw reached about 250 cm3h−1 calculated per unit tree-trunk segment as given by 1 cm length of its circumference. In soil water-stress conditions (when
Ψw.leaf = = −15 × 105Pa), birch stopped transpiration and wilted. Oak transpired even when Ψw.leaf fell below −20 × 105Pa. The relation between Qw and Ψw.leaf was always linear and with various Ψw.soil differed in the slopes of regression lines only. Hydraulic conductance (Kwcu) with nonlimiting moisture conditions reached about 6 × 10−9m3 10−5Pa−1s−1 and “conductivity” (“kwa”) when calculated per leaf area unit reached about 23 m 10−5Pa−1s−1. Kwcu and “kwa” were of about one half to nine times greater in birch than in oak. On the basis of relations between Ψw.soil at various depths, Ψw.leaf and Qw (resp. Kw) it is possible to assess the maximal rooting depth and the effective depth where the maximum of absorption of roots occurs.
It is to be seen that the root system macrostructure substantially participates in the drought avoidance of adult trees in
a forest stand. 相似文献
5.
Francesco Ripullone Maria Rosa Guerrieri Angelo Nole’ Federico Magnani Marco Borghetti 《Trees - Structure and Function》2007,21(3):371-378
In this study, tree hydraulic conductance (K
tree) was experimentally manipulated to study effects on short-term regulation of stomatal conductance (g
s), net photosynthesis (A) and bulk leaf water potential (Ψleaf) in well watered 5–6 years old and 1.2 m tall maritime pine seedlings (Pinus pinaster Ait.). K
tree was decreased by notching the stem and increased by progressively excising the root system and stem. Gas exchange was measured
in a chamber at constant irradiance, vapour pressure deficit, leaf temperature and ambient CO2 concentration. As expected, we found a strong and positive relationship between g
s and K
tree (r = 0.92, P = 0.0001) and between A and K
tree (r = 0.9, P = 0.0001). In contrast, however, we found that the response of Ψleaf to K
tree depended on the direction of change in K
tree: increases in K
tree caused Ψleaf to decrease from around −1.0 to −0.6 MPa, but reductions in K
tree were accompanied by homeostasis in Ψleaf (at −1 MPa). Both of these observations could be explained by an adaptative feedback loop between g
s and Ψleaf, with Ψleaf prevented from declining below the cavitation threshold by stomatal closure. Our results are consistent with the hypothesis
that the observed stomatal responses were mediated by leaf water status, but they also suggest that the stomatal sensitivity
to water status increased dramatically as Ψleaf approached −1 MPa. 相似文献
6.
Water status of Pinus taeda L. callus supported on Murashige and Skoog (MS) liquid medium was characterized over an 8 week period using thermocouple
psychrometry. Medium with 30 gl−1 sucrose was used to produce a high water potential (Ψw) of −0.4 MPa (H), and the same medium was used to create a moderate Ψw of −0.7 MPa (M) by the addition of 10% polyethylene glycol (PEG, w/v, MW=8000). Calli were produced from cotyledon explants
on H medium for 2 weeks and then transferred to either M or H medium. Callus absorption of PEG accounted for 40% of the callus
dry weight and less than 7% of the callus fresh weight. Callus dry weight (without the PEG fraction) on M medium was 40% of
that observed on H medium. Fresh weight on M medium was only 15% of that observed on H medium. The Ψw of both H and M media remained constant throughout the culture period. On H medium, callus Ψw and osmotic potential (Ψs) both increased 0.05 MPa/week with the callus Ψw approaching that of the external medium. On M medium, callus Ψw and Ψs both decreased more than 0.1 MPa/week with the callus Ψw decreasing greatly below that of the external medium. The latter was attributed to a rapidly produced osmotic shock induced
upon callus transfer and/or PEG which caused less callus hydration and resulted in reduced growth. Callus turgor potential
(Ψp) was estimated to be +0.02 to +0.09 MPa and turgor was maintained as callus Ψw increased or decreased. After 8 weeks, cell volumes from callus on M medium were 50 to 60% less than on H medium, suggesting
that reduced cell volumes were related to turgor maintenance. 相似文献
7.
Leaf gas exchange in a clonal eucalypt plantation as related to soil moisture, leaf water potential and microclimate variables 总被引:7,自引:0,他引:7
M. S. Mielke M. A. Oliva N.F. de Barros R. M. Penchel C. A. Martinez S. da Fonseca A.C. de Almeida 《Trees - Structure and Function》2000,14(5):263-270
In order to determine how environmental and physiological factors affect leaf gas exchange in a 9-year-old clonal eucalypt
plantation (Eucalyptus grandis Hill ex. Maiden hybrids) in the State of Espirito Santo, Brazil, the diurnal patterns of predawn leaf water potential (Ψpd), and leaf gas exchange were monitored from November 1995 to August 1996. Soil water content (Θ) and microclimatic variables
were also recorded. Most of the rainfall during the experimental period occurred from October to December 1995 and from March
to April 1996, causing a significant variation in Θ and Ψpd. A high positive correlation (r
2=0.92) was observed between Ψpd and Θ measured at 0.3 m depth from the soil surface. During conditions of high soil water availability, the maximum values
of stomatal conductance for water vapor (g
s) and net photosynthetic rate (A) were over 0.4 mol m–2 s–2 and l5 μmol m–2 s–1, respectively. The results showed that Ψpd and leaf gas exchange of the examined trees were susceptible to changes in the water content of the upper soil layers, where
the major concentration of active roots occur. Multiple linear regression analysis indicated that photosynthetic active radiation
(Q), vapor pressure deficit (VPD), atmospheric CO2 molar fraction (C
a), and Ψpd were the most important factors controlling g
s whereas Q and VPD were the main microclimatic variables controlling A.
Received: 5 November 1998 / Accepted: 10 November 1999 相似文献
8.
A. L. García L. Marcelis F. Garcia-Sanchez N. Nicolas V. Martínez 《Biologia Plantarum》2007,51(4):707-712
The responses of water relations, stomatal conductance (gs) and growth parameters of tomato (Lycopersicon esculentum Mill. cv. Royesta) plants to nitrogen fertilisation and drought were studied. The plants were subjected to a long-term, moderate
and progressive water stress by adding 80 % of the water evapotranspirated by the plant the preceding day. Well-watered plants
received 100 % of the water evapotranspirated. Two weeks before starting the drought period, the plants were fertilised with
Hoagland’s solution with 14, 60 and 110 mM NO3
− (N14, N60 and N110, respectively). Plants of the N110 treatment had the highest leaf area. However, gs was higher for N60 plants and lower for N110 plants. At the end of the drought period, N60 plants showed the lowest values
of water potential (Ψw) and osmotic potential (Ψs), and the highest values of pressure potential (Ψp). N60 plants showed the highest Ψs at maximum Ψp and the highest bulk modulus of elasticity. 相似文献
9.
The effects of propagation microclimate and foliar area on the rooting of Cordia
alliodora (Ruiz & Pavon) Oken cuttings were investigated using non-mist propagators with and without shade. Photosynthetic rates (P
n
), stomatal conductance (g
s
) and chlorophyll fluorescence ratio (Fv/Fm) of the cuttings were assessed during propagation. Pronounced differences in microclimate were recorded between treatments,
with lower temperatures and vapour pressure deficit (VPD) under shade. During the first 8 days after insertion, P
n
varied between 2.21 and 4.96 and 0.47 – 2.54 μmol CO2 m –
2s –
1 in the shaded and unshaded propagators, respectively. In the unshaded propagator, Fv/Fm decreased to a minimum of 0.72 2 days after insertion, recovering thereafter. In two separate rooting experiments, rooting
percentage was reduced by high irradiance in the 20 and 30 cm2 leaf area treatments, but not in the 10 cm2 treatment. P
n
decreased with an increase in leaf area in both shaded and unshaded propagators. Fv/Fm also declined with increasing leaf area in the high irradiance treatment. PAR and P
n
were positively correlated under shade (r
2 = 0.51) but negatively correlated in the unshaded treatment (r
2 = 0.49); maximum P
n
values were recorded at a PAR of 400 μmol m –
2 s –
1. No significant differences in g
s
were found between treatments, values ranging between 130 and 194 mmol H2O m –
2 s –
1. Positive correlations were found between rooting percentage and mean Fv/Fm. These results indicate that rooting of C. alliodora cuttings is related to photosynthetic activity during propagation, which is itself influenced both by propagator microclimate
and cutting leaf area.
Received: 7 May 1996 / Accepted: 17 December 1996 相似文献
10.
研究外源GA3对盐胁迫下黄瓜种子萌发和幼苗生长的影响。结果表明,添加不同质量浓度GA3的各处理,其发芽率、发芽势和发芽指数均显著高于NaCl胁迫处理,其中以100 mg/L GA3处理的发芽势、发芽率和发芽指数最高,幼苗的叶面积、根长、根冠比也最大,同时叶片中叶绿素含量最高,幼苗叶片的光合速率(Pn)、气孔导度(Gs)、胞间CO2摩尔分数(Ci)及蒸腾速率(Tr)等均达到最大;而当赤霉素的质量浓度为50 mg/L时,叶片中的POD活性为2 005 U/(g·min),达最大值。 相似文献
11.
Chun-Wang Xiao Osbert J. Sun Guang-Sheng Zhou Jing-Zhu Zhao Gang Wu 《Trees - Structure and Function》2005,19(6):712-721
We studied the responses of leaf water potential (Ψw), morphology, biomass accumulation and allocation, and canopy productivity index (CPI) to the combined effects of elevated
CO2 and drought stress in Caragana intermedia seedlings. Seedlings were grown at two CO2 concentrations (350 and 700 μmol mol−1) interacted with three water regimes (60–70%, 45–55%, and 30–40% of field capacity of soil). Elevated CO2 significantly increased Ψw, decreased specific leaf area (SLA) and leaf area ratio (LAR) of drought-stressed seedlings, and increased tree height, basal
diameter, shoot biomass, root biomass as well as total biomass under the all the three water regimes. Growth responses to
elevated CO2 were greater in well-watered seedlings than in drought-stressed seedlings. CPI was significantly increased by elevated CO2, and the increase in CPI became stronger as the level of drought stress increased. There were significant interactions between
elevated CO2 and drought stress on leaf water potential, basal diameter, leaf area, and biomass accumulation. Our results suggest that
elevated CO2 may enhance drought avoidance and improved water relations, thus weakening the effect of drought stress on growth of C. intermedia seedings. 相似文献
12.
Bartolomeo Dichio Giovanna Margiotta Cristos Xiloyannis Sabino A. Bufo Adriano Sofo Tommaso R. I. Cataldi 《Trees - Structure and Function》2009,23(2):247-256
Two-year-old olive trees (Olea europaea L., cv. Coratina) were subjected to a 15-day period of water deficit, followed by 12 days of rewatering. Water deficit caused
decreases in predawn leaf water potential (Ψw), relative water content and osmotic potential at full turgor (Ψ
π100) of leaves and roots, which were normally restored upon the subsequent rewatering. Extracts of leaves and roots of well-watered
olive plants revealed that the most predominant sugars are mannitol and glucose, which account for more than 80% of non-structural
carbohydrates and polyols. A marked increase in mannitol content occurred in tissues of water-stressed plants. During water
deficit, the levels of glucose, sucrose and stachyose decreased in thin roots (with a diameter <1 mm), whereas medium roots
(diameter of 1–5 mm) exhibited no differences. Inorganic cations largely contribute to Ψ
π100 and remained stable during the period of water deficit, except for the level of Ca2+, which increased of 25% in water-stressed plants. The amount of malate increased in both leaves and roots during the dry
period, whereas citrate and oxalate decreased. Thin roots seem to be more sensitive to water deficit and its consequent effects,
while medium roots present more reactivity and a higher osmotic adjustment. The results support the hypothesis that the observed
decreases in Ψw and active osmotic adjustment in leaves and roots of water-stressed olive plants may be physiological responses to tolerate
water deficit. 相似文献
13.
Predawn disequilibrium between plant and soil water potentials in two cold-desert shrubs 总被引:15,自引:0,他引:15
L. A. Donovan D. J. Grisé J. B. West R. A. Pappert N. N. Alder J. H. Richards 《Oecologia》1999,120(2):209-217
Classical water relations theory predicts that predawn plant water potential should be in equilibrium with soil water potential
(soil Ψw) around roots, and many interpretations of plant water status in natural populations are based on this expectation. We examined
this expectation for two salt-tolerant, cold-desert shrub species in glasshouse experiments where frequent watering assured
homogeneity in soil Ψw and soil-root hydraulic continuity and where NaCl controlled soil Ψw. Plant water potentials were measured with a pressure chamber (xylem Ψp) and thermocouple psychrometers (leaf Ψw). Soil Ψw was measured with in situ thermocouple psychrometers. Predawn leaf Ψw and xylem Ψp were significantly more negative than soil Ψw, for many treatments, indicating large predawn soil-plant Ψw disequilibria: up to 1.2 MPa for Chrysothamnus nauseosus (0 and 100 mm NaCl) and 1.8 MPa for Sarcobatus vermiculatus (0, 100, 300, and 600 mm NaCl). Significant nighttime canopy water loss was one mechanism contributing to predawn disequilibrium, assessed by comparison
of xylem Ψp for bagged (to minimize transpiration) and unbagged canopies, and by gas exchange measurements. However, nighttime transpiration
accounted for only part of the predawn disequilibrium. Other mechanisms that could act with nighttime transpiration to generate
large predawn disequilibria are described and include a model of how leaf apoplastic solutes could contribute to the phenomenon.
This study is among the first to conclusively document such large departures from the expectation of predawn soil-plant equilibrium
for C3 shrubs, and provides a general framework for considering relative contributions of nighttime transpiration and other plant-related
mechanisms to predawn disequilibrium.
Received: 12 November 1998 / Accepted: 5 May 1999 相似文献
14.
J. Václavík 《Biologia Plantarum》1984,26(3):206-214
A study was made on the effect of increasing photon fluence rate (I) at a unilateral irradiation of adaxial (normal leaf position) and abaxial (inverse leaf position) blade surface of maize
leaves of various insertion levels on net photosynthetic CO2 uptake (P
n
) by the leaves, as well as the contribution of individual surfaces toP
n
of the leaves, and the significance of, or relationship between the stomatal (g
s
) and intracellular (gm) conductances at the CO2 transport.P
n
of leaves of various age according to their insertion level was unaffected by the direction of incident irradiation. Upon
irradiation of the leaves in normal and inverse position the contribution of the adaxial and abaxial surfaces toP
n
,g
s
and gm was different. On irradiating the leaves in normal position, the contribution of the irradiated adaxial surface to the characteristics
mentioned made on the average 55% of total values, the contribution of the abaxial surface irradiated in inverse position
made on the average 70% inP
n
andg
m
, and 80% ing
s
. At lowerI’s g
m
was higher thang
s
both in irradiated and non-irradiated surfaces. The ratio ofg
s
to gm gradually got square with increasingI. In the irradiated adaxial surface the equilibrium (g
s
/g
m
= 1.0) took place at the highestI’s, in the irradiated abaxial surface between 500 to 1000 μmol m−2 s−1. The significance of the ratiog
m
in the CO2 transport through the individual surfaces is discussed. 相似文献
15.
The role of gibberellins (GAs) in the regulation of shoot elongation is well established but the phytohormonal control of
dry-matter production is poorly understood. In the present study, shoot elongation and dry-matter production were resolved
by growing Brassica napus L. seedlings under five light intensities (photon flux densities) ranging from 25 to 500 μmol m−2 s−1. Under low light, plants were tall but produced little dry weight; as light intensity was increased, plants were progressively
shorter but had increasing dry weights. Endogenous GAs in stems of 16- and 17-d-old plants were analyzed by gas chromatography-selected
ion monitoring with [2H2] internal standards. The contents of GAs increased dramatically with decreasing light intensity: GA1, GA3, GA8 and GA20 were 62, 15, 16 and 32 times higher, respectively, under the lowest versus highest light intensities. Gibberellin A19 was not measured at 25 μmol m−2 s−1 but was 9␣times greater in the 75 compared to 500 μmol m−2 s−1 treatment. Shoot and hypocotyl lengths were closely positively correlated with (log) GA concentration (for example: r
2 = 0.93 for GA1 and hypocotyl length) but shoot dry matter was negatively correlated with GA concentration. The application of gibberellic
acid (GA3) produced elongation of plants grown under high light, indication that their low level of endogenous GA was limiting shoot
elongation. Although endogenous GA20 showed the greatest influence of light treatment, metabolism of [3H]GA20 and of [3H]GA1 was only slightly influenced by light intensity, suggesting that neither 2β- nor 3β-hydroxylation were points of metabolic
regulation. The results of this study indicate that GAs control shoot elongation but are not directly involved in the regulation
of shoot dry weight in Brassica. The study also suggests a role of GAs in photomorphogenesis, serving as an intermediate between light condition and shoot
elongation response.
Received: 18 June 1998 / Accepted: 29 July 1998 相似文献
16.
Relative water content (RWC), leaf water potential (w) and osmotic potential (s), contents of chlorophyll (Chl) a, Chl b, soluble sugars, and seed quality (gum content) were used to evaluate the role of phosphorus in alleviation of the deleterious effect of water deficit in clusterbean (Cyamopsis tetragonoloba L. Taub). Under water stress, w, s, and Chl and gum contents decreased and soluble sugar contents increased. Phosphorus application increased Chl and sugar contents in control plants and ameliorated negative effects of water stress. 相似文献
17.
Jin-Dong Wu Jin-Cai Li Feng-Zhen Wei Cheng-Yu Wang Yi Zhang Genlou Sun 《Acta Physiologiae Plantarum》2014,36(1):207-216
Waterlogging is a main stress factor during the late growing stage of winter wheat (Triticum aestivum L.) in the southern Huanghuai and Yangtze Valley regions of China. The effects of nitrogen spraying on post-anthesis of winter wheat under waterlogging stress were studied in continuous growing seasons from 2009 to 2011. The results showed that waterlogging after the anthesis stage significantly reduced root respiratory activity, leaf greenness (SPAD reading), photosynthetic rate (P n), stomatal conductance (G s) and transpiration rate (T r) by averages of 11.09, 10.75, 15.18, 8.97 and 8.82 %, respectively, increased intercellular CO2 concentration (C i) by 9.74 % and decreased grain number per spike, 1,000-grain weight and grain yield by 8.07, 12.68 and 20.11 %, respectively. Nitrogen spraying significantly improved root respiratory activity, leaf greenness (SPAD reading), photosynthetic rate (P n), stomatal conductance (G s) and transpiration rate (T r) by 4.96, 7.35, 7.01, 5.09 and 5.09 %, respectively, reduced intercellular CO2 concentration (C i) by 9.74 % and increased grain number per spike, 1,000-grain weight and grain yield by 4.71, 6.45 and 11.48 %, respectively. However, neither nitrogen spraying nor waterlogging had significant effects on spike number. There was significant interaction between waterlogging and nitrogen spraying. Our results suggest that nitrogen spraying is an effective way to alleviate the negative effects of waterlogging stress after anthesis stage in winter wheat. 相似文献
18.
Carbon assimilation in contrasting streamside and inland Spartina alterniflora salt marsh 总被引:1,自引:0,他引:1
Carbon assimilation and standing crop biomass of Spartina alterniflora were studied in a contrasting streamside and inland salt marsh in Louisiana Gulf coast, USA. A substantially lower leaf dry weight, leaf area index, and standing crop biomass were recorded for inland plants as compared to streamside plants. Net assimilation rates ranged between 8 to 25 mol m–2 s–1 for streamside and between 4 to 19 mol m–2 s–1 for inland plants. The average photosynthetic rates were significantly lower for inland plants which were growing in an apparently more stressed environment. In addition, the differences were more profound with progression of the growing season. The reduced photosynthetic activity in the inland marsh was attributed to greater soil waterlogging, increased anaerobic root respiration, plant toxins (sulfide), restricted nutrient uptake or a combination of these factors.Abbreviations Eh =
redox potential
- gw =
stomatal conductance
- LAI =
leaf area index
- Pn =
net photosynthesis
- PPFD =
photosynthetic photon flux density
- T1 =
leaf temperature 相似文献
19.
In Vitis vinifera L. berries, the onset of ripening (known as “veraison”) involves loss of turgor (P) in the mesocarp cells. We hypothesized
that P loss was associated with an accumulation of apoplastic solutes in mesocarp tissue prior to veraison. Apoplastic sap
was extracted from the mesocarp by centrifugation at the appropriate gravity to measure the apoplast solute potential (ΨsA) and assay the sap composition. The ΨsA was about −0.2 MPa early in development, decreased about 1.0 MPa by veraison, and continued to decrease during ripening to
almost −4.0 MPa by the end of berry development. Potassium, malate, tartrate, proline, glucose, fructose, and sucrose were
quantified in apoplastic sap. The calculated contribution of these solutes was about 50% of the total ΨsA preveraison, but increased to about 75% as fructose and glucose accumulated during ripening. The contribution of the estimated
matric potential to apoplast water potential decreased during development and was only 1.5% postveraison. We conclude that
high concentrations of solutes accumulated in the mesocarp apoplast prior to veraison, and that P loss was a direct result
of decreased ΨsA. Because ΨsA decreased before veraison, our findings suggest that apoplast solutes play an important role in the events of cellular metabolism
that lead to the onset of ripening. 相似文献
20.
M. Gomathinayagam V. E. Anuradha Changxing Zhao Gloria A. Ayoola C. Abdul Jaleel R. P. Anneerselvam 《Frontiers of Biology in China》2009,4(3):337-341
In this study, 5 μmol·L−1 abscisic acid (ABA) and gibberellic acid (GA3) were used to study the effect of both growth regulators on the morphological parameters and pigment composition of Andrographis paniculata. The growth regulators were applied by means of foliar spray during morning hours. ABA treatment inhibited the growth of
the stem and internodal length when compared with control, whereas GA3 treatment increased the plant height and internodal length. The total number of leaves per plant decreased in the ABA-treated
plants, but GA3 treatment increased the total number of leaves when compared with the control. Both growth regulators (ABA and GA3) showed increased leaf area. ABA and GA3 treatments slightly decreased the total root growth at all the stages of growth. The growth regulator treatments increased
the whole plant fresh and dry weight at all stages of growth. ABA enhanced the fresh and dry weight to a larger extent when
compared with GA3. An increase in the total chlorophyll content was recorded in ABA and GA3 treatments. The chlorophyll-a, chlorophyll-b, and carotenoids were increased by ABA and GA3 treatments when compared with the control plants. The xanthophylls and anthocyanin content were increased with ABA and GA3 treatments in A. paniculata plants. 相似文献