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1.
U. Celikkol Akcay O. Ercan M. Kavas L. Yildiz C. Yilmaz H. A. Oktem M. Yucel 《Plant Growth Regulation》2010,61(1):21-28
Two cultivars of peanut (Arachis
hypogaea L.) which were designated as resistant (Florispan) and sensitive (Gazipasa) according to their growth retardation under drought
stress conditions were compared for their oxidative damage and antioxidant responses. Sixteen days-old peanut seedlings were
subjected to PEG-6000 solutions of two different osmotic potentials; −0.4 and −0.8 MPa, and various growth parameters, photosystem
II activity, changes in malondialdehyde (MDA), hydrogen peroxide (H2O2) and proline levels, activities of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX) and gluthatione reductase
(GR) enzymes were determined. Both cultivars exhibited water deficit at −0.8 MPa osmotic potential of PEG-6000 and H2O2 levels significantly increased during exposure to −0.4 MPa osmotic potential. However, H2O2 levels were under control in both cultivars at exposure to −0.8 MPa osmotic potential. Significant proline accumulation was
observed in the tissues of cv. Florispan at −0.8 MPa osmotic potential, whereas proline accumulation did not appear to be
an essential part of the protection mechanism against drought in cv. Gazipasa. No significant variation in chlorophyll fluorescence
values were detected in neither of the cultivars. Enzyme activity measurements revealed that Gazipasa copes well with lesser
magnitudes of drought stress by increasing the activity of mainly APX, and during harsh stress conditions, only APX maintains
its activity in the tissues. In cultivar Florispan, GR activity appears to take role in lesser magnitudes of drought stress,
whereas CAT and APX activities appear to be very crucial antioxidative defenses during intense stress conditions. The results
indicate that, the level of proline and activities of the enzymes CAT and APX are important mechanisms for the maintenance
of drought tolerance in peanut plants. 相似文献
2.
Hanna Bandurska 《Acta Physiologiae Plantarum》1998,20(4):375-381
The aim of this work was to examine the ability of ABA and proline to counteract the deleterious effect of water deficit stress
on cell membrane injuries.
Six-day-old seedlings of two barley genotypes (cv. Aramir, line R567) were treated with ABA (2·10−4 M) or proline (0.1 M) for 24 h, and then subjected to osmotic stress for 24h, by immersing their roots in polyethylene glycol
(PEG 6000) solution of osmotic potential of −1.0 MPa and −1.5 MPa or by submerging the leaf pieces in PEG solution of osmotic
potential of −1.6 MPa.
Pretreatment of plants with ABA and proline caused an increase of free proline level in the leaves. Plants treated with ABA
exhibited a lower membrane injury index under water stress conditions than those untreated even when no effect of this hormone
on RWC in the leaves of stressed plants was observed. Pretreatment of plants with proline prevented to some extent membrane
damage in leaves of the stressed seedlings, but only in the case when stress was imposed to roots. Improvement in water status
of leaves was also observed in seedlings pretreatment with proline. The protective effect of both ABA and proline was more
pronounced in line R567 that exhibited higher membrane injury under water deficit stress conditions. 相似文献
3.
Global warming will likely exacerbate the negative effects of limited water availability in the Mediterranean area. The Italian
Aleppo pine (Pinus halepensis Mill.) provenances are distributed along the coasts except Otricoli provenance growing in an unusual location between 300
and 1,000 m a. s. l., in Umbria (central Italy). The aim of the present study was to investigate the photosynthetic response
to a 28-day-long drought and to a subsequent reestablishment of water availability in Otricoli and North Euboea (Greece) provenances,
representing different locations along a rainfall gradient in the natural range of this species. Six-month-old seedlings were
used in this experiment since at this age Aleppo pine plants in Mediterranean climate face their first water stress potentially
affecting plant survival. Water potential (ψw), net photosynthesis and stomatal conductance decreased during drought in both provenances and showed minimal values 28 days
after beginning the treatment (DAT). Otricoli seedlings adjusted ψw gradually as the stress level increased and 21 DAT showed a lower ψw than North Euboea. In contrast, in North Euboea seedlings ψw that was not affected until 21 DAT rapidly dropped to a minimum of −3.81 MPa 28 DAT. At the onset of the stress the intercellular
CO2 concentration (C
i) was reduced, and the “instrinsic” water-use efficiency (WUEi) was enhanced in both provenances, as stomatal conductance decreased more rapidly than photosynthesis. However, 28 DAT, C
i increased and WUEi decreased as stomatal conductance and photosynthesis declined to minimum levels, revealing nonstomatal
limitations of photosynthesis. A rapid decrease in PSII maximal photochemical efficiency estimated by chlorophyll (Chl) fluorescence
(Fv/Fm) was also observed when the stress became severe. At the final stage of water stress, North Euboea seedlings maintained significantly
higher values of Fv/Fm than Otricoli seedlings. Upon rewatering, photosynthesis did not fully recover in Otricoli seedlings (41 DAT), while all
other parameters recovered to control levels in both provenances. No drought-induced physiological differences were consistent
with the regional climatic features of these two provenances. Our results suggest that phenotypic plasticity in drought response
may help Otricoli provenance cope with global warming, but that recurrent drought episode may slow down the primary productivity
of this provenance. 相似文献
4.
为了鉴别不同种源的栓皮栎(Quercus variabilis)耐旱性,对4个种源的3年生盆栽幼苗进行了控制条件下的土壤干旱胁迫实验,系统测定了超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性、MDA(丙二醛)含量、膜透性,以及叶片P-V曲线导出的水分关系参数(Ψπsat、Ψπtlp、WSDtlp、εmax)。结果表明:在土壤干旱胁迫下,种源4(黄龙)和种源3 (秦岭北坡) 抗氧化能力较强, 种源2 (伏牛山)居中, 种源1(巴山)的表现最差。干旱胁迫使各种源 MDA的含量及膜透性均有不同程度的提高,其中种源4的MDA含量及膜透性比较平稳, 种源1变化剧烈。在干旱胁迫下,各种源渗透调节和保持膨压的能力均有提高,但存在差异,以种源4和种源3表现较好,种源2居中,种源1较差。应用Fuzzy方法,对不同种源的叶片水分关系参数、保护酶活性和膜透性在干旱胁迫中的动态进行综合评判,认为不同种源的耐旱性强度次序为:种源4>种源3>种源2>种源1。其中种源4与种源1和种源2差异显著(p<0.05)。 相似文献
5.
Hanna Bandurska 《Acta Physiologiae Plantarum》2001,23(4):483-490
The purpose of this research was to examine whether proline accumulation in leaves of barley under conditions of mild water
deficit (PEG — 0.75 MPa imposed on roots) may modify membrane injuries caused by subsequent severe osmotic stress (PEG — 1.6
MPa imposed on leaves). Six-day-old seedlings of four barley genotypes were used in the experiments. Substantial and different
proline accumulation was found in the leaves of mild water deficit-stressed plants of the most investigated genotypes. This
stress factor caused rather a small decrease in RWC and did not lead to membrane injuries. Severe osmotic stress imposed on
leaves caused considerable membrane injuries in all the genotypes investigated. Leaves of plants pre-stressed with mild water
deficit and then subjected to severe osmotic stress exhibited about a 50% lower membrane injury than those of not pre-stressed
plants. A possible role of proline accumulated in the leaves of pre-stressed plants in the process of alleviating cell membrane
injuries in the leaves subsequently exposed to severe water deficit is discussed. 相似文献
6.
The responses of leaf water parameters to drought were examined using three sunflower (Helianthus annuus L.) genotypes. Osmotic potential at full water saturation (π100), apoplastic water fraction (AWF) and bulk elastic modulus (BEM) were determined by pressure-volume curve analysis on well
watered or on water-stressed plants (−1.0 MPa Ψ1 < −1.5 MPa) previously drought-pretreated or not. The drought-pretreated plants were subjected to a 7-day drought period
(predawn leaf water potential reached −0.9 MPa) followed by 8 days of rewatering. In well watered plants, all genotypes in
response to drought acclimation displayed a significantly decreased π100 associated with a decrease in the leaf water potential at the turgor-loss point (decrease in Ψtlp was between 0.15 and 0.21 MPa, depending on the genotype). In two genotypes, drought acclimation affected the partitioning
of water between the apoplastic and symplastic fractions without any effect on the total amount of water in the leaves. As
a third genotype displayed no modification of AWF and BEM after drought acclimation, the decreased π100 was only due to the net accumulation of solutes and was consistent with the adjustment of the photochemical efficiency observed
previously in this genotype in response to drought acclimation. In water-stressed plants, the osmotic adjustment (OA) can
increase further beyond that observed in response to the drought pretreatment. However, the maintenance of photosynthetic
rate and stomatal conductance at low leaf water potentials not only depends on the extent of osmotic adjustment, but also
on the interaction between OA and AWF or BEM. Adaptative responses of leaf water parameters to drought are thus quite contrasted
in sunflower genotypes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
Responses of Quercus ilex L. seedlings from three different localities in Italy to experimentally imposed drought stress were analysed. Predawn (Ψpd) and midday (Ψm) leaf water potential of stressed seedlings decreased on an average until −4.0 and −4.2 MPa, respectively, in the severe
water stress. At the end of the severe water stress the relative water content (RWC) was 72.5 – 83.6 % and the photosynthetic
rates (PN) near zero. The critical threshold value of Ψpd for complete stomatal closure was from −4.0 to −4.5 MPa. The leaf damage after the severe water stress was significantly
greater in seedlings originated from the acorns of climax area (45 % total leaf injured area and 40 % fallen leaves) than
in the other seedlings (on an average 20.5 % total leaf injured area and 21 % fallen leaves).
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Mehdi Ladjal Nathalie Deloche Roland Huc Michel Ducrey 《Trees - Structure and Function》2007,21(2):201-213
Three- and four-year-old potted, greenhouse-grown cedar seedlings were subjected to two different watering regimes: half received
full water supply and the other half was submitted to moderate drought (50% of the full water supply). Height growth was the
greatest for C. atlantica and the most-limited for C. brevifolia in the well-watered set. However, in the dry set, height growth was less affected by drought conditions for C. brevifolia than for C. atlantica. Cedrus libani gave intermediate results for both watering regimes. Moderate drought provoked a decrease in osmotic potential at full leaf
turgor and a long-lasting osmotic adjustment. When irrigation was withheld completely to induce severe soil drying, gas exchange
decreased and then stopped at predawn water potentials of −3.0 MPa for C. brevifolia, between −2.6 and −2.8 MPa for C. libani, and at −2.4 MPa for C. atlantica, irrespective of watering regime. For all species, the dry set showed lower net photosynthesis (A) and stomatal conductance (g
s) than the plants in the well-watered set. A and g
s responded to variations in atmospheric water-vapour pressure deficit (VPD). As VPD increased, A and g
s decreased, and this trend was proportionate to initial values at low VPD, but remained independent of previous watering treatments,
plant water status or species. To conclude, C. brevifolia appears to be a species with limited growth potential but strong soil drought tolerance whereas C. atlantica has strong growth potential when an adequate water supply is available but is more sensitive to soil drought. C. libani shows an intermediate behaviour for growth and drought tolerance. 相似文献
9.
Seasonal changes in water relations, production and mineral composition were studied in a sward ofCynodon dactylon (L). Pers. subjected to water deficits during a dry summer, and at recovery in autumn. The experiment was carried out under
Mediterranean field conditions. Water deficits during summer reduced total dry matter production by 60%, but in autumn there
were no differences between treatments. Compared to well-watered sward, the sward grown under drought showed an increase in
potassium, calcium and nitrogen of 55, 10 and 10% respectively. These differences decreased with the arrival of autumn rains.
Leaf osmotic potential (ΨΠ) fell during the dry summer to −2.8 MPa in well-watered plants and to −4.2 MPa in stressed plants. In autumn there were no
differences between treatments. Nevertheless, relative water content (RWC) only decreased to 0.86 in droughted plants. In
summer potassium contributed to the osmotic adjustment. In contrast, under water deficits a decrease of 71% in sodium and,
to a lesser but significant extent decreases in phosphorus, magnesium and chlorine was observed. Nitrogen, phosphorus and
sulphur showed low concentrations during summer and increased in autumn. 相似文献
10.
We studied the impact of mild and severe drought stresses for 42 days and rehydration for 21 days on 4-year-old seedlings
of Norway spruce. Water relations in spruce tissues were determined on the basis relative water content of needles and shoot
water potential (Ψshoot). During the stress, we measured the level of: reactive oxygen species (ROS), antioxidants, and degradation of cell membranes.
In the seedlings subjected to severe stress, Ψshoot decreased to −2.4 MPa, while in those subjected to mild stress, to −0.8 MPa. After rehydration, shoot water potential increased,
but did not reach the control level. Water deficit caused oxidative stress, reflected in an increased production of ROS: superoxide
anion radical (
) and hydrogen peroxide (H2O2). Their concentrations in needles were the highest in seedlings subjected to severe stress, where they exceeded the control
level by 116% and 30%, respectively. During rehydration, the differences in ROS levels between treated and control seedlings
diminished. Oxidative stress causing degradation of cell membranes included: de-esterification of phospholipids, oxidation
of fatty acids, and increase in concentration of malondialdehyde, as their permeability to ions increased by 125%. In the
defence against the oxidative stress in needles, an important role was played by low-molecule antioxidants such as glutathione,
ascorbic acid, flavonoids, α-tocopherol and antioxidant enzymes. An increase in intensity of water deficit caused a significant
reductio in the level of low-molecular antioxidants, which attests to their utilization during the process of scavenging for
free radicals. Water deficit at Ψshoot=−1.7 MPa caused a decline in ascorbic acid level by 37% in needle cells. An effective defensive mechanism removing the excess
of ROS was also reflected in the activity of the main enzymes of oxidative stress: superoxide dismutase (SOD) and guaiacol
peroxidase (PO). As a result of water deficit, SOD activity increased by 80 %, while PO activity decreased by 82 %. 相似文献
11.
Dehydration-induced alterations in growth and osmotic potential of callus from six tepary bean lines varying in drought resistance 总被引:1,自引:0,他引:1
Growth and osmotic potential of calli induced from leaf- and root-derived tissues of six tepary bean lines (Phaseolus acutifolius) varying in drought resistance were assessed in vitro after polyethylene glycol-induced (10%, PEG-10,000) dehydration. Calli of resistant teparies were characterized by low initial osmotic potential (ψs) and relative growth rate (RGR) on medium lacking PEG (−0.30 MPa). However, calli of both resistant and sensitive lines were similar in dry matter percent (DM). Presence of PEG in the medium (−0.58 MPa) elevated DM in all teparies except one resistant line. Both leaf- and root-derived calli of sensitive teparies exhibited osmotic adjustment (OA) but reduced RGR that remained after rehydration in one line. We concluded that preexisting force of low cellular ψs rather than induced OA plays an important role in buffering adverse effects of dehydration and conditioning drought resistance of tepary beans. This information may aid Phaseolus breeders in screening for drought resistance among large number of accessions. 相似文献
12.
Danuta Chołuj Romualda Karwowska Agnieszka Ciszewska Marta Jasińska 《Acta Physiologiae Plantarum》2008,30(5):679-687
Accumulation of various osmolytes was examined in plants of sugar beet cv. Janus grown under two soil water treatments: control
(60% of the field water capacity; FWC) and drought (30–35% FWC). The water shortage started on the 61st day after emergence
(DAE), at the stage of the beginning of tap-roots development and was imposed for 35 days. Osmotic potential of sugar beet
plant organs, particularly tap-roots, was decreased significantly as a consequence of a long-term drought. Water shortage
reduced univalent (K+, Na+) cations concentrations in the petioles and divalent (Ca2+, Mg2+) ions level in the mature and old leaves. Cation concentrations in the tap-roots were not affected by water shortage. The
ratio of univalent to divalent cations was significantly increased in young leaves and petioles as a consequence of drought.
Long-term water deficit caused a significant reduction of inorganic phosphorus (Pi) concentration in young and old leaves. Under the water stress condition, the concentration of proline was increased in all
individual plant organs, except proline concentration in the youngest leaves. Drought treatment caused a significant increase
of glycine betaine content in shoot without any change in tap-roots. Glucose concentrations were significantly increased only
in tap-roots as the effect of drought. In response to water shortage the accumulation of sucrose was observed in all the examined
leaves and tap-roots. Overall, a long-term drought activated an effective mechanism for osmotic adjustment both in the shoot
and in the root tissues which may be critical to survival rather than to maintain plant growth but sugar beet organs accumulate
different solutes as a response to water cessation. 相似文献
13.
Response of Split-Root Sour Orange Seedlings to NaCl and Polyethylene Glycol Stresses 总被引:10,自引:0,他引:10
Soil water cotent and salinity levels are seldom uniform inthe field, particularly with the use of micro-irrigation systemsthat may water only a portion of the root zone. For studyingnon-uniform salinity, a split-root experiment was designed toevaluate growth and water relations when half of the root systemof sour orange (Citrus aurantium) seedlings was stressed withsodium chloride (NaCl) or polyethylene glycol (PEG). This studyalso determined if non-stressed portions of the root systemcompensated for the decrease in water uptake by the stressedportions. One or both halves of the root system were treated for fourmonths with nutrient solution adjusted with NaCl or PEG to osmoticpotentials of 0.10, 0.20, or 0.35 MPa.Shoot dry weight was reduced by only 9% when half of the rootsystem was irrigated with saline solution at 0.10 MPa,but with both halves of the root system at 0.10 MPa,shoot and root dry weights were reduced as much as 45%. Similarly,leaf water and osmotic potentials were also more disturbed underuniform salinity than under non-uniform salinity conditions. Plant growth, leaf water potential, osmotic potential, stomatalconductance, and evapotranspiration decreased with increasingNaCl and PEG concentrations in the nutrient solution. Turgorpotential and leaf thickness increased in response to NaCl treatments.Microscopic examination showed that the increase in leaf thicknesswas due to the development of larger cells in the spongy mesophyll. Shoot growth did not correlate with the average osmotic potentialof the two root halves. Seedlings with one stressed half-rootsystem had shoot dry weight and leaf water potential valuescloser to those of the non-stressed control than to those withthe completely stressed root system. Key words: Non-uniform salinity, water relations, citrus 相似文献
14.
Carla V. Giordano Aranzazú Guevara Hernán E. Boccalandro Carmen Sartor Pablo E. Villagra 《Plant Ecology》2011,212(7):1123-1134
Prosopis flexuosa trees dominate woodlands in the Central Monte Desert (Mendoza, Argentina), with <200 mm rainfall, exploiting the water table
recharged by Andean rivers, and also growing in dunes with no access to the water table. Prosopis woodlands were extensively logged during development of the agricultural oasis, and surface and groundwater irrigation could
lower the depth of the water table in the future. We evaluated tree populations with decreasing access to the water table:
valley adult trees, valley saplings, and dune adult trees, in order to assess their ecophysiological response to water table
accessibility. High and seasonally stable pre-dawn leaf water potentials (−2.2 ± 0.2 to −1.2 ± 0.07 MPa) indicated that valley
adults utilize larger and more stable water reservoirs than valley saplings and dune adults (−3.8 ± 0.3 to −1.3 ± 0.07 MPa),
with higher midday leaf conductance to water vapor (valley adults ~250; dune adults <60 mmol m−2 s−1), potentially higher CO2 uptake, and increased radial growth rate (valley adults 4.1 ± 0.07; dune adults 2.9 ± 0.02 mm year−1). Trees with poor access to the water table exhibited drought tolerance responses such as midday stomata closure, leaflet
closure, and osmotic adjustment. Stomata density decreased in response to drought when leaf expansion was restricted. The
combination of phreatophytism and drought tolerance would enlarge P. flexuosa habitats and buffer populations against changes in rainfall dynamics and water table depth. 相似文献
15.
Low soil water potential and low or high root temperatures are important stresses affecting carbon allocation in plants. This
study examines the effects of these stresses on carbon allocation from the perspective of whole plant mass balance. Sixteen-day
old spring wheat seedlings were placed in a growth room under precisely controlled root temperatures and soil water potentials.
Five soil water potential treatments, from −0.03 MPa to −0.25 MPa, and six root temperature treatments, from 12 to 32°C were
used. A mathematical model based on mass balance considerations was used, in combination with experimental measurements of
rate of net photosynthesis, leaf area, and shoot/root dry masses to determine photosynthate allocation between shoot and root.
Partitioning of photosynthates to roots was the lowest at 22–27°C root temperature regardless soil water potential, and increased
at both lower and higher root temperatures. Partitioning of photosynthates to the roots increased with decreasing soil water
potential. Under the most favourable conditions, i.e. at −0.03 MPa soil water potential and 27°C root temperature, the largest
fraction, 57%, of photosynthates was allocated to the shoots. Under the most stressed conditions, i.e. at −0.25 MPa soil water
potential and 32°C root temperature, the largest fraction, more than 80%, of photosynthates was allocated to roots. 相似文献
16.
以不同种源1年生乌桕幼苗为材料,采用盆栽控水试验研究了持续干旱条件下其外部形态及主要生理指标的变化,探讨各种源乌桕的抗旱性特性与差异。结果显示:(1)随着干旱持续时间的延长,各种源乌桕幼苗生长均受到不同程度抑制,外形表现出明显的缺水特征;其叶片相对含水量逐渐减小,复水后明显回升。(2)在极度干旱条件下(停水后第12天),幼苗叶片净光合作用速率仍维持一定的强度,而且细胞膜透性的变化不显著;在干旱胁迫条件下,幼苗叶片的过氧化物酶和超氧化物歧化酶活性增强,可溶性糖和可溶性蛋白质质量分数增加,丙二醛含量上升,脯氨酸积累,复水后呈现相反的变化趋势。(3)极度干旱条件下,不同种源乌桕幼苗间除丙二醛和相对电导率外,其它生理指标的变化差异显著或极显著,即不同种源具备比较稳定的抗旱性差异。(4)采用隶属函数法对不同种源幼苗的抗旱性分析发现,安徽黄山、河南商城两种源综合评价指数最大,为抗旱性较强的种源。研究表明,各种源乌桕幼苗能够通过调控自身保护酶活性和渗透调节物质含量来有效缓解干旱胁迫的伤害,从而表现出较强的抗旱性和适应性,但种源间存在稳定的差异,并以安徽黄山和河南商城种源抗旱性较强,可应用推广于季节性干旱区造林。 相似文献
17.
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
18.
B. R. Lee L. S. Li W. J. Jung Y. L. Jin J. C. Avice A. Ourry T. H. Kim 《Biologia Plantarum》2009,53(3):505-510
The objective of this study was to determine the development of the antioxidant enzymes induced by drought stress in white
clover (Trifolium repens L.) leaves. Water stress was imposed during 28 d by decreasing the daily irrigation. Leaf water potential (Φw) gradually decreased from −0.46 to −2.33 MPa. For the first 7 d, dry mass (DM), H2O2 and lipid peroxidation were not significantly affected by water deficit. From 14 d of treatment, water stress decreased dry
mass and increased content of reactive oxygen species (O2
·− and H2O2) and oxidative stress (malondialdehyde content). The ascorbate peroxidase (APOD) was activated most rapidly, already during
the first week of water stress, but then its activity slowly decreased. Activation of superoxide dismutase (SOD) and catalase
(CAT) by water deficit continued during the 14 d (Φw ≥ −1.65 MPa) and then their activities remain on the similar level. The activity of guaiacol-peroxidase (GPOD) increased
mostly under progressive water stress and was correlated with increase in lipid peroxidation and growth restriction. 相似文献
19.
The effects of provenance, salinity (0, 100, 200, 300 and 400 mm NaCl) and water deficit (0, -0.6, -1.1, -1.6 and -2.1 MPa mannitol solutions) on germination success of Polypogon monspeliensis were investigated. Eight Tunisian provenances from different bioclimatic origins were considered. Seed mass varied significantly between populations. Germination percentage was significantly affected by provenance, salinity and their interaction. Even at 300 mm NaCl, germination percentage of Tabarka, Kelbia and Kebili ranged from ca. 60% to ca. 85%, whereas Monastir, Gabes and El Haouaria succeeded in germinating in 200 mm NaCl. The 300 mm NaCl treatment highly reduced germination of Monastir and El Haouaria, and inhibited that of Gabes. Soliman and El Jem were the least salt-tolerant provenances. The severity of water deficit impact on seed germination was also provenance-dependent, especially at osmotic potentials of -1.1 to -1.6 MPa. At -1.6 MPa, germination percentage of Tabarka, Monastir and Kebili was close to 80%, while that of Gabes, El Jem and Kelbia was 0%, 5% and 20%, respectively. Regardless of provenance, germination was strongly impaired at -2.1 MPa. The variability of stress tolerance in P. monspeliensis could be of practical significance in programmes aimed at restoring arid and salt-affected lands since it allows use of provenances that germinate and establish successfully under unfavourable conditions prevailing in such zones. 相似文献
20.
Chlorophyll (Chl) content, dry mass, relative water content (RWC), leaf mass per area (LMA), proline (Pro) content, malondialdehyde
(MDA) content, superoxide dismutase (SOD) and peroxidase (POD) activity, P
N-PAR response curves and gas exchange were studied to determine the effects of water stress on photosynthetic activity, dry
mass partitioning and metabolic changes in four provenances of neem (Azadirachta indica A. Juss). The results indicated that provenance differences existed in the adaptation response to water stress that included
changes to growth strategies coupled with ecophysiological and metabolic adjustments. As water stress increased, stomatal
conductance (g
s), net photosynthetic rate (P
N), transpiration rate (E), and leaf RWC decreased while LMA increased in all provenances. Dry mass was reduced in droughted plants and the percentage
increased in dry mass allocated to roots, and enzyme activities of SOD and POD were highest in neem originating from Kalyani
(KA) provenance and lowest in neem originating from New Dehli (ND) provenance. In contrast, water stress increased MDA content
least in KA and most in ND. Furthermore, neem originating from ND also had the greatest decrease in Chl a/b ratio while the ratio was least affected in neem originating from KA. These findings suggest neem originating from KA may
have more drought resistance than neem originating from ND. The data from P
N-PAR response curves are less clear. While these curves showed that drought stress increased compensation irradiance (I
c) and dark respiration (R
D) and decreased saturation irradiance (I
s) and maximum net photosynthetic rate (P
max), the extent of decline in P
max was provenance dependent. P
max under non-waterlimiting conditions was higher in neem originating from Jodhpur (MA) (about 14 μmol m−2 s−1) than in the other three provenances (all about 10 μmol m−2 s−1), but mild water stress had minimal effect on P
max of these three provenances whereas P
max of MA provenance declined to 10 μmol m−2 s−1, i.e. a similar value. However, under severe water stress P
max of MA and KA provenances had declined to 40% of non-stressed values (about 6 and 4 μmol m−2 s−1, respectively) whereas the decline in P
max of neem originating from Kulapachta (KU) and ND provenances was about 50% of nonstressed values (about 5 μmol m−2 s−1). These data suggest the P
N responses of KU and ND provenances are most tolerant, and KA and MA least tolerant to increasing water stress, but also suggest
MA provenance could be the most desired under both non-water-limiting and water-limiting conditions due to highest P
max in all conditions. 相似文献