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991.
Here, patterns of phenotypic plasticity and trait integration of leaf characteristics in six geographically discrete populations of the perennial herb Pelargonium australe were compared. It was hypothesized that populations would show local adaptation in trait means, but similar patterns of plasticity and trait integration. Further, it was questioned whether phenotypic plasticity was positively correlated with environmental heterogeneity and whether plasticity for water-use traits in particular was adaptive. Seedlings were grown in a glasshouse at six combinations of water and nutrient availability. Leaf anatomical, morphological and gas exchange traits were measured. High amounts of plasticity in leaf traits were found in response to changes in growth conditions and there was evidence of local adaptation among the populations. While there were significant correlations between plasticity and environmental heterogeneity, not all were positive. Notably, patterns of plasticity and trait integration varied significantly among populations. Despite that variation, some of the observed plasticity was adaptive: fitness was correlated with conservative water use when water was limiting. Pelargonium arrived in Australia approximately 5 million yr ago. It is concluded here that high amounts of plasticity, in some cases adaptive, and weak integration among traits may be key to the spread and success of this species. 相似文献
992.
The purpose of this study was to determine the seasonal water use patterns of dominant macrophytes coexisting in the coastal
Everglades ecotone. We measured the stable isotope signatures in plant xylem water of Rhizophora mangle, Cladium jamaicense, and Sesuvium portulacastrum during the dry (DS) and wet (WS) seasons in the estuarine ecotone along Taylor River in Everglades National Park, FL, USA.
Shallow soilwater and deeper groundwater salinity was also measured to extrapolate the salinity encountered by plants at their
rooting zone. Average soil water oxygen isotope ratios (δ
18O) was enriched (4.8 ± 0.2‰) in the DS relative to the WS (0.0 ± 0.1‰), but groundwater δ
18O remained constant between seasons (DS: 2.2 ± 0.4‰; WS: 2.1 ± 0.1‰). There was an inversion in interstitial salinity patterns
across the soil profile between seasons. In the DS, shallow water was euhaline [i.e., 43 practical salinity units (PSU)] while
groundwater was less saline (18 PSU). In the WS, however, shallow water was fresh (i.e., 0 PSU) but groundwater remained brackish
(14 PSU). All plants utilized 100% (shallow) freshwater during the WS, but in the DS R. mangle switched to a soil–groundwater mix (δ 55% groundwater) while C. jamaicense and S. portulacastrum continued to use euhaline shallow water. In the DS, based on δ
18O data, the roots of R. mangle roots were exposed to salinities of 25.4 ± 1.4 PSU, less saline than either C. jamaicense (39.1 ± 2.2 PSU) or S. portulacastrum (38.6 ± 2.5 PSU). Although the salinity tolerance of C. jamaicense is not known, it is unlikely that long-term exposure to high salinity is conducive to the persistence of this freshwater
marsh sedge. This study increases our ecological understanding of how water uptake patterns of individual plants can contribute
to ecosystem levels changes, not only in the southeast saline Everglades, but also in estuaries in general in response to
global sea level rise and human-induced changes in freshwater flows. 相似文献
993.
Interactive effects of ozone and climate on tree growth and water use in a southern Appalachian forest in the USA 总被引:1,自引:0,他引:1
* A lack of data on responses of mature tree growth and water use to ambient ozone (O(3)) concentrations has been a major limitation in efforts to understand and model responses of forests to current and future changes in climate. * Here, hourly to seasonal patterns of stem growth and sap flow velocity were examined in mature trees from a mixed deciduous forest in eastern Tennessee (USA) to evaluate the effects of variations in ambient O(3) exposure and climate on patterns of stem growth and water use. * Ambient O(3) caused a periodic slowdown in seasonal growth patterns that was attributable in part to amplification of diurnal patterns of water loss in tree stems. This response was mediated by statistically significant increases in O(3)-induced daily sap flow and led to seasonal losses in stem growth of 30-50% for most species in a high-O(3) year. * Decreased growth and increased water use of mature forest trees under episodically high ambient O(3) concentrations suggest that O(3) will amplify the adverse effects of increasing temperatures on forest growth and forest hydrology. 相似文献
994.
Wei W Alexandersson E Golldack D Miller AJ Kjellbom PO Fricke W 《Plant & cell physiology》2007,48(8):1132-1147
The aim of the present study was to identify water channel(s) which are expressed specifically in the growth zone of grass leaves and may facilitate growth-associated water uptake into cells. Previously, a gene had been described (HvEmip) which encodes a membrane intrinsic protein (MIP) and which is particularly expressed in the base 1 cm of barley primary leaves. The functionality of the encoding protein was not known. In the present study on leaf 3 of barley (Hordeum vulgare L.), a clone was isolated, termed HvPIP1;6, which has 99% amino acid sequence identity to HvEmip and belongs to the family of plasma membrane intrinsic proteins (PIPs). Expression of HvPIP1;6 was highest in the elongation zone, where it accounted for >85% of expression of known barley PIP1s. Within the elongation zone, faster grower regions showed higher expression than slower growing regions. Expression of HvPIP1;6 was confined to the epidermis, with some expression in neighboring mesophyll cells. Expression of HvPIP1;6 in Xenopus laevis oocytes increased osmotic water permeability 4- to 6-fold. Water channel activity was inhibited by pre-incubation of oocytes with 50 microM HgCl(2) and increased following incubation with the phosphatase inhibitor okadaic acid or the plant hormone ABA. Plasma membrane preparations were analyzed by Western blots using an antibody that recognized PIP1s. Levels of PIP1s were highest in the elongation and adjacent non-elongation zone. The developmental expression profile of HvPIP2;1, the only known barley water channel belonging to the PIP2 subgroup, was opposite to that of HvPIP1;6. 相似文献
995.
A new immobilization matrix based on zeolite has been developed to immobilize Azotobacter chroococcum, for fixing nitrogen, with an intention to hold the cells in the root zone of the plants and to protect them under stressful
conditions. The matrix has been developed by modifying the surface of the zeolite with surfactant. This enhances the hydrophobicity
of the material and also modifies the surface charge, which in turn enhances the immobilization. Surface modified zeolite-A
(SMZ-A) has been compared with commercial zeolite-A (CZA) for immobilization efficiency. CZA is non-toxic for A. chroococcum but is inefficient to adsorb the cells whereas SMZ-A showed 100% adsorption of the microbial cells wherein it was observed
that for 1 l of broth culture with total viable count of 108 cfu ml−1 cells of A. chroococcum, a minimum dose of 0.7 g SMZ-A and minimum contact time of 10 h is required to achieve 100% adsorption. Adsorption was confirmed
by the cell count and light as well as scanning electron microscopy. Most importantly, the cells adsorbed on SMZ-A could fix
the atmospheric nitrogen up to 13 mg g−1 sucrose consumed, which was comparable with the control (unadsorbed cells), which confirms the survival and nitrogen fixation
activity of the bacteria.
Responsible Editor: Euan K. James. 相似文献
996.
Comparison of APRI and Hydrus-2D models to simulate soil water dynamics in a vineyard under alternate partial root zone drip irrigation 总被引:2,自引:0,他引:2
Alternate partial root zone irrigation (APRI) is a new water-saving irrigation technique. It can reduce irrigation water and
transpiration without reduction in crop yield, thus increase water and nutrient use efficiency. Understanding of soil moisture
distribution and dynamic under the alternate partial root zone drip irrigation (APDI) can help to develop the efficient irrigation
schemes. In this paper, a two-dimensional (2D) root water uptake model was proposed based on soil water dynamic and root distribution
of grape vine, and a function of soil evaporation related to soil water content was defined under the APDI. Then the soil
water dynamic model of APDI (APRI-model) was developed based on the 2D root water uptake model and soil evaporation function
combined with average measured soil moisture content at 0–10 cm soil layer. Soil water dynamic in APDI was respectively simulated
by Hydrus-2D model and APRI-model. The simulated soil water contents by two models were compared with the measured value.
The results showed that the values of root-mean-square-error (RMSE) range from 0.01 to 0.022 cm3/cm3 for APRI-model, and from 0.012 to 0.031 cm3/cm3 for Hydrus-2D model. The average relative error between the simulated and measured soil water content is about 10% for APRI-model,
and from 11% to 29% for Hydrus-2D model, indicating that two models perform well in simulating soil moisture dynamic under
the APDI, but the APRI-model is more suitable for modeling the soil water dynamic in the arid region with greater soil evaporation
and uneven root distribution. 相似文献
997.
Anjana Sharma Sachin Kumar Chandraker Manisha Bharti 《Indian journal of microbiology》2007,47(3):233-240
Sixteen isolates of Nontubercular Mycobacteria species were isolated from drinking water supply of some educational institutes
in Jabalpur during July 2006 and were identified by biochemical test, thin layer chromatography (TLC) and high performance
liquid chromatography (HPLC) analysis and PRA ( PCR restriction enzyme analysis) of rpoB gene. Out of 21 water samples total
16 isolates of nontuberculous mycobacteria were identified, as M. terrae (6), M. szulgai (4), M. gordonae (3), and one each as M. malmoense, M. kansasii, and M. gastri. 相似文献
998.
Busche R Schröder B Huber K Sallmann HP Breves G 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(1):135-142
In ruminants, the uptake of inorganic phosphate (Pi) across the intestinal mucosa epithelium by Na-dependent and Na-independent mechanisms is a main regulatory factor in P homeostasis.
The aim of the study was to elucidate to which extent Na-independent mechanisms, including pH effects or composition of mucosal
brush-border membranes, could be involved in positive stimulation of Pi absorptive processes seen under the P deficient condition. Therefore, luminal, surface and intracellular pH of the jejunal
epithelial cells in control and P depleted goats were compared and biochemical analyses of membrane phospholipids in the apical
membrane of the jejunal epithelium were performed. Dietary P depletion resulted in decreased plasma Pi levels. While pH in jejunal ingesta was not significantly changed, P depletion resulted in a significantly lower surface
pH in the crypt region compared to control animals (7.62 ± 0.02 vs. 7.77 ± 0.04, n = 4, P < 0.01). Inhibition of apical Na+/H+-exchange resulted in an increase of the jejunal surface pH in P depleted animals by 0.07 ± 0.01 (n = 6, P < 0.01) and 0.05 ± 0.01 (n = 6, P < 0.01) for the villus and the crypt region, respectively. This increase were inversely correlated with the initial surface
pH prior to inhibition. In contrast to surface pH, intracellular pH of the jejunal epithelium and the phospholipid composition
of the apical jejunal membrane were not affected by P depletion. Although the data suggest the existence of a Na+/H+-exchange mechanism at the luminal surface of goat jejunum they do not support the hypothesis that adaptational processes
of active Pi absorption from goat jejunum in response to low dietary P could be based on “non Pi transporter events”. 相似文献
999.
Lourdais O Hoffman TC Denardo DF 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(5):569-577
Parental care provides considerable benefits to offspring and is widespread among animals, yet it is relatively uncommon among
squamate reptiles (e.g., lizards and snakes). However, all pythonine snakes show extended maternal egg brooding with some
species being facultatively endothermic. While facultative endothermy provides thermal benefits, the presence of brooding
in non-endothermic species suggests other potential benefits of brooding. In this study we experimentally tested the functional
significance of maternal brooding relative to water balance in the children’s python, Antaresia childreni, a small species that does not exhibit facultative endothermy. Clutch evaporative water loss (EWL) was positively correlated
with clutch mass and was much lower than expected values based on individual eggs. The conglomerate clutch behaved as a single
unit with a decreasing surface area to volume ratio as clutch size increased. Maternal brooding had a dramatic impact on evaporation
from eggs, reducing and possibly eliminating clutch EWL. In a separate experiment, we found that viability of unattended eggs
is highly affected by humidity level, even in the narrow range from 75 to 100% relative humidity at 30.5°C (20–33 mg m−3 absolute humidity). However, the presence of the brooding female ameliorated this sensitivity, as viability of brooded clutches
at 75% relative humidity was higher than that of non-brooded eggs at either the same absolute humidity or at near-saturated
conditions. Overall, these results demonstrate that brooding behavior strongly promotes egg water balance (and thus egg viability)
in children’s pythons. 相似文献
1000.
In prior studies we learned that colonization of soil can be as important as colonization of roots in determining mycorrhizal influence on the water relations of host plants. Here we use a path analysis modeling approach to test (a) whether quantity of hyphae in soil contributes to variations in stomatal behavior and soil drying, and (b) whether soil colonization or root colonization has a stronger influence on these stomatal and soil drying responses. Experiments were performed on Sorghum bicolor and Cucurbita pepo, with soils and roots colonized by a mixture of Glomus intraradices and Gigaspora margarita. Soil colonization generally made more significant contributions to stomatal conductance than did root colonization. Soil colonization did not make significant direct contributions to soil water potential measures (soil water potential at stomatal closure or soil drying rate), whereas root colonization did contribute a potentially important path to each. The findings further support a role for mycorrhization of the soil itself in contributing to the regulation of stomatal behavior of host plants. 相似文献