scholarly journals Comparison of Branch Water Relations in Two Riparian Species: Populus euphratica and Tamarix ramosissima

2019 ◽  
Vol 11 (19) ◽  
pp. 5461
Author(s):  
Duan Li ◽  
Jianhua Si ◽  
Xiaoyou Zhang ◽  
Yayu Gao ◽  
Huan Luo ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Water Supply ◽  
Water Relations ◽  
Water Status ◽  
Populus Euphratica ◽  
Hydraulic Conductance ◽  
Leaf Water ◽  
Tamarix Ramosissima ◽  
Water Potentials ◽  
Branch Dieback

Water relations in plants maintain healthy tree branches and drought conditions during plant growth may affect water relations, but the mechanisms are poorly known. In our study, we determined the stomatal conductance, hydraulic conductance, water potential and ion concentration of xylem sap to increase the understanding of changes in water relations in branches of Populus euphratica (P. euphratica) and Tamarix ramosissima (T. ramosissima), which are the dominant plant species in the lower reaches of the Heihe River Basin in China. The results showed that both species responded to vapor pressure deficit (VPD) during the growing season by adjusting stomatal conductance to achieve homeostasis in leaf water potentials. The leaf-specific hydraulic conductance (LSC) of the branch was determined using water status in the branch, and the LSC of the leaf was determined using water status in the leaf. Because of homeostasis in leaf water potentials, hydraulic conductance in leaves remained stable. As a result, branch dieback, which might be induced by deficits in water supply, could rarely be seen in T. ramosissima owing to the homeostasis in branch and leaf water status. The ion sensitivity of xylem hydraulic conductance in P. euphratica induced an increase in hydraulic conductance caused by the deficits in the water supply which might lead to branch dieback. The evaluation of water relations provides a further understanding of the internal mechanisms of drought acclimation for riparian plants.

Relationship Between Root/Soil Hydraulic Properties and Stomatal Behaviour in Sugarcane

1989 ◽  
Vol 16 (3) ◽  
pp. 241 ◽  
Author(s):  
NZ Saliendra ◽  
FC Meinzer
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Leaf Water Potential ◽  
Water Status ◽  
Hydraulic Conductance ◽  
Leaf Water ◽  
Soil Drying ◽  
Root Hydraulic Conductance ◽  
High Soil Moisture

Stomatal conductance, leaf and soil water status, transpiration, and apparent root hydraulic conductance were measured during soil drying cycles for three sugarcane cultivars growing in containers in a greenhouse. At high soil moisture, transpiration and apparent root hydraulic conductance differed considerably among cultivars and were positively correlated, whereas leaf water potential was similar among cultivars. In drying soil, stomatal and apparent root hydraulic conductance approached zero over a narrow (0.1 MPa) range of soil water suction. Leaf water potential remained nearly constant during soil drying because the vapor phase conductance of the leaves and the apparent liquid phase conductance of the root system declined in parallel. The decline in apparent root hydraulic conductance with soil drying was manifested as a large increase in the hydrostatic pressure gradient between the soil and the root xylem. These results suggested that control of stomatal conductance in sugarcane plants exposed to drying soil was exerted primarily at the root rather than at the leaf level.

Effect of Water Stress on Stomatal Conductance and Leaf Water Relations of Leaves Along Current-Year Branches of Peach

1989 ◽  
Vol 16 (6) ◽  
pp. 549 ◽  
Author(s):  
SL Steinberg ◽  
MJ Mcfarland ◽  
JC Miller
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Water Status ◽  
Stomatal Closure ◽  
Water Flux ◽  
Leaf Water ◽  
Leaf Water Status ◽  
Mature Leaves ◽  
Water Potentials

A gradation, that reflects the maturity of the leaves, exists in the leaf water, osmotic and turgor potential and stomatal conductance of leaves along current and 1-year-old branches of peach. Predawn leaf water potentials of immature folded leaves were approximately 0.24 MPa lower than mature leaves under both well-watered and dry conditions. During the daytime the leaf water potential of immature leaves reflected the water potential produced by water flux for transpiration. In well- watered trees, mature and immature unfolded leaves had a solute potential at least 0.5 MPa lower than immature folded leaves, resulting in a turgor potential that was approximately 0.8 MPa higher. The turgor requirement for growth appeared to be much less than that maintained in mature leaves. As water stress developed and leaf water potentials decreased, the osmotic potential of immature folded leaves declined to the level found in mature leaves, thus maintaining turgor. In contrast, mature leaves showed little evidence of turgor maintenance. Stomatal conductance was lower in immature leaves than in fully mature leaves. With the onset of water stress, conductance of mature leaves declined to a level near that of immature leaves. Loss of turgor in mature leaves may be a major factor in early stomatal closure. It was concluded that osmotic adjustment played a role in maintenance of a leaf water status favorable for some growth in water-stressed immature peach leaves.

scholarly journals Stomatal conductance and root-to-shoot signalling in chestnut saplings exposed to Phytophthora cinnamomi or partial soil drying

2004 ◽  
Vol 31 (1) ◽  
pp. 41 ◽  
Author(s):  
Marion Maurel ◽  
Cécile Robin ◽  
Thierry Simonneau ◽  
Denis Loustau ◽  
Erwin Dreyer ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Potential Role ◽  
Phytophthora Cinnamomi ◽  
Castanea Sativa ◽  
Hydraulic Conductance ◽  
Leaf Water ◽  
Split Root

The effects of root infection by Phytophthora cinnamomi on stomatal conductance in Castanea sativa L. saplings were investigated to determine the potential role of root-derived chemical signals. A split-root experiment was carried out, in which inoculation of the pathogen or drought was applied to the root systems in either one or both compartments. At the end of the experiment plant sap extracts were collected and their effects on stomatal conductance were determined by leaf bioassay. Inoculation or drought imposed in both compartments resulted in decreases in stomatal conductance (gs), transpiration rate, soil-to-leaf specific hydraulic conductance, leaf water potential, xylem [ABA] and root biomass, but not in the ratio of root-to-leaf mass in inoculated plants. Conversely, only gs and xylem [ABA] were affected in plants inoculated or droughted in one compartment, and no changes were detectable in leaf water potential and soil-to-leaf specific hydraulic conductance. The leaf bioassay showed that gs in chestnut was sensitive to ABA but not to Phytophthora elicitins. Stomatal conductance was reduced by some sap extracts, both from control and inoculated plants. Our results suggest the involvement of different signals, chemical and hydraulic, in regulating stomatal conductance of chestnut at different stages of stress.

The effect of ectomycorrhizae on water relations in aspen (Populus tremuloides) and white spruce (Picea glauca) at low soil temperatures

2002 ◽  
Vol 80 (6) ◽  
pp. 684-689 ◽  
Author(s):  
Simon M Landhäusser ◽  
Tawfik M Muhsin ◽  
Janusz J Zwiazek
Keyword(s):  
Stomatal Conductance ◽  
Soil Temperature ◽  
Water Uptake ◽  
Water Relations ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
White Spruce ◽  
Hydraulic Conductance ◽  
Root Hydraulic Conductance ◽  
Soil Temperatures

Low soil temperatures, common during the growing season in northern forests, have the potential to impede plant growth. In this study, water uptake, water relations, and growth characteristics were examined in aspen (Populus tremuloides) and white spruce (Picea glauca) seedlings that were inoculated with ectomycorrhizal fungi and grown at 20°C daytime air temperatures and low soil temperatures of 4°C and 8°C. Mycorrhizal associations had little effect on root and shoot biomass at both soil temperatures. Root hydraulic conductance (Kr) was higher in both mycorrhizal plant species compared to nonmycorrhizal plants, but there was no soil temperature effect on Kr in either species. Mycorrhizae also increased shoot water potential (Ψw) in Populus tremuloides but had no effect on Ψw in Picea glauca. The increases in Kr and Ψw were not reflected by changes in stomatal conductance (gs) and transpiration rates (E), suggesting that the reduction of water flow in seedlings exposed to low soil temperature was not likely the factor limiting gs in both plant species.Key words: boreal forest, root hydraulic conductance, root growth, stomatal conductance, water uptake.

Water relations characteristics of Alnusrubra and Populustrichocarpa: responses to field drought

1988 ◽  
Vol 18 (9) ◽  
pp. 1159-1166 ◽  
Author(s):  
S. R. Pezeshki ◽  
T. M. Hinckley
Keyword(s):  
Water Relations ◽  
Root Development ◽  
Osmotic Potential ◽  
Stomatal Closure ◽  
Leaf Age ◽  
Leaf Water ◽  
Black Cottonwood ◽  
Red Alder ◽  
Mature Leaves ◽  
Water Potentials

Water relations of red alder (AlnusrubraBong.) and black cottonwood (populustrichocarpa Torr. & Gray) were studied in the field during the 1980, 1981, and 1982 growing seasons. Stomatal closure in response to drought was noted in both species; however, the following major differences were noted between the 1980 observations and those of 1981 and 1982; (i) stomatal conductance was greater in black cottonwood than in red alder, whereas the reverse was noted in 1980, and (ii) even though 1981 and 1982 were warmer and drier than 1980, corresponding changes in predawn and minimum leaf water potentials were not observed. These differences were attributed to greater root development, particularly in black cottonwood, in the second (1981) and third (1982) years following establishment (1980) of these species. Leaf age and drought exposure were observed to influence osmotic potentials in both species. Values of the osmotic potential at saturation varied from −0.80 to −1.03 MPa in newly mature leaves of red alder and from −1.00 to −1.26 MPa in similarly aged leaves of black cottonwood. Values in mature leaves ranged from −0.84 to −1.27 MPa in red alder and from −1.37 to −1.75 MPa in black cottonwood. There appeared to be a continued decrease in osmotic potential in both species throughout the growing season, a response associated with leaf development and drought exposure. Throughout the study, significantly lower values of osmotic potential at saturation and at the turgor loss point were found in black cottonwood than in red alder. Consequently, black cottonwood had a potential adaptive advantage in comparison with red alder. Leaf shedding in response to drought was noted mainly in red alder. Generally, both of these riparian species exhibited slight to moderate capabilities of surviving exposure to low leaf water potentials and moderate to excellent capabilities of stomatal closure under conditions potentially leading to low water potentials. The role played by root development in the differences observed among the years and between black cottonwood and red alder is discussed.

Water Relations of Root-Pruned Jarrah (Eucalyptus marginata Donn ex Smith) Saplings

1987 ◽  
Vol 35 (6) ◽  
pp. 653 ◽  
Author(s):  
DS Crombie ◽  
JT Tippett ◽  
DJ Gorddard
Keyword(s):  
Water Relations ◽  
Phytophthora Cinnamomi ◽  
Leaf Water ◽  
Lateritic Soil ◽  
Root Pruning ◽  
Deep Roots ◽  
Eucalyptus Marginata ◽  
Water Potentials ◽  
Severe Water Stress ◽  
Leaf Shedding

Roots were pruned from jarrah (Eucalyptus marginata Donn ex Smith) saplings to simulate the effects of root loss induced by Phytophthora cinnamomi Rands. Stomatal conductance was more sensitive to root loss than was leaf water potential. Stomatal conductances of trees on moist soils declined when more than 50% of roots were removed but were more variable and were affected more severely by root pruning when soils were dry. Predawn leaf water potentials were unaffected by removal of up to 80% of roots irrespective of whether surface soils were dry or moist. The effects of root pruning on midday water potentials were variable especially when soils were dry. Leaf shedding and efficient stornatal closure prevented severe water stress developing in leaves until nearly 90% of the roots had been removed. It is suggested that destruction of the deep 'sinker' roots by P. cinnamomi has greater effects on jarrah's water relations during summer than does loss of shallow roots. The deep roots are especially important as jarrah grows on highly developed lateritic soil profiles.

scholarly journals Water Relations of Acer rubrum in Response to Summer Digging

HortScience ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 595C-595
Author(s):  
P.R. Knight ◽  
J.R. Harris ◽  
J.K. Fanelli ◽  
M.P. Kelting
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Sap Flow ◽  
Acer Rubrum ◽  
Leaf Water ◽  
Xylem Embolism ◽  
Ball Diameter ◽  
Old Trees

Two experiments were conducted on Acer rubrum L. to determine the influence of root severance on sap flow, stomatal conductance, leaf water potential (ψ), and stem xylem embolism. Experiment 1 utilized 3-year-old trees, and experiment 2 utilized 2-year-old trees. Sixteenmm sap flow gauges were installed on both groups. Trees for experiment 1 were harvested on 31 May 1996 with a root ball diameter of 30.5 cm. Sap flow was reduced within one day after plants were harvested and was still lower 1 week after harvest. On 7 June 1996, harvested trees had lower stomatal conductance measurements, compared to not-harvested trees, but ψ were similar. A second experiment was initiated on 20 Aug. 1996, using the same protocol as in experiment 1. Sap flow was reduced within 2 h after harvest for harvested trees compared to not-harvested trees. Leaf stomatal conductances were reduced within 4 h of harvest. Leaf water potentials were not influenced on the day that the trees were harvested. Embolism levels were increased by harvest within 24 h. These results indicate that transplant stress begins shortly after harvest and not at the actual time of transplant.

scholarly journals Leaf water potentials of sunlit and/or shaded grapevine leaves are sensitive alternatives to stem water potential

OENO One ◽  
2012 ◽  
Vol 46 (3) ◽  
pp. 207
Author(s):  
Larry E. Williams
Keyword(s):  
Stomatal Conductance ◽  
Solar Radiation ◽  
Water Potential ◽  
Water Status ◽  
Direct Solar Radiation ◽  
Cabernet Sauvignon ◽  
Direct Sunlight ◽  
Water Potentials ◽  
Significant Difference ◽  
Highly Correlated

<p style="text-align: justify;"><strong>Aims</strong>: Leaf (Ψ<sub>l</sub>) and stem (Ψ<sub>stem</sub>) water potentials were measured on grapevines to determine the effects of shoot location on both methods to assess vine water status.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Cabernet-Sauvignon and Merlot used in this study were grown at two locations in California. Measurements were taken at midday in July (Merlot) and at two times of the day (morning and afternoon), on two dates in August (Cabernet- Sauvignon). Measurements of Ψ<sub>l</sub> and Ψ<sub>stem</sub>, stomatal conductance and transpiration were taken on shoots entirely exposed to direct solar radiation or on shoots totally in the shade at the times of measurement. There were significant differences (<em>P</em> &lt; 0.05) between Ψ<sub>l</sub> and/or Ψ<sub>stem</sub> measured on shoots exposed to direct solar radiation and those in the shade. Both Ψ<sub>l</sub> and Ψ<sub>stem</sub> were significantly greater on the shoots exposed to direct sunlight compared to those in the shade. There was no significant difference between Ψ<sub>l</sub> measured on shaded leaves and Ψ<sub>stem</sub> determined on the fully exposed shoots.</p><p style="text-align: justify;"><strong>Conclusions</strong>: Regardless of method used, water potentials were highly correlated with stomatal conductance measured on leaves in direct sunlight at the same time. All means of measuring grapevine water potential used in this study were highly correlated with one another.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: The data indicate that any of the techniques used in this study would be a sensitive indicator of vine water status and that the Ψ of shaded leaves would be an alternative to the measurement of Ψ<sub>stem</sub>.</p>

Stomatal and photosynthetic response of drought-stressed cherrybark oak (Quercusfalcata var. pagodaefolia) and sweet gum (Liquidambarstyraciflua)

1986 ◽  
Vol 16 (4) ◽  
pp. 841-846 ◽  
Author(s):  
S. R. Pezeshki ◽  
J. L. Chambers
Keyword(s):  
Stomatal Conductance ◽  
Stomatal Closure ◽  
Net Photosynthesis ◽  
Leaf Water ◽  
Dominant Factor ◽  
Controlled Environment ◽  
Photosynthetic Response ◽  
Stomatal Limitation ◽  
Water Potentials ◽  
Relative Decline

The effects of water stress on stomatal conductance and net photosynthesis of cherrybark oak (Quercusfalcata var. pagodaefolia Ell.) and sweet gum (Liquidamberstyraciflua L.) seedlings were studied under controlled environment conditions during the 1983 growing season. Drought stress induced stomatal closure and significant declines in net photosynthesis for both species. Stomatal conductance declined by as much as 43% in cherrybark oak and 82% in sweet gum compared with predrought levels. Net photosynthetic rates also declined 85% from predrought levels in sweet gum and fell below zero in cherrybark oak. The remarkable decline in net photosynthesis in cherrybark oak while stomata remained partially open suggests that in addition to a stomatal effect, nonstomatal factors were involved in the reduction of net photosynthesis. In sweet gum, however, stomatal limitation of net photosynthesis seems to be the dominant factor. The greater relative decline in mean leaf conductance in sweet gum suggests a greater reaction to drought by this species through effective and rapid stomatal closure resulting in avoidance of leaf desiccation. Stomata of cherrybark oak, on the other hand, were less sensitive to low leaf water potentials; therefore, stomatal closure occurred at significantly lower (more negative) leaf water potentials when compared with sweet gum.

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