scholarly journals Xylem Sap Abscisic Acid Concentrations and Stomatal Conductance in Mycorrhizal Cowpea

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 838A-838
Author(s):  
Robert C. Ebel ◽  
Xiangrong Duan ◽  
Robert M. Augé
Keyword(s):  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Water Status ◽  
Xylem Sap ◽  
Mycorrhizal Colonization ◽  
Mycorrhizal Symbiosis ◽  
Leaf Water Status ◽  
Host Nutrition ◽  
Mycorrhizal Plants ◽  
Induced Changes

Mycorrhizal colonization can alter stomatal behavior of host leaves before or during soil drying, but the mechanism of influence is not always clear. We examined the possibility that mycorrhizal symbiosis might result in either altered stomatal sensitivity to abscisic acid (ABA) moving from roots to shoots in xylem sap, or altered movement of ABA in xylem as a function of soil water content (θ). Mycorrhizal colonization of Vigna unguiculata did not change the relationship between stomatal conductance (gs) and xylem [ABA] during drying of whole root systems. Stomatal conductance was higher in mycorrhizal than in similarly sized and similarly nourished nonmycorrhizal plants when soil moisture was relatively high, perhaps related to lower xylem [ABA] in mycorrhizal plants at high soil θ. Neither gs nor xylem [ABA] was affected by mycorrhizae at low soil θ. Higher gs in mycorrhizal plants was evidently not related to a mycorrhizal effect on leaf water status, as neither gs/shoot Ψ nor shoot Ψ/soil θ relationships were altered by the symbiosis. Stomatal conductance was much more closely correlated with xylem [ABA] than with soil θ or shoot Ψ. Decreased xylem [ABA] may explain why mycorrhizal colonization sometimes increases gs of unstressed mycorrhizal plants in the absence of mycorrhizae-induced changes in host nutrition. This work was supported by USDA NRICGP grant 91-37100-6723 (R.M.A).

Abscisic Acid Levels in Nacl-Treated Barley, Cotton and Saltbush

1991 ◽  
Vol 18 (1) ◽  
pp. 17 ◽  
Author(s):  
Z Kefu ◽  
R Munns ◽  
RW King
Keyword(s):  
Abscisic Acid ◽  
Water Deficit ◽  
Water Status ◽  
Xylem Sap ◽  
Leaf Water ◽  
Leaf Water Status ◽  
Cotton Plants ◽  
Presence And Absence ◽  
Leaf Water Deficit

Exposing barley and cotton plants to 75 mol m-3 NaCl reduced transpiration and increased abscisic acid (ABA) levels in leaves, roots and xylem sap. Exposing saltbush (Atriplex spongiosa) plants to 75 mol m-3 NaCI, at which concentration they grow best, did not affect transpiration or ABA levels but when the NaCl was increased to 150 mol m-3 transpiration fell and ABA levels rose. ABA levels in leaves were high in salt-treated barley and saltbush even when the leaf water status was raised by pressurising the roots. These responses indicate that an increased leaf ABA level was not triggered by leaf water deficit, but by the root's response to the salinity. The flux of ABA in the xylem sap of the three species was more than enough to account for the amount of ABA in leaves, in the presence and absence of salinity. This suggests that the roots may be the source of at least part of the ABA found in leaves.

scholarly journals Stomatal conductance and xylem-sap abscisic acid (ABA) in adult oak trees during a gradually imposed drought

1996 ◽  
Vol 53 (2-3) ◽  
pp. 207-220 ◽  
Author(s):  
MB Triboulot ◽  
ML Fauveau ◽  
N Bréda ◽  
P Label ◽  
E Dreyer
Keyword(s):  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Xylem Sap ◽  
Oak Trees

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.

Abscisic acid content and components of water status in leaves of Populus deltoides

1986 ◽  
Vol 64 (10) ◽  
pp. 2295-2298 ◽  
Author(s):  
Tsai-Yun Lin ◽  
Edward Sucoff ◽  
Mark Brenner
Keyword(s):  
Abscisic Acid ◽  
Populus Deltoides ◽  
Water Status ◽  
Leaf Water ◽  
Leaf Water Status ◽  
Eastern Cottonwood ◽  
Detached Leaves ◽  
Aba Content ◽  
The Relationship ◽  
Abscisic Acid Content

The relationship between abscisic acid (ABA) and leaf water status was studied during the air drying of detached leaves of eastern cottonwood (Populus deltoides Marsh.). The ABA content increased exponentially as leaf water potential and leaf turgor potential decreased. No clearly defined thresholds were observed between ABA content and these variables. ABA content was linearly related to the relative fresh weight and was not related to the osmotic potential.

Effects of growth temperature on the response of lupin stomata to drought and abscisic acid

1999 ◽  
Vol 26 (6) ◽  
pp. 549 ◽  
Author(s):  
M. Leonor Osório ◽  
M. Lucília Rodrigues ◽  
M. Manuela Chaves ◽  
Maria João Correia
Keyword(s):  
Abscisic Acid ◽  
Growth Temperature ◽  
Water Status ◽  
Lupinus Albus ◽  
Xylem Sap ◽  
Effect Of Temperature ◽  
Exogenous Aba ◽  
Higher Temperature ◽  
Stomatal Sensitivity ◽  
The Relationship

To assess how growth temperature affects stomatal responses to xylem-transported abscisic acid (ABA), leaf conductance (g), the concentrations of ABA and calcium ions, and the pH of the xylem sap were measured in well-watered and water-stressed Lupinus albus L. plants grown under two thermal regimes: 10/15°C and 20/25°C, night/day temperature. Moderate water deficit was imposed, at the same thermal time, and induced a significant reduction in g regardless of temperature. In the morning, g was higher in plants grown at 20/25°C than in cooler conditions, and these differences could not be explained by dissimilarities in shoot water status or xylem ABA concentration. At midday, the apparent stomatal sensitivity to xylem-carried ABA was increased and the effect of temperature on the relationship between g and xylem ABA was no longer observed. A positive effect of higher temperature on stomatal aperture was also evident when artificial sap containing ABA was fed to leaves of well-watered plants. In response to exogenous ABA, stomata closed to the same extent as observed in the morning in water-stressed plants. However, exogenous ABA feeding could not mimic the relationship between g and xylem ABA determined at midday in intact plants. The pH and the concentration of calcium in xylem were not affected by temperature. At midday, however, the calcium concentrations were higher in water-stressed than in well-watered plants. These changes in the concentrations of calcium or other xylem components, such as ABA conjugates, together with possible changes in the ability of the leaves to degrade and/or to compartmentalise ABA, may partly explain the midday increase in the apparent stomatal sensitivity to xylem ABA.

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