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

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).

Seasonal patterns of xylem sap pH, xylem abscisic acid concentration, leaf water potential and stomatal conductance of six evergreen and deciduous Australian savanna tree species

2002 ◽  
Vol 50 (2) ◽  
pp. 229 ◽  
Author(s):  
Dane S. Thomas ◽  
Derek Eamus
Keyword(s):  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Tree Species ◽  
Xylem Sap ◽  
Leaf Water ◽  
Deciduous Species ◽  
Evergreen Species ◽  
Water Potentials

Deciduous trees of Australia’s northern savannas typically have less-negative leaf water potentials than evergreen species and their stomata are more sensitive to soil drought than those of evergreen species. This paper presents the first investigation of the role of xylem sap pH and abscisic acid content in explaining stomatal behaviour of Australian trees in the field. We measured stomatal conductance, leaf-to-air vapour pressure difference (D) and leaf water potential, xylem abscisic acid (ABA) concentration and xylem sap pH of evergreen, semideciduous and fully deciduous tree species in the field over a 15-month period. Measurements were made during both the wet and the dry seasons. Stomata closed in response to increasing D in both evergreen and deciduous species and were equally sensitive to increasing D or declining leaf water potential. Xylem ABA concentration increased with declining leaf water potential in evergreen and semi-deciduous species, but not deciduous species. Similarly, there was an inverse correlation between stomatal conductance and xylem ABA concentration. Xylem sap pH increased as leaf water potential declined from wet to dry season for evergreen and semi-deciduous species but not for deciduous species. Deciduous species had less-negative water potentials and lower xylem ABA concentrations than evergreen species or semi-deciduous species. We conclude that changes in xylem sap pH and ABA content do occur seasonally in the wet–dry tropics of Australia and that these changes influence stomatal conductance, but only in evergreen and semi-deciduous species. Deciduous species do not appear to modulate either of these chemical signals.

Abscisic Acid and Cytokinins as Possible Root-to-Shoot Signals in Xylem Sap of Rice Plants in Drying Soil

1993 ◽  
Vol 20 (1) ◽  
pp. 109 ◽  
Author(s):  
A Bano ◽  
K Dorffling ◽  
D Bettin ◽  
H Hahn
Keyword(s):  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Root System ◽  
Nutrient Solution ◽  
Xylem Sap ◽  
Zeatin Riboside ◽  
Stem Water Potential ◽  
Rice Plants ◽  
Stem Water

Seedlings of rice cv. IR 36 were grown in soil in small pots with a horizontally divided root system: after 6-7 weeks, about 20% of the entire root system had protruded through the holes at the base of the pots and was kept in contact with nutrient solution. At this stage the plants were exposed to three different treatments: (a) the soil was kept watered and the protruding free roots were dried in air; (b) the free roots were kept moist and the soil left unwatered; (c) both soil and protruding roots were left unwatered for 30 h and then rewatered. During the first hours of treatment a and b, a decline in stomatal conductance was observed, whereas the stem water potential remained unchanged. The concentration of abscisic acid (ABA) in the xylem, however, increased. At later stages of treatment a and b, the stem water potential began to decrease with a parallel further increase of xylem ABA. Xylem sap contained considerable amounts of bound ABA, the level of which increased during total root drying and decreased again after rewatering. Level of cytokinins, zeatin (t-Z)+zeatin riboside (t-ZR) and isopentenyladenine (2iP) + isopentenyladenosine (2iPA), on the contrary, decreased during root drying and increased again after rewatering. The results are discussed with regard to a possible function of ABA and cytokinins as root-to-shoot signals.

scholarly journals Xylem sap abscisic acid concentration and stomatal conductance of mycorrhizal Vigna unguiculata in drying soil

1997 ◽  
Vol 135 (4) ◽  
pp. 755-761 ◽  
Author(s):  
ROBERT C. EBEL ◽  
XIANGRONG DUAN ◽  
DAVID W. STILL ◽  
ROBERT M. AUGE
Keyword(s):  
Abscisic Acid ◽  
Stomatal Conductance ◽  
Acid Concentration ◽  
Vigna Unguiculata ◽  
Xylem Sap
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