A Possible Role for Abscisic Acid in Controlling Dormancy in Jojoba Flower Buds

1985 ◽  
Vol 12 (5) ◽  
pp. 463 ◽  
Author(s):  
A Benzioni ◽  
RL Dunstone
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Low Temperatures ◽  
Water Status ◽  
Effect Of Temperature ◽  
Flower Buds ◽  
Controlled Conditions ◽  
Effects Of Temperature ◽  
Delayed Flowering ◽  
Endogenous Aba

Jojoba flower buds break dormancy in response to low temperatures in the presence of adequate water. The possibility that abscisic acid (ABA) is involved in the regulation of dormancy was examined by following endogenous ABA levels in flower buds and leaves and by applying synthetic (�)-ABA. Under controlled conditions endogenous levels of ABA were high in dormant flower buds and decreased under conditions of low temperatue that led to flowering. Similar results were obtained in the field. Levels in the leaves were low and changes in response to environmental treatments were small. Daily spraying of the plants with water containing 0.01% Tween enhanced flowering while water stress inhibited it. The application of (�)-ABA delayed flowering and reduced the percentage of flowers open at the end of the experiment. An experiment aimed at distinguishing between the effects of temperature and of water status was inconclusive and part of the effect of temperature on ABA may be related to the effect of temperature on the water status of plant.

Inhibition of cambial activity in Abies balsamea by internal water stress: role of abscisic acid

1975 ◽  
Vol 53 (24) ◽  
pp. 3041-3050 ◽  
Author(s):  
C. H. A. Little
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Indoleacetic Acid ◽  
Stomatal Closure ◽  
Abies Balsamea ◽  
Cambial Activity ◽  
Inhibitory Effect ◽  
Internal Water ◽  
Endogenous Aba

In experiments with attached and detached shoots of balsam fir, Abies balsamea L., synthetic (±)abscisic acid (ABA) (1) reduced photosynthesis and transpiration by inducing stomatal closure, (2) inhibited indoleacetic acid (IAA) - induced cambial activity in photosynthesizing and non-photosynthesizing shoots, and (3) inhibited the basipetal movement of [14C]IAA. Neither gibberellic acid nor kinetin counteracted the inhibitory effect of (±)ABA on IAA-induced cambial activity. In addition it was demonstrated that increasing the internal water stress increased the level of endogenous ABA in the phloem–cambial region of bark peelings and decreased the basipetal movement of [14C]IAA through branch sections. On the basis of these findings it is proposed that internal water stress inhibits cambial activity, partly through increasing the level of ABA; the ABA acts to decrease the provision of carbohydrates and auxin that are required for cambial growth.

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.

scholarly journals Effects of Vine Water Status and Exogenous Abscisic Acid on Berry Composition of Three Red Wine Grapes Grown under Mediterranean Climate

Horticulturae ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 12
Author(s):  
Massimiliano Cocco ◽  
Luca Mercenaro ◽  
Mauro Lo Cascio ◽  
Giovanni Nieddu
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Water Status ◽  
Irrigation Treatment ◽  
Climatic Conditions ◽  
Exogenous Aba ◽  
Set Up ◽  
Qualitative Performance ◽  
Berry Composition ◽  
Response To Water

Beyond climatic conditions, qualitative performance is led by the intrinsic characteristics of the genotype. The aim of this study was to investigate the relationship between vine water status and exogenous abscisic acid (ABA) application on berry composition of the cultivars Cannonau, Merlot and Sangiovese. The experiment, carried out in 2016 and 2017, consisted of comparing two levels of irrigation treatments, full irrigation versus a non-irrigation treatment. Within each treatment, two sub-treatments were set up: (i) 4 mL L−1 of exogenous ABA applied at veraison to clusters only and subsequently repeated after six days; (ii) a control (untreated vines). The application of different irrigation regimes confirmed that the response to water stress is highly cultivar-dependent. Berry composition was influenced differently among cultivars by water stress. In terms of metabolites, positive influences were observed with Cannonau. No significant effects were observed by spraying exogenous ABA directly on grapes. Moreover, no significant interactions were found between the application of water stress and ABA. Exogenous ABA application did not appear to be a viticultural practice capable of influencing must composition in environments characterized by severe environmental conditions such as heat and drought.

scholarly journals Characterizing Concentration Effects of Exogenous Abscisic Acid on Gas Exchange, Water Relations, and Growth of Muskmelon Seedlings during Water Stress and Rehydration

2012 ◽  
Vol 137 (6) ◽  
pp. 400-410 ◽  
Author(s):  
Shinsuke Agehara ◽  
Daniel I. Leskovar
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Gas Exchange ◽  
Water Status ◽  
Stomatal Closure ◽  
Membrane Integrity ◽  
Dry Matter Accumulation ◽  
Assimilation Rate ◽  
Concentration Effects ◽  
Post Stress

Excess transpiration relative to water uptake often causes water stress in transplanted vegetable seedlings. Abscisic acid (ABA) can limit transpirational water loss by inducing stomatal closure and inhibiting leaf expansion. We examined the concentration effect of exogenous ABA on growth and physiology of muskmelon (Cucumis melo L.) seedlings during water stress and rehydration. Plants were treated with seven concentrations of ABA (0, 0.24, 0.47, 0.95, 1.89, 3.78, and 7.57 mm) and subjected to 4-day water withholding. Application of ABA improved the maintenance of leaf water potential and relative water content, while reducing electrolyte leakage. These effects were linear or exponential to ABA concentration and maximized at 7.57 mm. Gas-exchange measurements provided evidence that such stress control is attributed to ABA-induced stomatal closure. First, net CO2 assimilation rate and stomatal conductance initially decreased with increasing ABA concentration by up to 95% and 70%, respectively. A follow-up study (≤1.89 mm ABA) confirmed this result with or without water stress and further revealed a close positive correlation between intercellular CO2 concentration and net CO2 assimilation rate 1 day after treatment (r2 > 0.83). In contrast, ABA did not affect leaf elongation, indicating that stress alleviation was not mediated by leaf area adjustment. After 18 days of post-stress daily irrigation, dry matter accumulation showed a quadratic concentration-response, increasing up to 1.89 mm by 38% and 44% in shoot and roots, respectively, followed by 16% to 18% decreases at >1.89 mm ABA. These results suggest that excess levels of ABA delay post-stress growth, despite the positive effect on the maintenance of water status and membrane integrity. Another negative side effect was chlorosis, which accelerated linearly with increasing ABA concentration, although it was reversible upon re-watering. The optimal application rate of ABA should minimize these negative effects, while keeping plant water stress to an acceptable level.

Effect of temperature on metabolism of glucose in vitro

1964 ◽  
Vol 207 (4) ◽  
pp. 849-852 ◽  
Author(s):  
Geraldine J. Fuhrman ◽  
Frederick A. Fuhrman
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Low Temperatures ◽  
Arrhenius Equation ◽  
Effect Of Temperature ◽  
Rat Diaphragm ◽  
Abnormal Metabolism ◽  
Effects Of Temperature ◽  
Straight Lines

We recently showed that hypothermic rats fail to remove glucose from the extracellular phase. This information led to these studies on the uptake of glucose at low temperatures by rat diaphragm and red blood cells and its phosphorylation by hexokinase. It is shown here that rat diaphragm and red blood cells utilize glucose at all temperatures from 1 to 38 C. Both processes follow the Arrhenius equation and give µ equal to 18,000 and 21,900, respectively. The velocities of the phosphorylation of glucose by hexokinase from yeast and from rat muscle both yield straight lines on an Arrhenius plot with µ equal to 13,300 and 14,900. The temperature coefficient of the velocity of action of hexokinase is consistent with the effects of temperature on other enzymes. Penetration of glucose into cells at low temperatures apparently equals or exceeds the rate of phosphorylation. Thus the abnormal metabolism of glucose in hypothermia is not caused by failure of glucose to penetrate cells, and there is no unusual sensitivity of hexokinase to changes in temperature.

Effect of temperature during the synthesis process of CdSe nanoparticles using the colloidal technique

MRS Advances ◽  
2020 ◽  
Vol 5 (63) ◽  
pp. 3389-3395
Author(s):  
R. González-Díaz ◽  
D. Fernández-Sánchez ◽  
P. Rosendo-Francisco ◽  
G. Sánchez-Legorreta
Keyword(s):  
Scanning Tunneling Microscope ◽  
Electron Cloud ◽  
Cdse Nanoparticles ◽  
Effect Of Temperature ◽  
Synthesis Process ◽  
Scanning Tunneling ◽  
Tunneling Microscope ◽  
First Results ◽  
Effects Of Temperature ◽  
Scanning Electron

AbstractIn this work, the first results of the effects of temperature during the production of Se2- ions and the effect during the interaction of Cd2+ and Se2- ions in the synthesis process of CdSe nanoparticles are presented. The synthesis of CdSe was carried out by the colloidal technique, in the first one we used a temperature of 63 °C to produce Se2- ions and in the second one an interaction temperature of 49 °C. The samples were characterized using a Scanning Electron Microscope (SEM) and a Scanning Tunneling Microscope (STM). From the SEM micrographs it was possible to identify the thorns formation and irregular islands. STM micrographs reveal elliptical shapes with a regular electron cloud profile.

Monitoring Crop Water Status and Irrigation Needs Using Multispectral Airborne Sensors

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 905D-905
Author(s):  
Thomas R. Clarke ◽  
M. Susan Moran
Keyword(s):  
Water Stress ◽  
Near Infrared ◽  
Water Status ◽  
Canopy Cover ◽  
Stress Index ◽  
Crop Water ◽  
Vegetative Cover ◽  
Crop Water Stress Index ◽  
Water Stress Index ◽  
Subsurface Drip

Water application efficiency can be improved by directly monitoring plant water status rather than depending on soil moisture measurements or modeled ET estimates. Plants receiving sufficient water through their roots have cooler leaves than those that are water-stressed, leading to the development of the Crop Water Stress Index based on hand-held infrared thermometry. Substantial error can occur in partial canopies, however, as exposed hot soil contributes to deceptively warm temperature readings. Mathematically comparing red and near-infrared reflectances provides a measure of vegetative cover, and this information was combined with thermal radiance to give a two-dimensional index capable of detecting water stress even with a low percentage of canopy cover. Thermal, red, and near-infrared images acquired over subsurface drip-irrigated cantaloupe fields demonstrated the method's ability to detect areas with clogged emitters, insufficient irrigation rate, and system water leaks.

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