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 Stem Water Potential and Apple Size

1995 ◽  
Vol 120 (4) ◽  
pp. 577-582 ◽  
Author(s):  
Amos Naor ◽  
Isaac Klein ◽  
Israel Doron
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Fruit Size ◽  
Plant Water ◽  
Stem Water Potential ◽  
Plant Water Stress ◽  
Stem Water ◽  
Irrigation Treatments ◽  
Highly Correlated

The sensitivity of leaf (ψleaf) and stem (ψstem) water potential and stomatal conductance (gs) to soil moisture availability in apple (Malus domestics Borkh.) trees and their correlation with yield components were studied in a field experiment. Two drip irrigation treatments, 440 mm (H) and 210 mm (L), were applied to a `Golden Delicious' apple orchard during cell enlargement stage (55-173 days after full bloom). Data collected included ψstem, y leaf, gs, and soil water potential at 25 (ψsoil-25) and 50 cm (ψsoil-50). No differences in midday ψleaf's were found between irrigation treatments. Stem water potential was higher in the H treatment than in the L treatment in diurnal measurements, and at midday throughout the season. Stomatal conductance of the H treatment was higher than the L treatment throughout the day. Stomatal conductance between 0930 and 1530 hr were highly correlated with ψstem. The H treatment increased the percentage of fruit >65 mm, and increased the proportion of earlier harvested fruit reaching marketable size compared to the L treatment. Fruit size in the first harvest and the total yield were highly correlated with ψstem. The degree of correlation between plant water stress indicators and yield component decreased in the following order: ψstem>ψsoil-25,>ψsoil-50>ψleaf. The data suggest that midday ψstem may serve as a preferable plant water stress indicator with respect to fruit size.

scholarly journals Variation in scion water relations mediated by two newly released Geneva series rootstocks

2021 ◽  
Author(s):  
Erica Casagrande Biasuz ◽  
Lee Kalcsits
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Potential ◽  
Water Relations ◽  
Isotope Composition ◽  
Water Status ◽  
Physiological Traits ◽  
Stem Water Potential ◽  
Carbon And Oxygen Isotope ◽  
Stem Water

Dwarfing rootstocks are used to control tree vigor allowing for increased densities that increase apple production. Although there is considerable variation among rootstocks in dwarfing capacity, the mechanisms by which rootstocks affect vigor in apple scions remains unclear. Here, Honeycrisp apple growth and water relations were compared among three rootstocks; M-9 as the industry standard and two less studied Geneva series rootstocks; G.87 and G. 814 in Washington, USA. Trees were acquired from a commercial nursery and planted in 2017. In 2018 and 2019, scion physiological, isotopic and morphological traits were measured to better understand the link between rootstock-driven vigor and physiological traits. Rootstock affected scion shoot growth (P <0.001), stomatal conductance (P< 0.01) and stem water potential (P <0.001). Rootstocks with low vegetative vigor like M.9 also had lower stomatal conductance and enriched leaf δ13C and δ18O isotope composition. Plant growth was positively correlated with stomatal conductance and stem water potential. Rootstocks also affected plant water status and net gas exchange. Here, we report an association between rootstock-induced vigor and scion physiological traits such as gas exchange, stem water potential, and leaf carbon and oxygen isotope composition. This research has implications for the understanding of the mechanisms of dwarfing by rootstocks in apple.

scholarly journals Physiological Response of Carambola Trees to Soil Water Depletion in Krome Soils

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 857B-857
Author(s):  
Rashid Al-Yahyai* ◽  
Bruce Schaffer ◽  
Frederick S. Davies
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Potential ◽  
Soil Water ◽  
Leaf Gas Exchange ◽  
Stem Water Potential ◽  
Soil Water Depletion ◽  
Water Depletion ◽  
Loam Soil ◽  
Stem Water

The effect of soil water depletion on plant water potential and leaf gas exchange of carambola (Averrhoa carambola L. cv. Arkin) in Krome very gravelly loam soil was studied in an orchard and in containers in the field and in a greenhouse. The rate of soil water depletion was determined by continuously monitoring soil water content with multi-sensor capacitance probes. Stem water potential and leaf gas exchange of carambola in containers were reduced when the soil water depletion level fell below 50% (where field capacity = 100%). Although there was a decrease in the rate of soil water depletion in the orchard as the soil dried, soil water depletion did not go below an average of 70%. This was presumably due to sufficient rainfall and capillary movement of water in the soil. Therefore, soil water content did not decline sufficiently to affect leaf gas exchange and leaf and stem water potential of orchard trees. A decline in soil water depletion below 40% resulted in a concomitant decline in stem water potential of the container trees in the field and greenhouse to below -1.0 MPa. Stomatal conductance, net CO2 assimilation, and transpiration declined significantly when stem water potential was below -1.0 MPa. The reduction of net CO2 assimilation and transpiration was proportional to the decline in stomatal conductance of container trees in the field and greenhouse. Thus, soil water depletion in Krome very gravelly loam soil must be less than 50% before water potential or leaf gas exchange of carambola is affected. Based on these results, irrigation scheduling should be based on physiological variables such as stem water potential and stomatal conductance or the amount rather than the rate of soil water depletion.

Estimation of stomatal conductance and stem water potential threshold values for water stress in olive trees (cv. Arbequina)

2019 ◽  
Vol 37 (4) ◽  
pp. 461-467 ◽  
Author(s):  
L. Ahumada-Orellana ◽  
S. Ortega-Farías ◽  
C. Poblete-Echeverría ◽  
P. S. Searles
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Stem Water Potential ◽  
Threshold Values ◽  
Stem Water ◽  
Olive Trees ◽  
Potential Threshold

scholarly journals Performance Assessment of Thermal Infrared Cameras of Different Resolutions to Estimate Tree Water Status from Two Cherry Cultivars: An Alternative to Midday Stem Water Potential and Stomatal Conductance

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3596 ◽  
Author(s):  
Marcos Carrasco-Benavides ◽  
Javiera Antunez-Quilobrán ◽  
Antonella Baffico-Hernández ◽  
Carlos Ávila-Sánchez ◽  
Samuel Ortega-Farías ◽  
...  
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Prunus Avium ◽  
Water Status ◽  
Thermal Infrared ◽  
Stem Water Potential ◽  
Cherry Tree ◽  
Stem Water ◽  
Irrigation Treatments

The midday stem water potential (Ψs) and stomatal conductance (gs) have been traditionally used to monitor the water status of cherry trees (Prunus avium L.). Due to the complexity of direct measurement, the use of infrared thermography has been proposed as an alternative. This study compares Ψs and gs against crop water stress indexes (CWSI) calculated from thermal infrared (TIR) data from high-resolution (HR) and low-resolution (LR) cameras for two cherry tree cultivars: ‘Regina’ and ‘Sweetheart’. For this purpose, a water stress–recovery cycle experiment was carried out at the post-harvest period in a commercial drip-irrigated cherry tree orchard under three irrigation treatments based on Ψs levels. The water status of trees was measured weekly using Ψs, gs, and compared to CWSIs, computed from both thermal cameras. Results showed that the accuracy in the estimation of CWSIs was not statistically significant when comparing both cameras for the representation of Ψs and gs in both cultivars. The performance of all evaluated physiological indicators presented similar trends for both cultivars, and the averaged differences between CWSI’s from both cameras were 11 ± 0.27%. However, these CWSI’s were not able to detect differences among irrigation treatments as compared to Ψs and gs.

scholarly journals Irrigation and Crop Load Influence Fruit Size and Water Relations in Field-grown `Spadona' Pear

2001 ◽  
Vol 126 (2) ◽  
pp. 252-255 ◽  
Author(s):  
Amos Naor
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Fruit Size ◽  
Leaf Water ◽  
Stem Water Potential ◽  
Crop Load ◽  
Water Potentials ◽  
Stem Water ◽  
Highly Correlated

Interrelations between water potential and fruit size, crop load, and stomatal conductance were studied in drip-irrigated `Spadona' pear (Pyrus communis L) grafted on quince C (Cydonia oblonga L.) rootstock and growing in a semi-arid zone. Five irrigation rates were applied in the main fruit growth phase: rates of 0.25, 0.40, 0.60, 0.80, and 1.00 of “Class A” pan evaporation rate. The crop in each irrigation treatment was adjusted to four levels (200 to 1200 fruit per tree) by hand thinning at the beginning of June 1999. The crop was harvested on 1 Aug. 1999, and fruit size was determined by means of a commercial sorting machine. Soil, stem, and leaf water potentials and stomatal conductance were measured during the season. Crop yield was highly correlated with stem and soil water potentials. The highest midday stem water potential was lower than values commonly reported for nonstressed trees, and was accompanied by high soil water potential, indicating that the maximal water absorption rate of the root system under those particular soil conditions was limited. Stomatal conductance was highly correlated with leaf water potential (r2 = 0.54), but a much better correlation was found with stem water potential (r2 = 0.80). Stomatal conductance decreased at stem water potentials less than -2.1 MPa. Both stem water potential and stomatal conductance were unaffected by crop load under a wide range of irrigation rates.

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