Rehydration rates and the prevalence of xylem-hydration of flowers

Mapping Intimacies ◽

10.1101/255042 ◽

2018 ◽

Author(s):

Adam B. Roddy ◽

Craig R. Brodersen

Keyword(s):

Water Potential ◽

Water Transport ◽

Plant Canopy ◽

Abiotic Conditions ◽

Physiological Constraints ◽

Diverse Species ◽

Extant Species ◽

Significant Difference ◽

Potential Gradients ◽

Floral Form

AbstractAngiosperm flowers are remarkably diverse anatomically and morphologically, yet they all must satisfy the physiological constraints of supplying sufficient amounts of water and carbon effectively promote pollination. Flowers often occur in the hottest, driest parts of the plant canopy and can face harsh abiotic conditions. Prior evidence suggests that extant species vary dramatically in how water is delivered to flowers, with some evidence that water may be imported into flowers by the phloem. Here we measured midday water potential gradients between flowers, leaves, and stems often phylogenetically diverse species. We further tested the likelihood of xylem-hydration by measuring rates of rehydration after experimentally induced desiccation. There was no significant difference in rehydration rates between leaves and flowers. These results are consistent with xylem-hydration of flowers and suggest that there has been little modification to the mechanisms of water transport despite the diversity of floral form.

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Accuracy and Usefulness of Psychrometer and Pressure Chamber for Evaluating Water Potentials of Pinus radiata Needles

Functional Plant Biology ◽

10.1071/pp9820499 ◽

1982 ◽

Vol 9 (5) ◽

pp. 499 ◽

Cited By ~ 5

Author(s):

BD Millar

Keyword(s):

Water Potential ◽

Pinus Radiata ◽

Xylem Sap ◽

Pressure Chamber ◽

Pressure Potential ◽

Pine Trees ◽

Average Water ◽

Potential Gradients ◽

Fundamental Uncertainty ◽

The One

Pressure chamber evaluations of xylem sap pressure potential (P) and thermocouple psychrometric evaluations of average water potential (Ψl) in needles from both transpiring and non-transpiring pine trees (Pinus radiata D. Don) were compared in order to determine the relative accuracy and usefulness of these methods for assessing Ψl. Markedly different but linear P v. Ψl relationships were obtained for pine needles of different age and also for the case where resin exudation masked the xylem and led to a 'resin error'. Evidence suggests that these differences are mainly due to injection and resin errors in pressure chamber determinations totalling as much as 1 MPa (a 10 bar). The psychrometric method appears to be the much more accurate. Radial water potential gradients across leaves did not result in differences between evaluations of P and Ψl, at least in P. radiata. The need for multiple 'calibrations' of the pressure chamber and the fundamental uncertainty about the constancy of such calibrations on the one hand and the slowness of the excised-needle psychrometer on the other can restrict the usefulness of these methods.

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Drought reduced monoterpene emissions from the evergreen Mediterranean oak <i>Quercus ilex</i>: results from a throughfall displacement experiment

Biogeosciences ◽

10.5194/bg-6-1167-2009 ◽

2009 ◽

Vol 6 (7) ◽

pp. 1167-1180 ◽

Cited By ~ 63

Author(s):

A.-V. Lavoir ◽

M. Staudt ◽

J. P. Schnitzler ◽

D. Landais ◽

F. Massol ◽

...

Keyword(s):

Water Potential ◽

Leaf Water Potential ◽

Quercus Ilex ◽

Photochemical Efficiency ◽

Leaf Water ◽

Control Treatment ◽

Summer Drought ◽

Drought Period ◽

Significant Difference ◽

Monoterpene Emission

Abstract. The effects of water limitations on the emission of biogenic volatile organic compounds are not well understood. Experimental approaches studying drought effects in natural conditions are still missing. To address this question, a throughfall displacement experiment was set up in a natural forest of Quercus ilex, an evergreen Mediterranean oak emitting monoterpenes. Mature trees were exposed in 2005 and 2006 either to an additional drought, to irrigation or to natural drought (untreated control). In both years, absolute monoterpene emission rates as well as the respective standard factors of the trees exposed to normal and additional drought strongly declined during the drought periods. Monoterpene emissions were lower in year 2006 than in year 2005 (factor 2) due to a more pronounced summer drought period in this respective year. We observed a significant difference between the irrigation and additional drought or control treatment: irrigated trees emitted 82% more monoterpenes during the drought period 2006 than the trees of the other treatments. However, no significant effect on monoterpene emission was observed between normal and additional drought treatments, despite a significant effect on leaf water potential and photochemical efficiency. During the development of drought, monoterpene emissions responded exponentially rather than linearly to decreasing leaf water potential. Emissions rapidly declined when the water potential dropped below −2 MPa and photosynthesis was persistently inhibited. Monoterpene synthase activities measured in vitro showed no clear reduction during the same period. From our results we conclude that drought significantly reduces monoterpene fluxes of Mediterranean Holm oak forest into the atmosphere due to a lack of primary substrates coming from photosynthetic processes.

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Numerical investigation on the characteristics of water transfer in PEMFC with bionic flow channel

E3S Web of Conferences ◽

10.1051/e3sconf/20198301005 ◽

2019 ◽

Vol 83 ◽

pp. 01005

Author(s):

Tao Chen ◽

Shihua Liu ◽

Li Yang

Keyword(s):

Water Transport ◽

Polymer Electrolyte Membrane ◽

Flow Channel ◽

Water Drainage ◽

Transmission Characteristics ◽

Electrolyte Membrane ◽

Numerical Studies ◽

Flow Channels ◽

Significant Difference ◽

Different Types

The content and the transmission characteristics of the water in the polymer electrolyte membrane fuel cell (PEMFC) have a significant influence on its performance. So far, there are few separate numerical studies on the process of water transport in the bionic flow channel, and the performance of bionic flow channel is different from conventional flow channel in part owing to the differences of their water drainage. Therefore, in order to understand the water drainage process of bionic flow channel, two different types of bionic flow channels are adopted in this paper. The method of numerical simulation is used to study the transmission process of liquid water in the bionic flow channel of different placement orientations. The simulation results found that the orientations of bionic flow channel has an influence on the process of water transport in the flow channel, and the process of water drainage also has a significant difference in the two different types of bionic flow channel.

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Comparative analysis reveals gravity is involved in the MIZ1-regulated root hydrotropism

Journal of Experimental Botany ◽

10.1093/jxb/eraa409 ◽

2020 ◽

Vol 71 (22) ◽

pp. 7316-7330

Author(s):

Ying Li ◽

Wei Yuan ◽

Luocheng Li ◽

Hui Dai ◽

Xiaolin Dang ◽

...

Keyword(s):

Water Potential ◽

Double Mutant ◽

Root Elongation ◽

Vertical Orientation ◽

Tomato Plants ◽

Oblique Orientation ◽

Experimental Systems ◽

Potential Gradients ◽

Insight Into

Abstract Hydrotropism is the directed growth of roots toward the water found in the soil. However, mechanisms governing interactions between hydrotropism and gravitropism remain largely unclear. In this study, we found that an air system and an agar–sorbitol system induced only oblique water-potential gradients; an agar–glycerol system induced only vertical water-potential gradients; and a sand system established both oblique and vertical water-potential gradients. We employed obliquely oriented and vertically oriented experimental systems to study hydrotropism in Arabidopsis and tomato plants. Comparative analyses using different hydrotropic systems showed that gravity hindered the ability of roots to search for obliquely oriented water, whilst facilitating roots’ search for vertically oriented water. We found that the gravitropism-deficient mutant aux1 showed enhanced hydrotropism in the oblique orientation but impaired root elongation towards water in the vertical orientation. The miz1 mutant exhibited deficient hydrotropism in the oblique orientation but normal root elongation towards water in the vertical orientation. Importantly, in contrast to miz1, the miz1/aux1 double mutant exhibited hydrotropic bending in the oblique orientation and attenuated root elongation towards water in the vertical orientation. Our results suggest that gravitropism is required for MIZ1-regulated root hydrotropism in both the oblique orientation and the vertical orientation, providing further insight into the role of gravity in root hydrotropism.

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Modeling Root Water Potential and Soil-Root Water Transport: II. Field Comparisons

Soil Science Society of America Journal ◽

10.2136/sssaj1991.03615995005500050003x ◽

1991 ◽

Vol 55 (5) ◽

pp. 1213-1220 ◽

Cited By ~ 26

Author(s):

L. Bruckler ◽

F. Lafolie ◽

F. Tardieu

Keyword(s):

Water Potential ◽

Water Transport

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Leaf Gas Exchange and Water Relations of Lupins and Wheat. II. Root and Shoot Water Relations of Lupin During Drought-Induced Stomatal Closure

Functional Plant Biology ◽

10.1071/pp9890415 ◽

1989 ◽

Vol 16 (5) ◽

pp. 415 ◽

Cited By ~ 13

Author(s):

CR Jensen ◽

IE Henson ◽

NC Turner

Keyword(s):

Water Potential ◽

Soil Water ◽

Water Transport ◽

Water Uptake ◽

Water Relations ◽

Leaf Gas Exchange ◽

Stomatal Closure ◽

Soil Water Potential ◽

Root Water Uptake ◽

Leaf Conductance

Plants of Lupinus cosentinii Guss. cv. Eregulla were grown in a sandy soil in large containers in a glasshouse and exposed to drought by withholding water. Under these conditions stomatal closure had previously been shown to be initiated before a significant reduction in leaf water potential was detected. In the experiments reported here, no significant changes were found in water potential or turgor pressure of roots or leaves when a small reduction in soil water potential was induced which led to a 60% reduction in leaf conductance. The decrease in leaf conductance and root water uptake closely paralleled the fraction of roots in wet soil. By applying observed data of soil water and root characteristics, and root water uptake for whole pots in a single-root model, the average water potential at the root surface was calculated. Potential differences for water transport in the soil-plant system, and the resistances to water flow were estimated using the 'Ohm's Law' analogy for water transport. Soil resistance was negligible or minor, whereas the root resistance accounted for 61-72% and the shoot resistance accounted for about 30% of the total resistance. The validity of the measurements and calculations is discussed and the possible role of root- to-shoot communication raised.

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Hypernodulating soybean mutant line nod4 lacking ‘Autoregulation of Nodulation’ (AON) has limited root-to-shoot water transport capacity

Annals of Botany ◽

10.1093/aob/mcz040 ◽

2019 ◽

Vol 124 (6) ◽

pp. 979-991 ◽

Cited By ~ 2

Author(s):

Emile Caroline Silva Lopes ◽

Weverton Pereira Rodrigues ◽

Katherine Ruas Fraga ◽

José Altino Machado Filho ◽

Jefferson Rangel da Silva ◽

...

Keyword(s):

Plant Growth ◽

Water Potential ◽

Water Transport ◽

Leaf Water Potential ◽

Root Nodules ◽

Leaf Water ◽

Transport Capacity ◽

N Content ◽

Photosynthetic Rates ◽

Root Conductance

AbstractBackground and AimsAlthough hypernodulating phenotype mutants of legumes, such as soybean, possess a high leaf N content, the large number of root nodules decreases carbohydrate availability for plant growth and seed yield. In addition, under conditions of high air vapour pressure deficit (VPD), hypernodulating plants show a limited capacity to replace water losses through transpiration, resulting in stomatal closure, and therefore decreased net photosynthetic rates. Here, we used hypernodulating (nod4) (282.33 ± 28.56 nodules per plant) and non-nodulating (nod139) (0 nodules per plant) soybean mutant lines to determine explicitly whether a large number of nodules reduces root hydraulic capacity, resulting in decreased stomatal conductance and net photosynthetic rates under high air VPD conditions.MethodsPlants were either inoculated or not inoculated with Bradyrhizobium diazoefficiens (strain BR 85, SEMIA 5080) to induce nitrogen-fixing root nodules (where possible). Absolute root conductance and root conductivity, plant growth, leaf water potential, gas exchange, chlorophyll a fluorescence, leaf ‘greenness’ [Soil Plant Analysis Development (SPAD) reading] and nitrogen content were measured 37 days after sowing.Key ResultsBesides the reduced growth of hypernodulating soybean mutant nod4, such plants showed decreased root capacity to supply leaf water demand as a consequence of their reduced root dry mass and root volume, which resulted in limited absolute root conductance and root conductivity normalized by leaf area. Thereby, reduced leaf water potential at 1300 h was observed, which contributed to depression of photosynthesis at midday associated with both stomatal and non-stomatal limitations.ConclusionsHypernodulated plants were more vulnerable to VPD increases due to their limited root-to-shoot water transport capacity. However, greater CO2 uptake caused by the high N content can be partly compensated by the stomatal limitation imposed by increased VPD conditions.

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