High light decreases xylem contribution to fruit growth in tomato

Hanssens, Jochen; Swaef, Tom De; Steppe, Kathy

doi:10.1111/pce.12411

Cited by 30 publications

(37 citation statements)

References 52 publications

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“…Hanssens et al . () showed that the relative xylem contribution increased significantly when the light intensity was lowered by shading. Unfortunately, many of the techniques that have been used to estimate phloem and xylem influx into fruits have significant drawbacks or are based on questionable assumptions.…”

Section: Introductionmentioning

confidence: 99%

“…Quantification of these contributions has been the objective of many studies (e.g. Ho et al, 1987;Lang & Thorpe, 1989;Morandi et al, 2007;Windt et al, 2009;Hanssens et al, 2015), but often produced contrasting results. In tomato, for example, xylem contributions ranging from 10% (Liu et al, 2007) to 75% (Windt et al, 2009) have been reported.…”

Section: Introductionmentioning

confidence: 99%

“…So far, there is no conclusive proof for the validity and accuracy of the girdling technique, and many of the authors who apply the technique acknowledge that it may induce errors (Hanssens et al, 2015;Nordey et al, 2015;Torres-Ruiz et al, 2016). The extent of these possible errors has been assessed by a theoretical fruit growth model for peach (Fishman et al, 2001) and others have used a microscopic study on tomato peduncles to ensure that the xylem remains intact (Guichard et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Heat girdling does not affect xylem integrity: an in vivo magnetic resonance imaging study in the tomato peduncle

et al. 2017

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Heat girdling is a method to estimate the relative contribution of phloem vs xylem water flow to fruit growth. The heat girdling process is assumed to destroy all living tissues, including the phloem, without affecting xylem conductivity. However, to date, the assumption that xylem is not affected by heat girdling remains unproven. In this study, we used in vivo magnetic resonance imaging (MRI) velocimetry to test if heat girdling can cause xylem vessels to embolize or affect xylem water flow characteristics in the peduncle of tomato (Solanum lycopersicum cv Dirk). Anatomical and MRI data indicated that, at the site of girdling, all living tissues were disrupted, but that the functionality of the xylem remained unchanged. MRI velocimetry showed that the volume flow through the secondary xylem was not impeded by heat girdling in either the short or the long term (up to 91 h after girdling). This study provides support for the hypothesis that in the tomato peduncle the integrity and functionality of the xylem remain unaffected by heat girdling. It therefore confirms the validity of the heat girdling technique as a means to estimate relative contributions of xylem and phloem water flow to fruit growth.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Heat girdling does not affect xylem integrity: an in vivo magnetic resonance imaging study in the tomato peduncle

et al. 2017

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“…The application of the same method in all sizes of trees and their organs may increase an accuracy and reliability of comparable tree water relation studies. Recently the exosensors were effectively applied in such small plant organs as tomato peduncle (Hanssens et al 2013) and truss (Hanssens et al 2015).…”

Section: Sensor Design and Configurationmentioning

confidence: 99%

Revisiting the Heat Field Deformation (HFD) method for measuring sap flow

Nadezhdina¹

2018

iForest

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The Heat Field Deformation (HFD) technique is a thermodynamic method for measuring sap flow. Based on continuous heating the HFD method allows for high time resolution measurements which are highly important when studying plant responses to abrupt environmental changes. This work provides a succinct review of previously described features of the HFD methodology. Analyzing symmetrical and asymmetrical temperature differences around a measured linear heater (dTsym and dTas) relative to their ratio dTsym/dTas (so called a K-diagram) is at the heart of this methodology. This key concept, however, has to date only been generally described in previous works on the HFD technique. My objective here is to provide a comprehensive overview describing different types of K-diagrams, their interpretation and application for determining Kvalues or dTas for a zero flow condition. The K-value is a measured parameter which is particularly important for objectively characterizing heat conducting properties at the sensor insertion point under specific local measurement conditions. Correctly determining the K-value is critical for accurately calculating sap flow based on recorded temperature measurements. I have included in this review several examples demonstrating how the K-value is dependent upon changes to the environment and its important role in sap flow estimation. Keywords: K-diagram, K/R-diagram, K-value, Sap Flow per Section, Sap Flux Density, Sensor IntroductionThermodynamic methods for measuring sap flow are widely used in forestry, hydrology, agronomy and eco-physiological studies to accurately estimate tree water use, to identify specific drought stress conditions or to understand plant functionality. These methods which depend on heat transfer, however, differ fairly widely in their capabilities and limitations, notably in their sensitivity to low, zero and reverse flow rates. Reverse sap flow is particularly important for understanding the whole plant physiology and tree architecture, and acts as an indicator of hydraulic redistribution (Nadezhdina 1999, 2010, Burgess et al. 1998. In thermodynamic methods, thermometers are commonly used to gauge temperature changes of the heat field around a heater in response to sap movement. Thermometers may be arranged around the heater either symmetrically or asymmetrically. For symmetrical measurements, they are placed above and below and at equal distance from the heater in the axial direction (Daum 1967, Vieweg & Ziegler 1960, Sakuratani 1981, Tikhov 1979, Nadezhdina 1989, 1999, Burgess et al. 2001, while for asymmetrical measurements, the above thermometer is substituted by one placed together with the heater. (Ittner 1968, Cermák et al. 1973, Granier 1985.The majority of methods using thermometers arranged symmetrically around a heater produce accurate sap flow measurement with good dynamic resolution with the true sap flow under low flow conditions (Vieweg & Ziegler 1960, Leyton 1970, Saddler & Pitman 1970, Nadezhdina 1999. The situation can be different, however, under hig...

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“…For example, high light intensities have been demonstrated to improve dry matter content through an increase in available photoassimilates (Bertin et al, 2000;Dorais et al, 2001;Anza et al, 2006, Hanssens et al, 2015. Vapour pressure deficit (VPD) is another factor known to affect fruit dry matter content, since high VPDs increase fruit transpiration and decrease xylem influx, while phloem influx is hardly influenced (Guichard et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Application of drought and salt stress can improve tomato fruit quality without jeopardising production

Wal¹,

Meulebroek²,

Steppe³

2017

Acta Hortic.

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High-tech tomato greenhouse systems, which are the standard in Northern Europe (especially in Belgium and the Netherlands), mainly aim for high yields, up to 60 kg m -2 . However, quality should be considered equally important, as consumers are willing to pay higher prices per kg for a high quality product. Influencing the plant water status is acknowledged to strongly influence fruit quality, as water deficit or increased salinity may result in higher dry matter content, a main determinant of tomato quality. Unfortunately, this increase in quality is often associated with a decrease in fresh yield, making a thorough insight on the controlling factors of both aspects critical if one aspires to optimise the final product value. The objective of the current research was therefore to combine plant water status monitoring with the assessment of an array of fruit quality parameters and yield, for both drought and salinity treatments in order to further clarify this interrelationship. To this end, we set up an experiment in a controlled greenhouse environment, where tomato plants (Solanum lycopersicum 'Dirk') were exposed to four different treatments: control, drought stress, and two levels of salt stress (EC levels of 4 and 6 dS cm -1 ). Plant water status was monitored by measuring stem water potential. Furthermore, fruit yield, as well as a set of fruit quality parameters (hexose sugars content, organic acids content, and firmness) was evaluated. Results showed that fruit quality does benefit from both drought and increased salinity, and that the highest salinity level scored the best on all measured quality aspects. Moreover, we observed that even small water deficits, induced either by mild drought or salt stress, improved fruit quality, without jeopardising yield. The acquired insights, combined with mechanistic modelling, may ultimately lead to a more efficient greenhouse management with higher quality tomatoes.

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High light decreases xylem contribution to fruit growth in tomato

Cited by 30 publications

References 52 publications

Heat girdling does not affect xylem integrity: an in vivo magnetic resonance imaging study in the tomato peduncle

Heat girdling does not affect xylem integrity: an in vivo magnetic resonance imaging study in the tomato peduncle

Revisiting the Heat Field Deformation (HFD) method for measuring sap flow

Application of drought and salt stress can improve tomato fruit quality without jeopardising production

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