Measurement of sap flow dynamics through the tomato peduncle using a non-invasive sensor based on the heat field deformation method

Jochen Hanssens, Tom De Swaef, Nadezhda Nadezhdina, Kathy Steppe

    Onderzoeksoutput: Boek/rapportP1: Proceedings in ISIpeer review

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    Recent contradicting evidence on the contributions of xylem and phloem to
    tomato fruit growth highlights the need for a more thorough insight into the dynamics of sap flow through the tomato peduncle. In fact, knowledge on sap flow dynamics through small plant parts remains scarce, due to a lack of direct measurements. Most of currently available sap flow sensors use needles, making them inappropriate for the direct measurement of sap flow through small plant parts such as a tomato peduncle. Therefore, a non-invasive sap flow sensor based on the heat field deformation (HFD) principle was tested on the peduncle of a tomato truss. This mini HFD sensor, consisting of a heater element and three thermocouples stitched on insulation tape, was wrapped around the peduncle and allowed continuous monitoring of changes in the heat field around the
    heater caused by sap flow. Actual influx into the tomato truss was calculated based on fruit growth data and estimates of fruit transpiration and was compared with the dynamics measured with the mini HFD sensor. Additionally, heat girdling of the peduncle was performed to block phloem influx to study the dynamics of xylem and phloem influx using the mini HFD sensor. First results of the mini HFD sensor were promising and the measured sap flow dynamics through the tomato peduncle agreed well with the calculated sap influx. Results of the girdling experiment suggested opposite patterns of xylem and phloem influx, with a decreased xylem influx during the daytime. Furthermore, the pattern of xylem influx revealed a close relation with the total water potential in the stem.
    As such, the mini HFD sensor provided direct measurements of sap flow dynamics
    through a tomato peduncle and, hence, has a large potential to finally resolve the
    controversy on water influx into developing fruits.
    Oorspronkelijke taalEngels
    Volume991
    PublicatiestatusGepubliceerd - 2014

    Publicatie series

    NaamActa Horticulturae

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