Vine Canopy and Root Physiology

Gould, Nick; Clearwater, Michael J.

doi:10.1079/9781800620933.0015

Cited by 1 publication

(3 citation statements)

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“…In order to focus on the possible cause of the hydraulic failure, the root xylem vessel diameters were analysed. Interestingly, the more represented frequency classes of the distribution of xylem vessel diameters were between 30 and 45 µm; then, in all plants, the xylem vessels were considerably narrower in comparison to the usual values reported in the literature, in the range of 120-500 µm [70]. This could be considered a general sign of the long-term adaptation to climate change of kiwifruit plants in this area, where a progressively rising VPD has been detected, as narrow vessels are less exposed to cavitation risk [19,20].…”

Section: Discussionmentioning

confidence: 49%

“…Kiwifruit is a woody liana, with very long flexible vines and shallow fleshy roots. Xylem vessels are large to allow high rates of water conductancel; in cultivated Actinidia spp., the xylem vessel diameters in younger stems are up to 80 µm [33], but larger diameters (up to 500 µm) are signalled in secondary xylem [69], and root xylem vessel diameters range from 120 to 500 µm [70]. For these reasons, kiwifruit is potentially highly vulnerable to water transport failure under drought stress.…”

Section: Discussionmentioning

confidence: 99%

“…As expected, due to the lower transpiration, a significantly higher leaf temperature was also detected in plants from O1 throughout the whole vegetative season; indeed, transpiration regulates the homeostasis of leaf temperature, and when transpiration is reduced due to low water availability or other stress factors inducing stomata closure, the leaf temperature can increase to harmful levels. Photosynthetic activity is directly hindered by high temperatures as well as by drought stress [70,71]; this could have contributed to the early growth arrest observed in plants from O1. Moreover, CO 2 assimilation rose with the increases in the stomatal conductance in all plants, whereas transpiration for the same stomatal conductance was lower in plants from O1 when compared to plants from O2.…”

Section: Discussionmentioning

confidence: 99%

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Xylem Hydraulic Conductance Role in Kiwifruit Decline Syndrome Occurrence

Mandalà,

Monaco,

Nari

et al. 2024

Horticulturae

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Kiwifruit decline syndrome (KiDS) has affected kiwifruit orchards for more than ten years in the Mediterranean area, severely compromising productivity and causing extensive uprooting. The affected plants go through an irreversible and fast wilting process. The problem has not been solved yet, and a single cause has not been identified. In this work, we carried out a survey on ten five-year-old healthy kiwifruit cv. Hayward plants cultivated in an area strongly affected by KiDS are characterised by a rising temperature and vapor pressure deficit (VPD). Five plants were located in a KiDS-affected orchard. Our goal was to assess the hydraulic conductance of asymptomatic plants in a KiDS-affected area where rising climate change stress is underway. Our hypothesis was that a rising temperature and VPD could impair xylem functionality, leading the plants to develop strategies of tolerance, such as vessel narrowing, or stress symptoms, such as cavitation or implosion, inducing a higher risk of KiDS onset. Hydraulic conductance was investigated using a physiological and morphological approach to detect trunk sap flow; trunk growth and daily diameter variations; leaf gas exchanges and temperature; stem water potential; and the root xylem vessel diameter and vulnerability to cavitation. A strong xylem vessel narrowing was observed in all plants, with the highest frequency in the 30–45 µm diameter class, which is an indicator of long-term adaptation to a rising VPD. In some plants, cavitation and implosion were also observed, which are indicative of a short-term stress response; this behaviour was detected in the plants in the KiDS-affected orchard, where a high leaf temperature (>39 °C), low stomatal conductance (<0.20 mol H2O m−2 s−1) and transpiration (<3 mmol H2O m−2 s−1), low stem water potential (<−1 MPa), high vulnerability to cavitation (3.7 μm mm−2), low trunk sap flow and high daily stem diameter variation confirmed the water stress status. The concurrence of climate stress and agronomic management in predisposing conditions favourable to KiDS onset are discussed, evidencing the role of soil preparation, propagation material and previous crop.

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Section: Discussionmentioning

confidence: 49%