title: Peach water relations, gas exchange, growth and shoot mortality under water deficit in semi-arid weather conditions.
abstract: In this study the sensitivity of peach tree (Prunus persica L.) to three water stress levels from mid-pit hardening until harvest was assessed. Seasonal patterns of shoot and fruit growth, gas exchange (leaf photosynthesis, stomatal conductance and transpiration) as well as carbon (C) storage/mobilization were evaluated in relation to plant water status. A simple C balance model was also developed to investigate sink-source relationship in relation to plant water status at the tree level. The C source was estimated through the leaf area dynamics and leaf photosynthesis rate along the season. The C sink was estimated for maintenance respiration and growth of shoots and fruits. Water stress significantly reduced gas exchange, and fruit, and shoot growth, but increased fruit dry matter concentration. Growth was more affected by water deficit than photosynthesis, and shoot growth was more sensitive to water deficit than fruit growth. Reduction of shoot growth was associated with a decrease of shoot elongation, emergence, and high shoot mortality. Water scarcity affected tree C assimilation due to two interacting factors: (i) reduction in leaf photosynthesis (-23% and -50% under moderate (MS) and severe (SS) water stress compared to low (LS) stress during growth season) and (ii) reduction in total leaf area (-57% and -79% under MS and SS compared to LS at harvest). Our field data analysis suggested a Ψstem threshold of -1.5 MPa below which daily net C gain became negative, i.e. C assimilation became lower than C needed for respiration and growth. Negative C balance under MS and SS associated with decline of trunk carbohydrate reserves--may have led to drought-induced vegetative mortality.
authors.affiliation: INRA, UR1115 Plantes et Systèmes de culture Horticoles, Domaine St Paul, Site Agroparc, Avignon, France; Ferdowsi University of Mashhad, Faculty of Agriculture, Mashhad, Iran.
authors.forename: Mitra
authors.initials: M
authors.lastname: Rahmati
authors.affiliation: Ferdowsi University of Mashhad, Faculty of Agriculture, Mashhad, Iran.
authors.forename: Gholam Hossein
authors.initials: GH
authors.lastname: Davarynejad
authors.affiliation: INRA, UR1115 Plantes et Systèmes de culture Horticoles, Domaine St Paul, Site Agroparc, Avignon, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Génard
authors.affiliation: Ferdowsi University of Mashhad, Faculty of Agriculture, Mashhad, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Bannayan
authors.affiliation: Ferdowsi University of Mashhad, Faculty of Agriculture, Mashhad, Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Azizi
authors.affiliation: INRA, UR1115 Plantes et Systèmes de culture Horticoles, Domaine St Paul, Site Agroparc, Avignon, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Vercambre
mesh_terms: D002244:Carbon / Q000378:metabolism; D055864:Droughts; D005740:Gases / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development*; D000068239:Prunus persica / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D013312:Stress, Physiological; D014867:Water / Q000494:pharmacology*
chemical_list: D005740:Gases; D014867:Water; D002244:Carbon
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