Évaluation de la résistance de dix porte-greffes d’agrumes résistants à la tristeza vis-à-vis du déficit hydrique

Abstract

-Introduction. In Morocco, citriculture faces up an increasing combination of biotic (Citrus tristeza virus (CTV) / Phytophthora spp.) and abiotic stresses (salinity, alkalinity and drought). Most of these constraints should be individually managed by adapted rootstock choice. However, the spread of CTV in the Mediterranean Basin will soon prohibit the use of the traditional sour orange rootstock, which currently provides sufficient tolerance to salinity and alkalinity. Therefore, the selection of new citrus rootstocks becomes urgent. Our study sought to investigate the effect of different water regimes on growth of ten citrus rootstocks: citrange Carrizo (France), citrange Carrizo (Morocco), citrange Troyer, citrange Yuma, Citrus volkameriana; two Poncirus trifoliata of different origins, citrumelo, Mand. Sunki × Poncirus trifoliata, and Poorman. Materials and methods. For each rootstock, three months old seedlings were grown in plastic pots (0.5 L) in a greenhouse at El Menzeh, INRA, Morocco; they were subjected to three water regimes [(100%, 75% and 50%) moisture field capacity (Hcc) of the substrate]. The experiment was arranged in a split-plot design with three treatments. The morphological parameters measured were the plant height and dry and fresh matter accumulation. Physiological parameters studied were the Relative Water Content, transpiration rates and chlorophyll, soluble sugars and proline contents. Results. The morphological and physiological parameters were affected by the intensity of water stress applied. However, rootstocks behaved differently regarding to this constraint. Water stress induced an increase in the proline and soluble sugars content in the rootstock leaves. Conclusion. Water stress significantly affects the physiological and morphological characteristics of citrus rootstocks and, in conditions of extreme water deficit (50% Hcc), a differential behavior of the rootstock was found. Based on our results, the rootstocks Carrizo citrange (Morocco) and Poorman present the best overall ability to withstand water stress.Morocco / Citrus / rootstocks / drought stress / drought resistance / proline / carbohydrate content Évaluation de la résistance de dix porte-greffes d'agrumes résistants à la tristeza vis-à-vis du déficit hydrique.Résumé -Introduction. Au Maroc, les agrumes sont confrontés à une combinaison de stress biotiques [virus de la tristeza (CTV) / Phytophthora] et abiotiques (salinité, alcalinité et sécheresse). La plupart de ces contraintes doivent être gérées individuellement par le choix d'un porte-greffe adapté. Cependant, la propagation de la CTV dans le bassin méditerranéen va bientôt interdire l'utilisation du bigaradier, porte-greffe traditionnel, qui offre actuellement une tolérance suffisante à la salinité et l'alcalinité. Par conséquent, la sélection de nouveaux porte-greffes d'agrumes devient pressante. Notre étude a cherché à étudier l'effet de différents régimes hydriques sur la croissance de dix portegreffes d'agrumes : citrange Carrizo (France), citrange ...

Scheduling peach orchard irrigation in water stress conditions: use of relative transpiration and predawn leaf water potential

“…Plant water stress indicators are becoming necessary to move towards deficit irrigation strategies [3] without prejudice to yield or quality of the product [4]. Such an approach should be more efficient at saving water if coupled with the use of varieties and rootstock tolerant to drought, as recently shown for citrus [5]. Stress indicator studies have been limited [2,[6][7][8], given the difficulty of automating some of the measurements, e. g., plant water potential and stomatal conductance, although some advances have been made in relating it to automated measurements [9].…”

Évaluation de l’effet du stress hydrique et du portegreffe sur la clémentine <i>Citrus reticulata</i> Swingle var. Sidi Aissa.

“…Chez les plants d'agrumes, le statut hydrique et le degré de la tolérance aux stress abiotiques est généralement liés au porte-greffe utilisé (Syvertsen et Levy, 2005). En effet, plusieurs études ont rapporté que chez les agrumes en distingue entre des porte-greffes tolérants au stress hydrique et autres sensibles à cette contrainte (Castel et al, 1993;Garcia-Sanchez et al, 2002;Garcia-Sanchez et Syvertsen, 2006;Beniken et al, 2011 …”

“…Le déficit hydrique sévère affecte négativement la productivité des plants d'agrumes à différentes niveaux, entre autres via la diminution de la croissance et le métabolisme et par la suite par une réduction du rendement et la qualité des fruits (Zekri,1991;Gonzalez-Altozano et al, 2000;Pérez-Pérez et al, 2008;Wu et al, 2008;Rodriguez-Gamir et al, 2010et 2011. En effet, plusieurs études ont montré que le stress hydrique diminue significativement la croissance chez les porte-greffes d'agrumes (Wu et al, 2008;Rodriguez-Gamir et al, 2010et 2011Beniken et al, 2011). En outre, le déficit hydrique induit une diminution de la transpiration et la photosynthèse chez les plants d'agrumes.…”

Connection between the disease resistance of sour cherry genotypes and the carbohydrate content of the leaf and phloem tissues

“…The optimal concentrations of glucose, fructose and sucrose and the consumption and degradation time of the different carbohydrates utilized by Erwinia amylovora were determined in artificial nectar. Beniken et al (2011) compared citrus rootstocks exposed to water deficit and to inoculation by Citrus tristeza virus and Phytophtora spp. The combined effect of the virus, bacterium and water deficit increased the quantity of soluble carbohydrates and amino acids in the leaves of rootstocks.…”