Evaluation sous serre de la tolérance à la salinité de quelques porte-greffes d'agrumes : Citrus aurantium et deux hybrides de Poncirus trifoliata (Poncirus x Citrus sinensis et Poncirus x Mandarinier sunki)
2005
Abdellatif R. | Bousarhal A. | Lemsellek J. | Rochdi A.
Citrus rootstocks response to salinity. To determine the effects of salinity on the intensity of chlorosis, growth and uptake of Na+ and Cl-, we grew three Citrus rootstocks (sour orange Citrus aurantium (C.a) and two new hybrids of Poncirus trifoliata [P.t. x Citrus sinensis (PXC) and P.t. x Mandarinier sunki (PXM)]) in nutrient solutions containing 0, 35 or 70 mM NaCl during 30 or 60 days. Foliar damages increase with time for all treatments and rootstocks. The intensity and the frequency of the chlorosis caused after 30 days of saline stress reveal the sensitivity of PXC and the tolerance of PXM. Moreover, if apical growth of the C.a is not affected by 35 mM NaCl, it is stimulated on the other hand for PXM and is inhibited for PXC. The concentration 70 mM NaCl affects the vigour of rootstocks more severely and shows the tolerance of PXM and the sensitivity of PXC. The biomass decreases with time for all treatments and rootstocks. However, it appears that the concentration 35 mM NaCl is insufficient for the discrimination between rootstocks against salt stress. But, at 70 mM NaCl, the reduction of the biomass confirms the sensitivity of PXC and proves the tolerance of PXM. Furthermore, the content of leaves in Cl- and Na+ is affected meaningfully by salinity, time of stress and rootstocks (PXM appears to be efficient excluding of Cl-). Contents in Na+ and Cl- are correlated with foliar toxicity symptoms. This content is also correlated with biomass reduction of PXC. Therefore, in addition to inhibitory effects of high concentrations of Cl- and Na+, an imbalance of essential nutrients may also contribute to the reduction in growth of this rootstocks under saline conditions.
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