The relative salt tolerance of 'rangpur' seedlings and 'Arbequina' olive cuttings

Juan Carlos Melgar, James P. Syvertsen, Vicente Martinez, Francisco Garcia-Sanchez

Abstract


The salinity tolerance of citrus rootstocks varies but grafted citrus trees are generally considered to be more sensitive to salinity stress than olive trees that are usually grown from cuttings. We compared the salt tolerance of 6-month-old seedlings of the relatively salt tolerant citrus rootstock Rangpur (Citrus limonia Osbeck) with similar sized rooted cuttings of olive (Olea europaea L. cv. Arbequina). Well-fertilized plants were grown in native Candler sand in a greenhouse and watered with either no salt (0 mM NaCl) or 50 mM NaCl for citrus, or with 0 or 100 mM NaCl for olive. Salinity increased Cl- and Na+ concentration in leaves and roots of both species and reduced total plant growth, leaf photosynthetic rate and stomatal conductance. High concentrations of Cl- and Na+ caused a decrease in leaf chlorophyll a in citrus but not in olive even at the higher salinity level. Decreased growth and gas exchange were apparently due to toxic effects of Cl- and/or Na+ and not due to osmotic stress since both species were able to osmotically adjust to salinity and maintained higher leaf turgor than the non-salinized control plants. The lower osmotic potential values in salinized olive (100 mM NaCl) than in citrus (50 mM NaCl) implied that osmoregulation was more efficient in olive than in citrus.

Keywords


Olea europaea; Citrus limonia; rootstock; NaCl; photosynthesis; leaf chlorophyll; citrus; olive

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283