SALT STRESS TOLERANCE IN ACIDIC AND SWEET MANDARINS

Mandarin genotypes can be split in two main groups: the acidic and the sweet mandarins. Commonly, acidic are used as rootstocks when sweet mandarins are the varieties that are consumed as fruits. The acidic ‘Cleopatra’ mandarin (Citrus reshni Hort. ex Tan.) is considered to be the most salt stress tolerant rootstock since it is able to limit the absorption of chloride and sodium at root level. As a consequence, limited amount of toxic ions are translocated from root to leaves. If salt stress tolerance of ‘Cleopatra’ mandarin and its hybrids has been well documented, little data exist for sweet mandarins. We investigated 16 genotypes representing a large diversity in mandarins subjected to salt stress. Physiological parameters such as stomatal conductance and leaf chloride contents were analyzed. If most of the acidic varieties were tolerant, also some sweet varieties presented traits of tolerance. Taking into account the results of leaf ion contents, we observed that large leaf chloride contents were not always associated with sensitivity.