Morpho-physiological evaluation and RAPD markers-assisted characterization of date palm (Phoenix dactylifera L.) varieties for salinity tolerance.

Date palm (Phoenix dactylifera L.) is one of the important fruit crops in arid land. The conservation of date palm genetic diversity is thus an important task to maintain the genetic resources. In order to identify salinity tolerant date palms, evaluation of four varieties was conducted based on analysis of morphological and physiological parameters, e.g. growth and pigment analysis, respectively. Randomly amplified polymorphic DNA (RAPD) technique was employed to characterize the varieties. The varieties were irrigated with increasing concentrations of saline water from 7.8, 11.7, 15.6, 19.5, 23.4 and 27.3 dS/m at regular intervals of three months duration. The growth parameters were plant height, collar girth and number of leaves. The physiological parameters were the types and quantities of the photosynthetic pigments. The varieties responded differentially to the increasing salt concentration with Bugal White acquiring maximum plant height, collar girth and production of leaves. The sensitivity to high salinity recorded reduced growth, leaf production and collar girth in varieties Mesalli and Razez. Chlorophyll and carotenoid contents of the treated varieties were highest in the varieties Bugal White and Khashkar and significantly superior to Mesalli and Razez. The date palm varieties were fingerprinted using fourteen random primers to detect the DNA polymorphism. Primer OPC-02 revealed a 1400 bp fragment amplified in ‘Bugal White’ (salinity tolerant) and ‘Khlas’ which is known to be drought tolerant. Primer OPD-02 distinguished ‘Bugal White’, which proved to be salinity tolerant, with a DNA fragment of about 1200 bp. Primer OPD-02 amplified a 1600 bp fragment in ‘Khashkar’, ‘Bugal White’, ‘Shaham’ and ‘Khlas’.