FACTORS AFFECTING IN VITRO ROOTING OF DATE PALM (PHOENIX DACTYLIFERA L.)

Date palm is a dioecious, perennial monocot plant species of the Arecaceae family cultivated in 56 countries including European and American countries. The success of date palm micropropagation is strongly linked to the in vitro root quality. The identical shoots of 8-10 cm long of three different varieties (vars.) were cultured in rooting experiment to study the combined impact of genotype, sucrose concentration, activated charcoal (AC), basal salts (MS or MS B5) and subculture number. The adventitious roots were planned to be initiated on media included different combinations of sucrose and basal salts for a couple of subcultures (each a month) and after then were transferred onto media contained 1.5 and 3.0 g/l AC for additional two subcultures. Findings indicated that using 40 g/l sucrose in the rooting medium encouraged the adventitious roots production where 5 roots per plantlet of 7.8 cm long and 1.4 mm width were averagely induced. The average leaves number reached 3-4 leaves per plantlet, leaf length 18-28 cm and the leaf width 3.5-6.9 mm. Full strength of MS basal salts proved better than macro elements of B5 micro elements of MS. The leaves and roots growth was affected by the genotype since the shoots of var. Gajar were initiated before other two varieties and in higher number. Incorporation of 3.0 g/l AC to the rooting medium found to be necessary to enhance the whole plantlet growth as the length of white roots and leaves increased. AC addition encouraged the secondary and tertiary roots formation. By adjusting factors affected rooting, the ideal in vitro roots have been achieved within a short period of time (4 months) and the survival percentage of ex vitro plants exceeded 90%. The in vitro roots development and proper handling of the plantlets during rooting stage was described in current study.