EFFECTS OF SOME GROWTH FACTORS ON STRUCTURE AND GROWTH BEHAVIOUR OF STEM SHOOT TIP CULTURES OF DATE PALM (Phoenix dactylifera, L.) Helali, M.N. and Hanan R. El-Hosieny Agric. Bot. Dep., Faculty of Agric., Mansoura Univ., Egypt

Some aspects of micropropagation of date palm ( Phoenix dactylifera , L ) Zaghloul cv . as affected by certain growth factors including type of explants ,media and some growth substance were examined . indirect somatic embryogenesis by initation callus from shoot apices , axillary buds,and leaf primordia explants and germination of somatic empryoes from callus were used.
   Shoot tips explants were superior for surviving and swelling valus fllowed by leaf  primordia and axillary buds. The callus obtained in all culture media were yellowish and aggregated
 Callus formation /explant was positive correlated with levels of auxins used  (2,4-D and NAA) especially in the presence of 2 ip and friable callus growth/explant was increased with culturing period.
   The presence of auxins and cytokinins in compinations gave the best results for date palmempryogenic callus formation  at the stage of callus formation ,callus differentiation and the balances between these substances are important at these stages .However ,MS alone gave the lowest results in this respect and the exogenous supply of growth substances  is recommended.For the Mature somatic embryoes production, Average number of embryos per explant was found to be dependent on the explant used as well as the exogenous growth substans.
As for Shooting multiplication , the data show that shoot number formed from different sources of the explants used as well as average number of the secondary mature somatic embryoes which developed and produced on the   basal part of the developed shoot explants in all treatments were increased with an increase in culturing period up to the 3rd one . Therefore,repeated subculture explants on a fresh medium stimulated shoot formation /explant .
All auxin treatments increased number of adventitious roots and root length of the plantlets formed from the different developed shoots. NAA gave higher values than IBA and the increase was a concentration dependent