Offshoots from three cultivars of date pahn showed different rooting ability, in response to the same root inducing treatment (25 mM indole butyric acid), under misting system. Offshoots from Mejhoul rooted easily and produced numerous roots, while those from Khalt rooted poorly and produced fewer roots. No relationship was found between soluble and ionically bound peroxidase and polyphenoloxidase activities and phenolics level, determined spectrophotometrically in the offshoot leaves prior to the auxin application, and the rooting ability of these cultivars. However, changes of these parameters during the first month of culture were correlated with the rooting ability. In the well rooting cultivar, the soluble peroxidase th activi!~ showed a minimum on the 4 day and a maximum on the 10 day, while phenolics level and polyphenoloxidase activity showed an inverse trend. In the poorly rooting cultivar, these parameters changed weakly. List of abbreviations: IBA = indote butyric acid; K H L = Khalt; MJH = Mejhoul; P H E = phenolics; POX = peroxidase; PPO = polyphenyloxidase;

Abstract.-The wheat immature embryos are often taken 14 days after the anthesis. At this age, the embryos size vary from 1 to 2 mm. The incubation of these embryos in the MS (1962) solid medium with 2 mg/1 of 2,4-D show a genotypic effect to in vitro culture capacity. In order to study the effect of developmental stage of embryos on this capacity, two cultivars (Jouda and Saada) considered as recalcitrant and two others varieties which present a good capacity taken as control (Potam and Marchouch) are chosen. The culture of embryos at early stages (size less than 1 mm in lengh) permit to improve the embryogenesis capacity, the regeneration ability and the mean number of regenerated plantlets/morphogenesis callus. This improvement is more effective in the case of the recalcitrant varieties. On the contrary, at the late stages (size more than 2 mm), the embryos put into medium culture tend rather to germinate for all varieties. Key-words

Mots-cles : Palmier dallier-rejets -acide indole butyrique -enracinement.Abstract.-Treatment with indole-3-butyric acid (IBA) showed a significant effect on the rooting ability of young offshoots of two reputed Moroccan date Palm cultivars, Boufeggous (BFG) and Mejhoul (MJH). While 73.6% of rooting (the highest percentage for both genotypes confounded) was induced by 5% IBA, only 51.2% of offshoots produced roots without auxin. Further more, untreated offshoots formed fewer roots than those treated with IBA. Variation in rooting among offshoots from the two cultivars was highly significant in response to IBA: offshoots from MJH rooted highly (78.6%) with 5% IBA, while the highest rooting percentage (73.7%) was induced with 7% IBA in BFG. Moreover, offshoots from MJH produced significantly more roots per rooted offshoots and were more affected by the inhibitory effect of high concentration (15% IBA) than those from BFG. On the other hand, treatments with IBA combined to IAA were unfavourable for rooting. But combined treatments IBA-NAA, showed a significant effect when the IBAINAA ratio was superior to 1.

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Amelioration de l'embryogenese somatique a partir d'embryons immatures chez le Ble tendre (Triticum aestivum L.). II-Effet des regulateurs de croissance sur Ia callogenese