A comparative study between temporary immersion system and semi-solid cultures on shoot multiplication and plantlets production of two Moroccan date palm (Phoenix dactylifera L.) varieties in vitro

Date palm micropropagation is commonly performed on gelled media. However, it’s typically a labour-intensive system and consequently plantlets production cost is very high. Therefore, it is necessary to develop cost effective alternatives without compromising the quality of produced plant material. New technologies based on liquid media in bioreactors have been developed to reduce the handling time, while increasing the multiplication rates and plant quality. The present research focuses on the comparison between Temporary Immersion System (TIS) and gelled media (GM) culture systems of two Moroccan date palm varieties ‘Mejhool’ and ‘Boufeggous’. Obtained results indicated that shoot and root lengths as well as shoot fresh and dry weights were significantly (P < 0.05) higher in TIS compared to GM. Moreover, the vigour of obtained shoots was better in TIS compared to GM. Therefore, TIS-derived plantlets have shown an acclimatization rate of 95% while this rate for GM-derived plantlets was 82%. Hence, bioreactors, as a growing system based on TIS, can be a valid alternative to conventional systems for in vitro culture, resulting in a reduction of cost, shelving area requirements, labour and time for the mass propagation of date palm cultivars.