EFFECTS OF CARBON SOURCE, CARBON CONCENTRATION AND CULTURE CONDITIONS ON IN VITRO ROOTING OF PINUS PINEA L. MICROSHOOTS

Abstract

Clonal propagation via adventitious bud stimulation from cotyledon explants has been reported before in stone pine (Pinus pinea L.), however the number of rooted shoots had low frequency and short growth span. Therefore the main objective of the present work was to increase the number and quality of roots per shoot in order to ensure the survival and growth of a great number of plants in the acclimation phase. To achieve this, different combinations of carbon source (sucrose or glucose) at different concentrations, under different environmental conditions (temperature and light), were tested in the induction and expression phases of the adventitious root formation. Shoots of different clones obtained via organogenesis have been employed for the experiments. Observations were made on the rooting percentage, root length and number of roots per shoot. The results showed a general increased of the number of roots per shoot and an earlier root formation when glucose was used as a carbon source. However, there were no differences in the percentage of rooting between the carbons sources tested. The best results were obtained using 0.117 M of glucose and dark treatment combined with 19 oC during the induction phase of the rhizogenic process. Light and low sugar concentration proved to be beneficial for the expression phase, increasing the root length. A remarkable interclonal difference in the ability to form roots was observed. It was possible to obtain a rooting percentage of more than 75% in several of the tested