In vitro ROOTING KINETICS OF GRAPEVINE ROOTSTOCKS IN RESPONSE TO SUGAR SOURCE AND CONCENTRATION

Abstract

The source and concentration of sugars are important in micropropagation because they affect the organogenesis processes. In this study explants of the ‘Saltcreek’ and ‘Freedom’ grapevine (Vitis sp.) rootstocks, were compared when grown in a low-salt culture medium, combined with three sugar sources (sucrose, glucose and mannitol) at three concentrations (43.82, 87.64 and 175.28 mM), plus a control without sugars. The rooting kinetics, root number and length and medium osmotic potential were determined. The highest rooting occurred in the ‘Freedom’ rootstock, in which it started on the fifth day of culture, while in ‘Saltcreek’ it started until the tenth day. The maximum rooting rates (100 % for ‘Freedom’ and 75 % for ‘Saltcreek’) were obtained with glucose, while the highest number of roots in ‘Freedom’ happened with sucrose and in ‘Saltcreek’ with glucose, both carbon sources at 175.28 mM. Root length in ‘Freedom’ was superior in glucose at 175.28 mM, whereas in ‘Saltereek’ was with sucrose at 87.64 mM. It was observed that as the concentration of sugars raised from 43.82 to 175.28 mM, the medium osmotic potential diminished from -0.26 MPa in mannitol at 43.82 mM to -0.69 MPa in sucrose at 175.28 mM. In rootstock ‘Freedom’ rooting can be as high as 97 % when cultivated at -0.69 MPa of osmotic potential.