OSMOTIC POTENTIAL OF CULTURE MEDIUM WITH DIFFERENT COMPOUNDS FOR THE in vitro PROPAGATION

Abstract

Some species propagated in vitro show several physiological disorders, such as hyperhidricity caused among other factors by a high
relative humidity in the vessels. Therefore, it is important to know the osmotic potential of the culture medium as affected by its solute concentration. Different sources of carbon (sucrose, glucose, mannitol, sorbitol, myoinositol) and three different concentrations of NH₄NO₃, KNO₃, Ca(NO₃)₂.4H₂O, MgSO₄.7H₂O, and KH₂PO₄, were evaluated in vitro. Treatments osmotic potential was measured in a  vapor pressure osmometer Wescor 5100C. The osmotic potential of the 90 mM sucrose medium was -0.39 MPa. When the sources and levels of carbon were increased, the osmotic potential became more negative. The osmotic potential was also more negative when the concentrations of NH₄NO₃ and KNO₃ were increased, while the other mineral compounds studied did not show significant differences. These results show the importance of studying the effect of solutes in the culture medium because of the possible physiological disorders which may affect plants growth in vitro.