Salinity and Salicornia bigelovii Torr. Seedling Establishment. Water Relations

Seedling establishment of Salicornia bigelovii was inhibitedwhen seeds were sown in vermiculite watered with 0 ppt NaCl(control treatment) while the presence of 10 or 30 ppt NaClhad no inhibitory effect. During most of the experimental periodthe rate of water absorption in both cotyledons and embryo-axisof the salt treatments was at least twice that of the control.The organic material decreased in the cotyledons at the sametime that it was increasing in the embryo-axis. Salinity didnot show any apparent effect on reserve mobilization from thecotyledons to the embryo-axis. Ions accumulated with the increasedsalinity of the root environment in both the cotyledons andthe embryo-axis. The former accumulated more than the latterexcept in the control treatment. After the 8th day from sowingthe cotyledon was —1•38, —1•95 and —2•74MPa for the 0, 10 and 30 ppt treatments, respectively. The gradients between external solution and the cotyledons were(0•80, 1•19 and 1•15 MPa for the 0, 10 and 30ppt, respectively. The _p of the control treatment was very low(0•02 MPa) when compared to the ones for the 10(0•53MPa) and the 30 ppt (0•99 MPa) treatments. Glycinebetaineand soluble amino nitrogen accounted for over 90% of the organiccomponent of the tissue osmolality with soluble sugars beingresponsible for the remainder. In the control the inorganicand organic components were of the same magnitude while in the10 and 30 ppt treatments the inorganic was 8•6 and 14•1fold greater than the organic component, respectively. Watermovement into the control plants was apparently inhibited bythe lack of inorganic solutes and as a consequence the cotyledonsfrom these plants did not expand and seedling growth was severelyreduced. Key words: Halophyte, seedling establishment, tissue osmolality components