OSMOREGULATION IN YOUNG JOJOBA SEEDLINGS

Abstract

The possibility of osmotic adjustment to salinity in Jojoba was studied in a sand culture system. After being stablished, 2 WKs old seedlings were exposed to 1/2 strength hoagland's solution plus NaCl salt to make up -0.7., -0.4, -0.6, -0.8, & -1 MPa. Shoot & leaf elongation, components of Ψleaf, proline accumulation, & inorganic salts were determined every 24 hour for 9 days. Shoot & leaf length were reduced at -0.8 and -0.4 MPa respectively. Osmotic adjustment occured only above -0.8 MPa at the rate of 0.21 If MPa/day. Total inorganic salts in whole plant increased with a decrease in solution Ψw. However, above -0.8 MPa excess Na & Cl ions were excluded from the leaves & accumulated within the roots, while K/Na ratio remained higher above -1 MPa. The selective uptake of K ions seems a possible mechanism for osmotic adjustment in Jojoba. Accumulation of Na & Cl ions under -1 MPa correlated with occasional pale green discoloration & tip-burn of leaves. Although the accumulation of proline was considerable at & below -0.8 MPa, but did not play a significant role in osmoregulation.