Does salinity induce early ageing of pea root tissue?

The effect of salinity on ageing of pea roots was studied. The distance from the apex at which differentiation of xylem elements occurred and the relative increase in the function of pentose phosphate pathways were taken as parameters for maturation or ageing. Pea seeds (Pisum stivum L.) of the varieties Alaska and Dan were used in these experiments. The seeds were germinated and grown in vermiculite moistened with Hoagland's solution or Hoagland's solution containing either 96 or 120 mM NaCl. In Alaska roots salinity induced differentiation in a lower section of the root than in controls, and the increase in the function of the pentose phosphate pathway paralleled the advance of maturation. Salinity apparently induces earlier ageing in Alaska roots. This is not the case in Dan roots which tolerate slightly higher salinity levels than Alaska.