The effect of salinity on glucose absorption and incorporation by pea roots

Osmotic adaptation was observed in pea plants grown in Na₂SO₄salinized media but no complete adaptation was observed in plantsgrown in NaCl salinized media. The absorption of externally supplied glucose was depressedin pea root tips from plants grown in media salinized with eitherNaCl or Na₂SO₄. Under NaCl salinity this depression increasedwith increasing salinity. Under Na₂SO₄ salinity, no significantinhibition of absorption was observed in roots exposed to waterpotentials higher than –5 atmosphere. The amount of ¹⁴Creleased as CO₂, expressed as the percent of absorbed ¹⁴C, increasedwith increasing salinity of both types. In roots grown underNaCl salinity, the incorporation of ¹⁴C into ethanol non-soluble,acid hydrolyzable substances was markedly inhibited. This inhibitionwas increased by increasing the external salinity. The effectof Na₂SO₄ salinity was similar but not so pronounced. The incorporation of ¹⁴C from externally supplied glucose intothe alkali-soluble fraction was practically uneffected by salinity.Non-extractable ¹⁴C was decreased in roots exposed to NaCl butwas not, apparently, effected by Na₂SO₄). Because of the smallnessof this fraction no clear cut conclusion can be made. Possiblemechanisms for the events are discussed. (Received October 26, 1972; )