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

Abstract

Osmotic adaptation was observed in pea plants grown in Na2SO4 salinized media but no complete adaptation was observed in plants grown in NaCl salinized media. The absorption of externally supplied glucose was depressed in pea root tips from plants grown in media salinized with either NaCl or Na2SO4. Under NaCl salinity this depression increased with increasing salinity. Under Na2SO4 salinity, no significant inhibition of absorption was observed in roots exposed to water potentials higher than −5 atmosphere. The amount of 14C released as CO2, expressed as the percent of absorbed 14C, increased with increasing salinity of both types. In roots grown under NaCl salinity, the incorporation of 14C into ethanol non-soluble, acid hydrolyzable substances was markedly inhibited. This inhibition was increased by increasing the external salinity. The effect of Na2SO4 salinity was similar but not so pronounced. The incorporation of 14C from externally supplied glucose into the alkali-soluble fraction was practically uneffected by salinity. Non-extractable 14C was decreased in roots exposed to NaCl but was not, apparently, effected by Na2SO4). Because of the smallness of this fraction no clear cut conclusion can be made. Possible mechanisms for the events are discussed.