Recovery of orange trees following severe water stress.
Abstract
Twelve-year old cv. Valencia orange trees were subjected to a single water stress, under field conditions at Tacna, Arizona, inducing leaf water potentials of between -1 and -6.6 MPa before dawn. The water status of trees was then studied after irrigation. Rehydration began immediately after irrigation and leaf water potentials reached normal values in less than a week. The stomatal conductance of leaves recovered more slowly, the time being related directly to leaf water potential prior to irrigation. The stomatal conductance of trees which had leaf water potentials of less than -5 MPa before dawn, prior to irrigation, did not fully recover in 2 months. Leaves that had undergone severe water stress had lower leaf water potentials, for a given relative water content, than unstressed leaves. These differences are discussed in terms of osmotic adjustment and changes in bound water.<new para>ADDITIONAL ABSTRACT:<new para>Valencia orange trees were subjected to water stress under field conditions at Tacna, Arizona, inducing leaf water potentials between -1 and -6.6 MPa before dawn. The water status of trees was then studied after irrigation. Rehydration began immediately after irrigation, and leaf water potentials reached normal values in less than a week. The stomatal conductance of leaves recovered much more slowly, the time being related directly to leaf water potential prior to irrigation. The stomatal conductance of trees which had leaf water potentials of less than -5 MPa before dawn, prior to irrigation, did not fully recover in 2 months. Leaves that had undergone severe water stress had lower leaf water potentials, for a given relative water content, than unstressed leaves. These differences are discussed in terms of osmotic adjustment and changes in bound water.