Date of Award:

5-1973

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Botany

Committee Chair(s)

H. H. Wiebe

Committee

H. H. Wiebe

Committee

Orson S. Cannon

Committee

T. W. Daniel

Abstract

Silver foil psychrometers were used to monitor water potential in different portions of maize leaves which were subjected to temperature gradients. The psychrometers were preliminarily calibrated over standard NaCI solutions at temperatures ranging from 5°C to 45°C in an aluminum plate apparatus designed to provide uniform temperatures within each psychrometer even while overall temperature was changing. Based on the calibrations, empirical temperature correction equations were derived and used to correct psychrometer readings at different temperatures to equivalent values at 25°C. Temperatures on a single maize leaf were varied by placing the long leaf through an insulated box with several compartments in each of which the temperatures could be separately varied by passing warm or cold air through the compartment. As many as five psychrometers were attached to the leaf to monitor water potentials along the leaf. Although there was some variation, water potentials tend to become lower (more negative) toward the tip of the leaf; the gradient was steeper in moisture stressed plants. Raising or lowering the temperature of proximal and mid portions of leaves between 10°C and 45°C had no measurable influence on the water potentials of more distal leaf parts. In the heated portions themselves, the water potential after correction for temperature, was higher while in cooled portions it was lower.

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