ELECTRICAL RESISTANCE IN ALFALFA ROOTS AS AFFECTED BY TEMPERATURE AND LIGHT

Abstract

Alfalfa plants grown in the greenhouse and field were used to study the development of coldhardiness as measured by electrical resistance of the root. Electrical resistance was measured with chloridized silver electrodes embedded in the roots. Electrical resistance measurements from electrodes embedded in living root tissue for periods of at least 30 days were comparable to measurements of newly embedded electrodes. A highly significant negative correlation of −0.810 was found between resistance and area of root cross sections. Hardening was induced by reducing temperature and light. Electrical resistance was increased by independent temperature and light changes. Periods of light as short as 30 seconds during the cooling period caused sharp increases in electrical resistance which was indicative of rapid development of hardening in the alfalfa plants.