THERMIC RELATIONSHIPS AMONG SOIL, PLANT AND ATMOSPHERE UNDER FREEZING OR CHILLING CONDITIONS

Abstract

During the Autumn-Winter season of 1991-92, the thermic relations between soil, plant, and atmosphere were studied in an experiment icluding six corn (Zea mays L.) varieties (H-28, H-30, H-32, CPV20, Zac.58 SMC15 and Zac.58Or) and three cultivars of faba beans (Vicia faba L.) (CAOr, CASel y CrJuch) in five sowing dates. The objetive was to analyze the thermal relationships between plant and its environment before, during, and after chilling or freezing conditions and their effects on the plants. There were differences in cold tolerance between corn and faba beans, corn being the less tolerant. Lethal injury in corn occurred with leaf temperature of –0.4 and –0.7 °C, while in faba beans ocurred at –5 °C and 7.5 hours under freezing conditions. In faba beans, leaves and fruits covered with foliage, suffered less damage due to canopy protection.