TEMPERATURE OF POTATO AND TOMATO LEAVES

Open Access
Publisher Website
Google Scholar
Abstract
An energy economy equation was developed to predict the difference in temp.between a leaf and its environment. The proposed economy was tested by comparing the predictions with observations in the field. The effects of several factors upon leaf temp. were predicted and verified. The factors considered were changes in radiation due to time of day, sky cover, angle of incidence and shading; changes in ventilation due to location on the plant and density of stand, and differences in plant species. A leaf perpendicular to insolation was 3.2[degree]C warmer than a leaf parallel to insolation. Shaded leaves on all parts of the plant had nearly equal temps. while leaves exposed to insolation at the top of the plant and near the soil line were 7.8 and 12[degree]C, respectively, warmer than the shaded leaves. Upper exposed leaves were 3.3 to 8[degree]C warmer on clear days and 0.8[degree]C cooler on cloudy days than the air temp. in an instrument shelter. At night the same leaves were 0.5[degree]C cooler than the air in the shelter. Lower sheltered leaves were 0.5 to 0.8[degree]C cooler during the day than temps. in an instrument shelter. On a cloudy night lower sheltered leaves were 0.5[degree]C warmer than the air 1 cm. above them. Air temps. 1 cm. below an exposed upper leaf were about 1[degree]C warmer than temps. in an instrument shelter on a clear, windy day. No temp. differences were observed between similarly exposed potato and tomato leaves or between similarly exposed tomato leaves in open and closed plantings.