PHOTOSYNTHESIS IN MAIZE AS INFLUENCED BY A TRANSPIRATION-REDUCING SPRAY

Abstract

A study was made of the influence of a transpiration-reducing emulsion on the daily variations in the soluble carbohydrate content of Maize leaves. Using accumulation of sugars in the leaves as a measure of photosynthetic activity, the maximum accumulation of sugars in the sprayed plants on the day following application of the spray was 62.10% of that in the controls. Analysis of samples collected twenty days after treatment showed that the total sugar content of the leaves of the sprayed plants was about 18% greater than at the time of the earlier study. The relatively low rate of apparent photosynthesis in the sprayed plants probably can be attributed largely to a limited supply of carbon dioxide. The increased rate of production of carbohydrates shown by the sprayed plants on August 30 compared with the rate on August 10 may be explained in either one or both of two ways. A change in the permeability of the waxy covering to carbon dioxide may have occurred during the 20-day interval. Carbon dioxide may also have become more readily available as a result of shrinking or cracking of the spray film. Although conclusive data are not available, the most reasonable inference from themore » results is that the normal supply of carbon dioxide to the photosynthesizing cells of the control plants was not adequate to meet the requirements for maximum photosynthesis under the existing conditions. 12 references, 4 figures, 4 tables.« less