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 variation in the soluble carbohydrate content of maize leaves. The max. accumulation of sugars in the sprayed plants on the day following application of the spray was about 62% of that in the controls. Samples collected 20 days after treatment showed a max. total sugar content of the leaves of sprayed plants to be about 18% greater than at the time of the earlier collection compared with no material difference in the controls. The low rate of photosynthesis in the sprayed plants can be attributed largely to a limited supply of CO2. On the basis of apparent photosynthetic activity, greater COs absorption occurred at the later date either because of a change in the permeability of the waxy covering or as a result of shrinking or cracking of the spray film. There was some evidence also that the supply of CO2 to the photosynthesizing cells of the control plants was not adequate to meet the requirements for max. photosynthesis.