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Thesis (M.S.)—University of Nebraska—Lincoln, 1971. Department of Horticulture and Forestry.


Copyright 1971, the author. Used by permission.


The aim of this research is to evaluate the possibility of reducing transpiration of plants by altering their reflection characteristics without directly affecting the stomatal mechanisms.The soybean crop (Glycine max. L.) was chosen for study because of some useful characteristics.Soybeans grow into dense and uniform canopy which is very favorable to achieve a maximum treatment effect.Soybean plants have broad leaves which hold the white coating materials well.

Ground kaolinite clay was used as the reflectant material and sprayed onto the crop.This study, as conducted, had four major phases:

  1. Spectral properties of soybeans.

  2. Energy balance studies.

  3. Field photosynthesis studies.

  4. Agronomic studies.

Effects of the treatment on the water use efficiency appear encouraging.There is definite evidence of a decrease in water use by the treated crop, the degree of decrease depending on environmental factors.Two of the important environmental factors are radiation intensity and wind speed.At high radiation intensity differences in energy level of the treated and untreated crop will be maximal.High wind speeds cause a decreasing effect of treatment and no difference in evapotranspiration will exist between the treated and untreated areas.The photosynthetic rate was not found to be significantly altered by the treatment.The limitations of the CO2 measurement system may not have permitted detection of such an effect.The water use efficiency—the amount of CO2 fixed for each unit of water transpired by the plant was increased.

Advisor: Norman J. Rosenberg