EFFECTS OF THE APPLICATION OF AMORPHOUS SILICA ON TRANSPIRATION AND PHOTOSYNTHESIS OF SOYBEAN PLANTS UNDER VARIED SOIL AND RELATIVE AIR HUMIDITY CONDITIONS

In epidermal cell walls of soybean leaves treated with amorphous silica accumulation of silica could be detected by means of electron microscopy and electron probe microanalysis. This changed the physical properties of the cell wall and affected the cuticular transpiration and uptake of CO2: When the soil in which the plants were grown was dry (60 % of the field capacity) and relative air humidity was below 50 %, the loss of water through the cuticle was smaller than the loss of CO2 uptake. This caused a higher grain yield under the conditions of temporarily restricted low air humidity.