Growth of some Range Grasses in Reduced Light Intensities at Cheyenne, Wyoming

Abstract

1. Plants of Agropyron cristatum, A. smithii, and Bouteloua gracilis were grown at Cheyenne, Wyoming, in 100 per cent, 57 per cent, 42 per cent, and 28 per cent sunlight in 1938 and in 100 per cent, 70 per cent, and 50 per cent sunlight in 1939, and the height, dry weight, and number of plants that flowered recorded. 2. The plants grown in the shade were taller than those grown in full sunlight but had a smaller dry weight. 3. Reducing the light intensity to a certain extent increased the number of plants of A. cristatum and A. smithii which flowered but greatly decreased the number of plants of B. gracilis which flowered. 4. Using the dry weight as a measure of growth, the results indicate that these species make their best growth in full sunlight; but that full sunlight, while favoring the flowering of B. gracilis, is so intense as to retard the flowering of A. cristatum and A. smithii.