Abstract
Grasses undergo seasonal change in their growth habit, i.e. upright or prostrate. This may be caused by the curvature of leaf-sheath. To clarify this point, the effects of environmental conditions and CCC or GA application on the curvature were tested by using an orchardgrass clone. Low air-and soil-temperature, short days, stronger daylight or supplemental light in the longday treatment, abundant nutrition, and CCC application all tended to increase the curvature resulting in the more prostrate growth of the plant. The inverse environments and GA application, on the contrary, made the plant to grow more upright (Table 1-5.) Since there is an inverse relation between environmental conditions favouring shoot elongation and those favouring tillering, and the conditions which promote the curvature as mentioned above are favourable for tillering, the curvature has a positive or a negative correlation with tiller number or plant height, respectively. (Fig. 2-3)
