Abstract
Effects of intraspecific and interspecific competition on the growth of red clover were investigated, using some varieties of red clover and orchardgrass. Planting methods were set up with pure and mixed stand of red clover varieties and mixed stand of red clover and orchardgrass arranged high, medium, and low density. Results were summarized as follows : 1. Higher plant density of red clover produced less yield per plant, but more yield per unit area. However, when early variety of red clover was mixed with late variety in high density, the yield per plant of the former was more than that of pure early variety stand of the same density. On the contrary, the yield of late variety per plant was much less than that of pure late variety stand. 2. When early and late varieties of red clover were mixed with orchardgrass, they decreased in their yield per plant and per units area, but the decreasing rate was more remarkable in late varieties than in early ones. 3. Therefore, it is considered that productivity of the variety of red clover dense mixed with grasses should not be estimated from that under pure stands of them. 4. Effects of competition within a variety of red clover on the growth of plants were almost similar to those found among varieties. Under lower plant density, many high yielding plants were found in the late flowering plants within a variety, while under higher plant density, there were no high yielding plant in late flowering plants. Time of flowering of strains or lines of red clover might be getting later by selection under spaced planting, but might be getting a little earlier under ordinary dense planting. 5. Under higher plant density of red clovers in pure stands or in mixture with orchardgrasses, high correlation was found between yield of red clover at fist cutting time in seeding year and total yield of them over 2 years. This indicates the possibility of close relationship between light-catching capacity of a plant based on plant-types in seeding year and subsequent growth.
