Abstract
This experiment was carried out in order to know the relationship between yield and yield components and the interactions among yield components in 12 varieties of orchardgrass grown under individual plant basis. The results are summarized as follows: 1. Dry weight of a plant indicated significant correlation with the dry weight of a tiller, but not correlated with the number of tillers per plant. There was highly negative significant correlation between the dry weight of a tiller and the number of tillers per plant. The dry weight of a tiller indicated highly significant correlation with (stem thickness)^2×plant height. But the weight of a tiller was influenced by the plant height more than the stem thickness. 2. The tiller number type and the tiller weight type which were classified by the plant type index (dry weight of a plant/(number of tillers per plant)^2) corresponded very well with the distinction of pasture type and the hey type. The plant type index may be a very useful method to classify the grass varieties. 3. The dry weight of a plant in the tiller weight type varieties had highly significant correlation with both of the weight of a tiller and the number of tillers per plant. But in tne tiller number type varieties, it was positively correlated with the number of tillers per plant, but negatively correlated with the dry weight of a tiller. 4. In the tiller weight type, the heading tiller contributed to the yield more than the vegetative tiller. On the contrary, the vegetative tiller did more than the heading tiller in the tiller number type. 5. From the facts described above, we may conclude that the stemmy type is advantageous in the varieties of tiller weight type, and the leafy type is advantageous in the varieties of tiller number type for dry matter production under the individual plant basis.
