抄録
According to the previous reported line (2, 3, 4), studies on the varietal differences in morphological characteristics of rice were carried out. In this paper, a morphological characteristic was estimated by principal component analysis using all the data of three plant-spacings at high-nitrogen level and non-nitrogen level. The result at standard nitrogen level was already reported in the previous paper (4). The present results Were as follows: (1) A morphological characteristic of each variety at each nitrogen level can be shown by two principal components which are indices of the morphological characteristic. These indices were as follows: High-nitrogen level: X1= 0.445x1+0.314x2+0.288x3+0.361x4+0.500x5+0.490x6, X2= -0.339x1+0.422x2+0.638x3+0.529x4-0.056x5-0.131x6, Non-nitrogen level: X1= 0.462x1+0.262x2+0.273x3+0.341x4+0.531x5+0.514x6, X2= -0.306x1+0.515x2+0.585x3+0.538x4-0.053x5-0.078x6 (2) The meaning of these indices was not changed by the levels of nitrogen application, even if the result of previous report (4) was considered together. The first index is concerned chiefly with the yield of an individual plant, and the second index is concerned chiefly with the plant type whether it is a long culm, heavy panicle one, or a short culm, high tillering one. (3) The plant type showed by the second index varied with plant-spacing at each nitrogen level, and these variations could be classified into three types as mentioned in the previous paper (4).
