トマトの芯止り型品種における連続的変異

Abstract

There are two types of growth habit in the tomato, i.e. normal and self pruning. Several forms of the self pruning type of tomato are known. The author attempted to analyse quantitatively the varietal differences in the self pruning type. The branches (main stem and lateral branches) of the tomato are sympodially formed. Sympodial axillary shoots terminate after a few leaves in an apical inflorescence. There are basically four types of sympodial axillary shoots (Table 1) . The branches of the normal type usually consist of Type III alone (Fig. 1A), while those of the self pruning type consist of various combinations of four types (Figs. IB-J) . Frequency distributions for types of sympodial axillary shoots in five successive shoots of the main stem showed that the eight varieties differed markedly from each other in degree of self pruning (Table 2) . Scores from O to 3, corresponding to the four types of sympodial axillary shoots, were given :for quantitative analysis (Table 1). From the results shown in Figs. 2 and 3, it was accepted that the average mean score of the first and second sympodial axillary shoots of the main stem was good enough to represent the relative degree of self pruning among varieties and was designated as the self pruning index (SPI) of the variety. The SPI of a variety may be obtained easily by the following formula :