Abstract
The varieties of Asiatic cotton were collected from various localities in Japan Proper, Korea, Manchukuo and Chine. They were grown on the Konosu Farm of the Imperial Agricultural Experiment Station, and their plant habit were investigated for classifying and selection of cotton varieties. According to Mr.ONODERA'S classification of Asiatic cotton (1938), all the varieties studied were found generally belonging to "Eastern Asia Cotton" (Gossypium arboreum var.neglectum forma burmanica). The results of the study are briefly summarized as follows: 1. Observations in the plant habit were made chiefly at the time of pinching when it was most distinctive. The plant height and plant form were firstly considered in this study and the length of internode, number of vegetative branches. etc. were also studied. Thus the varieties studied were grouped into six different types according to their growing habit, i.e., A, B, C, D, M and N as shown in Figure 1 and Table 1. 2. Controlling the vegetative growth of the plant is a key point in the cotton cultivation in Japan Proper. As well be seen from Tables 1.and 2 and Figures 2 and 3, the classification represents the intensity of the nature of vegetative growth; i.e., the relation of plant habit, with the growth of the main stem, flowering progress and maturing date. 3. From Table. 3(i, ii, iii, iv), it may be seen that the plant habit is also closely related to the weight of seed-cotton per boll, number of bolls per plant, lint percentage and tactile sense of the fiber. 4. As to the types A, B, C, and D, there exist parallel relations within many characters, while as to the other 2 types, M and N, there were not found such a tendency, both being believed to have little connection with the former groups. The schematic representation of the connection among the 6 types is shown in Figure 4. 5. In response to growth environmental factors (temperature, humidity, soil fertility, etc.), the 6 types differed with each other; i.c., type D is the most sensitive while type A the least. 6. Taking into consideration the local climate and soil fertility, each district may have its own type of plant habit. Therefore the proper consideration on the plant habit in breeding work are indispensable (Figure 5). 7. Geographical distribution of the different types of the plant habit of cotton in the East Asia was roughly described in Table 4, however, its ecological explanation is reserved for further studies.
