抄録
In order to know the varietal defferences of stalk-strength, the experiments were carried out in 1964∼1966 at Hatano Tobacco Experiment Station. Five varieties; Shirodaruma, Shirohatano, Shirogiri, Odaruma and Ky 57, were selected for this study. After stalk-cutting, tobacco stalks were fixed in a vise at the base and horizontally loaded at the free end as cantilever beams, for deflection observations. For beam bending tests, each stalk was cut at the base of the plant and divided into several sections. These samples were used for testing at once to minimise drying. Results obtained were as follows. 1. The deflection of tobacco stalks were different with varieties and Ky 57 and Shirodaruma showed the largest value and Odaruma, Shirogiri and Shirohatano followed in order. 2. The flexural rigidity of stalks in the maturing stage were much larger than in the early growing stage, and in all stage Shirogiri showed the largest value and Shirodaruma showed the smallest value. 3. The values of bending moment at breaking were large in order of Shirohatano, Shirogiri and Odaruma, while Shirodaruma and Ky 57 showed smaller values. 4. The bending stress showed different values with each variety and through all stage Ky 57, and Shirodaruma were the weakest and Odaruma, shiro hatano and Shirogiri fellowed in order, although some differences in the value itself were observed with growing season. 5. Among these varieties Shirodaruma has the tendency to suffer from stalk break and root lodging because of it stalk characteristics. 6. From these results, auther suggested to prevent these damages of Shirodaruma by earlier transplanting.
