Mechanism of Wind Injury on Tobacco Plants : I. Root lodging and stalk breakage of tobacco plants

[摘要] In order to find the reasons for root lodging and stalk breakage of tobacco plant, the experiment was conducted in 1963 and 1967 in the field of Hatano Experiment Station. The experimental samples were excised from Bright Yellow and Shirodaruma varieties grown under normal cultural practices. The slugs in a small basket was hung by means of a fine rope hook to the top of a tobacco plant, and caused the stalk bent. The root lodging load an inclined distance of stalk the treatment were measured to determine the lodging resistance. For beam bending tests, each stalk was cut at the ground level into three or several sections. Samples were tested as soon as possible after cutting, to minimize the drying. Results obtained are as follows: 1) The root lodging was significantly increased by application of mulching with plastic film in tobacco cultivation, and the root lodging resulted primarily from poor stalksupport of the soil, especially when it was wet and loose. 2) The stalk breakage strength was foumd to depends on variety of tobacco, and severe stalk breakage occurred with Shirodaruma. 3) The deflection values of stalks in a simple beam with loading at the middle were different by stalk sections. The bending breaking strength in the base of the stalk were very large, but those in the top were snall. 4) The bending breaking stress, flexural rigidity and Young's Modulus of the stalk showed different values by each stalk section. It was observed that those values became less in proportion to the distance from the base of the stalk. 5) Physical properties of the stalk were found to be greatly different according to the growth stage. The bending breaking stress, flexural rigidity and Young's Modulus of the stalk in the maturing stage were much higher than in the early growing stage. These facts seem to be related not only to the diameter of stalk but also to the development of woody tissue.

[学科分类] 农业科学（综合）