抄録
The drag forte exerted on plant by wind is a fundamantal force for the lodging of plants. The authors previously reported the relationship between the force and wind velocity. This paper deals with varietal difference of the force. Nine barley and four wheat varieties were used as materials. Plants were grown in bots (barely) and in field (wheat), and the latter were transplanted in pots before the measurement of drag force in a wind tunnel. Four experiments were made to measure the force using whole and leaf- or ear-removed plants, and the fifth one was made using detached culm with or without flag leaf and ear. Results obtained are as follows: 1. The drag force exerted on a whole plant varied with varieties, and the force on each organ also. varied (fig. 1). 2. The difference of the drag force on a whole plant seemed to be due to the difference of the force on leaves in barley varieties and of the force on culms in wheat varieties. 3. The tendency of the force of varieties obtained by detached culms agreed with the force obtained by whole plants (fig. 3). 4. The drag force on leaves was closely related to leaf area, and drag coefficient (of leaves) to bending rigidity of leaves which was considered to be related to leaf flattering. 5. It is considered that total drag force on plants consists of silhouette area and drag coefficient. The extent of the former might be due to the size of plants and bending rigidity of culms, and the latter to the roughness of plant surface and flattering of plants. 6. It could not be found that drag force was related to the strength of culms (fig. 5).
