1993 Volume 62 Issue 3 Pages 378-384
We investigated which cell wall components of the culm affect the bending stress of the culm using seven rice cultivars. A small difference in the cell wall composition was noticed among the cultivars. The relationship between this composition and the varietal difference of the bending stress was not found. In order to clarify the relationship between the quantity of the culm materials and the bending stress, the densities of the cell wall materials (the cell wall contents of the culm per volume of the culm tissue) were compared among cultivars. There was a large varietal difference in the densities of glucose, xylose and lignin. In Tainung 67 and Taichung 189 with a large bending stress, the densities of glucose, xylose and lignin were higher than those in Koshihikari and Fujiminori with a small bending stress. On the other hand, in Milyang 23 with a large section modulus and a small bending stress, the densities of glucose and xylose were as large as those in Tainung 67 and Taichung 189, and the density of lignin in Milyang 23 was as small as those in Koshihikari and Fujiminori. Furthermore, the partial correlation coefficients were calculated among the bending stress, the density of lignin and the density of cell wall monosaccarides. The results showed that density of lignin of the culm was significantly correlated with the bending stress (r=0.81) in the seven cultivars. The results of this study indicate that the density of lignin is the main factor responsible for the varietal difference in the bending stress which is related to the lodging resistance in paddy rice.
