Abstract: Lodging is a big problem in wheat (Triticum aestivum L.) production, which severely influences wheat yield and quality. Lodging resistance varies among wheat varieties, and its inheritance has been rarely studied yet. The objecive of this study was to explore the genetic mechanism of culm lodging resistance index (CLRI) and its correlations with culm traitistics. Using seven wheat cultivars with diverse resistance to lodging (CLRI varying from 6.31 to 13.87), 21 crosses were obtained by the Griffing diallel-cross design. Parents Yangmai 9 and Ningmai 8 had the largest general combining ability for CLRI and significantly increased the CLRI in their crossing progenies. The inheritance of CLRI was in agreement with the additive–dominance model. Both additive and dominant effects were significant, and dominant effect was more important than the additive effect. The degree of dominance was from complete dominance to superdominance. The alleles increasing CLRI were recessive. The frequencies of alleles that increased or reduced CLRI were not significantly different among the seven parents. Yangmai 9 and Ningmai 8 had more recessive genes controlling CLRI, while Wangshuibai and Sumai 3 had more dominant genes. CLRI might be controlled by three or four pairs of major recessive genes with moderate narrow sense heritability. Correlation analysis showed that CLRI was positively correlated with diameter of the second basal internode (r = 0.4062, P < 0.05), filling degree of the first basal internode (r = 0.7743, P < 0.01), and filling degree of the second basal internode (r = 0.8712, P < 0.01); but negatively correlated with length of the first basal internode (r = -0.7064, P < 0.01), length of the second basal internode (r = -0.8182, P < 0.01), length of internode below spike (r = -0.8432, P < 0.01), plant height (r = -0.8737, P < 0.01), and height of gravity center (r = -0.9259, P < 0.01). Yangmai 9 and Ningmai 8 are recommended as important parents in logding-resistant breeding. Because CLRI is controlled by recessive genes and its narrow sense heritability is moderate, a relatively large population is suggested in early breeding generations and the phenotypic selection should not be too intensive.

Key words: Wheat, Lodging resistance index, Additive-dominance model, Culm traitistics