Genetic analysis of main characters of ramie F₁ generation

To understand the inheritance law of complex traits in hybrid progenies of ramie (Boehmeria nivea), we crossed two ramie varieties ‘Zhongzhu 1’ with ‘Xiangsi Xian 1’ and obtained a F₁ asexual propagation population of 1 012 progenies. We analyzed the heterosis and mixed inheritance of this F₁ population. The results showed that the F₁ generation was rich in genetic diversity, and the heredity of each character was basically the same as that from reciprocal cross, which belonged to nuclear inheritance. Analysis of heterosis in F₁ hybrid population showed that plant height, stem diameter, skin thickness, effective plant, and dry weight of single stalk showed strong positive heterosis, which was more inclined to the inheritance of high value parent ‘Zhongzhu 1’. The flax yield of fresh skin and the fineness of single fiber showed a strong negative heterosis, which was more inclined to the inheritance of the low-value parent ‘Xiangsi Xian 1’. Except for the strong super-parent heterosis of dry weight, the super-parent heterosis of other traits was negative, and the negative direction of single fiber fineness was the most significant. Based on the mixed genetic model of major gene and polygene, the inheritance of plant height, effective plant, dry weight, and fineness of single fiber may be controlled by two pairs of additive-dominant-epistatic major genes. The inheritance of stem diameter may be controlled by two pairs of equal additive-dominant major genes, and the inheritance of skin thickness and fresh skin flax rate may be controlled by a pair of additive-dominant major genes. Each character had a medium heritability, probably owing to the influence of the environment. Therefore, it is important to understand the inheritance pattern of the main traits of F₁ generation of ramie, and this will help in cross breeding and selection of good single roots for future generations.