| Lodging not only affects the yield and quality of rape seed, and also causes low efficiency of machine harvest. Because of the complexity of causes and genetic mechanism for lodging phenotype, studies available on different crops are sometimes contradict. Therefore, exploring efficient methods for the lodging study is an important and urgent task and it is necessary to understand genetic control of lodging. In this study we analyzed the lodging-related trais in several segregating populations derived from two crosses (Huashuang 5 x Jia7005,Zhongshuang 9x Jia6104)or lodging in one cross. The main results obtained were as follow:1. The stem strength, stem diameter and their ratio were measured among parents and their progeny populations. We found that the mean of stem strength and stem diameter of the parents'were significantly different, while the correlation coefficients of stem strength and stem diameter were above 0.7, indicating that stem resistance had great relation with stem diameter. In Cross 1 (Huashuang 5 x Jia7005), the frequency distribution in all segregating generations except F3 that showed a 3:1 ration, followed a pattern of a normal distribution. The F1 average of stem diameter was near to the high-value parent Huashuang 5 while stem strength far higher than its high value parent Huashuang 5. The heritabilities of stem diameter and stem strength were 0.44 and 0.13, respectively. In Cross 2(Zhongshuang 9 x Jia6104), the trait means in segregating generations'are close to the high value parent and the frequency distribution is a normal distribution. The ratio was equal to the performance of stem strength in the two crosses.2. A total of 448 pairs of SSR makers were selected for the analysis on an F2 population. A linkage group which included 20 chromosomes through Mapmaker 3.0 was constructed. The total length of the linkage group was 3,497.58cM and the average maker space was 12.27cM (the work was accomplished together with Cai Guangqin).With the phenotypic measurement, the QTL of lodging related traits by using Wincart QTL 2.0 software were scanned. We used three methods of IM,CIM and single marker analysis to identify QTLs. There were three high reliable QTLs detected, and they were located in the chromosomes 4,13 and 16, respectively explaining phenotypic variation 11.9%,12.1%,19.8%.3. We analyzed cellulose content and lignin content with lodging materials and lodging resistance materials. Both cellulose content and lignin content in lodging materials were higher than in lodging resistance materials. In the mature stage, cellulose content and lignin content of lodging materials are 1.6 and 1.5 times of lodging resistance materials, respectively. |
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