| A lot of experiments revealed that there exists a significant heterosis for rapeseed (Brassica napus L.). At present, Cytoplasmic male sterility has been one of main approachs to utilize heterosis in rapeseed. However, majority rapeseed hybrids in China employed Pol CMS (Shaan 2A CMS), which will result in a narrow genetic base, and has vulnerability to disease, insects, and other hazards. Therefore, discovery and characterization of novel male sterile cytoplasm is the base for rapeseed breeding. We have transfered a sterile CMS from Chinese cabbage and breeded a new CMS system, named improved Ogu CMS.The morphology, restoring and maintaining relationship, the cytological characters of anther abortion and molecular character of the improved Ogu CMS and orginal Ogu CMS were compared in this investigation, the main results obtained are as follows:1,Morphological observation showed that the improved Ogu CMS line grows strong,has normal nectary, not wrinkled petals. In all, it has overcomed etiolation of the original Ogu CMS line. Stamen of the improved Ogu CMS line aborted completely .2,Analysis of the restoring and maintaining relationship between the improved Ogu CMS line and the original Ogu CMS line by 104 rapeseed breeding lines from China and abroad indicated that all the materials are the maintaining line for both the improved Ogu CMS and the original Ogu CMS, So, discovery of restorer is still main task for the improved Ogu CMS line before it could be used in repaseed breeing programme.3,Traditional squash and paraffin section experiment showed that anthor abortion of the original Ogu CMS line starts from the tetrad to the microspore uninucleate stage, which belongs to the type of microspores abortion; The abortion of the improved Ogu CMS line starts later than origal Ogu CMS line,which belongs to the type of single nucleus pollen abortion.The tapetums of the abortion anther appear thickening and vacuoling, or delay such as polarization phenomenona. The abortion of anthers may be caused by the breakdown of tapetal cells or the excessive growth. In short, the improved Ogu CMS line and original Ogu CMS line can not form the normal fertile pollen.4,Molecular characters of the improved Ogu CMS line and the original Ogu CMS line by gene-specific PCR tests showed that the improved Ogu CMS line could amplify both Ogu CMS system specific gene-orf138 and the Nap CMS system specific gene-orf222. In one word, The improved Ogu CMS line has the genetic component of the original Ogu CMS and Nap CMS.In summary, the improved Ogu CMS stamen abort thoroughly, and it overcomes lacking green phenomenon of the orginal Ogu CMS; The improved Ogu CMS has the same restoring and maintaining relationship with the orginal Ogu CMS; The improved Ogu CMS has both Ogu system specific gene-orf138 and the Nap system specific gene-orf222. Searching the restoring line for the improved Ogu CMS and revealing the molecular mechanism of the improved Ogu CMS will be the tasks for the next step. This findings will have relevance for the heterosis utilization in Brassica napus and other related Brassica crops.In the second part of this paper,six male-sterile lines carrying the widely used Shaan2A cytoplasm were crossed with five restorer lines to produce 30 F1 hybrids. These 30 hybrids were evaluated for sixteen agronomical traits at Yangling, Shaanxi province in Northwest China for two years. Grey relational analysis showed that,among 30 hybrid combinations,eight were grouped as the best group,fifteen the second group and seven the third group. Among 30 hybrids, L89×L161 was the best one. As for the parent lines, L451 and L89 were identified as the best female parents, L161 and Qinyou 3 as the best male parents. Therefore, this research will provide some reference to the hybrid and parent selection in rapeseed breeding programme.
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