Study On The Creation Of Herbicide-Resistant Rapeseed Germplasm And Utilization Of Heterosis Based On Chemical Induced Male Sterility In Rapeseed (Brassica Napus L)

Brassica napus L.as one of the most important oil crops in China,the consumption demand of it is rising because of the diversity of functions.However,the yield and quality are seriously affected by weeds,because rapeseed is sensitive to herbicides,which leading the limitation of herbicides in the field.Therefore,creating herbicide-resistant rapeseed germplasm and breeding new herbicide-resistant varieties have become an urgent need for the development of rapeseed industry.On the other hand,low concentration of herbicide could degrade the stamens of rapeseed and create chemical induced male sterility（CIMS）lines.There is a wider selection of male parent in CIMS lines,which can further improve the utilization potential of heterosis in rapeseed.Therefore,it is profound significance to study the chemical emasculation techniques and determinate the ability of combining for the heterosis of rapeseed.This research was performed by the above-mentioned two aspects and the main results are as follows.1.Germplasm creation of glyphosate-resistant rapeseedTo obtain the updated version of backbone parent contained the glyphosate resistant gene,backcross breeding combined with molecular marker-assisted selection was applied,in which the donor（transgenic glyphosate resistant material H6）was crossed with 13 non-resistant backbone parental materials（recurrent parents）At the same time,150:1 concentration of glyphosate was applied to screen the resistant plants of each generation.The results showed that the molecular markers and spraying results are consistent,and the resistance of the progenies of 4 lines crossed with AH6 was strong and stable.2.Germplasm creation of tribenuron-resistant rapeseedThe F₁ generation was obtained by crossing DS3,an anti-tribenuron-methyl material provided,with 11 backbone parents.The F₁ generation was screened by continuous backcross and self-cross and spraying tribenuron-methyl.Finally,the DS3 resistance gene was obtained to the backbone parents.In this study,13 lines of F₂ and BC₁ populations were sprayed with different concentrations of 10%tribenuron-methyl granules,it was found that 0.3 g/L tribenuron-methyl could be used as a suitable screening concentration for resistant germplasm.Further,13 lines of F₂ populations and 10 lines of resistant lines（F₃ populations）were phenotypically identified with 0.3 g/L tribenuron-methyl.The photosynthetic rate,SPAD value,soluble sugar content and Peroxidase activity were significantly differences in different families ten days after spraying,which could be used as screening indexes.Based on this,three sensitive families（20-3997,20-3999,20-4003）,five middle resistant families,four resistant families and one highly resistant family（20-3998）were selected.3.Identification of chemical emasculation concentration and parental selection in rapeseed.At first,ninety-six rapeseed cultivars were treated with 0.05 mg/L tribenuron-methyl when the buds were 1～2 mm.the effects of chemical emasculation and pesticide damage were observed and investigated in the initial,full,the final flowering period.The 6×6 diallel cross combinations were made for artificial pollination,and then fifty-three of them were tested at the mature stage,fifteen materials suitable for paternity and thirteen materials suitable for paternity were screened out.Then the cross combinations of 6×6 were selected were selected from twelve parents with different sensitivities（male parent:2902,2908,2924,2927,2931,2936,female parent:2903,2904,2915,2924,2927,3018）.After spraying tribenuron at the concentration of 0.06 mg/L,the morphological and agronomic characters of the flower tube were investigated.The results showed that 2904 and 2905 were damaged obviously,and the effect of chemical emasculation was not ideal,2903 had the best effect on male sterility,but the sterile period was short and had light powder in the later period.2927 had the best effect on male sterility,and the sterile period was longer.Different parents should be sprayed with different concentrations in batches,early-budding parents can be sprayed early,and sensitive materials can be reduced concentration and dose.4.Hybrid combination advantage and parental combining ability appraisalWe investigated agronomic characters of the parent and the obtained 29 hybrid combinations F₁ in the first year,and analyzed their combining ability and heterosis.The results suggested that female parent 2902,2907,2924,male parent 2901,2927.2902×2901（MPH 89.49%,BPH 63.22%）,2904×2908（MPH 56.57%,BPH 109.41%）,2907×2908（MPH 106.998%,BPH 69.84%）,2924×2901（MPH 83.23%,BPH 66.84%）,2924×2908（50.60%,BPH 13.68%）were selected as the heterosis with good combining ability in per plant yield.