Characterization And Evaluation Of Stem Lodging Resistance In Rapeseed(Brassica Campestris L.)

Two groups of rapeseed varieties of contrasty stem lodging resistance were selected to study stem lodging resistance.Stem lodging resistant ratios,anatomical characteristics:diameter,pith diameter,the thickness outside the vascular bundle(TOV),the vascular bundle length(VBL),the thickness outside the pith(TOP),TOP/radius,VBL/radius,VBL/TOP,the degree of vascular lignification, chemistry compositions:stem dry matters,lipoid-wax,water soluble compounds, pectin,hemicellulose,lignin,cellulose contents,physical properties:stem height, stem girth, maximum breaking strength,flexural stress,the breaking strength per unit of 10 cm stem section(Bp) were compared between two groups and the correlations between lodging resistant ratios and various stem characteristics were analyzed. Significant different cell morphology,cell wall thickness,the degree of vascular lignification,TOV,VBL/TOP,lipoid-wax,hemicellulose,cellulose contents, flexural stress,Bp indicated apparently different developments of secondary cell walls of stem cells between two groups.Correlation analysis results showed that lodging resistant ratios was positively correlated with VBL/TOP,cellulose content, flexural stress,Bp but negatively correlated with TOV,lipoid-wax,hemicellulose contents.In a stepwise regression analysis,a six-variable model consisting of cellulose content, VBL/TOP,water soluble compounds content,pectin content,VBL/Radius and lignin content had a coefficient of determination(R2) of 0.997 suggesting that 99.7% of the variability in stem lodging resistant was due to variability in these characters acting together.These results suggested that the secondary cell walls play a key role in stem lodging resistance,stem characteristics changes with the deposition of the secondary cell should be focused on when we breeding for lodging resistance in rapeseed.