Correlation analysis between agronomic traits and yield of rapeseed (Brassica napus L.) for high-density planting.

Objective The difference in the relation of agronomic traits and yield between rapeseeds suitable for mechanized high-density planting and conventional-density planting was studied. Method Twenty-two hybids (or lines) for high-density planting were studied in national winter rapeseed regional test from 2008 to 2009. The correlation and path analysis of nine major agronomic traits to yield per plot were conducted by contrast of seventy-two rapeseeds which are suitable for conventional-density planting.ResultFor the former, seeds per silique,the number of effective siliques on main inflorescence,the number of effective siliques per plant and density of siliques with yield per plot showed a significant or extremely significant correlation.The order of direct effect of traits on yield per plot was density of siliques (0.881)branch height (-0.614)plant height (0.586)seeds per silique (0.360)the number of branches (-0.144)the number of effective siliques on main inflorescence (-0.143)the number of effective siliques per plant (0.111)effective length of main inflorescence (0.095)1000-seed weight (-0.055). However, the number of branches,the number of effective siliques on main inflorescence,the number of effective siliques per plant,seeds per silique and branch height showed a significant or extremely significant correlation with yield per plot for rapeseeds suitable for conventional-density planting.The order of direct effect was the number of effective siliques per plant (0.412)plant height (0.297) the number of effective siliques on main inflorescence (0.260)seeds per silique (0.249)effective length of main inflorescence (-0.224)1000-seed weight (0.156)branch height (-0.104)the number of branches (0.095)the density of siliques (-0.003).Conclusion Compared with rapeseeds suitable for conventional-density planting,the breeding aims of rapeseed selected specically for high-density planting should lay more emphasis on density of siliques and the number of effective siliques on main inflorescence. Furthermore, efforts in increase of the number of effective siliques per plant as well as seeds per silique and decrease of the number of null branches should be made.