Distribution of Rapeseed Clubroot Disease in Hubei Province and Evaluation of Yield Loss

[Objective] The aim of this study was to reveal the distribution of rapeseed clubfoot disease in Hubei Province and to assess the yield loss caused by the pathogen, Plasmodiophora brassicae. [Method] Field surveys were conducted in Shayang, Dangyang, Zhijiang, Yidu and Changyang of Hubei Province during 2009- 2011. Clubfoot disease of rapeseed samples from the surveyed locations were con- firmed by PCR detection and plants infection experiment. The factors of yield and plot yields influenced by clubroot disease were determined in plot experiment. [Re- salt] Rapeseed clubroots were confirmed in Zhijiang and Dangyang and not found in Shayang and Yidu. Clubroot was found in cruciferous vegetables but not in rapeseed d in Changyang. Infection of P. brassicae significantly decreased of the first effective branch numbers of rapeseed, effective pod number per plant, seed number per pod and 1 000-grain weight. Yield of infected rapeseed decreased by 56.4% over non-infected control. [Conclusion] Rapeseed clubroot disease mainly distributed in Zhijiang and Dangyang of Hubei Province. The disease had an economic impact on rapeseed production.

早稻田杂草出草规律初探

早稻田杂草萌发总量为 380株 /m 2 ,萌发量随水稻生长发育进程而下降 ,其下降动态的回归方程式为 :Y =87 6 981- 1 15 85X± 11 3142 (rXY =0 842 2 ,P <0 0 5 ) ;各类杂草萌发动态态不同 ,稗草为幂函数曲线Y =42 42 5 5 30X-2 2 2 2 3 ± 0 1412 ,节节草为S形曲线Y =37 81+e5 2 52 2 -0 150 2X± 0 8819。