油菜根肿病症状、病原形态及产量损失研究

Study on symptom, yield loss of clubroot and modality of Plasmodiophora brassicae in rape

油菜苗期和成株期均可感染根肿病,被害根膨大形成大小不等、形状各异的肿瘤,一般主根肿瘤大而少,侧根肿瘤小而多。根肿菌存在于油菜根部肿大的细胞内,散生或密集呈鱼卵块状。扫描电镜下油菜根肿菌的休眠孢子近球形,有乳突,孢壁不平滑,直径1.9~4.3μm。透射电镜下游动孢子呈肾形、椭圆形或近球形,大小1.6~3.8μm,同侧着生不等长尾鞭式双鞭毛。以上症状和病原形态与十字花科甘蓝根肿病菌相似,但休眠孢子的大小存在差异。游动孢子鞭毛脱落后形成圆形休止孢,休止孢可发育形成管腔（侵入结构）。油菜根肿病苗期发病率达17%。成株期田间平均发病率为15%,造成油菜减产10.2%。健株的平均株高、角果数、每角粒数、千粒重和单株产量均极显著高于病株。

Rape can be infected by Plasmodiophora brassicae during all its growth periods. The roots mostly were damaged by forming lots of tumours, with different shape and different size. Usually the tumours were bigger and fewer in taproot than in side root. P. brassicae were in the tumid cells of roots in rape. The section of clubroot gall was examined by electron microscope scanning. The resting spores were spherical with mammilla on the wall, and their diameters ranged from 1.9μm to 4.3μm. Using electron microscope transmission, the primary zoospores with unequal length biflagellate were nephroid, oval or spherical, and their size varied widely from 1.6μm to 3.8μm. The symptoms and modality were similar between rape and cabbage with clubroot, except the size of resting spores. The silent spores could grow into tube antrums. The occurrence of the disease was 17% when rapes were young, and 15% after they grew up. And it caused rape 10.2% yield loss. The average height, the number of rape＇s fruits and kernels of each fruit, the weight of thousand kernels, the yield of each plant were significantly different between the healthy plants and the diseased ones, the results of healthy plants were better than the diseased ones.