小麦秆锈菌不同小种间竞争能力的研究

COMPETITIVE ABILITY AMONG RACES OF PUCCINI A GRAMINIS F. SP. TRITICI IN MIXTURES

本试验首次在小麦成株期把我国致病力较弱的优势小种21C3和致病力较强的低频或稀有小种34C2、34C4及116的新鲜夏孢子等量混合后,在长江流域选出的8个感病品种上继代转接。试验结果表明:温室转接5代与田间重复侵染3代后,小种21C3出现频率显著上升,小种34C2频率明显下降,小种34C4和116则下降更快,甚至完全消失。小种21C3与34C2、34C4和116相比或小种34C2与34C4和116相比,其出现频率都表现极显著差异。而小种34C4和116之间则差异不明显。说明小种21C3致病力虽不强,但竞争能力最强,故在自然界能维持优势;34C2竞争能力弱于21C3,但强于34C4和116,而且致病力较强,故在自然界也能维持一定数量。小种34C4和116致病力虽强,但竞争能力极弱,因此在自然界数量极少。

The competitive abilities of race 21C3 being less virulent but most prevalent, and races 34C2, 34C4 and 116 being virulent but very uncommon or rare, were studied on adult plants of eight susceptible winter wheat cultivars selected from of the Yangtse River reaches by growing equal urediospores in mixtures of the four races in greenhouses and field plots. The race 21C3 consistently predominated and race 34C2 considerably went down, while race 34C4 and 116 decreased very fast or even disappeared either after 5 uredial generations in greenhouses or after 3 uredial generations in field plots, indicating that race 21C3 though less virulent was the best competitor which could maintain its prevalence in nature, race 34C2 was not a good competitor but in combination with its virulence could maintain itself in nature in a low quantity, while races 34C4 and 116 had little competitive ability and couldn't maintain themselves in nature.