小麦秆锈菌新致病小种21C3CTR致病谱分析

用从国内１６个小麦主产省收集的１１２个小麦主栽品种及抗源，分析测定秆锈菌新致病小种２１Ｃ３ＣＴＲ的致病谱，并与国内另７个致病小种２１Ｃ３ＣＫＨ，２１Ｃ３ＣＫＲ，３４ＭＫＧ，３４ＭＫＨ，３４Ｃ２ＭＫＲ，３４Ｃ２ＭＦＧ和３４Ｃ２ＭＦＲ的致病谱进行比较。２１Ｃ３ＣＴＲ的致病谱为４３．８％，另７个致病小种的致病谱则分别为４４．６％，４８．３％，５２．７％，５２．７％，５６．３％，４５．５％，６６．８％。２１Ｃ３ＣＴＲ的致病谱除比２１Ｃ３ＣＫＨ高外，比另６个致病小种都低，与３４Ｃ２ＭＦＲ的差异已达极显著水平。说明２１Ｃ３ＣＴＲ（Ｓｒｌｌ毒力）的出现引起抗病性丧失尚不十分严重。其原因是尽管２１Ｃ３ＣＴＲ对Ｓｒｌｌ有毒力，但对国内生产品种及抗源出现频率最高的抗秆锈病基因Ｓｒ５不具有毒力，制约了其致病谱。通过测定还明确了来自不同省份的小麦品种抗秆锈病水平存在极显著差异，具体阐明了各省小麦品种的抗性水平。建议今后秆锈病测报重点应放在品种抗性差的地区。

Pathogenic Spectrum Analysis of 21C3CTR of Puccinia graminis f. sp. tritici in China

Pathogenic spectrum of newly found pathotype 21C3CTR, the first to defeat the resistance of Srll in China, of Puccinia graminis f. sp. tritici was with 112 widely grown commercial and resistance source wheat cultivars collected from 16 major wheat producing provinces. Meanwhile,the spectrum of 21C3CTR was compared with those of other 7 pathotypes, i. e., 21C3CKH,21C3CKR, 34MKG, 34MKH, 34C2MKR, 34C2MFG, and 34C2MFR. It was showed that the pathegenic spectrum of 21C3CTR to the 112 cultivars tested was 43.8%, being significantly narrower than that of 34C2MFR(66. 8%) and by no means wider than those of the other 6 pathotypes:21C3KH (44.6% ), 21C3CKR(48. 3% ), 34MKC(52. 7%), 34MKH(52. 7 % ), 34C2MKR(56. 3 %) and 34C2MFG (45. 5%). These findings implied that there was little severe outbreak threat by 21C3Ctr recently. It was also found that the difference of frequencies of resistant cultivars among regions or provinces tO the pathogen used was statistically striking. So it was suggested that the epidemic forecast for wheat stem rust be emphasized in the regions where cultivars are poor resistant