Diversity and variability of Puccinia striiformis f.sp. tritici in Rajasthan - Devendra

Ten districts of Rajasthan i.e.,Udaipur, Rajsamand, Pratapgarh, Chittorgarh, Bhilwara, Kota, Bundi, Ajmer, Jaipur and Alwar were surveyed during Rabi season 2023-24 for incidence and severity of yellow rust of wheat caused by Puccinia striiformis f. sp. tritici. The maximum incidence (86.11%) and severity (37.27%) of yellow rust of wheat was in Rajsamand district while minimum incidence (31.67%) and severity (12.09%) was in Alwar district. The overall data revealed that the disease incidence and severity of yellow rust of wheat in different wheat growing areas of Rajasthan varied from 26.67 - 88.33 per cent and 10.36 - 38.88 per cent, respectively, with an average of 61.61 per cent incidence and 27.04 per cent severity. Ten isolates of Puccinia striiformis f. sp. tritici were collected from surveyed districts. All isolates exhibited variability in respect to morphological and pathogenic characters. In morphological variation, maximum diameter (27.5 μm) of urediospore was measured in isolate RJPst-10 with bright orange to yellow color. The shape of urediospore varied from round to ovule. The length and width of teliospore varied from 45.2 - 54.7 μm and 16.1 - 24.2 μm, respectively in different isolates. Maximum length (54.7 μm) and width(24.2μm) of teliospore was measured in isolate RJPst-02 while minimum length (45.2μm) and width (16.1 μm) was in RJPst-10 isolate. The isolate RJPst-02 collected from Rajsamand district was highly virulent with 40.12 per cent disease severity.. KEYWORDS :Puccinia striiformis f. sp. tritici, variability, wheat, yellow rust