Screening of elite maize lines for resistance against downy mildews

A study was conducted to identify resistant sources against sorghum downy mildew (SDM) incited by Peronosclerospora sorghii and Rajasthan downy mildew (RDM) incited by Peronosclerospora heteropogoni. A set of 200 elite maize lines were evaluated during kharif 2010, against sorghum downy mildew and Rajasthan downy mildew at three hotspots of the disease, viz., Mandya and Coimbatore for sorghum downy mildew and Udaipur for Rajasthan downy mildew. Out of 83 lines re-tested during kharif 2011, three lines were identified as resistant against Rajasthan downy mildew at Udaipur, whereas; at Coimbatore 16 lines were screened to be resistant and 15 lines as moderately resistant, to sorghum downy mildew. Two lines (‘CM 117-3-4-1-2-2-1’ and ‘PFSR-R10’) showed moderate resistance to both SDM and RDM at Coimbatore and Udaipur, whereas; ‘JCY3-7-1-2-1-B-2-1-2-1’ showed moderate resistance to sorghum downy mildew and Rajasthan downy mildew consistently at all the three hotspots during kharif 2010 and 2011.These identified elite lines could be potentially utilized as resistance sourcesin breeding programme. The present investigation can serve as basis for marker assisted screening for resistance breeding.