Background:
Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is one of the major production constraint especially in irrigated and rainfed lowland ecosystem in India. BB is primarily a monsoon season disease and yield loss due to the disease may be as high as 50% or more. Analyses of survey data of last 40 years has revealed that in last one decade, BB has appeared in epidemic proportion in several parts of South India causing significant yield loss in fine grain rice varieties like Samba Mahsuri. Even though, the rice variety, Improved Samba Mahsuri (possessing three bacterial blight resistance genes, Xa21, xa13 and xa5) has shown good level of resistance against bacterial blight, at some locations it has shown only moderate resistance indicating evolution of new virulence forms of the pathogen. Therefore, DRR Dhan 53 was developed by adding a new gene, Xa38 in the genetic background of Improved Samba Mahsuri to provide a higher level and broad spectrum resistance against bacterial blight of rice.:
Technology Details:
DRR Dhan 53 (RP-6113-Patho-BB9; IET 27294) is a durable bacterial blight (BB) resistant, high-yielding, fine-grain type rice variety, suitable for irrigated ecosystem and developed through marker assisted backcross breeding in the genetic background of Improved Samba Mahsuri by adding an additional BB resistance gene, Xa38. The variety possesses four major bacterial blight resistance genes, Xa21+xa13+xa5+Xa38 with seed to seed maturity of 130-135 days and average yield of 5.5- 6 t/ ha. The variety has semi-dwarf stature and non-lodging habit, with long deflexed panicles which are completely exerted (100% exertion). The variety exhibited very high level of BB resistance and significantly higher yield (>7%) over the recurrent parent across different locations in AICRIP trials. DRR Dhan 53 possesses medium-slender grain type with very good HRR (78.7%), intermediate amylose content (22.2), optimum GC (22) and intermediate ASV (5.0) and is comparable to the recurrent parent in all the grain and cooking quality parameters. Under conditions of BB incidence, the variety shows a significant yield advantage of 15-30% compared to bacterial blight susceptible variety like Samba Mahsuri. The variety has shown very high level of resistance to bacterial blight and significantly higher yield in farmers’ fields in BB endemic areas of Andhra Pradesh and Telangana. The unique feature of the variety is that it possesses four major bacterial blight resistance genes (Xa21+xa13+xa5+Xa38) resulting in very high level and broad spectrum BB resistance andhigher yield (more than 7% yield than Improved Samba Mahsuri).