Exploring the Sources of Red Rot Resistance Available in National Breeding Gene Pool and their Potential Utilization for Sugarcane Improvement in India

The breeding gene pool maintained in ICAR-SBI, Coimbatore serves as the prime source for generating genetic variability for sugarcane varietal development in India. About 417 parents from five different zones of sugarcane cultivation in India, exotic hybrids and interspecific hybrids, were initially tested for their resistance against the tropical (mixed inoculums of the tropical pathotypes CF06 [ Cf 671] and CF12 [ Cf 94012]) of Colletotrichum falcatum , followed by the subtropical pathotype CF08 ( Cf 64) in order to identify stable red rot resistant parents. Among them, mixed inoculums of CF 06 and CF 12 were found more virulent than CF 8. The highest number (48 of 155) of resistant (R) or moderately resistant (MR) parents to the mixed virulent inoculums was from North West Zone (30.97%) followed by North Central and North East Zone (18 of 37), Peninsular Zone (16 of 134) and East Coast Zone (2 of 34). Only one exotic parent (CP 61–23) among the 18 was found to be MR to all the tested pathotypes of C. falcatum . Overall, the subtropical parents had higher proportion of R types due to high accumulation of stress tolerant genes, while the tropical parents had more susceptible types. In case of interspecific hybrids, nine out of 39 were moderately resistant to the subtropical pathotypes. Among the 417 parents screened, 83 parents were stable in their resistance against tropical and subtropical pathotypes. Since selection for red rot resistance may lead to low sucrose content, the potential parents having high sucrose combining red rot resistance were identified from different sources and efforts were made to collect other characters of breeding importance of these stable resistance parents. Red rot resistant parents identified in this study have a greater potential in breeding for red resistance in the sugarcane improvement in the country.