Development of a Field Screening Technique and Identification of Blast Resistance in Finger Millet Core Collection

Effective management of blast disease in finger millet can best be achieved through host-plant resistance. In this study, field screening technique was developed and core collection evaluated to identify sources of resistance to blast. The field screening technique involved: use of systematic susceptible checks after every four test rows, artificial spray inoculation at pre-flowering stage with an aqueous conidial suspension (1×10⁵ spores ml⁻¹) of Magnaporthe grisea fm strain multiplied on oatmeal agar medium at 27±1ºC for 10 days, and maintaining high humidity and leaf wetness through sprinkler irrigation twice a day for 4 weeks following inoculation. Neck blast was recorded on a 1–5 scale and finger blast as severity percentage on all the tillers of selected 10 plants in a row at physiological maturity. The finger millet core collection consisting of 622 accessions was evaluated for neck and finger blast resistance. Among the core collection, 402 accessions were found resistant to neck blast, 436 to finger blast and 372 had combined resistance to both the diseases. Blast resistant accessions belonged to one wild and four cultivated races of finger millet that originated from 19 countries indicating the wide geographical diversity among resistant accessions. Most of the accessions from Asian origin were susceptible to neck and finger blasts while, those from African origin were resistant. A significant strong positive correlation (r = 0.85, P<0.0001) was found between neck blast and finger blast ratings. Core collection accessions with stable resistance to blast would be useful for finger millet breeding programs.