Screening techniques and resistance sources for foliar blast in pearl millet

Once considered a minor disease of pearl millet,incidence of blast disease caused by Pyricularia grisea,has increased at an alarming rate in the recent past,particularly on commercial hybrids in several states ofIndia. The disease can be best managed through hostplant resistance. In this study, attempts were made todevelop the field and greenhouse screening techniquesand screen some elite hybrid parental lines to identifyresistance to this disease. The field screening techniqueinvolved the use of a highly susceptible line as an infectorrow grown after every four test rows, artificial sprayinoculation of 30-day-old plants using P. grisea sporesuspension (1 × 105 spores ml-1) and maintaining highhumidity (>90% RH) through perfo-irrigation for 2weeks following inoculation. The greenhouse screeningtechnique involved spray inoculation of 15-day-oldpotted seedlings with P. grisea spore suspension andmaintaining moderate temperature (25±1°C) and highhumidity through a misting system for 10 days afterinoculation. In all, 211 elite hybrid parental lines,including 126 designated B-lines, 20 designated R-linesand 65 potential R-lines were evaluated for blastresistance in the disease nursery. Forty-five linesidentified as blast resistant (score ≤3.0 on 1–9 scale)were further screened through greenhouse screeningtechnique. Twenty-five (8 designated B-lines, 3designated R-lines and 14 potential R-lines) of the 45lines were found resistant to blast under greenhouse. Allof these 25 foliar blast resistant lines were also resistantto downy mildew under field conditions. These resistantlines would be useful in breeding blast resistant pearlmillet hybrids.