Screening for plant resistance to sorghum head bug, Calocoris angustatus Leth uri icon

abstract

  • Sorghum head bug, Calocoris angustatus is an important pest of sorghum in the semi-arid tropics. A technique to screen for resistance to C. angustatus under field conditions was tested in Andhra Pradesh. Planting infester rows of the susceptible sorghum cultivars (CSH 1 or CSH 5) 20 days before the test material or planting early (40-50 days) flowering lines (IS 802, IS 13429 and IS 24439) along with the test material, split planting of test material at 15-day intervals, grouping test material according to maturity and using sprinkler irrigation to maintain high humidity were effective measures which increased the efficiency of screening and selecting for resistance to C. angustatus. A headcage technique to screen for resistance under no-choice conditions was also developed. Panicles infested with 10 pairs of C. angustatus at pre- and half-anthesis resulted in maximum population build-up and grain damage under headcage conditions. This technique was useful for confirming the resistance observed under field conditions. Under natural infestation conditions, 5 genotypes harboured relatively lower numbers of C. angustatus than susceptible genotypes, but only IS 17610, IS 17618 and IS 17645 maintained their level of resistance under the headcage conditions. Seed germination was >70% in these genotypes compared to <10% in CSH 1 and CSH 5

publication date

  • 1992