Stability of Resistance in Sorghum to Calocoris angustatus (Hemiptera: Miridae) uri icon

abstract

  • Eight sorghum genotypes were evaluated for resistance to Calocoris angustatus at 3 infestation levels (5, 10 and 15 pairs of adult bugs per panicle) over 6 seasons (1984-87) under no-choice conditions in the head cage. 'IS 17610' and 'IS 17645' had a significantly lower bug population increase compared with the susceptible controls 'CSH 5' and 'CSH 9'. These genotypes also suffered less grain damage and percentage loss in grain mass and showed higher seed germination than the susceptible controls. 'IS 2761' and 'IS 9692' generally had lower bug numbers, but suffered higher grain damage, showed poor seed germination, or both. Bug population increases did not differ significantly across infestation levels. However, grain damage and loss in grain mass were lower in panicles infested with 5 pairs per panicle. Among the commercial hybrids, 'CSH 9' was more susceptible as compared with 'CSH 1' and 'CSH 5'. 'IS 17610' was the most resistant and stable genotype over seasons and different infestation levels. 'IS 17618' and 'IS 17645' were relatively unstable and their regression coefficients were significant across infestation levels in some seasons. The results suggested that environmental conditions play an important role in determining the interaction between the insects and the host plants

publication date

  • 1991
  • 1991