Development of screening methods and identification of stable resistance to anthracnose in sorghum uri icon

abstract

  • Effective greenhouse- and field-screening techniques were developed to identify resistance to anthracnose (Colletotrichum graminicola) in grain sorghum (Sorghum bicolor). In greenhouse screening, sorghum plants were spray-inoculated at the 6?8 leaf stage with a conidial suspension (4 × 105 conidial ml?1) of C. graminicola. Inoculated plants were incubated in a high humidity chamber (? 90% RH) for 24 h at 25?28°C and relocated to a greenhouse at 25 ± 2°C. Anthracnose development was scored 7?8 days after inoculation. In the field-screening technique, in every fifth row, a highly anthracnose-susceptible sorghum line was sown as an infector row. Ten days later, test lines were sown between infector row plants were inoculated at the 6?8 leaf stage with either spore suspension or by dropping infected sorghum grains into the leaf whorl. High humidity was provided by frequent overhead sprinkler or furrow irrigation. Test lines were scored for anthracnose development at the hard-dough stage. Significant positive correlation (r = 0.88, P < 0.001) was found for anthracnose severity between seedling screening in greenhouse and adult plant screening in the field. The field-screening technique was successfully transferred to several locations in Africa and India. Thirty lines were selected from more than 13 000 sorghum germplasm accessions and advanced breeding lines screened for anthracnose resistance, using the field-screening technique at Pantnagar (North India) between 1982 and 1991. They were evaluated in multilocational tests at hot spots in Burkina Faso, India, Nigeria, Zambia, and Zimbabwe for 1?10 years. Eleven lines (A 2267-2, IS 3547, IS 8283, IS 9146, IS 9249, IS 18758, SPV 386, PB 8892-2, PS 18601-3, PM 20873-1, and M 35610) showed stable resistance across these locations over the years. Some of the resistant lines are being converted into male-sterile lines through backcrossing with different sources of cytoplasmic male sterility

publication date

  • 1994
  • 1994