Inoculation methods and resistance of 30 peanut genotypes to Sclerotium stem rot disease
2004
Yusnita | Sudarsono((Institut Pertanian Bogor (Indonesia). Fakultas Pertanian))
Stem rot disease due to infection of Sclerotium rolfsii fungus in peanut is difficult to control by chemical or plant rotation because it has a wide range of hosts and produces Sclerotia that are persistent in soil. The use of resistance or tolerance peanut cultivars is the most effective way to control this disease. Since breeding for disease resistance of peanut requires an established method of screening for resistant plants, in this study were evaluated the best inoculation methods to show responses of 30 peanut genotypes to infection of S. rolfsii. Tested inoculation methods were (i) control, without inoculation (INO-0); (ii) sticking a mycelial plug at peanut stem base without wounding (INO-1); (iii) sticking a mycelial plug at peanut stem base with wounding (INO-2); (iv) sowing mycelial plugs around peanut root neck (INO-3); and (v) sowing mycelial plugs and 10 sclerotia around peanut root neck (INO-4). Results of the experiment showed INO-2 was the most effective method of inoculation since it resulted in the highest disease severity as indicated by the highest disease incidence and scores. Although slightly less effective INO-2, INO-3 and INO-4 were also resulted in high disease severity. To screen responses of 30 peanut genotypes, inoculation of S. rolfsii was done by sowing mycelial plugs in the close perimeter of the wounded peanut root neck. None of tested genotypes showed resistance to stem rot disease. Disease severity of the tested genotypes ranged from 13 to 76 percent, and they were grouped into slightly susceptible (4 genotypes), susceptible (15 genotypes), and highly susceptible (11 genotypes). On the other hand, two genotypes (Kelinci and Lokal Madura) were classified as tolerance to the disease according to their disease sensitivity index based on the number of filled-pods per plant. For these genotypes, infection of S. rolfsii only slightly reduced the number of filled pods per peanut plant.
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