Reaction of Rice (Oryza sativa) Cultivars to Penetration and Infection by Curvularia tuberculata and C. oryzae

Plant Disease
Lilian Z de LunaTimothy C Paulitz

Abstract

Isolates of Curvularia species were collected from weedy Cyperaceae species and are being evaluated as possible biocontrol agents of sedge weeds in rice (Oryza sativa). Curvularia species have been reported from rice; thus cultivars of rice were tested to determine rice seedling responses to these potential biocontrol agents. All 13 rice cultivars were resistant to Curvularia tuberculata isolate 93-022, 12 were resistant to C. tuberculata isolate 93-020, and 7 were resistant to C. oryzae isolate 93-061. In the resistant cultivars, lesions on the leaf laminae were small, light to dark brown, with a dry appearance. Spots on the leaf margins and leaf tips were light brown to cream and dry. In the susceptible cultivars, the brown lesions coalesced with necrotic centers. Sporulation was observed in the lesions on susceptible cultivars but not on the resistant cultivars. The histopathology of C. tuberculata and C. oryzae was studied in two resistant rice cultivars, IR 64 (IRRI Acc. no. 66970) and Norin 21 (IRRI Acc. no. 7686), by light microscopy. C. tuberculata exhibited polar germination beginning at 4 h postinoculation (HPI); whereas C. oryzae was characterized by bipolar germination starting at 2 HPI. Simple terminal or intercala...Continue Reading

References

Mar 1, 1982·American Journal of Public Health·A A JohnsonD A Roe

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