Description

Abstract: The genetic nature of resistance to early (Cercospora arachidicola Hori) and late [Cercosporidiumpersonatum (Berk. &Curt.) Deigh-tonl eafspot oi peanut (Arachis hypogaea L.) is quantitative, making selection for resistance difficult in segregating populations. In many areas of peanut production, without fungicide application one or both diseases may significantly reduce yields. A study was conducted to obtain heritability estimates, responses to selection, and relationship of resistance of two peanut populations for early and late leafspot resistance. Selection based on F2 family means in the F, generation via defoliation, infection, and sporulation Aas performed for early and late leafspot in North Carolina and Georgia, respectively, within populations of P] 314817/[TG3/EC 76446 (292)l and (FIl 314817/ ICGS 4). Divergent selections for each disease were evaluated in the F, generation at the same locations the following year for resistance by visual rating of infection and defoliation. Broad-sense heritability estimates ranged from to” to high (0.12-0.88) for components of resistance to each leaf-spot disease. Narron-sense her-itability estimates from parent-otfspring regression (0.18-0.74) and realized heritability (0.60-1.41) were significant for late leafspot re- sistance and early leafspot resistance in the 1 314817/ITG3/EC 76446 (292)1 population. Results indicated that selection based on family means would be successful. Seiection of individual plants within families did not significantly improve genetic progress. NIod- erate to high correlations (0.41-0.86) existed between early and late leafspot disease components indicating possible genetic linkage or host-plant physiology that conferred resistance to both diseases in one population.