Survey on Nigerian Castor Germplasm for Potential Resistant Genotypes to Cercospora Leaf Spot

Fungal diseases cause a lot of economic damage in castor and in some instances; it is a limiting factor to commercial cultivation of the crop. In the present study, survey on castor germplasm for sources of resistant genes to Cercospora leaf spot was carried out at National Cereals Research Institute Badeggi, Nigeria. The genotypes were grown in a resolvable incomplete block design with three replications. The results obtained revealed high variability of host resistance among the genotypes. Percentage disease incidence ranged between 16.67% and 100%. A range between 1.43 score and 4.17 scores with average score of 2.89 were recorded for disease severity among the genotypes. Highest (95.92%) and lowest (13.03%) damage index were observed in the genotypes Acc. 059 and Acc. 022 respectively. The Principal component (PC) 1 to 4 explained 100% of the variability in the germplasm. PC1 explained 69.72% of the variability with the major contributory parameters being the disease incidence, severity and damage index. Significant negative correlations were recorded between the seed yield and all the three disease indices. The result of cluster analysis revealed six cluster groups among the germplasm with cluster membership ranging between 4 and 40 members. The cluster I contained members (Acc. 002, Acc. 017, Acc. 022, Acc. 026, Acc. 027, Acc. 048 and Acc. 061) with low average disease incidence, severity and damage index. The results reported here could serve as a basis for further screening of the potential resistant genotypes under controlled condition to develop resistant lines.