Evaluation of world castor (Ricinus communis L.) germplasm for resistance to Fusarium wilt (Fusarium oxysporum f. sp. ricini)

Castor (Ricinus communis L.) is an important industrial oilseed crop grown worldwide. Wilt caused by Fusarium oxysporum f. sp. ricini is a devastating disease of this crop. The objective of this research was to identify stable sources of wilt resistance among the global castor germplasm collections available in India for use in cultivar improvement. The global collections comprising 1,779 Indian and 190 exotic accessions from 36 countries were screened against wilt in wilt sick plots at two sites in India in preliminary screening. None of the accessions showed high resistance to wilt, 133 accessions comprising 111 Indian and 22 exotic accessions representing 13 countries exhibited resistance. Thirteen of the 133 resistant accessions were tested further for multiple years in wilt sick plots and glasshouse under controlled artificial inoculation at two sites. All the 13 accessions consistently showed wilt resistance in both wilt sick plot and glasshouse at both sites in multiple years. Eleven of these 13 accessions were from India and two were from former USSR. Evaluation for agro-morphological traits identified high seed yielding and early maturing resistant accessions. Diversity analyses precisely revealed diversity among the resistant accessions. These 13 resistant accessions would be great value as donors of resistance.