Parental lines and advanced breeding material of castor resistant to wilt disease

Abstract

Castor plant (Ricinus communis) belonging to Euphorbeaciae family is one of the ancient oilseed crops of the world. Castor is cultivated around the world because of its commercial importance where India is the largest producer of castor oil which has much demand. Wilt disease of castor caused by Fusarium oxysporum f.sp. ricini is one of the major disease influencing serious yield losses. Host plant resistance is one of the best options for managing the wilt disease. Several parental lines were developed through a resistance breeding programme involving wilt resistant donors both from wild and cultivated genotypes. Standard screening procedures developed at IIOR in a wilt sick plot led to identification of wilt resistance parents and hybrids during last three years (2012-13 to 2014-15).The wilt sick plot is maintained with a Fusarium load of 2 x 10 3 cfu / gm of soil and further confirmed by 100% mortality of JI-35 a highly susceptible parental line after every 5 test entries in the sick plot within 30 days after sowing. The total germination and wilt incidence was recorded at monthly interval up to 150 days after sowing. Among advanced breeding material screened, 17 preliminary hybrids viz.,PHT-2013-11, PHT-2013-15, PHT-2013-23, PHT-2013-27, PHT-2013-32, PHT-2013-46, PHT-11-13-56, PHT-11-13-60, PHT-11-13-62, PHT-11-13-72, PHT-11-13-73, PHT-11-13-77, PHT-11-13-78,PHT-11-13-79,PHT-11-13-80, PHT-11-13-81,PHT 13-2 were highly resistant without wilt incidence. 51 advanced breeding material have shown resistant reaction with < 20% disease incidence. Among 167 castor parental lines screened against wilt, six lines ie Kh 12-317-2, Kh 12-1498-1, DCS-81, DCS-89, DCS-108 and DCS 120 were highly resistant to wilt without wilt disease.73 parental lines were resistant to wilt with <20% disease incidence. Parental lines DCS-86, DCS, 105, DCS 107, DCS 118, DPC 23 and M-571 consistently showed wilt resistance for two consecutive years. These parental lines can be used in breeding programme for development of resistant castor cultivars.