Bio-Assay Screening of Sorghum [Sorghum bicolor (L.) Moench] Inbred Lines for Resistance to Striga [Striga hermonthica (Del.)] in Ethiopia

The experiment was carried out to validate the reaction of sorghum inbred lines for low germination stimuli using bio-assay in the laboratory. Twenty-two (22) sorghum genotypes with two resistant checks (Gobiye and SRN-39) and one susceptible check (Teshale) were conducted in a completely randomized design (CRD) with three replications at National Agricultural Biotechnology Research Center of Holetta. During the laboratory study, four parameters were measured among which germination rate of Striga around the host root and maximum germination distance from the host root was used as the index of resistance. Maximum germination distance (MGD), germination percentage near the host roots, germination index, and haustorial initiation percentage were recorded and significant differences were observed among the genotypes tested. Germination rate of Striga around the host root and maximum germination distance from the host root was also used as the index of resistance. Sorghum genotypes 2006 MW 6044, ETSC 300080, ETSC 300081, 05 MW 6019, ETSC 300086, 2006 MW 6123, ETSC 300003, ETSC 300082, and 05 MW 6028 induced less Striga seed germination and lower maximum germination distance, which was not significantly different from the resistant checks Gobiye and SRN-39. Out of the 22 genotypes, eight had a maximum germination distance of less than the threshold value of MGD (< 10 mm) that made the genotypes of low germination stimulant of Striga. These genotypes also showed the lowest Striga germination percentage near the host root which indicated the strong and positive correlation of MGD and GP %. Therefore, these sorghum genotypes were low in pre-attachment to Striga and are said to be resistant and/or tolerant to Striga infestation and thus important in increasing production and productivity of sorghum in Striga infested areas.