Screening and identification of potential Striga [Striga hermonthica (Del.)] suppressing rhizobacteria associated with Sorghum [Sorghum bicolor (L.) Moench] in Northern Ethiopia

Abstract

Sorghum (Sorghum bicolor (L.) Moench) is one of the globally important cereal crops well adapted to Sub-Saharan Africa (SSA) agro-ecology. However, the productivity of sorghum is hindered by both abiotic and biotic factors including drought, Striga, insect pests, poor soil fertility, and diseases. Among the constraints, Striga (genus), also called witch weed, is the most important production problem in the area. Although there have been various control methods practiced for years, none of these have been practically effective in eradicating Striga, neither are they easily accessible for small holder farmers, while some are also not environmentally friendly. Therefore, this study was designed with the objective of identifying potential Striga suppressing rhizobacteria associated with sorghum. Treatment of S. hermonthica seeds with isolates E19G12, E29G2b and E19G10 resulted in the lowest S. hermonthica seed germination of 0%, 1%, and 2.7% respectively, which were significantly lower than any of the treatments. Mean germination percentage ranged from 9 to 59.7 and 0 to 27 in the absence and presence of host plants, respectively. The results showed a statistically significant germination inhibition (p < 0.001). Finally, the most effective isolates were shortlisted, E19G6a, E19G9, E19G6b, E19G10, E19B, E19G12, E29G2a, and E29G7 were morphologically and biochemically identified to belong to the genera of Pseudomonas, Klebssiella, Bacillus and Entrobacter. The results of the study demonstrated the existence of promising soil-borne bacteria that could be exploited as bioherbicides to control Striga infestation on sorghum provided that broader samples from various parts of the country are explored.

Keywords

• bioherbicides
• germination inhibition
• rhizosphere
• striga infestation
• susceptible host