Studies on Microbial Succession Inhabiting the Phyllospheres of Local and Foreign Varieties of Sorghum bicolor

Aims: Sorghum bicolor has been identified as a prolific food producer, drought resistant and adapts well to other harsh environment. Its importance as a crop plant is being highlighted. This study investigates the isolation and succession of microorganisms inhabiting the phyllospheres (leaves, seeds, and stems) of four local varieties obtained from a market in Ado-Ekiti, Nigeria and two foreign varieties of sorghum obtained from Aberystwyth University, United Kingdom in order to scrutinize the disease-causing microorganisms that could inhabit the species of the plant and also to identify the varieties of sorghum that will adapt well to South West Nigerian soil.

Study Design: A piece of farmland with good soil was acquired from the management of Federal Polytechnic, Ado-Ekiti, Nigeria for plantation of sorghum.

Methodology: The six varieties of sorghum were planted and monitored for a succession of microorganisms on the leaves, stems, and seeds for 16 weeks.

Results: The fungal isolates include Aspergillus flavus, Aspergillus glaucus, Aspergillus niger, Fusarium spp., Mucor spp., Penicillium chrysogenium, Penicillium notatum, Penicillium oxalicum, Rhizopus spp., Syncephalastrum spp. and Butrysporium spp. The bacterial isolates were Staphylococcus aureus, Mycobacterium smegmatis, Pseudomonas syringae, Escherichia coli and Bacillus subtilis.

Discussion: The entire microorganisms were isolated from the local varieties except for Butrysporium spp. which was isolated from the foreign varieties. Some microorganisms were isolated early in the study but disappeared towards the end of the study. In the two foreign varieties of sorghum, the persistent bacterial isolates were Mycobacterium segmatis and Pseudomonas syringes while the fungal isolates were Rhizopus stolonifer, Mucor and Aspergillus flavus. In the four local varieties, the persistent bacterial isolates were Staphlococcus aureus and Bacillus subtilis while the persistent fungal isolates were Mucor, Aspergillus niger, Aspergillus flavus and Rhizopus stolonifer.

Conclusion: Irrespective of the microorganisms on the phyllospheres of both foreign and local varieties of sorghum, the plants thrived; therefore, sorghum can be planted to sustain food security in South West Nigeria.