Evaluation of Sweet Potato (Ipomoea batatas) for Early Blast Disease (Alternaria solani)

Aims: Early blight disease (Alternaria solani) is one of the main biotic factors limiting sweet potato production in the tropics. A multi-locational research was carried out to screen and identified sweet potato accessions that are resistant to the disease.

Methodology: 21 sweet potato accessions were collected from different agro-ecological zones of Nigeria and screen against Alternaria solani by artificial inoculation of the pathogen in three diverse agro-ecological conditions. The accessions were named against their place of condition. The research were laid out in a Randomized Complete Block Design (RCBD) with three replications. Data were collected on days to 50% flowering, fresh root weight per plant, number of root per plant, number of main branches per plant, and above ground fresh biomass yield per plant at 15 weeks after planting (WAP). Disease scoring was done using rating scale 0f 0-9 and analyzed with IRRI STAR software.

Results: The result revealed that there are variations in the 21 accessions studied. Offa performed best across the three environments followed by Umudike while Ado-Ekiti had the least performance in term of root yield. The screening shows that none of the 21 accessions is highly resistant. Four of the accessions were resistant, six accessions were moderately resistant, four accessions were susceptible, and three accessions were moderately susceptible while 4 accessions were highly susceptible to the pathogen.

Conclusion: The findings concluded that the resistant accessions that gave high number roots could be used as a gene pool for Alternaria solani resistance breeding for cultivar improvement. The use of the identified resistant accessions with high root yield by farmers is encouraged pending the time commercial Alternaria solani resistant cultivars will be readily available and accessible.