Assessment of Sweet Potato Propagules for Re- infection by Various Viruses in East Kamagak Location – Homa Bay County-Kenya

Abstract

Sweet potato, Ipomea batatas (L) Lam is an important subsistence food crop as well as cash crop in East Kamagak location and is also very popular in the major cities in the country including Nairobi. Sweet potato is easily managed with fewer field management practices compared to other root crops and it can similarly be stored for a prolonged length of time in the soil before harvesting. However sweet potato production is constrained by virus infection. At least 13 viruses are reported to infect sweet potato naturally of which most of them are insect transmitted. The study aimed at screening and selecting virus free germplasm. A survey was conducted in East Kamagak using questionnaire which aided in germplasm collection. Twelve genotypes were used for the study. The collected germplasm was virus indexed using visual scoring with severity of infection ranging from 1-9, serological and molecular detection. During the survey SPFMV and SPCSV were found to be common. Virus-free accessions were planted using Randomized Complete Block Design in three replicates. Harvesting was done 180 days post planting. The germplasm was again subjected to molecular detection of virus to ascertain whether the materials remained virus free and to detect new infections. All the germplasm tested positive for sweet potato feathery mottle virus (SPFMV) but negative for SPMMV, CMV, SPCSV and SPCFV an indication that SPFMV is a common virus in sweet potato and does not significantly affect sweet potato yield. Analysis of variance showed that Nyakowino, Nyawo, Zapallo and SPK004 total yield were significantly different at p< 0.05 with a range between 68.00-12.33.Sweet potato should be screened for viruses in commercial production.