Efficacy of Ipomoea setosa as an alternative detection technique for propagation of virus-free sweetpotato

Abstract

Virus diseases pose major limitations to sweetpotato production in sub-Saharan Africa and use of virus-clean planting material is a management option commonly embraced among growers. However, virus detection and in vitro processes of producing clean material are expensive, thus making such materials unaffordable to most smallholder farmers. The objective of this study was to examine the efficacy of Ipomoea setosa as a cheaper virus-detection method and macro-propagation of virus-tested sweetpotato vines. The efficiency of virus detection using Ipomoea setosa was compared to polymerase chain reaction (PCR)/reverse transcriptase (RT)-PCR. The rate of virustested plantlet multiplication was also compared for screen house macro-propagation vis-à-vis laboratory micro-propagation; and the yield of planting material from these different sources compared in screen house and field trials. The rate of degeneration in the field of sweetpotato derived from macro-propagation versus micro-propagation material, was determined for four generations. Sweetpotato viruses were significantly (P<0.05) better detected using I. setosa than PCR/RT-PCR; and detection results varied with viruses and cultivars. The rate of plantlet multiplication was significantly (P<0.05) higher for macro-propagation than micro-propagation. Tissue culture-derived and screen house-derived materials did not differ in yield for both screen house and field experiments. Sweetpotato yield was highest in the first generation and declined significantly (P<0.05) from generation two through four. Virus-clean macro-propagated material has potential to give good yields, but farmers should use such materials for one season, after which they should get new clean materials from screen house multipliers.