Effect of Vine Cuttingon Multiplication Ratio and Yield of Three Orange-fleshed Sweetpotato (<i>Ipomoea batatas</i> (L) Lam) Varieties in South Eastern Nigeria

Abstract

A major constraint to sweetpotato production in Nigeria is the lack of clean and sufficient quantities of vine cutting at the time of planting in May or June. Inorder to obtain planting materials, farmers subject sweetpotato to vine harvest at various times but there is dearth of information on the effect of the level or intensity of defoliation on the crop. In this study, the response of three orange-fleshed sweetpotato varieties to cutting regimes in 2014 and 2015 cropping seasons in a tropical ultisol of South eastern Nigeria was evaluated. In each year, the experiment was laid out as 3 x 4 factorial arranged in randomized complete block design with three replications. Treatments comprised all combinations of three orange-fleshed sweetpotato varieties (Umuspo 1, Umuspo 3 and Ex-Igbariam) and four cutting regimes (6, 10 and 14 weeks after planting [WAP], 8 and 12 WAP, 10 and 14 WAP and no-cutting). Cutting regimes did not influence fresh shoot biomass in both year but cutting at 10 and 14 WAP significantly increased multiplication ratio compared to no-cutting or other cutting schedules. Storage root yield was, however, significantly higher with no-cutting than with the 4 weekly cuts, regardless of cutting dates. In all situations, Umuspo 1 produced significantly higher multiplication ratio and higher top and storage root yields than other varieties. Conversely, Umuspo 3 produced higher carotene yield at 10 and 14 WAP cutting compared to other varieties and cutting regimes.