Screening of some sweet potato (Ipomoea batatas (L.) Lam) genotypes for yield and damage by Cylas puncticollis under rainfed conditions in Umudike, Southeastern Nigeria

Abstract

A field experiment was conducted at the National Root Crops Research Institute, Umudike, Southeastern Nigeria during the 2015 and 2016 cropping seasons to evaluate diversity among F1 population of sweet potato, namely: Sauti × 442162 (6), Ligri × Faara (17), Sauti × Bohye (17), including two checks (Umuspo 3 and TIS 87/0087). This experiment was laid out in a randomized complete block design with three replicates under rainfed condition. Data on fresh storage root yield were recorded at 120 days after planting. Analysis of variance, correlation and principal component analysis were utilized for data analysis. The study revealed that yield of fresh storage root showed significant differences (P< 0.05) among the sweet potato genotypes. Sauti X Bohye produced the highest storage root yield (19.33 t/ha) in 2015 and performed better than the national check TIS 87/0087 that recorded a storage root yield of 10.84 t/ha. The result from the study showed that out of the forty genotypes evaluated, twenty-six (26) genotypes recorded attack of C. puncticollis. The extent of the damge recorded among the genotypes attacked by C. puncticollis ranged from severe damage to little damage among the genotypes that recorded fresh storage root damage. SautiXBohye/11, SautiXBohye/13, SautiXBohye/17 recorded severe damage caused by C. puncticollis while LigriXFaara/15 recorded moderate damaged caused by C. puncticollis. Fifteen (15) genotypes did not record any infestation by Cylas puncticollis. All characters except unmarketable storage root weight at harvest exhibited positive and significant (P< 0.01) correlation with total roots weight (yield). Principal component analysis had three main principal components explaining 84.25% of the total variation with number of marketable roots, weight of marketable roots, storage root yield and Cylas incidence contributing the most to the first PCA. These genotypes could possess resistance genes to Cylas puncticollis and these genotypes could be incorporated in breeding programs for further trail.