Assessment of selected orange-fleshed sweetpotato cultivars for sweetpotato weevil (Cylas puncticollis Boheman) (Coleoptera: Brentidae) infestation at Umudike, south east Nigeria
EHISIANYA, C. N., LALE, N.E.S. and UMEOZOR, O. C.
ABSTRACT. Selected orange-fleshed sweetpotato (OFSP) cultivars namely: NRSP/05/022, CIP199004.2, CIP440293,
Centennial and a cream-fleshed check TIS2532.op.1.13 were evaluated for yield and Cylas puncticollis (Boheman) (Coleoptera: Brentidae) infestation at the research limns in the National Root Crops Research Institute (NRCRI), Umudike (05°29°N, 07°33°E and 122 m above sea level), Abia State, Nigeria during the 2010 and 2011 cropping seasons. Field experiments were laid out in a randomized complete block design with each sweetpotato cultivar replicated three times. The results showed that OFSP cultivars had higher beta-carotene ranging from 7.76 Jlg/I00g (CP440293) to 3.03 J.Lg/lOOg (CIP199004.2), than the cream- fleshed check (0.03 Jlg/I00g). The number of plant stand and fresh roots at harvest of the OFSP cultivars showed no significant differences when compared with the check in both years, whereas the mean weights of their biomass
showed that cv.TIS2532.op.l.13 (12.05 t/ha) was significantly (P =0.05) higher than the others, except Centennial (10.84 t/ha) and NRSP 105/022 (8.41 t/ha). The total number of C. puncticollis progeny and percentage root damage on NRSP/05/022 (1.33 and 0.56) were significantly lower than on the check (15.67 and 23.35) cultivar. The coefficient of association between total root yield (number and weight) and weight of biomass was positive, whereas, the relationship between the weight of biomass and weevil severity
score and percentage infestation were negative. There was a positive coefficient of relationship between soil crack and C. puncticollis incidence (infestation and damage). This implies that higher weevil infestation was observed in roots from plants in soils with higher number of cracks.
Keywords: Orange-fleshed, Sweetpotato, Weevils