Journal of Agricultural Science; Vol. 4, No. 11; 2012 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 281 Morpho-Agronomic Characterization and Evaluation of In-Country Sweet Potato Accessions in Southeastern Nigeria I. I. M. Nwankwo 1 , E. E. Bassey 2 , S. O. Afuape 1 , J. Njoku 1 , D. S. Korieocha 1 , G. Nwaigwe 1 & T. N. C. Echendu 1 National Root Crops Research Institute, Umudike, Nigeria 2 Department of Crop Science, Faculty of Agriculture, University of Uyo, Nigeria Correspondence: E. E. Bassey, Department of Crop Science, Faculty of Agriculture, University of Uyo, Nigeria. E-mail: emmanuelbas_129@yahoo.com Received: June 29, 2012 Accepted: July 23, 2012 Online Published: October 17, 2012 doi:10.5539/jas.v4n11p281 URL: http://dx.doi.org/10.5539/jas.v4n11p281 Abstract The experiment was conducted in 2010 and 2011 to evaluate and characterize fifteen in-country sweet potato accessions for root characteristics and root yield, plant habits, ground cover, severity of root damage by Cylas puncticollis and Meloidogyne incognita and identify duplications. Significant differences (P<0.05) were observed for number of roots per plot, salable roots per plot, unsalable roots per plot and root yield. The highest number of roots per plot, salable roots and root tuber yield were given by E 10 , followed by B 21 while the lowest came from E 17 . The result indicated B 26 as highly susceptible to C. puncticollis, E 3 , E 11 , E 6 , E 27 and TIS 87/0087 were resistant, while B 6 , E 5 , B 2 , E 17 , B 21 , E 14 , E 7 , B 23 and E 10 were highly resistant to the pest. Seven accessions (E 5 , B 6 , B 2 , E 14 , E 7 , B 23 and E 10 ) were highly resistant, five accessions (E 3 , B 26 , E 11 , E 2 and TIS 87/0087) showed moderate resistance while B 2 , E 6 and E 17 were highly susceptible to root knot disease. Ground cover of less than 50% was identified with B 21 (erect type), the semi-erect types (E 5 , E 6 , and B 23 ) had ground cover of 50-75%, while the spreading types (B 6 , B 2 , E 11 , E 17 , E 14 and E 7 ) had 76-90% ground cover. The extremely spreading types (E 3 , B 26 and E 27 ) had more than 90% ground cover. Six accessions (E 5 , E 3 , E 6 , E 14 , B 23 and E 10 ) had white skin, seven (B 6 , B 26 , B 2 , E 27 , E 17 , E 7 and TIS 87/0087) were pale pink while two (E 11 and B 12 ) were pink. The root flesh of one accession (B 6 ) was white, three yellow, while the remaining eleven accessions were creamy, and E 27 and TIS 87/0087 were duplicates. Keywords: characterization, evaluation, sweet potato accessions, root characteristics, Cylas puncticollis, Meloidogyne incognita 1. Introduction Sweet potato (Ipomoea batatas (L) Lam) is an important food crop in the tropical and sub-tropical countries and belongs to the family convolvulaceae (Gill, 1988). It is cultivated in more than 100 countries (Woolfe, 1992). The area under sweet potato cultivation in Nigeria is estimated at about 200,000-300,000 hectares annually (Enwezor et al., 1989). Nigeria is the third largest producer in the world with China leading, followed by Uganda (FAO, 2004). Sweet potato ranks seventh among the world food crops, third in value of production and fifth in caloric contribution to human diet (Bouwkamp, 1985). Small holder farmers have developed more interest for sweet potato production in Nigeria. This is so because sweet potato has a short gestation period of about four months and tolerates wide ecology. Once fully established, it suppresses weeds and reduces the overhead cost of production compared to cassava and yam (Chukwu, 2001; Antiaobong & Bassey, 2008). It has high photosynthetic efficiency (Kapinga et al., 1997), and high yield per unit area and also serves as a bridge between periods of food shortages (Bouwkamp, 1985). The non-edible parts (vines) are used for planting material and so do not compete for human food, in addition to the fact that they are easy to transport to the field (Antiaobong & Bassey, 2008). Sweet potato blends with rice, cowpea and plantain in Nigerian diets. It is also becoming popular as a substitute to yam and garri (Chukwu, 2001). It can be reconstituted into fofoo or blended with other carbohydrate flour sources, such as wheat (Triticum aestivum) and cassava (Manihot esculenta) for baking bread, biscuits and other confectioneries (Woolfe, 1992). The leaves are rich in protein and the orange flesh varieties contain high