Abstract
Root thickness was evaluated in the diploid species, Ipomoea trifida. Variation in root thickness was observed among the accessions and some of them produced thick roots >15 mm in diameter. One clone from an Indonesian I. trifida population had storage root like root formation, however, dry matter content was much lower than that of sweetpotato. Most of the progenies of the cross between sweetpotato and diploid accessions of I. trifida produced storage roots. The highest storage root obtained was 1, 800 g/plant. High storage root weight was also found in back crossed progeny of the hybrids to sweetpotato but dry matter content was low. Therefore, diploids with thick roots are considered to have a high potential for storage root formation. In order to develop cultivars with high storage root yield and high dry matter content, improvement of dry matter content of diploids and/or use of high dry matter content sweetpotato may be required. Diploid I. trifida with thick roots or storage root-Iike roots will be useful not only for development of new cultivars with high storage root yield but also for studying phylogeny of sweetpotato.
