Morphological and agronomical characterization of sweet potato [Ipomoea batatas (L.) Lam.] germplasm collection from Tanzania

Abstract

One hundred and thirty six sweet potato (Ipomoea batatas) landraces collected from three different agro-ecological Zones of Tanzania [Lake Victoria basin (LZ), Eastern (EZ) and Southern Highlands Zones (SHZ)] were characterized morphologically and agronomically using International Potato Centre (CIP) descriptors in two seasons. The cluster analysis revealed existence of two major groups, 1 and 2 with low genetic variability of 0.52. Number of roots, weight of roots, fresh weight/plant and dry matter content differed significantly among and within agro-ecological Zones. Landraces Lubisi from southern highlands Zone had the highest number of roots (12 per plant) and Shinamugi from Eastern Zone had highest dry matter content of 39.4%. Overall, landraces from Lake Zone recorded highest average root weight of 8,977.7 kg ha-1 followed by Southern highlands (7,561.2 kg ha-1) and Eastern zone (4,333.0 kg ha-1). Principal coordinate analysis (PCA) indicated variances accumulated by the first five components of the six major morphological characters was 52.5% and produced similar groups corresponding to those of cluster analysis. Our data indicate low genetic variation despite significant variations shown by agronomical traits. Many landraces recorded in different names from three different agro ecological Zones showed close resemblance and grouped into two major groups suggesting presence of duplicates or mislabelling. Keywords: Morphological traits, agronomical traits, diversity, germplasm characterization, Ipomoea batatas, sweet potato