Abstract:

Sweetpotato (Ipomoea batatas (L.),
2n=6x=90 chromosomes, is the seventh most important food crop in the world. Uganda
is the third largest global producer after China and Nigeria, and a secondary center of
diversity where subsistence farmers mostly grow it as a starchy staple for food
security. Through
sweetpotato accessions with 565 vernacular names were collected from farmers’ fields in
171 sub-counties. Great variations were observed in the numbers of accessions grown in
the different districts and morphological characteristics in the farmers’ fields.
The level of morphological variation as estimated using the Shannon Weaver diversity
index (H1) for the traits ranged from 0.10 to 0.99 with an overall mean of 0.71±0.03, an
indication of high diversity. Cluster analysis using the unweighted pair-group method
using arithmetic averages (UPGMA) grouped 1256 of the accessions into 20 major
clusters and many sub-clusters and classified 899 accessions as morphologically distinct
and 357 as duplicates.
The morphologically distinct genotypes differed significantly for yield, dry matter
content, sweeetpotato virus disease and Alternaria blight resistance (p=0.05). Most of the
genotypes had mean total root yields of less than 20.0 t/ha, low specific gravity values of
less than 2.0, and low disease resistance. A total of 192 superior genotypes were selected
for further evaluation and use in hybridization schemes and variety development.
v
a purposive sampling of 21 districts of Uganda, a total of 1303
a hexapioid, self-incompatible species with
Ten fluorescent-labeled simple sequence repeat (SSR) markers were used to assess the
genetic relationships among the superior genotypes. The mean pair-wise genetic distance
among the 192 genotypes was 0.57, an indication of high genetic diversity. The 192
genotypes were grouped into four major clusters. The SSR markers used in the study
highly informative were with average polymorphic information content (PIC) of 0.62.
Two duplicate genotypes were identified through SSR genotyping. The genetic potential
of sweetpotato germplasm in Uganda has been understood through this study.