Variability, Divergence, Heterosis, Combining Ability and Yield Component Studies in Sweet Potatoes (Ipomoea Batatas (L) Lam.) from Sabah and Sarawak, Malaysia
Studies were conducted to examine the breeding potential of the
Malaysian indigenous sweet potato germplasm. A total of 99 sweet potato
accessions was collected from five different regions in the states of Sabah
and Sarawak, Malaysia. A total of 220 polycross progenies was obtained
from sixteen randomly chosen accessions planted in a polycross block. The
99 accessions and their 220 progenies were evaluated in the field and 1 6
characters were measured. With the exception of plant type and vine
thickness, other characters showed more than 20% CV values. The CV
values for yield, tuber number and mean tuber woight were 76%, 57% and
48%, respectively. The means and CV's were similar for all characters
between the regions indicating the presence of similar sweet potato type in
all the regions. Cluster analysis showed the presence of three main groups
of sweet potatoes in the states. Group 1 comprised cultivars with low yield.
Cultivars in Group 2 were high yielding with spreading plant type. The third
group comprised only six cultivars with orange flesh colour, big leaves,
semi-compact plant type and slightly lower yield. The mean, range and CV
values for all characters studied were much larger for the polycross
progenies as compared to the parents. Cluster analysis showed the
presence of seven groups among the progenies indicating the formation of
new genotypes as a result of outcrossing. Gene interactions in the new
genotypes probably have led to the presence of larger means and ranges
of many characters