Phenotypic And Genetic Diversity Of Sweet Sorghum (Sorghum Bicolor L.) Varieties And Their Suitability For Ethanol Production In Tanzania

ABSTRACT

Sweet sorghum (Sorghum bicolor L.) has been recognised widely as a potential alternative

source of biofuel because of its high fermentable sugar content in the stalk. With

international focus on alternative fuel sources, investors are looking at sweet sorghum as a

feedstock source for bioethanol production without compromising sorghum’s primary use

for food, fodder, and animal feed. However, for researchers to maximize its feedstock

potential and to be used in future there is a need to understand the genetic diversity and

relationships among sweet sorghum landraces existing in Tanzania. The objective of this

study was to assess the genetic diversity and relationships among sweet sorghum

accessions using SSR markers, to examine brix level variability within accessions and to

establish their genetic relationships for the informed use of these accessions in breeding

programs. Forty three accessions [32 accessions from farmers’ fields, 10 accessions from

ICRISAT] were genotyped with 42 SSR markers that generated 220 alleles with an average

of 5.07 alleles per locus. Polymorphic SSRs revealed a genetic diversity of 0.48 with a

range of 0.07 to 0.87 and a total of 220 alleles. Cluster analysis using dissimilarity matrices

and hierarchical clustering with un-weighted pair group method with arithmetic averages

was employed to analyse the genetic relationships among accessions, thus 43 accessions

were grouped into 3 distinct clusters. A sufficiently large degree of genetic diversity was

observed in the collected germplasm and ICRISAT Materials. (>0.75

dissimilarity between ICSV_93046 and WEG_Bu; between ICSV_93046 and NJG and

between S_Ind_35 and KULY_Mch). However, further evaluation tagging gene for sugar

content is important. The information obtained from this study coupled with phenotypic

characterization can be used by plant breeders to select parents for improving the sugar

content in the adapted sorghum varieties and to develop segregating populations to map

genes controlling sugar content in sweet sorghum.