Abstract:
Drought is one of the most important environmental challenges farmers face around the globe
including in Ethiopia and it is the main cause of yield reduction. Improvement of the crop for
drought tolerance related traits requires studying the genetics of the traits. Therefore, the
present study was initiated to evaluate the performance of sorghum genotypes and to identify
chromosomal regions associated with drought tolerance and other agronomic traits using
genome wide association studies (GWAS). The field experiment was conducted at Sheraro,
Northern Ethiopia, in 2018/19 growing season. The experimental materials consisted of 945
genotypes and the experiment was laid out in an alpha lattice design replicated twice. The
experimental materials were genotyped with a total of 25,634 SNPs markers (minor allele
frequency > 0.01) to perform GWAS. Analysis of variance revealed that there was highly
significant difference (p<0.01) among the genotypes for all the traits. Genotypic coefficient of
variation (GCV) ranged from 2.75 % (days to maturity) to 29 % (leaf angle), whereas
phenotypic coefficient of variation (PCV) ranged from 3.81 % (days to maturity) to 31.53 %
(leaf angle). Heritability ranged from 47.78 % (number of tillers) to 92.55 % (number of
leaves) and genetic advance as percentage of mean (GAM) ranged from 4.09 % (days to
maturity) to 57.38 % (leaf angle). Traits like panicle length, leaf angle and chlorophyll
content at maturity had high GCV and PCV. High heritability coupled high GAM was
observed for leaf area, leaf angle, panicle length, chlorophyll content at maturity, plant height
and number of leaves. The studied genotypes were grouped into five subgroups with 73.62%
of individuals had ancestry membership coefficient greater than 60% and the remaining
26.38% of the individuals were admixed. A total of 98 different SNPs having significant
associations with 15 traits were detected. The identified marker-trait associations could be
useful in marker-assisted selection. In General, this study had contributed to the
characterization of genes and alleles controlling drought related traits, and will serve as a
source of markers for molecular breeding
