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Table 3.9. Kruskal-Wallis analysis, and significant tests of six qualitative traits in sorghum.
Trait X2
Awns 0.110
Glume color 0.947
Glume coverage 0.471
Head shape and compactness 0.496
Midrib color < 0.001
Grain color 0.968
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matter, head length, and width, leaf area index, and duration (Kadam et al., 2001). In many studies grain yield per panicle was also reported to have a positive significant correlation with plant height, panicle length, panicle weight, and number of seeds per panicle (Prasuna et al., 2012). Grain yield was also reported elsewhere that it was found to be positively correlated with plant height, panicle length and number of seeds per head (Chavan et al., 2011; Mahajan et al., 2011).
El-Din et al. (2012) reported a positive and highly significant correlation between number of grain/head and grain yield and positive significant correlation between panicle length and grain yield. Moreover, non-significant negative correlation was observed between panicle width and grain yield/panicle. Jankovic et al. (2012) also reported presence of very strong to almost complete, statistically very significant positive correlations among the morphological productive indicators per species. Plant height, leaf length, leaf width, stem diameter, and other quality traits were significantly and positively correlated with fodder yield per plant (Prakash et al., 2010). In sorghum, grain yield was significantly and positively correlated with panicle weight and fodder yield per plant. It further had a positive correlation among days to flowering, plant height, leaf number and panicle width (Mallinath et al., 2004). Ramesh et al.
(2012) reported positive and highly significant association between yield and other quality components at two sites.
There was enormous variation among the quantitative and qualitative traits measured in the study. The variation in qualitative traits was also observed and reported in Ethiopian and South African sorghum accessions by Gerrano et al. (2014). Updhyaya et al. (2010) reported variation on the qualitative and quantitative traits and identified specific traits as new sources in sorghum germplasm. The traits included early flowering, short plant height, medium panicle exsertion and medium sized seeds. Shegro et al. (2013) further reported highly significant differences among the quantitative traits in sorghum accessions under study and the qualitative diversity index values ranged from 31% for panicle shape and compactness to 84% of the glume color. Lekgari and Dweikat (2014) reported genetic diversity based on the plant height, days to anthesis and moisture content in sweet sorghum. Knowledge of patterns of diversity of genetic material is of great importance and is key component in crop improvement and breeding (Warburton et al., 2008).
Analysis of genetic diversity (clustering and genetic distance)
Studies on analysis of genetic diversity using qualitative and quantitative phenotypic traits in sorghum were reported (Ayana and Bekele, 2002; Abdi et al., 2002; Agrama and Tuinstra, 2003; Geleta and Labuschagne, 2005; Torkpo et al., 2006; Bucheyeki et al., 2009;
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Ganesamurthy et al., 2010; Ngugi and Maswili, 2010; Abdel-Fatah et al., 2013). Shegro et al.
(2013) further reported genetic diversity among the sorghum lines from Ethiopia using morphological descriptors. In addition, Suliman and Abdelbagi (2010) further reported the presence of genetic diversity among the sorghum accessions for Sudan.
Characterization of the accessions gives an overview of the traits and helps to understand similarities and differences among the accessions under investigation (IBPGR and ICRISAT, 1993). Based on the dendrogram, some accessions among the clusters and the sub-clusters were distantly related. The closely related accessions are those that are grouped within the same subgroup and share the same ancestral history. The DAFF collections were found in almost all of the clusters and were mixed in terms of the provincial collection. The grouping of accessions was not based on the source of collection, hence were mixed. This shows the presence of genetic diversity among the accession within and among the South African provinces. It may also be due to gene flow from the neighboring areas/provinces and sharing of seeds by farmers amongst themselves (Manzelli et al., 2005). Moreover, farmers share seeds and name the same accessions differently in various areas or regions (Chakauya et al., 2006). Farmer’s practices may also influence the handling and conservation of the genetic material on their fields.
The results in this study concur with the study of Uptmoor et al. (2003) where the authors reported genetic diversity among the sorghum accessions, and the clustering of accessions was not based on the place of origin or source. The presence of vast diversity among the genotypes in this study was clearly shown by the distant relationships among the genotypes.
The diverse genotypes could be useful for selections in plant breeding programmes and for further genetic improvement (Upadhyaya et al., 2010). They can also serve as potential parents for hybridization and for development of hybrids in line x tester analysis (Ngugi and Maswili, 2010; Ngugi and Onyango, 2012; Shehzad and Okuno, 2014). The presence of genetic diversity in the genetic pool allows breeders to make selections of the distantly related genotypes based on the phenotypic traits of interest, more especially the traits that may be appealing to researchers, farmers and end-users. Furthermore, for evaluation of inheritance of some of the specific traits of interest, and enhancing genetic gain (Abdel- Fatah et al., 2013). Morphological traits are excellent indicators of presence of genetic variability among the genotypes under investigation, local differentiation and conservation, and can be employed to categorize morphological diversity (Grenieret et al., 2001).
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