Abstract
Yam is a promising income source for small producers in the Reconcavo Baiano region. However, few genetic studies have been conducted with this culture. In this sense, the aim of this study was to assess genetic variability among 89 genotypes of yam (Dioscorea rotundata Poir.) collected in four municipalities in Bahia State, Brazil. These were assessed based on eight quantitative descriptors. Data were subjected to descriptive statistics, Spearman's rank correlation, Singh criterion, cluster analysis, principal component analysis and dispersion graph. The tuber weight showed the highest coefficient of variation and correlated positively and significantly with width and length of tuber. The tuber length characteristics contributed most to the genetic divergence. The criterion pseudo-t2 divided 89 genotypes into seven groups, being that groups 4, 5 and 7 showed the highest averages for the production characteristics. The first three principal components explained 69.49% variation and dispersion graph showed partly concordant with UPGMA method. This study revealed the existence of genetic variability of yam, which may be explored in future genetic improvement programs. Key words: Dioscorea rotundata Poir., multivariate methods, plant genetic resources, plant breeding.
Highlights
Yam (Dioscorea rotundata Poir.) is one of 600 species of Dioscoreaceae family, native from Africa and distributed through tropical and subtropical world regions (Lebot, 2009)
The first three principal components explained 69.49% variation and dispersion graph showed partly concordant with unweighted pair group method with arithmetic mean (UPGMA) method
This study revealed the existence of genetic variability of yam, which may be explored in future genetic improvement programs
Summary
Yam (Dioscorea rotundata Poir.) is one of 600 species of Dioscoreaceae family, native from Africa and distributed through tropical and subtropical world regions (Lebot, 2009) It is a diploid plant (2n=2x=40) (Scarcelli et al, 2005), monocotyledon, dioecious and propagated vegetative, which produces tubers rich in carbohydrates (Lebot, 2009), which confer great economic importance. Despite its importance to family farming, yam has suffered biotic and abiotic stresses caused by fungal diseases, lack of propagative material of excellent quality, that threaten the genetic variability of these genetic resources and consequent culture abandonment In this sense, it is necessary to conduct studies aiming at characterizing genetic variability existing in species of Dioscorea species genus, to identify superior genotypes to develop improved varieties that combine resistance to diseases and pests, and high productivity with attributes appreciated by consumers (Obidiegwu et al, 2009), such that contribute in maintaining sustainability of this culture agribusiness
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