Abstract
Yam (Dioscorea spp.) is an important food security crop in the tropics and subtropics. However, it is characterized by a narrow genetic base within cultivated and breeding lines for tuber yield, disease resistance, and postharvest traits, which hinders the yam breeding progress. Identification of new sources of desirable genes for these traits from primary and secondary gene pools is essential for this crop improvement. This study aimed at identifying potential sources of genes for yield and quality traits in a panel of 162 accessions of D. praehensilis, a semi-domesticated yam species, for improving the major yam species, D. rotundata. Significant differences were observed for assessed traits (p < 0.05), with D. praehensilis genotypes out-performing the best D. rotundata landraces for tuber yield (23.47 t ha−1), yam mosaic virus (YMV) resistance (AUDPC = 147.45), plant vigour (2.43) and tuber size (2.73). The study revealed significant genotypic (GCV) and phenotypic (PCV) coefficients of variance for tuber yield, YMV severity score, and tuber flesh oxidation. We had also a medium-to-high broad-sense heritability (H2b) for most of the traits except for the dry matter content and tuber flesh oxidation. This study identified some promising D. praehensilis genotypes for traits such as high yield potential (WNDpr76, CDpr28, CDPr7, EDpr14, and WNDpr63), resistance to YMV (WNDpr76, CDpr7, EDpr14, CDpr28, and EDpr13), high dry matter content (WNDpr76, CDpr28, and WNDpr24), low tuber flesh oxidation (WNDpr76, CDpr5, WNDpr31, CDpr40, and WNDpr94) and high number of tubers per plant (WNDpr76, CDpr7, CDpr68, CDpr29, and CDpr58). These genotypes could, therefore, be employed in breeding programmes to improve the white Guinea yam by broadening its genetic base.
Highlights
Yam (Dioscorea spp.) is an essential food security crop in sub-Saharan Africa, especially in West Africa where more than 95% of the global food yam is produced and ~300 million people depend on its cultivation and trade for food and income [1,2,3,4]
No significant variations were observed in dry matter content and tuber flesh oxidation between the two yam species, D. praehensilis recorded higher maximum values for dry matter content (41.96%) and the number of tubers per plot (~6.00) while D. rotundata had better tuber flesh hardness score (39.00) (Table 2)
Identification of new sources of genes for high yield potential, disease and pest resistance, and good post-harvest tuber quality traits is a prerequisite to the development of varieties that are acceptable by the farmers, consumers, and other end-users
Summary
Yam (Dioscorea spp.) is an essential food security crop in sub-Saharan Africa, especially in West Africa where more than 95% of the global food yam is produced and ~300 million people depend on its cultivation and trade for food and income [1,2,3,4]. Nigeria, Ghana, Côte d’Ivoire, and Benin are the leading producers with ~50, 8.3, 7.2 and 3.1 million tons, respectively, in 2019 [4]. In these countries, yam provides carbohydrates, proteins, essential minerals, vitamins, and lipids, and it is greatly involved into the social, economic, and religious lives of the local people [5,6]. Mostly abiotic (e.g., poor soil fertility, drought stress, etc.) and biotic stresses (e.g., insect pests and diseases such as yam mosaic virus (YMV), yam anthracnose disease (YAD), and yam nematodes) are responsible for the low productivity of cultivated yam species in West Africa [7,8,9,10,11]. Developing and deploying improved varieties, combining high yield potential and abiotic and biotic stress resistance, is the most cost-effective and practical way of rising yields in farmer fields in West Africa
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