Yield, Total Carotenoid Content, Dry Matter and Genetic Diversity of Yellow-Flesh Cassava (Manihot esculenta) Varieties

Abstract

Yellow-flesh cassava varieties are crucial for their potential nutritional benefits in addressing vitamin A deficiency and enhancing dietary diversity. To achieve our objective of identifying the root yield in kg/plant, total carotenoid in ug/g and dry matter in percentage profiles of four varieties of yellow-flesh cassava, varieties—Kpornu, Tetteh Bankye, Nyonku, and Genotype D—were evaluated over two years using a Randomised Complete Block Design with five replicates. Kpornu exhibited a yield range of 3.1 to 11.2 kg per plant, peaking at 11.2 kg in December, with an average of 7.15 kg. Tetteh Bankye showed a yield range from 3.2 to 16.1 kg, peaking at 16.1 kg in December, with an average of 9.65 kg. Nyonku's yield ranged from 2.2 to 8.4 kg, peaking at 8.4 kg in December, with an average of 5.3 kg, while Genotype D had the lowest yield range of 2.3 to 4.9 kg, peaking at 4.9 kg in December, with an average of 3.6 kg. Peak carotenoid content for all varieties was observed in December, with Genotype D showing the highest value of 18.7 µg/g, followed by Kpornu (14.3 µg/g), Tetteh Bankye (14.1 µg/g), and Nyonku (11.8 µg/g). The average dry matter content for all varieties peaked in June, with Nyonku recording the highest value of 38.5%, followed by Tetteh Bankye (31.8%), Kpornu (27.5%), and Genotype D (31.1%). To achieve our second objective of determining genetic diversity using cluster analyses, principal components analyses, and correlation of variables from the four yellow flesh cassava varieties. The study found positive correlations between yield and total carotenoids, suggesting opportunities to improve both productivity and nutritional quality, while negative correlations between yield and dry matter content pointed to trade offs in processing suitability. Cluster analysis showed that Nyonku and Kpornu were the most similar, sharing 80% of traits, while Tetteh Bankye showed 50% similarity with them. Genotype D was the most distinct, clustering at 90% dissimilarity, sharing only 10% of traits. Principal Component Analysis (PCA) revealed that PC1 explained 53.09%, PC2 accounted for 31.74%, and PC3 explained 15.17%, together capturing 100% of the total variation in the crop varieties. The PCA biplot analysis highlighted distinct genetic profiles influenced by traits such as leaf lobe number, petiole length, and leaf retention, with Genotype D showing unique contributions from these traits. Key traits like apical leaf colour and leaf lobe number shaped Kpornu and Nyonku, while Tetteh Bankye was dominated by petiole length, emphasising the importance of these traits in plant vigour and adaptability. The varieties exhibited moderate to high genetic diversity, with Genotype D offering unique traits valuable for breeding.