Genotypic variability and genetic parameters for root yield, dry matter and related traits of cassava in the Guinea Savannah ecological zone of Ghana

The aim of this study was to assess the agronomic performance and genetic parameters governing storage root yield and related traits in cassava genotypes in order to identify superior genotypes. The study involved 18 elite cassava genotypes which were arranged in a randomized complete block design with three replications and assessed for storage root yield and yield components (12 months after planting) in the Guinea savannah ecology of Ghana for three seasons. Analysis of variance indicated significant (p < 0.05) genotype and year main effects for fresh and dry root yields, dry matter content, starch yield and harvest index. Genotype × year effect was significant (p < 0.05) for fresh root yield, dry root yield and starch yield. Estimates of the variance components revealed greater genotypic influence for starch yield, fresh and dry root yields implying the potential for genetic gain with selection for these traits among the genotypes. Relatively high (69 %) broad sense heritability estimate was observed for dry storage root yield indicating the depth of genetic influence. Path coefficient analysis revealed a direct positive effect of dry matter content on dry storage root yield whilst dry storage root yield had direct positive effect on starch yield suggesting the possibility of indirect selection for starch yield through dry storage root yield. The study revealed ample genotypic variability among the cassava genotypes to warrant selection. Four genotypes, IBA 070134, IBA 419, IBA 950289 and IBA 980581 were identified for high and stable fresh and dry root yields for multilocational testing

Biochemical analysis and molecular cloning of methionine-rich proteins of sorghum (Sorghum bicolor) seed

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Phenotypic Diversity within Ugandan Yam (Dioscorea species) Germplasm Collection

A proper understanding of the diversity of the available germplasm is an initial step for the genetic improvement of a crop through breeding. However, there is limited information on the diversity of Uganda’s yam germplasm. The study sought to characterize the diversity of yam germplasm utilized for decades in Uganda together with germplasm recently introduced from West Africa using phenotypic traits. A germplasm collection of 291 genotypes was characterized using 28 phenotypic traits. Data were subjected to multivariate analysis using principal component analysis and cluster analysis. The traits assessed were informative and discriminating, with 62% of the total variation explained among the first six principal components. Results showed that the important phenotypic traits contributing to most of the variability among the genotypes were leaves, flowering, and tuber traits. Ugandan genotypes were identified with amorphous tuber shapes compared to West African genotypes. The study has shown that there is ample phenotypic variability within the major yam genotypes in Uganda yam germplasm that can be used for genetic improvement. More in-depth molecular and biochemical studies to further understand the diversity are recommended. The preprint was made available by research square in the following link: “https://www.researchsquare.com/article/rs-1518551/v1.

Genotype-by-Environment Interaction of Yam (<i>Dioscorea species</i>) for Yam Mosaic Virus Resistance, Dry Matter Content and Yield in Uganda

Often, yam cultivars grown in different agro-ecologies show differential responses across production environments, a term known as genotype-by-environment interaction. Such genotype-by-environment interaction makes selection of the best genotypes under varied production environments more complex. This study evaluated twenty yam genotypes in six test environments to assess genotype, environment, and their interaction effects on tuber yield, response to yam mosaic virus, and dry matter content. The experiments were conducted over two seasons across three locations in Uganda, using a randomized complete block design with three replications. There were significant effects (p ≤ 0.001) for genotype (G), environment (E), and genotype-by-environment interaction for all key traits assessed. Serere (2021) and Namulonge (2021) were identified as the most discriminating and representative environments for testing responses to yam mosaic virus, respectively. Serere (2021) was recognized as the most discriminating environment, whereas Arua (2021) emerged closest to an ideal environment for assessing yam tuber yield. The tested genotypes also exhibited resistance to yam mosaic virus disease, had high tuber yields and dry matter content. Genotypes UGY16020, UGY16034, UGY16042, and UGY16080 demonstrated highest resistance to yam mosaic virus disease, along with high yield and dry matter content, and are thus potential parents for yam genetic improvement. Further evaluation of the four genotypes should be carried out within farmers’ production systems for selection, improvement and release as new yam varieties for Uganda