Bivariate analysis of the genetic variability among some accessions of African Yam Bean (Sphenostylis stenocarpa (Hochst ex A. Rich)Harms)

Abstract

Variability is an important factor to consider in crop improvement programmes. This study was conducted in two years to assess genetic variability and determine relationship between seed yield, its components and tuber production characters among twelve accessions of African yam bean. Data collected were subjected to combined analysis of variance (ANOVA), Principal Component Analysis (PCA), hierarchical and K-means clustering analyses. Results obtained revealed that genotype by year (G × Y) interaction had significant effects on some of variables measured (days to first flowering, days to 50 % flowering, number of pod per plant, pod length, seed yield and tuber yield per plant) in this study.The first five principal components (PC) with Eigen values greater than 1.0 accounted for about 66.70 % of the total variation, where PC1 and PC 2 accounted for 39.48 % of variation and were associated with seed and tuber yield variables. Three heterotic groups were clearly delineated among genotypes with accessions AY03 and AY10 identified for high seed yield and tuber yield respectively. Nonsignificant relationship that existed between tuber and seed yield per plant of these accessions was recommended for further test in various agro-ecologies for their suitability, adaptability and possible exploitation of heterosis to further improve the accessions. Variabilnost je zelo pomemben dejavnik v žlahtnenjenju poljščin. Dvoletna raziskava je bila opravljena s ciljem ovrednotenja genetske variabilnosti in analize odnosov med komponentami pridelka semena ter tvorbe in značilnosti gomoljev med 12 akcesijami afriškega gomoljastega fižola. Zbrani podatki so bili obdelani z analizo variance (ANOVA), analizo glavnih komponent (PCA), hierarhično in klastersko analizo. Izsledki so pokazali, da so imele interakcije med genotipi in leti (G × Y) statistično značilen vpliv na nekatere analizirane spremenljivke kot so dnevi do prvega cvetenja, dnevi do 50 % cvetenja, število strokov na rastlino, dolžina stroka ter pridelek semen in gomoljev na rastlino. Prvih pet glavnih component (PC) z lastnimi vrednostmi več kot 1.0 je prispevalo 66.70 % celokupne variabilnosti, PC1 in PC 2 pa sta pridali še 39.48 % variabilnosti v povezavi s pridelkom semena in gomoljev. Med genotipi so se jasno oblikovale tri heterotične skupine in akcesija AY03 je bila prepoznana po velikem pridelku semen, AY10 pa po velikem pridelku gomoljev. Neznačilno povezavo med pridelkom semen in gomoljev pri teh akcesijah bi bilo priporočljivo dodatno testirati glede prilagodljivosti na različne agroekološke razmere, možnosti njihovega izboljšanja in potencialne uporabe heterotičnega učinka.

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“…However, each coefficient of proper vectors indicates the degree of contribution of every original variable with which each principal component is associated. The higher the correlation coefficient (positive or negative), the more effective in discriminating varieties [38,39]. In the current study, the results of PCA showed that PC1-8 was responsible for 75.13% of the total variation, and PC1-4 explained 50.39% of the total variation, accounting for most of the variability observed among the rice genotypes from different locations.…”

“…The dendrogram of 43 genotypes, their two parents, and three checks resulted in five clustered groups and one of the parents as an outgroup (TOG 5681) to the clusters at a similarity index of 0.49. The first cluster comprised of two intraspecific genotypes (1,3), the second cluster encompasses a majority of the genotypes distributed into four subclusters which include cluster IIA comprising of three intraspecific genotypes (2,4,7), cluster IIB comprised of six genotypes that are both intraspecific and interspecific (5,6,15,16,17,19), likewise cluster IIC comprised of twenty genotypes (8,9,10,11,18,24,28,36,40,35,37,38,39,27,23,45,30,33,34,12) while are all interspecific genotypes except genotype 45 which represents one of the parents, IR64,while the last subcluster, IID, comprised of three genotypes (20,29,42) that are interspecific in nature. The third cluster is composed of four interspecific genotypes (13,14,25,26).…”

Character association for yield parameters in Yam bean [Pachyrhizus erosus (L.) Urban]

“…However, tuber yield showed negative and non-significant association with seed yield indicating that both seed yield and tuber yield are not complementing each other. Similarly Akinyosoye et al, (2017) also reported that non-significant relationship existed between tuber and seed yield per plant. Tuber yield recorded negative association with pods per plant, pods per peduncle, number of seeds per pod and seed yield indicating that varieties should be developed in desired direction by considering these traits.…”

Characterization of African Yam Bean (Sphenostylis stenocarpa) Mutant Lines using Phenotypic Markers

“…Except for Africa, no other continent has a record of the crop's origin (Adewale et al, 2008). Although not all African yam bean (AYB) produce tubers, it is considered a dual crop because it has both tubers and seeds (Akinyosoye et al, 2017).…”

“…One of the major constraints affecting the utilization and adoption of AYB is late maturity, low seed yield, and extra agronomic practices like staking (Popoola et al, 2019). The majority of known accessions of AYB are late maturing, with physiological maturity occurring between 6 and 7 months following sowing, depending on genotypes (Akinyosoye et al, 2017). Mutation breeding is a fast, costeffective, reliable, and proven strategy for creating and selecting novel agronomic characters (FAO/IAEA, 2017), which aids in the identification and release of novel genes that govern the traits of interest (FAO/IAEA, 2017).…”