Additive main effects and multiplicative interactions analysis of harvest index performances in cassava (Manihot esculenta, Crantz) genotypes across 4 environments

Eight cassava genotypes were evaluated for harvest index performance across four environments. Data analysis was performed using MATMODEL and GGEbiplot. AMMI analysis of variance showed that 10.02% of the total sum of squares was attributable to environmental effects, 3.99% to genotypic effects and 50.13% to GEI effects. The GEI sum of squares contained approximately 76.52% (0.30709) pattern and 23.48% (0.09442) noise of the total GEI. The mean squares for IPCA 1 and IPCA 2 were significant at P = 0.000 and 0.002 respectively; all together they contributed 94.18% of the total GEI. Therefore, the post-dictive evaluation using an F-test at 0.000 and 0.002 suggested that two principal axes of the interaction were significant for the model with 16 degrees of freedom. The predictive assessment measured by the average root mean square predictive difference (RMS PD), selected AMMI1 with the first interaction PCA axis as the most predictively accurate. The AMMI1 model had the lowest average RMS PD (9.996). Mean performance and stability of the genotypes assessed by biplot analysis showed that the most stable genotypes were G2, G1 and G7. However G5 was highly unstable followed by G8 and G3. Two mega-environments were defined namely: G5-winning niche and G3-winning niche. The current study has demonstrated that the GGE biplot is a useful tool for the analysis of multi-environment trial (MET) data.Keywords: AMMI, GGEbiplot, stability, harvest index, mega-environmen

Genetic diversity of provitamin-A cassava (Manihot esculenta Crantz) in Sierra Leone

Open Access Article; Published online: 04 Mar 2020Understanding the genetic diversity among accessions and germplasm is an important requirement for crop development as it allows for the selection of diverse parental combinations for enhancing genetic gain in varietal selection, advancement and release. The study aimed to characterize 183 provitamin A cassava (Manihot esculenta Crantz) accessions and five Sierra Leonean varieties using morphological traits, total carotenoid content and SNP markers to develop a collection for conservation and further use in the cassava breeding program. Both morphological parameters and 5634 SNP markers were used to assess the diversity among the provitamin-A cassava accessions and varieties. Significant differences were observed among the accessions for most of the traits measured. The first five PCs together accounted for 70.44% of the total phenotypic variation based on yield and yield components among the 183 provitamin-A cassava accessions and five Sierra Leonean varieties. The present study showed that provitamin-A cassava accessions in Sierra Leone have moderate to high diversity based on morphological and molecular assessment studies. The similarity index among the 187 and 185 cassava accessions grouped them into 6 and 9 distinct clusters based on morphological and molecular analyses, respectively. A significant positive, but low correlation (r = 0.104; p\0.034), was observed between the two dendrograms. The results obtained will serve as a guide and basis of germplasm management and improvement for total carotenoid content, yield and African cassava mosaic disease resistance in Sierra Leone

Genetic characterization of cassava (Manihot esculenta) landraces in Brazil assessed with simple sequence repeats

Based on nine microsatellite loci, the aim of this study was to appraise the genetic diversity of 42 cassava (Manihot esculenta) landraces from selected regions in Brazil, and examine how this variety is distributed according to origin in several municipalities in the states of Minas Gerais, São Paulo, Mato Grosso do Sul, Amazonas and Mato Grosso. High diversity values were found among the five above-mentioned regions, with 3.3 alleles per locus on an average, a high percentage of polymorphic loci varying from 88.8% to 100%, an average of 0.265 for observed heterozygosity and 0.570 for gene diversity. Most genetic diversity was concentrated within the regions themselves (HS = 0.52). Cluster analysis and principal component based scatter plotting showed greater similarity among landraces from São Paulo, Mato Grosso do Sul and Amazonas, whereas those from Minas Gerais were clustered into a sub-group within this group. The plants from Mato Grosso, mostly collected in the municipality of General Carneiro, provided the highest differentiation. The migration of human populations is one among the possible reasons for this closer resemblance or greater disparity among plants from the various regions

Field screening of cassava (Manihot esculenta Crantz) germplasm for desirable traits by the use of augmented design

Ninety-eight cassava accessions were grown in augmented randomized complete block design to screen for superior clones with desirable traits. The desirable traits were root number (RTNO), fresh root yield (FYLD), harvest index (HI), dry matter (DM), cyanide potential (CNP), mean plant height (MPHT) and level of branching (LOBR). Three standard varieties were used, namely 30572, 91/01730 and 91/023227. Acessions that were superior to the standard types in more than one trait were 92/0681, 92/02325; 92/0455, 88/02555; Alice Local and 88/02555. These accessions could be selected and put into crossing blocks to combine the traits into one genotype. The present results show that augmented designs are efficient in the identification of superior cassava genotypes with desirable traits

Genotype by environment interaction effect on beta-carotene of yellow root cassava (Manihot esculenta Crantz) genotypes in Ghana

Nine yellow root and one white root cassava genotypes were evaluated in ten environments in Ghana for the variability of their beta carotene content in root. The aim was to identify cassava genotypes that have high beta carotene content in storage root to combat the widespread vitamin A deficiency for children under the age of five years and for pregnant and lactating women. This study was conducted in a Randomized Complete Bloc Design with nine yellow root genotypes namely 01/1224; 01/1235; 01/1368; 01/1371; 01/1412; 01/1417; 01/1442; 01/1610; 01/1663 and one white root cassava namely Wenchi009 as check. In 2005-2006 two experiments were conducted at Wenchi in the Forest-Savannah Transition zone and at Bunso in the Deciduous Forest zone and in 2006-2007, one additional location namely Pokuase in the costal savannah zone was added to Wenchi and Bunso to conduct the same field experiment. Each experiment was harvested two times (9 and 12 or 14 months after planting). At each harvest, beta carotene content analyses were carried out on yellow root cassava at the Nutrition Lab of Noguchi Medical Research Centre using High Performance Liquid Chromatography (HPLC) with a mobile phase made of acetonitrile: dichloromethane: methanol in the ratio 70:20:10 at a flow rate of 2.5 ml/min. Data collected were analyzed using the computer software GenStat Discovery Edition Release 4.2DE; MATMODEL 3.0; GGE biplot. Analyses of results showed statistically significant differences between genotypes for beta carotene content per root, beta carotene content in storage root per plant and but no difference for beta carotene concentration. The best genotype for beta carotene content was 01/1417 follow by 01/1371 and 01/1368.The differences between environments were highly significant for all beta carotene traits. The highest value of beta carotene concentration in fresh root was recorded in environments E , E , E and E . 9 1 7 5 These environments were all characterized by harvest at 9 months after planting. For beta carotene concentration, beta carotene content per storage root and beta carotene content in storage roots per plant the best environments were E (9 9 MAP at Pokuase) and E (9 MAP at Wenchi in 1 2005). The IMMI analysis has shown 01/1412 the most stable for beta carotene concentration. The highest average value of beta carotene content per storage root was registered for genotype 01/1253 followed by 01/1417 and 01/1412. The most stable genotype for beta carotene content per storage root was 01/1610 followed by 01/1371. The highest value was registered for genotype 01/1417 (also the most stable) followed by 01/1368 and 01/1235. Based on the above results the yellow root cassava genotypes 01/1368 and 01/1417 which combined high fresh storage root yield, high dry root yield with high beta carotene content in storage root and in storage root per plant were proposed for on farm testing and released to tackle the vitamin A deficiency in Ghana

Taxonomic Significance of Some Vernacular names of Okra Accessions (Abelmoschus Spp.) in Ghana

The aim of this study was to examine the folk criteria used by farmers to name their local okra varieties and also to assess the taxonomic significance of vernacular names in the identification and classification of these okra varieties in Ghana. Forty two okra accessions and their vernacu-lar names were obtained from PGRRI, Bunso for the study. The various vernacular names of okra accessions were taxonomically analysed by determining their linguistic meanings, their folk criteria and their folk classification. The folk classification of the different okra accessions were then compared with numerical classification of the same set of accessions of another study based on their quantitative and qualitative morphological characteristics. Based on the taxonomic analyses, the 42 vernacular names of okra accessions in Ghana consisted of languages like Twi, Ewe, Dagbani and Krobo and were also based on folk criteria such as morphology, fruit charac-ters, names of persons or locality, maturity periods and culinary properties. Folk classification of the 42 okra accessions produced 8 different taxonomic groupings which contrasted with numerical classification of the same set of okra accessions. Thus, vernacular names of okra accessions in Ghana could not be used as the sole criterion in the identification and estimation of okra diversity because of the low degree of consistency between the two different methods of classification

Breeding new sweetpotato genotypes combining elevated content of two antagonistic traits of high dry matter and beta-carotene content in a high root yield background

Published online: 29 Nov 2019This study was embarked upon to stack two key but inversely associated sweetpotato traits (dry matter and beta-carotene content) through conventional breeding methods. Thirty-seven elite sweetpotato genotypes were evaluated for both traits, and 15 parents comprising five orange-, five yellow- and five white-fleshed genotypes were selected from the 37 for hybridization. Using bi-parental mating fashion, an F1 progeny population for both traits was developed. Of the 13 families developed, eight families had above 30% of the progenies made of orange-fleshed (high beta-carotene) genotypes with three families having at least 50% of the progenies as OFSP. All the families (except two) showed wide variation for beta-carotene content (range 0.15–12.39 mg/100gFW) with some progenies exhibiting transgressive segregation. For dry matter content, most of the progenies across families had dry matter content > 30%. Overall, 17 high yielding F1 genotypes that combined elevated beta-carotene and dry matter content were identified. These 17 genotypes showed that although a strong inverse relationship exists between dry matter and beta-carotene, the relationship does not make the development of genotypes expressing both traits totally impossible through conventional breeding. These 17 superior genotypes that combine both traits will also serve as elite genetic background for many African sweetpotato breeding platforms in their quest to develop OFSP genotypes that meet the food culture of many African societies