Heterosis patterns and sources of self-compatibility, cross-compatibility and key nut traits within single and double hybrid crosses of kola [Cola nitida (Vent) Schott and Endl.].

Sexual incompatibility among kola genotypes accounted for over 50% yield loss. Compatible and high yielding varieties are in demand to develop commercial orchards. The objective of this study was to assess self-compatibility and cross-compatibility of kola (C. nitida) genotypes within self, single and double hybrid crosses and to determine heterosis pattern in the resulting hybrids for sexual compatibility and key nut yield and quality traits. Crosses among kola genotypes from three field gene banks (JX1, GX1, MX2) and one advanced germplasm (Bunso progeny) in Ghana were evaluated along their parents for sexual compatibility, nut yield and nut quality. Data were collected on pod set, pseudo-pod set, pod weight, number of nuts per pod, nut weight, brix, potential alcohol and nut firmness. Significant (P < 0.001) differential pod set was observed within Bunso progeny, JX1, GX1 and MX2 crosses; while pseudo-pod set differed only within JX1 and MX2 crosses (P < 0.001). Very large prevalence of mid-parent, heterobeltiosis, and economic heterosis was observed for sexual compatibility, outturn and brix for the single and double hybrid crosses. Heterosis was prominent among the double hybrid crosses as compared to the single hybrid crosses suggesting that recurrent selection of compatible varieties from advanced generations could result in genetic gain in kola improvement. The top five crosses with best heterosis for sexual compatibility and an appreciable positive heterosis for outturn and brix were B1/11 × B1/71 × B1/157 × B1/149, B1/11 × B1/71 × B1/296 × B1/177, GX1/46 × GX1/33 × B1/212 × B1/236, JX1/90 × JX1/51 and JX1/51 × JX1/36. These materials could serve as sources of beneficial alleles for improving Ghanaian kola hybrids and populations for yield and sexual compatibility.

Genetic variability for vigor and yield of robusta coffee (Coffea canephora) clones in Ghana.

Effectiveness of plant improvement programs, especially in perennial crops like coffee, may be improved by knowing the level of genetic variation which exist within a breeding population coupled with the knowledge of estimates of genetic parameters for key agronomic traits. Thus, this study was conducted to evaluate C. canephora clones for growth (stem diameter, number of laterals and span) and yield traits; estimate genetic parameters of these traits; and determine the phenotypic and genetic associations between these traits to guide future crop improvement efforts. The productivity of 56 coffee clones was assessed from 2012 to 2020 in a clonal experiment planted in a randomized complete block design with three replicates. Each plot consisted of eight plants spaced at 2 × 3 m at the Cocoa Research Institute of Ghana. There were significant (p < 0.001) differences among clones for all the traits assessed. Broad sense heritability was low-to-moderate for all the traits evaluated with the highest (0.34) observed for cumulative yield (CY). Cumulative yield was genetically correlated (p < 0.001) with span and number of laterals (NOL). For the growth traits, NOL was the most strongly associated with CY (r g = 0.49, p < 0.001). The results revealed that selection based on early years' yield (MY1) could be as effective as selection based on CY (r g = 0.87, p < 0.001). Our findings indicate that there is significant genetic variation among the test clones for the parameters assessed and presents a good opportunity for future variety development.

Genetic variability of bioactive compounds and selection for nutraceutical quality in kola [Cola nitida (Vent) Schott. and Endl.].

Cola nitida known as Kola serves as flavouring ingredient in the food industry and is also of great importance during traditional rites in Africa. Despite the well-known pharmaceutical values of the species, efforts to develop improved varieties with enhanced nutraceutical quality is limited due to unavailability of information on variation of genotypes in bioactive compounds in the nuts. The objectives of this research were to evaluate 25 genotypes of kola for bioactive contents, determine relationship between nutritional and phenolic traits and to identify kola genotypes with good nutraceutical quality for use in developing improved varieties. The kola genotypes were established in the field using a randomized complete block design with three replicates. Nuts harvested from the blocks, were bulked and used to quantify soluble and insoluble sugars, total protein, moisture, ash, fats, pH, polyphenols, tannins and flavonoids using completely randomized design with three replicates in the laboratory. Data were analysed by combining Analysis of Variance, Kruskal-Wallis test, correlation test and multivariate analysis. Significant variations (P < 0.05) were observed among the kola genotypes for the bioactive traits evaluated. Phenolic traits were more heritable than nutritional traits. Although not significant (P > 0.05), correlation between nutritional and phenolic traits was negative, whereas correlations among nutritional traits were weak. On the contrary, significant and positive correlations (P < 0.05) were observed among phenolic traits. The hierarchical clustering analysis based on the traits evaluated grouped the 25 genotypes of kola evaluated into four clusters. Genotypes A12, JB4, JB19, JB36, P2-1b, and P2-1c were identified as potential parental lines for phenolic traits selection in kola whereas genotypes A10, Club, Atta1 and JB10 can be considered for soluble and insoluble sugar-rich variety development. These findings represent an important step towards improving nutritional and nutraceutical quality of kola nuts.

Genotypic characterization of cashew (Anacardium occidentale L.) clones using agro-morphological traits.

High cropping efficiency implies that high yields are obtained from reasonably sized trees. We studied the general and specific combining ability (GCA and SCA) of selected cashew clones of Brazilian (A), Beninese (BE), and Ghanaian (SG) background for cropping efficiency and nut weight in the early years of bearing. Using North Carolina II mating design, four clones were crossed as males to three best clones recommended for farmers. The 12 F1 progenies were evaluated in the field at Wenchi (2012-2018) for increase in trunk cross-sectional area at the vegetative (TCSAv) and reproductive (TCSAr) stages, canopy spread in the east-west (CSew) and north-south (CSns) directions, nut yield (NY), nut weight (NW), and cropping efficiency (CE) using a randomized complete block design with three replications. Cropping efficiencies were in the range of 30.8-67.4 g/cm2/year while nut weight and nut yield varied from 5.9 to 10.5 g/year and 477.8 to 939.4 kg ha-1 year-1 in the fourth to sixth years after planting, respectively. The Beninese progenies outperformed the Brazilian progenies for cropping efficiency. GCA effects were more important than SCA effects. Narrow-sense heritability ranged from 0.47 (CE) to 0.80 (NW). Canopy spread in the north-south direction correlated (rg = 0.98; p ≤ .001) strongly with cropping efficiency at the genotypic level. Among males, BE203 showed positive GCA effects for cropping efficiency, TCSAv, and nut yield, whereas A2 and SG273 showed positive GCA effects for nut weight. Among females, SG287 showed negative GCA effects for TCSAr. Our study provides evidence that, cashew tree size and nut quality are under genetic control and the identified clones represent a suitable genetic resource pool to increase productivity.

Effectiveness of Single Nucleotide Polymorphism Markers in Genotyping Germplasm Collections of Coffea canephora Using KASP Assay.

Accurate genotype identification is imperative for effective use of Coffea canephora L. germplasm to breed new varieties with tolerance or resistance to biotic and abiotic stresses (including moisture stress and pest and disease stresses such as coffee berry borer and rust) and for high yield and improved cup quality. The present study validated 192 published single nucleotide polymorphism (SNP) markers and selected a panel of 120 loci to examine parentage and labeling errors, genetic diversity, and population structure in 400 C. canephora accessions assembled from different coffee-producing countries and planted in a field gene bank in Ghana. Of the 400 genotypes analyzed, both synonymous (trees with same SNP profiles but different names, 12.8%) and homonymous (trees with same name but different SNP profiles, 5.8%) mislabeling were identified. Parentage analysis showed that 33.3% of the progenies derived from controlled crossing and 0% of the progenies derived from an open pollinated biclonal seed garden had parentage (both parents) corresponding to breeder records. The results suggest mislabeling of the mother trees used in seed gardens and pollen contamination from unwanted paternal parents. After removing the duplicated accessions, Bayesian clustering analysis partitioned the 270 unique genotypes into two main populations. Analysis of molecular variance (AMOVA) showed that the between-population variation accounts for 41% of the total molecular variation and the genetic divergence was highly significant (Fst = 0.256; P < 0.001). Taken together, our results demonstrate the effectiveness of using the selected SNP panel in gene bank management, varietal identification, seed garden management, nursery verification, and coffee bean authentication for C. canephora breeding programs.