HERITABILITY FOR RESISTANCE TO ROSETTE DISEASE IN EXOTIC VALENCIA GROUNDNUTS

Groundnut rosette disease (GRD) is the most destructive virus disease of Valencia groundnuts ( Arachis hypogaea L.) in sub-Saharan Africa. Cultural, biological and chemical control measures have received limited success due to small scale farmers’ inability to use them. Use of host plant resistance provides the most effective and economically viable management option for the resource poor farmers. This study was conducted to determine heritability for resistance to GRD in Valencia groundnuts. Six crosses; Valencia C (P1) × ICGV-SM 90704 (P2), Valencia C (P1) × ICGV-SM 96801(P2), Valencia C (P1) × ICGV-SM 99566 (P2), NuMex-M3 (P1) × ICGV-SM 90704 (P2), NuMex-M3 × ICGV-SM 96801 (P2), and NuMex-M3 (P1) × ICGV-SM 99566 (P2), were made to generate F1, F2, BC1P1 and BC1P2 populations. Data on GRD severity were collected on a 1-9 score scale. Genetic Advance as a percentage of the mean (GAM) and heritability were estimated using variance components. Phenotypic Coefficient of Variation (PCV) and Genotypic Coefficient of Variation (GCV) estimates were high (20.04-70.1%) in the six crosses, except for Valencia C × ICGV-SM 96801(18.1%) and NuMex-M3 × ICGV-SM 96801(17.1%), which exhibited moderate GCV values. Broad and narrow sense heritability estimates for GRD disease score ranged from 64.1 to 73.7% and 31 to 41.9%, respectively, in all the crosses. GAM was high in all the crosses (21-50.7%), except for Valencia C x ICGV-SM 96801 (14.67), M3 x ICGV-SM 99566 (18%) and NuMex-M3 x ICGV-SM 96801 (13.5%) crosses that exhibited moderate GAM. The study revealed the presence of variability of GRD resistance, implying that genetic improvement of these exotic materials is possible.

Variation, correlation and heritability of interest characters for selection of African eggplant

The eggplant ( Solanum aethiopicum ) is the species of the Solanum genus, whose geographical distribution is broadest. It is grown throughout tropical Africa, and includes three groups of cultivars commonly called African or indigenous eggplant. Kumba group or “bitter eggplant” is an important Solanaceous vegetable crop in Burkina Faso. The objective of this study was to determine genetic variability, strength of association and level of heritability among agronomic interest traits. Phenotypic and genotypic variations and heritability of 14 traits were estimated in 61 accessions at Institut de Développement Rural (IDR), Gampela in Burkina Faso. High phenotypic and genotypic coefficients of variation were observed for fruit diameter, number of seeds per fruit, fruit weight, leaf blade length and width, and height at flowering. In addition, genetic and phenotypic variances were high for the number of seed, fruit weight, plant height at flowering and days to 50% flowering. High heritability estimates were recorded for all traits. Fruit weight showed a positive association with fruit diameter and thickness. The fifty percent flowering cycle registered positive correlations with plant height and fruit diameter. Fruit number showed a negative association with fruit weight and diameter, and 50% flowering cyle.