The study was initiated to determine the genetic variability of late leaf spot (LLS) resistance among segregating generations of Valencia groundnut varieties. Crosses were made between NuMex-M3 × ICGV-SM 02501, Valencia C × ICGV-SM 02501, Redbeauty × ICGV-SM 03590 and Valencia C × SGV-07009 parental lines and the resulting generations (F1, F2, BC1P1 and BC1P2,), along with parents for each cross, were evaluated for LLS resistance on a 1-9 scale under natural conditions in a randomized complete block design (RCBD) with three replications. Analysis of variance was performed for generations of each cross, coefficients of variation and heritability were estimated for all crosses except for the Valencia C × SGV-07009 cross. Three crosses showed highly significant differences among generations for LLS resistance (P≤ 0.05). The three crosses exhibited moderate to high levels of genotypic coefficient of variation (GCV) (15.43 to 23.13 %) and phenotypic coefficient of variation (PCV) (16.89 to 28.82%). The exception was the Redbeauty × ICGV-SM 03590 cross which showed low (9.50%) GCV. Broad-sense heritability (h2b) estimates for LLS disease scores were moderate to high (32 to 64%) for the three crosses. The results reveal substantial variation for LLS resistance in generations of these crosses indicating that the trait under study was heritable.
Key words: Valencia groundnut, Arachis hypogeae, late leaf spot, resistance, genetic variability.