The estimation of genetic parameters of the kenaf (Hibiscus cannabinus L.) plant resistance against root-knot nematodes (M. incognita) using full diallel cross analysis was the aim of this study. Seven H. cannabinus parental genotypes, KR-1, KR-4, KR-5, KR-6, KR-15, Kenafindo-2 (Kin-2), and DS-028, as well as their complete diallel F₁ hybrids, were samples used in the study. The experiment commenced by infecting kenaf plants aged 15 days after sowing (DAS) with M. incognita nematodes in a population of 40 second-stage juveniles/100 g soil. The resistance variables comprised the number of root-knot nematodes, reproductive factors, the number of second-stage juveniles, the total egg mass, and the average number of eggs per mass. The results showed no significant epistatic interaction between genes in determining H. cannabinus resistance against M. incognita. Moreover, the effect of the additive genetic variances was greater than the dominance genetic variances. The kenaf resistance against root-knot nematode revealed the primary control of a partially dominant-additive gene. Dominant genes proved more prevalent than recessive genes in the parental genotypes. Both broad- and narrow-sense heritability values emerged as high.

Keywords: Kenaf (H. cannabinus L.), root-knot nematodes (M. incognita), Hayman’s diallel analysis, genetic parameters, additive and dominance genetic variances, heritability

Key findings: The kenaf (H. cannabinus L.) resistance against root-knot nematode showed the control of a partially dominant gene. Dominant genes appeared more abundant than recessive ones in the parental genotypes. Both broad- and narrow-sense heritability values were high.