Inheritance Studies of Root-Knot Nematode (<i>Meloidogyne</i> Species) Resistance in Tomato (<i>Solanum Lycopersicum</i> L.)

Plant-parasitic nematodes threaten tomato cultivation in Ghana, particularly the root-knot nematodes, causing substantial economic yield losses. However, these yield losses can be prevented through resistant varieties. This study aims to determine the type of gene action, heritability, heterosis and inbreeding depression for root-knot nematode resistance in tomato. A cross between CSIR/CRI-P005 (P<sub>1</sub>), an adapted variety with good yield but susceptible to root-knot nematode and VFNT (P<sub>2</sub>), which is resistant to root-knot nematode but low-yielding were used to generate six tomato populations. Average fruit weight, yield, root gall index, and reproduction factor were evaluated using a randomized complete block design with three replications. The six tomato populations (P<sub>1</sub>, P<sub>2</sub>, F<sub>1</sub>, F<sub>2</sub>, BC<sub>1.1</sub>, and BC<sub>1.2</sub>) were subjected to generation mean analysis. The means of all the populations differed widely for all traits studied. The joint scaling test revealed significant mean, additive, and dominance gene effects for all traits. Still, the additive-dominance model alone was inadequate in explaining the genetic actions of the studied traits. Using the six-parameter model, epistatic, additive, and dominance gene actions were significant for most traits. Average fruit weight, reproduction factor, and root gall index were found to duplicate dominant or recessive epistasis, while fruit yield per plant showed complementary epistasis. Better parent heterosis was observed for root gall index. Broad sense heritability estimations were high for yield per plant (90.94%), root gall index (92.82%), average fruit weight (78.69%), and reproduction factor (84.71%). Narrow sense heritability estimates were high for reproduction factor (76.59%) and root gall index (71.73%), moderate for yield per plant (32.32%), and low for average fruit weight (0%). High levels of inbreeding depression were detected for average fruit weight (-34.61%), yield per plant (-31.04%), reproduction factor (41.54%), and root gall index (-125.33%). This research suggests that traits with fixed genetic effects can be enhanced through pedigree breeding, whereas traits with non-fixed genetic effects are suitable for heterosis breeding.