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Generation mean study was carried out in two interspecific crosses of diploid cotton i.e., GBhv-302 × PA-812 and GBhv-302 × ARBa-1502 using six parameter model. Simple scaling tests along with joint scaling test were carried out to check the sufficiency of additive-dominance model. The estimates of dominant (h) gene action were higher than the additive (d) gene action in one or more characters studied. Among epistasis, additive × additive (i) type of gene action was found to be significant in cross GBhv-302 × PA-812 for sympodia per plant and ginning outturn and in cross GBhv-302 × ARBa-1502 for sympodia per plant, bolls per plant and seed cotton yield per plant. While dominance × dominance (l) type of gene effect contributed significantly in cross GBhv-302 × PA-812 for sympodia per plant and in cross GBhv-302 × ARBa-1502 for sympodia per plant, average boll weight, bolls per plant, average boll weight and seed cotton yield per plant. Duplicate type of epistasis was observed for sympodia per plant in both the crosses, for bolls per plant and seed cotton yield per plant in cross GBhv-302 × ARBa-1502 and for ginning outturn in cross GBhv-302 × PA-812. While complementary type of gene interaction was detected for bolls per plant and seed cotton yield per plant in cross GBhv-302 × PA-812 and for average boll weight and ginning outturn in cross GBhv-302 × ARBa-1502.