Combining ability for beet armyworm, Spodoptera exigua, resistance and horticultural traits of selected Lycopersicon pennellii-derived inbred backcross lines of tomato

Ten selected inbred backcross lines (IBL), from a Lycopersicon esculentum cv. 'Peto 95' x Lycopersicon pennellii IBL population, with resistance to beet armyworm (BAW), Spodoptera exigua, higher fruit mass and fruit yield, were crossed with eight elite cultivated L. esculentum inbred lines in a Design II mating design. Three elite inbreds were also crossed to 'Peto 95', the IBL recurrent parent, as a control for combining ability. Field plots of all resulting F1 progenies and control cultivars were inoculated with BAW eggs and evaluated for resistance to BAW, fruit mass, fruit yield, vine size and maturity at three field locations. Reductions in fruit damage by BAW were found in four of the 10 IBL F1 progenies. Significant male and female general combining ability (GCA) estimates for BAW resistance were observed, but significant specific combining ability for BAW resistance was not detected. The fruit mass of F1 hybrids was significantly lower than large-fruited controls, but was not significantly different from elite inbred by 'Peto 95' F1 hybrids. Selection based on inbred performance identified IBL with positive GCA for BAW resistance and yields in Design II hybrids. BAW resistance in the 10 selected IBL and IBL-derived F1 progeny was associated with two undesirable traits, later maturity and larger vine size. Index selection of IBL was more effective at identifying IBL with positive GCA for fruit mass and fruit yield than GCA for BAW resistance.