Three Korean local cultivars, Kalmi, Punggak, and Subi, were crossed with PI201234, an introduction which is resistant to Phytophthora capsici, to incorporate the resistance into the Korean cultivars. Parents, F₁, F₂ and backcross populations were evaluated and the plants selected in the backcross to Korean cultivars were selfed and backcrossed to each Korean cultivar to obtain BC₁F₂ and BC₂F₁ populations, respectively.
Resistance to P. capsici appeared to be multigenic on the basis of root rot evaluation. The level of resistance rapidly declined with increased rounds of backcross so that frequency of resistant plants was very low or none in the BC₂F₁ populations. Therefore, alternating backcross and selfing instead of continuous backcrossing or recurrent method of selection after one or two generations of backcross is suggested to develop lines with high level of resistance and horticultural characters of the recurrent parents.
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