Gamete and recurrent selection for improving physiological resistance to white mold in common bean

Abstract

White mold (WM) is a widely distributed and severe disease of common bean in North America. The objective of this study was to determine the effectiveness of gamete (GS) and recurrent (RS) selection methods for improving WM resistance. Two double-crosses, namely USPT-WM-1/CORNELL 601//USPT-CBB-1/92BG-7 and ‘Chas’/I 9365-25//ABL 15/A 195 were made. Equal numbers of progenies from both crosses were subjected to GS and RS. The GS was practiced from F1 to F4 by selecting WM resistant single plants followed by progeny testing in the subsequent generation. Two cycles of RS were practiced by intermating selected WM resistant plants in each cycle. Thirteen selected families in each method and parents were evaluated at 16, 23, and 33 days post first inoculation in replicated trials in two greenhouse environments. Higher frequencies of families with lower WM scores were obtained from GS than RS. The average genetic gains due to GS and RS were 19.6 and 7.9%, respectively. Employing multiple-parent-crosses involving parents of diverse evolutionary origins delayed WM evaluation, and application of GS are recommended for improving physiological WM resistance in common bean.Key words: Interspecific breeding line, introgressing resistance, multiple-parent crosses, Phaseolus vulgaris, pyramiding resistance, Sclerotinia sclerotiorum