Identification of field corn populations to improve sweet corn for Atlantic European conditions

Sweet corn (Zea mays L.) has been intensively selected for quality and appearance, whereas less effort has gone into improving yield. Acceptance of sweet corn in Europe has increased in the last 10 yr. However, in regions with cool and humid springs and short growing seasons, sweet corn planting is still limited. Identification of donor parents useful far improving sweet corn hybrids would be greatly beneficial for sw-eet corn breeding programs. The objectives of this study were to identify field corn populations to increase yield in four sweet corn hybrids and to compare different methods for identifying populations with the greatest number of favorable alleles for yield and its components. Ten maize populations were crossed to five sweet corn inbreds. The 50 tresses along with five inbred parents, four sweet corn hybrids, and ten populations were evaluated in tno locations in northwestern Spain in 1992 and 1993. Six estimators of relative number of favorable alleles [<l(p)over bar (1) mu'>, predicted three-way cross (PTC), minimum upper bound (UBND), net improvement (NI), probabilities of net gain of favorable alleles gives complete dominance, and probabilities of net gain of favorable alleles given partial dominance or complementary epistasis] and general combining ability were calculated. The U.S. synthetic AS-3(HT)C3 and the northwestern Spanish populations Tuy and Oroso could improve yield and other yield components in sweet corn hybrids. However, European flint corn populations, such as Tuy and Oroso, should have less detrimental effect on kernel quality than U.S. dent populations. Moreover, European flint corn should be better adapted to cool and wet springs and short growing seasons. The <l(p)over bar (1) mu'>, PTC, UBND, and NI statistics identified the same populations as the best donors.