Exotic introgression incidence on two elite tropical maize populations [Zea mays L. - Brazil]
1998
Hainzelin, E. (Centre de Cooperation International en Recherche Agronomique pour le Developpement, Montpellier (France))
Exotic maize (Zea mays L.) inbreds were introgressed in two elite Brazilian populations - BR105 (Suwan) and BR106 (related to Tuxpeno) - to improve their breeding values at high plant density. Different traits were observed in a set of S1 families from each original population and its corresponding introgressed pool. These families were observed per se at 50,000 pl/ha and topcrossed to an inbred tester at 75,000 pl/ha. Means, genetic variances, expected progresses and correlated responses were estimated for four key traits: yield, earliness, stalk crushing strength and root strength. Based on topcross performances, introgression brought in BR105 a slight yield increase with no influence on flowering dates, whereas in BR106 a yield decrease and an earlier flowering were recorded. In both cases, ear rot drastically increased and root strength was reduced. Stalk strength tended to increase. Introgression reduced the genetic variances and the expected progress. The reduction of yield genetic variances might be due to changes in linkage equilibrium and epistatic interactions
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