Response to inbred progeny selection in leaming and midland yellow dent maize populations

Evaluation and improvement of diverse sources of maize (Zea mays L.) germplasm are possible ways to improve yield, pest resistance, and stress tolerance. Improved populations of well-chosen diverse germplasm (domestic or foreign) can serve as alternative sources of inbred lines for hybrid maize improvement. Our research objective was to evaluate the direct, indirect, and correlated responses of inbred progeny selection in two U. S. domestic maize landraces. Three cycles of S 1 -S 2 recurrent selection were performed in Leaming and Midland Yellow Dent, two open-pollinated varieties. S 0 (F = 0) and S 1 generations (F = 0.5) were evaluated in five Iowa environments. Response to selection was effective in both varieties. For grain yield, average increases cycle-1 of selection of 0.28 Mg ha -1 (10.1%) in Learning and of 0.22 Mg ha -1 (14.9%) in Midland Yellow Dent were highly significant (P ≤ 0.01). Favorable correlated responses were observed in other agronomic traits. Root lodging decreased 7.0% cycle -1 in Midland Yellow Dent, while stalk lodging decreased 3.8% cycle -1 (P ≤ 0.01) in Leaming. S 1 -S 2 recurrent selection improved both populations, suggesting an adequate balance between the selection among S 1 and S 2 progenies. More selection cycles are needed to enhance grain yield for both populations and to determine if reciprocal recurrent selection would enhance the development of the Leaming-Midland Yellow Dent heterotic pattern.