Breeding potential of European flint and US corn belt dent maize populations for forage use

Information about appropriate breeding populations and the type of forage m aize (Zea mays L.) hybrids that should be developed for cooler regions of E urope is scarce. Our objectives were to determine the potential, performanc e, and heterosis of flint (F) and dent (D) populations as base germplasm fo r developing silage maize hybrids. Four U.S. Corn Belt dent populations whi ch had been selected for early maturity and four European flint populations were included in our study. The eight populations, the 28 possible crosses among them, and topcrosses to inbreds A632 and EC18 were evaluated for sto ver, ear, and whole plant dry matter yield (DMY), as well as stover and who le plant-dry matter content (DMC), digestible organic matter (DOM), and aci d detergent fiber (ADF) content in northwest Spain. Means of F x D populati on crosses for stover and ear DMY (6.98 and 8.71 Mg:ha(-1), respectively) w ere greater than those of D x D crosses (6.12 and 8.05 Mg ha(-1), respectiv ely) and F x F crosses (6.03 and 7.64 Mg ha(-1), respectively). Average het erosis of whole plant DMY was greater for the F x D crosses (2.16 Mg ha(-1) ) than for the D x D and F x F crosses (0.23 and 0.56 Mg ha(-1), respective ly). No significant heterosis was found for DOM and ADF of the stover and w hole plant fractions, The only exception was a negative average heterosis o f population BSSS-M for stover DOM. Results suggest that forage maize hybri ds should be developed from the F x D heterotic pattern. Breeding strategie s should include selection for stover DOM for both parent-lines and hybrids because favorable recessive genes may be involved in this trait.