Because many exotic corn (Zea mays L.) races have different evolutiona
ry histories from those of U.S. races, they may possess unique, favora
ble alleles for physical grain quality traits. This study explored the
effectiveness of using exotic inbreds from Uruguay, Argentina, South
Africa, and Taiwan (representing 'Cateto'-type, intermediate, and non-
Cateto races) to improve physical grain quality of U.S. Corn Belt hybr
ids. Eighteen exotic inbreds were crossed to two Corn Belt inbreds, Mo
17 and B73, which represent the 'Lancaster Sure Crop' and the 'Iowa St
iff Stalk Synthetic' backgrounds, respectively. A randomized complete
block design was used to evaluate testcrosses (F(1)s), their F-2 and b
ackcross (to the Corn Belt inbreds) generations, and four checks grown
at two locations in Iowa and at one location in Missouri. The experim
ent showed significant differences among races for 1000-kernel weight,
test weight, grain yield, and harvest moisture content. Testcrosses a
nd generations were significantly different for kernel weight, test we
ight, breakage susceptibility, grain yield, and harvest moisture conte
nt. Significant differences were also found between testers for all tr
aits except moisture. Entry x tester interaction, however, was signifi
cant only for breakage susceptibility and yield, whereas entry x gener
ation interaction was significant for all the traits except breakage s
usceptibility. This study showed that Cateto-type inbreds have the pot
ential to improve test weight of Corn Belt hybrids. The Cateto race in
breds also contributed favorable alleles for lowering harvest moisture
content, which may indirectly help reduce breakage losses.