Maize yield and dry milling grain quality trade-offs in Argentinean flint germplasm

Trade-offs between yield and grain quality for dry milling are common in maize (Zea mays L.), but the magnitude of these correlations can differ depending on the specific quality trait. We aimed to quantify the relationship between yield and grain traits known to affect dry milling, with a focus on describing the genetic control of the traits that show no negative yield effects. For this, we tested commercial hybrids differing in grain hardness and a recombinant inbred line (RIL) population with their derived hybrids. Commercial hybrids showed that grain hardness (test weight, flotation index, and vitreousness) were all negatively correlated to yield, while screen retention, a key trait for the milling industry, showed no correlation with yield. Also, while all grain quality traits in the RIL and derived hybrid populations showed high heritability (>0.77), results showed that adequate hybrid test weight (>76 kg hL(-1)) and flotation index (<25%) did not depend on its midparental performance. High hybrid vitreousness was only achieved when both parental inbreds had high vitreousness. Hybrid screen retention was accurately predicted by an environmentally consistent quantitative trait locus and by inbred genetic and phenotypic information (p < 0.001). This suggests a strong genetic control that can be exploited without yield penalties. Our study shows that the trade-off between yield and grain quality is trait dependent, and highlights that only some traits measured in inbreds can help predict derived hybrid performance for dry milling.