Identification of heterotic patterns between expired proprietary, NDSU, and industry short-season maize inbred lines

Abstract

Maize (Zea mays L.) inbred lines are under restricted use, protected by Patent and Plant Variety Protection (PVP) laws. Research objectives were i) to identify and validate heterotic groups and patterns, and ii) to determine if ex-PVP lines are useful for continued genetic progress in short-season environments. Three groups of crosses were made following North Carolina Mating Design II (NCII) including 12 NDSU, 24 ex-PVP lines, and seven current industry testers. Hybrids were planted in four different experiments at six ND environments following partially balanced lattice experimental designs in 2011 and 2012. Top heterotic patterns were selected based upon grain yield and other agronomic traits. Our research indicates most ex-PVP lines are genetically narrow and may not be immediately useful. Less protection (5-yr vs. 20-yr) might increase usefulness of ex-PVP lines. This change in intellectual property will allow public breeders to develop better versions of industry lines carrying known weaknesses.