title: Soil water capture trends over 50 years of single-cross maize (Zea mays L.) breeding in the US corn-belt.
abstract: Breeders have successfully improved maize (Zea mays L.) grain yield for the conditions of the US corn-belt over the past 80 years, with the past 50 years utilizing single-cross hybrids. Long-term improvement for grain yield under water-limited conditions has also been reported. Grain yield under water-limited conditions depends on water use, water use efficiency, and harvest index. It has been hypothesized that long-term genetic gain for yield could be due, in part, to increased water capture from the soil. This hypothesis was tested using a set of elite single-cross hybrids that were released by DuPont Pioneer between 1963 and 2009. Eighteen hybrids were grown in the field during 2010 and 2011 growing seasons at Woodland, CA, USA. Crops grew predominantly on stored soil water and drought stress increased as the season progressed. Soil water content was measured to 300cm depth throughout the growing season. Significant water extraction occurred to a depth of 240-300cm and seasonal water use was calculated from the change in soil water over this rooting zone. Grain yield increased significantly with year of commercialization, but no such trend was observed for total water extraction. Therefore, the measured genetic gain for yield for the period represented by this set of hybrids must be related to either increased efficiency of water use or increased carbon partitioning to the grain, rather than increased soil water uptake.
authors.affiliation: DuPont Pioneer, 18369 County Rd 96, Woodland, CA, USA.
authors.forename: Andres
authors.initials: A
authors.lastname: Reyes
authors.affiliation: DuPont Pioneer, 7200 NW Avenue, Johnston, IA 50310, USA charlie.messina@pioneer.com.
authors.forename: Carlos D
authors.initials: CD
authors.lastname: Messina
authors.affiliation: Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Graeme L
authors.initials: GL
authors.lastname: Hammer
authors.affiliation: DuPont Pioneer, 7200 NW Avenue, Johnston, IA 50310, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Liu
authors.affiliation: Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Erik
authors.initials: E
authors.lastname: van Oosterom
authors.affiliation: DuPont Pioneer, 18369 County Rd 96, Woodland, CA, USA.
authors.forename: Renee
authors.initials: R
authors.lastname: Lafitte
authors.affiliation: DuPont Pioneer, 7200 NW Avenue, Johnston, IA 50310, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Cooper
mesh_terms: D001947:Breeding; D018556:Crops, Agricultural / Q000378:metabolism; D003433:Crosses, Genetic; D055864:Droughts; D060587:Groundwater; D012621:Seasons; D012641:Selection, Genetic; D012987:Soil; D013995:Time; D014867:Water / Q000378:metabolism*; D003313:Zea mays / Q000378:metabolism*
chemical_list: D012987:Soil; D014867:Water
keywords: Grain yield; maize; plant breeding; rooting; soil water uptake.