Abstract This study quantifies the effect of breeding and water supply on maize ( Zea mays L.) yields, yield components, grain quality, and water use efficiency in Bayer legacy maize hybrids. Thirty‐eight hybrids released from 1980 to 2020 were grown under three irrigation levels (non‐irrigated, partially, and fully irrigated) in a 3‐year experiment in Nebraska. Results indicate a significant grain yield increase across all irrigation treatments, with an average genetic gain of 111 kg/ha/year. New hybrids without irrigation produced as much yield as old hybrids with irrigation. Kernel number and weight increased with the year of hybrid release, with the kernel number being the primary driver of yield increase. This coincided with a reduced anthesis‐silking interval (delta of 3 days between old and new hybrids). Grain protein concentration decreased by 1% from 1980 to 2020 following a dilution curve. Starch concentration increased by the same amount (∼1%), while oil concentration remained unchanged. Water use efficiency, defined as grain yield per water supply unit (growing season rain and irrigation), increased by 28% in the 40‐year period. We concluded that maize breeding for high yields has indirectly affected several plant traits, including water use efficiency improvement, which is very encouraging for the future of crop production in the face of increased weather variability and climate change. Furthermore, we concluded that yield increase is the result of increasing both yield potential and drought stress tolerance. Present results can assist decision‐making regarding water management of modern hybrids and enhance our crop physiology knowledge.
Danalatos et al. (Thu,) studied this question.