Drought tolerant maize hybrids have higher yields and lower water use under water deficit compared with conventional genotypes
Su, Z and Xue, Q and Marek, TH and Liu, K and Harrison, MT, Drought tolerant maize hybrids have higher yields and lower water use under water deficit compared with conventional genotypes, Agricultural Water Management: An International Journal pp. 1-19. ISSN 0378-3774 (In Press) [Refereed Article]
Drought increasingly constrains the productivity of maize crops under the climate emergency, especially for low rainfall regions with limited irrigation. Here we characterize differences between conventional and drought-tolerant (DT) hybrids by quantifying yield and water-use efficiency under drought for a region in the Texas High Plains (THP). Using a validated version of APSIM-Maize, we next simulated yields of conventional and DT hybrids across 11 water regimes and 25 USA counties from 1984 to 2018. When irrigation regimes were constrained to 90%, 80%, 70%, 60% and 50% of total irrigation requirement for the baseline scenario (BS; a simulated scenario of conventional hybrid under full irrigation), DT hybrids exhibited lower yield penalties under drought stress relative to conventional hybrids. This improved productivity by 19%, 24%, 26%, 26%, and 21% for each of the irrigation levels above. When the yield target was set as 90%, 80%, 70% and 60% of BS, total irrigation applied for the DT hybrid saved more than that for the conventional hybrid, reducing irrigation required by 17%, 16%, 15%, and 15% of BS irrigation, respectively. We showed that DT hybrids realized greater yield gain and water savings through improved water productivity under less irrigation, highlighting the potential of deficit irrigation to aid realization of yield benefits associated with DT hybrid production. Our quantitative evaluation of the yield gains and water saving potential associated with DT hybrids highlights regional benefits associated with adoption of drought adaptive hybrids at scale.