COS 54-7
Variation in maize developmental sensitivity to temperature
It has been experimentally determined that maize is particularly sensitive to drought during the flowering period of development. However, this sensitivity has not been studied across highly varied geographic regions growing different cultivars of maize. Furthermore, the pattern of sensitivity will determine how much control farmers have to avoid particularly damaging weather. This will be particularly relevant as the climate warms. Here we examine the relationship between maize development from 16 states in the United States Department of Agriculture/National Agriculture Statistics Service (USDA/NASS) which contain data on six distinct phases of the development cycle, which we combine into four periods: vegetative, silking, grain filling, and mature. These development phases are then used to weight data from 549 United States Historical Climatology Network (USHCN) weather stations to determine the sensitivity in each phase of development to the number of Growing Degree Days and Killing Degree Days using a multiple linear regression model.
Results/Conclusions
The sensitivity to temperature varies substantially both spatially and temporally, with sensitivity as much as a factor of four higher during silking and/or grain filling than during the vegetative stage of development. To elaborate how this variable sensitivity affects yield over time we compare inferred yield responses from whole-season temperature variability against those inferred when computing responses for each of the four development stages individually and then combining them. We find that the combined stage sensitivity shows roughly twice the sensitivity of the whole-season responses. Indeed, the majority of states indicate this enhanced sensitivity increased yields more than would have been indicated by the single whole season sensitivity, implying that modifications of the growing season have improved yields more when accounting for the developmental variation of temperature sensitivity. Furthermore, perturbations towards earlier planting dates indicate a continued increase in yield from the development model but a decrease in yield for the whole season sensitivity; indicating that the benefits of earlier planting have not been captured under the assumption of uniform temperature sensitivity. This result has important implications for how farmers may respond to a warmer world.