Figure 1.

The relationship of temperature, growth, and heat stress in maize. (a) Optimal growth conditions overlap with heat stress. The optimal temperature range for maize growth is 25–33 °C, day/17–23 °C, night (https://www.extension.purdue.edu/extmedia/nch/nch-40.html), which are mid-summer temperatures in the US corn belt. The box indicates the average high temperatures (maximum daily temperatures) in June and July in Iowa, USA, a region representing an ideal climate for maize production. The trends shown here are from experiments conducted with the maize inbred line W22 grown under controlled environment conditions in the Enviratron at Iowa State University [14]. (b) An example of the temperature conditions used in the Enviratron to simulate diurnal temperature cycles under field conditions. Note the ramping up of the temperature to different maximum daily temperatures in the virtual afternoon and the ramping down in the virtual evening.