FIGURE LEGENDS
Figure 1. Temperature exposure of plants. (A) Average monthly temperature for Ghent (Belgium) between 1982 and 2012 (data retrieved from en.climate-data.org/europe/belgium/flanders/ghent-6350/t/july-7/).(B) Temperature in Melle (near Ghent) on 6th- 7th May 2020 (data retrieved from www.meteo.be/nl/weer/waarnemingen/belgie). (C) Hourly recorded soil temperature data in Redding (California, USA) in the station WBAN 04222 at distinct depths (5, 10, 20, 50, 100 cm) in October 2018 (data retrieved from www.ncdc.noaa.gov/crn/qcdatasets.html (J. E. Bell et al., 2013)). The blue, grey, red color indicate average cool, optimum and warm temperatures for distinct root systems, respectively. (D)Daily recorded mean temperatures by blended stations in Belgium (10-year moving average) from 1840-2019 (data retrieved from www.ecad.eu/dailydata/index.php). The temperature difference between the lowest and highest temperature in A, B and D is indicated in red.
Figure 2. Optimal temperature for crop plants. (A)Optimal temperature range of temperate, subtropical and tropical species for aboveground and belowground organs. (B) Optimal temperature ranges in four main developmental phases of crops and two biochemical processes. Tomato (left) and wheat (right) are shown as a dicot and monocot crop representative, respectively. The chloroplast and mitochondrion represent photosynthesis and respiration, respectively.
Figure 3. Growth responses of crops under high temperature.Wheat (Triticum aestivum var. Chinese Spring) shoot length of 14-day-old seedlings grown at indicated temperature. Scale bar: 5 cm.
Figure 4. The effect of warm temperature and heat on various stages of reproductive development. (A) Warm temperature affects the floral transition in cereal crops in a photoperiod-dependent way. Green and yellow means leaf and spikelet primordia on the apical meristem. SD / LD, short-day / long-day conditions. (B)Interruption of vernalization by warm temperature accelerates development of winter-habit plants, and leads to additional spikelets under long-day conditions. Grey bar with six vertical lines in the middle presents the whole life cycle of barley or wheat plants. Blue bar represents cold exposure (vernalization). Red color indicates high temperature interruption. (C) The effects on anther and pistil development at optimum (left grey part) and warm (right red part) ambient temperature, respectively. Top shows pollen numbers within a transverse section of the anther. Middle shows impact on anther development (filament length and anther dehiscence) and pollen numbers, and the effect on auxin levels. Bottom shows pistil with elongating pollen tubes (D) H2A.Z occupancy affects early seed development in a temperature-dependent way in Brachypodium . (E)Representative example of pre-harvest sprouting in rice. Image reproduced from Kai Shu, Liu, Xie, and He (2016) with permission.
Figure 5. The effect of warm temperature and heat on photosynthesis. The left (grey) and right (red) part of the leaf represent optimum and high temperature conditions, respectively. Dark and light green thylakoids indicate more or less chlorophyll, respectively. RuBisCO, ribulose-1,5-bisphosphate carboxylase/oxygenase. TCA cycle, tricarboxylic acid cycle.