3.2. Shoot architecture
In Arabidopsis , there is a suite of morphological changes (e.g.
hypocotyl and petiole elongation, leaf hyponasty, and decreased stomatal
density) induced by high ambient temperatures referred to as
thermomorphogenesis (Casal & Balasubramanian, 2019; Quint et al., 2016;
Vu et al., 2019). Similarly, warm temperature improves the cooling
ability of tomato by promoting stomatal opening and leaf hyponasty
(Havko et al., 2020). Although different crop species originating from
various climates have strikingly common response curves of developmental
processes over a whole temperature range
(6-37℃), each species has its own
optimum temperature range to promote maximum growth (Parent & Tardieu,
2012). The leaf and coleoptile of monocot seedlings (wheat, barley, rice
and maize) or the hypocotyl of dicots (soybean and tomato) are maximally
elongated at moderately high temperatures (Alsajri et al., 2019; Parent
& Tardieu, 2012; Quint et al., 2016) (Figure 3 ). However,
while in, for example Arabidopsis thaliana and tomato, these
rapid architectural changes are associated with leaf cooling (Crawford,
McLachlan, Hetherington, & Franklin, 2012; Havko et al., 2020; Park et
al., 2019; Rosado et al., 2019), this has not been shown in economically
important cereal crops.