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+## Plant Materials and Growth Conditions
+
+In this study, we selected two genotypes carrying a wild-type *Ppd-H1* allele and three genotypes with mutant *ppd-h1* allele to study the interaction between *Ppd-H1* and HT on shoot growth and inflorescence development. Golden Promise (GP) and Scarlett are spring barley cultivars carrying a natural mutation in the CCT domain of *PPD-H1* (G>T at CDS position 1969), according to gene model HORVU.MOREX.r3.2HG0107710.1 (Supplementary Dataset 1), causing a Gly-to-Trp amino acid exchange, and resulting in a late flowering time under long-day (LD; 16 h/8 h, day/night) conditions. GP-fast and S42-IL107 are two near-isogenic lines (NILs) derived from GP and Scarlett, respectively, carrying wild-type Ppd-H1 alleles from winter barley Igri and wild barley (*Hordeum vulgare ssp. spontaneum*) accession ISR42-8 (Supplementary Dataset 1). These lines are early flowering under LD (Schmalenbach et al., 2011; Digel, Pankin and von Korff, 2015; Gol, Haraldsson and Von Korff, 2021).
+
+Plants were sown in a 96-well growing tray with ED73 soil (Einheitserde Werkverband e.V., Germany) mixed with 7% sand and 4 g/L Osmocote Exact Hi.End 3-4M (ICL Group Ltd.). Seeds were stratified for three days at 4 °C in the soil for even germination and then transferred to controlled growth chambers (PAR 300 µM/m2s, humidity 60%) with inductive LD conditions (16 h/8 h, day/night) set to control (CT; 20 °C/16 °C, day/night) or high ambient temperature (HT; 28 °C/24 °C, day/night).
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