2.1 Plant materials and growth conditions
The oslhy mutants were generated by the CRISPR/Cas9 system on the Nipponbare (WT) background. Mutants and WT were grown in the field under natural summer conditions (day length >13.5, natural LD). The oslhy mutants and WT were also grown in the growth chambers at 30°C under LD photoperiod (14 h light/10 h dark) and SD photoperiod (10 h light/14 h dark), respectively. Heading date was recorded when the first panicle emergence to about 2 cm from the leaf sheath after germination.