Method for controlling flowering time of plant

A method for controlling flowering time of a plant, which comprises bringing a plant into contact with copper ions, wherein the plant has been transformed with the following DNA constructs (i) and (ii):

• (i) a first DNA construct comprising a nucleotide sequence encoding a chimeric transcription factor, wherein the chimeric transcription factor comprises the following a) and b) as operably linked elements:
• a) a DNA-binding domain of a first transcription factor that is capable of being activated by copper ion, and
• b) a transcriptional activation domain of at least one second transcription factor that is different from the first transcription factor;
• and
• (ii) a second DNA construct encoding a heterologous gene which controls flowering time of a plant, wherein the gene is under the control of a heterologous promoter capable of being stimulated by the chimeric transcription factor of (i) in the presence of copper ion.