Regulating flower and tuber formation in potato with light spectrum and day length

Solanum tuberosum (potato) can reproduce through tubers and through seeds. Recent developments have enabled hybrid breeding and propagation from seeds in this crop. This makes potato flowering a new focus of research interest. Tuberization and presumably flowering, followed by seed set, are strongly regulated by environmental cues. A well-studied environmental regulator of tuber formation is day length. Photoreceptors are involved in this photoperiodic control of tuberization, suggesting light spectrum may be an important factor for tuberization. However, it is not known how photoreceptors control potato flowering. Here, we aim to elucidate the influence of light spectrum and photoperiod on tuber and flower formation, by growing three potato genotypes in climate chambers with light-emitting diode (LED) lighting and additional far-red and blue LEDs under long and short days. Far-red light accelerated tuber formation up to eleven days and blue light slightly delayed it up to four days. An effect of light spectrum on flowering was not found. Long photoperiods delayed tuber formation compared to short-day conditions in two of the three tested genotypes. Aside from one genotype which only flowered in long-days, no effect of photoperiod on flowering was found.