Botanical Gazette, 144(2): 231-233 (June 1983)
Photoperiodic Flowering Responses in Hybrid Progenies between Latitudinal Ecotypes of Chenopodium rubrum L.
Takeshi Tsuchiya, Yoshio Ishiguri

Abstract
Photoperiodic flowering responses in hybrids between latitudinal ecotypes of Chenopodium rubrum, Sel-372 (day-neutral plant) x Sel-184 (short-day plant with a critical night length of 8 h), Sel-184 x Sel-372, and Sel-372 x Sel-194 (short-day plant with a critical night length of 10 h), were examined. In F1 plants, no flowering responses were observed under a 24-h photoperiod but were observed under a short-day, 8-h photoperiod The F2 progenies showed similar photoperiodic flowering responses in all cross combinations: 100% flowering under 8-16-h photoperiod but a drastic drop to ca 20%-30% under 18-h photoperiod and below 20% under 20-24-h photoperiod. These characters in F2 progenies, a drastic drop in 18-h photoperiod and the flowering response under 18-24-h photoperiod, were introduced from a day-neutral line, Sel-372. The flowering response of F2 progenies suggested that the day-neutral flowering response of Sel-372 was constructed from two different flowering responses: (1) a short day with a critical night length of 6 h and (2) 18-24-h photoperiod

See: Griesel: Photoperiod and Cestrum (1966)