Cornell University, Ithaca, New York
*Present Address: Punjab Agricultural University, Ludhiana (Punjab).
The effect of three photoperiods, 8-hour and 12-hour representing short days and 18-hour representing long days on time of flowering in two Phaseolus vulgaris L. lines was investigated. There was no difference between the effect of 8 and 12 hour photoperiods but under an 18-hour photoperiods, variety Great Northern was greatly delayed in flowering while variety Red Kidney was not affected. The flowering behaviour of parental and hybrid generations of the cross, Great Northern x Red Kidney, indicated that these two varieties differ by a single major gene. Variety Great Northern-1 has a dominant gene which caused delayed flowering under long photoperiod.
It was seen that in Great Northern-1 floral initiation had occurred under long photoperiod also but further development was delayed or completely inhibited.
