The study was conducted in the fiberglass house ،College of Agriculture - University of Kirkuk (35.53 North, 44.38 East) during September 2015 to April 2016, In order to study day length and spray of cycocel concentrahions (0, 1000 , 2000 ) mg. L-1 in the Vegetative growth and Flowering of Poinsettia plants، Experiment carrid out according to the design of Randomized complete block (RCBD) with in a split plot experiment، With three replicates .
The results can be summarized as follows:
1-The Treatment short day (9 hours) led to increase of leaf area the rate (865. 45) cm2 and age coordinating plant (129.50) day. While the resulting high concentration of cycocel to reduce the plant high and the number of bract per plant and dimeter bract.
2-The intraction between the length day and spraying of cycocel, significant effect, As given treatment of short day and spraying of cycocel (1000) mg .L-1 increased of leaf area (881.55) cm2, and prolong the time needed for the emergence of color in bract as it took the longest time when the treatment of intraction between the shortening day length and spraying of cycocel (2000) mg. L-1 was (29.85) day and number bract per plant when the treatment of intraction between the shortening day length without adding cycocel was(3.81) bract per plant, at treatment of the shortening day length and spraying of cycocel (1000) mg. L-1 it give higher dimeter bract reached (24.83) cm, and when the treatment of the shortening day length and spraying of cycocel (2000) mg . L-1 Recorded the longest life of the plant the coordinating took (131.31) day.