2002 Volume 71 Issue 6 Pages 765-769
Petunia×hybrida Vilm. plants were exposed to different photoperiodic cycles and light qualities to investigate their shoot development and flowering responses. Plants were reciprocally transferred from long-day (LD), extended by day-extension light by using either far-red rich tungsten light (TL) or red rich cool fluorescent light to short-day or vice versa. To produce commercially a high quality petunia having a compact shape and a number of flowers under insufficient light conditions, the initial 15 LD cycles (8-hr daylight followed by 8-hr TL) was most effective. The 30 LD cycles extended by TL resulted in excessive shoot elongation with poor quality. The results indicate that it is possible to improve the shape of petunia plants by using an optimum photoperiodic cycle and light quality.