GROWTH AND FLOWERING IN ROSES

Increasing temperature nastened flowering and the number of flowers in each flush was increased. At 18°C, 3–3.5 times more flowers per plant were harvested, compared with a constant temperature of 12°C, due to lower blind shoot formation at high temperature. With fluctuating day and night temperatures, an average temperature of 18°C produced approximately the same yield as a constant temperature of 18°C. Low temperatures released apical dominance and stimulated lateral shoot branching.

Day extension lighting with incandescent lamps (low R:FR ratio) inhibited lateral bud growth and induced blind shoot formation, while lighting with fluorescent lamps (high R:FR ratio) had the opposite effect. The use of red (R) and far-red (FR) lighting showed that FR inhibition of bud growth and flowering could be overcome by subsequent R lighting. These findings indicate that blind shoot formation is controlled by the phytochrome. The role of temperature and light quality on the assimilate supply to the buds and young shoots for optimum bud sprouting and flowering will be discussed.

Download Adobe Acrobat Reader (free software to read PDF files)