Studies On Cultivation Of New Cultivars Of Phlox Paniculata In Beijing Area

Characristics on Flowering control and vegetative propagation of three new cultivars of Phlox paniculata were under a series of experiments in Beijig area,The results can be summerised as followe:1 . The early stages of Visible floral buds on the three cultivars were microphotographed from middle of May to the beginning of June .The relationship between air temperature and the time to flower on 'Tai hongzi' is discussed,As the air temperature raises from 16℃ to 28℃ ,the time to flower decreases from 16 to 33 days.2. The capability of blooming within one year is compared among tissue-cultured young plants, rooted cuttings, and two-year old plants . Young plants are not able to bloom completely within one year except two-year old plants,3. At the early time of the spring , the rooting rate on 'Baixue' and 'Xinghong'was 92% and 75% respectively .During the summer time when the effective day-length ranged form 14.5 to 15.75 hours, the rooting rate on both were less than 30% ,and at the same time more rooted cuttings were got by using short-day grown mother stocks. These results don't support the ideal to build up a P. paniculata nursery to make cuttage year around in Beijing .4. Surviving rate for tissue-cultured young plants to transplant are improved 30% more and reached 100% by spraying exogenetic GA3 during winter time, while the net photosynthetic rates (P_N) and Chlorophyll contents are not influenced by exogenetic GA3 at different gradients .The reason for GA3 to improve the survival rate is discussed .5. Effects of exogenetic GA₃, night-interruption and type of young plants on the flower date for ' Tai hongzi ' is observed. Time to flower are decreased 67,47,42,29days separately, and varied with different treatment. Statistic analyse shows that the stem lenghth, days to flower and the number of flowers are influenced significantly by night-interruption , GA3 increased the stem lenghth , flower number and the thick of stems ; Stem thicks are also influenced significantly by the type of young plants...