Study On Characteristics Of The Flower Bud Development And Blooming Control Of Rhododendron Delavayi

The experiments were conducted to study the change of external form, internal organization structure and physiological indexs during the flower bud differentiation and development of Rhododendron delavayi. Based on the temperatures of Guangzhou and Hezhang, comparing the differences of physiological indexs during flower bud differentiation and development, the research explored the ways of florescence control by different concentrations of plant growth regulators and mineral nutrition preliminary treatments. The main results are as follows:1. In terms of external form, the flower bud diameter rising speed was slow at the begining then fast. It took 49 days for bud diameter became double than branch diameter, and 37 days for that to reach 3 times. The internal development of terminal bud is different despite of same collection time. It indicates that the flowering stage doesn’t reach a time point, but a period.2. In terms of internal morphology, Sepal primordium and petal primordium were formed at the same time. The R. delavayi bud differentiation process was divided in five stages: early stage of differentiation, the little flower primordium growing period, the sepals petal formation, the stamens formation period and pistil formation period.3. During the flower bud development, the total nitrogen content of the plant crown leaves remained unchanged, while the soluble sugar content was gradually diminishing. The C/N rate would gradually diminish at the same time.4. Comparing the samples of two places,the flower bud intamescentia was different, while the changes of leaf physiological indexes kept the same. The bud diameter/branch diameter kept rising in Hezhang, which reached 3 times in September, while it remained 1 time in Guangzhou.5. Comparing the crown bud differentiation rate from two places, it reached 77.8% in July and 86.7% in August in Hezhang area, while 22.2% in July and 6.7% in August in Guangzhou area. The result showed that high temperature is a restraining factor to the flower bud differentiation of R. delavayi.6. The experiment of blooming control, show that the flowering day could be changed by chemical ways. The IAA500mg/kg, NAA100mg/kg, GA3100mg/kg and F1(N:P:K=1:1:1) treatments were good for the buds swelling. The IAA500 mg/kg, NAA100 mg/kg, GA32000 mg/kg and F1 treatments could promote up the flowering time by 16.2d、22d、17.7d、7d separately, while the IAA10 mg/kg, NAA1000 mg/kg, GA31500 mg/kg, F2(N:P:K=1:2:1) could delay the flowering time by 9.3d、17d、11d、15.4d separately.