Study On The Change Of Endogenous Hormones During Flower Bud Formation And Regulation Of Blooming Time For Bougainvillea

In 2015, ‘Brasilliensis' cultivars of potted Bougainvillea grown in Nursery of Dashahe Park were studied the changes of endogenous hormones during the flower bud formation. And the ELISA method was used to measure the changes in phytohormones,including ABA, GA3 and IAA in the leaves. ‘Brasilliensis', ‘Rosa' and ‘Thimma' three cultivars of potted Bougainvillea were used to study the blooming time regulation. The three cultivars were treated in several ways, such as reduction of irrigation, pruning and using Paclobutrazol(PP333) and Chlorocholine chloride(CCC). The growth speed,flowering time, flowering branches situation and color of flower were recorded. Meanwhile,‘Brasilliensis' was used to study on effects of different light intensities and exogenous sucrose concentration on red pigment of flower. With a randomized block design, on the condition of different light intensities and sucrose concentration, the red pigment of Bougainvillea was tested systematically. All studies aimed to control and predict blooming time of Bougainvillea precisely through some treatments, and give more useful information for its application. The main results are as follow:1. The phytohormones including Gibberellins(GAS), Indoleacetic Acid(IAA), and bscisic acid(ABA) in leaves were analyzed. During the initial stage of flower bud formation, the content of GA3 in leaves kept high but contents of its and IAA were slightly lower. In the middle stage, the contents of GA3 and ABA increased gradually, and the content of IAA decreased and tended to steady. The ratio of ABA to IAA, ABA to GA3 and ABA to(GA3+IAA) present to descend trend.2. In comparison with the control, Pruning treatment was useful to ‘Brasilliensis' and‘Rosa' on making their blooming time earlier and making the flowering time of ‘Rosa'longer. To some extent, PP333 treatment can help blooming time earlier but delayed the full-bloom stage of all cultivars. Using CCC promoted these three cultivars blooming thanthat of control and it is apparent to ‘Brasilliensis' and ‘Thimma' that CCC treatment can prolong their florescence. The relationship between treatments of controlling water, using CCC and earlier flower blooming was more remarkable than other two treatments, and‘Brasilliensis' was more sensitive to those treatments than other two cultivars.3. Light intensities had influence on red pigment greatly. The flower color of ‘Brasilliensis' grown in natural light was magenta, under 60 percent of light the color became a bit of lighter, but under 30 percent light changed a lot and to be lilac-pink. With sucrose spraying,the content of red pigment of ‘Brasilliensis' in natural light seemed as if it would have no treatment, under 60 percent of light had no significant change but under 30 percent presented rising, and in some degree, being higher was caused by higher concentration of sucrose.