The Studies On The Floral Bud Formation Of Longan (Dimocarpus Longan Lour.) Induced By Potassium Chlorate

Longan trees were applied with potassium chlorate (KClO3) in soil in June and July 2001 and 2002, and the effects on inducing floral bud formation were investigated. The fluctuations of the length and diameter of summer shoots were measured, the changes of total protein, nucleic acid, starch, soluble carbohydrates and endogenous hormones in the leaves were also determined in period of floral bud formation. The results were as follows:1. Treatment B ( KClO3-K:TK)showed the best result on induction, and D (KClO3) is the second, that is to say, KClO3 added with CTK had better effects, but added with PP333, had poor effects.2. In general, the process of physiological differentiation in longan may lasts about 3 months, however, treated with KC103, the process was shortened to about 40 days.3. Treated with KC103, can not only induced floral bud differentiation in longan, but increased the length and diameter of the summer shoots which intended to be bearing shoots in the coining year.4. The content of starch in longan leaves decreased in the induction phase. At the start of morphological differentiation phase, the content of starch came to the minimum. The content of soluble carbohydrates increased gradually during the physiological differentiation phase, at the same time ,the content of fructose increased sharply. The content of sucrose increased, reached the peaks 47 and 41 days after treatment in B and D, and then declined.5. Contrast to CK, treated with KClO3, the content of RNA and the ratio of RNA/DNA in leaf increased significantly in period of induction. The fluctuation of RNA in the leaves of treatment B was similar to D, increased dramatically at first and then fell down, in CK the level of RNA was very low and didn't vary notably during the period. The content of DNA was similar to RNA but didn't change much between treatments and CK. The ratio of RNA/DNA increased during induction period and reached the peak before the morphological differentiation. The content of nucleic acid was continuously increased and reached the peak 47 days later, and in CK didn't vary obviously during the period.6. The content of protein in the leaves increased sharply, reached the peaks 47 days after treated with B and 36 days after D treatment, increased 145.17% and 88.05% of the content prior to treatment, respectively. Then the level of protein decreased gradually. In CK the content didn't change obviously and was in a lower level.7. ABA in the leaves was in a high level for 25 days, then fell down, the content of ABA in CK leaves was lower, in physiological differentiation phase and in morphological differentiation phase ,the content of ABA decreased, which suggested that higher level of ABA contributed to floral bud differentiation. The content of GA1+3 in the leaves was in a lower level in physiological differentiation phase and in morphological differentiation phase, increased to the peaks. The content of IAA in treatment B was different from D. In B, IAA increased at first and then declined in physiological differentiation phase, but in D it decreased at first and then rose. In morphological differentiation phase, the content of IAA kept in a high level. During the period, the content of IAA in CK didn't vary significantly .The content of ZRs in the leaves of treated trees was 2-3 times to the CK, and gradually decreased in the induction period, the content of iPA was 1/7-1/10 of ZRs, and had no regularity.8. The balances between different endogenous hormones also showed important roles in the KC103 inducing floral bud formation. Lower IAA/ABA, lAA/ZRs: higher IAA/GA1+3, ZRs/ABA ABA/GA, ZRs/ GAH3 all contributed to floral bud differentiation.