Studies On Morphology And Changes Of Physiology-Biochemistry During Flower Bud Differentiation In Oncidium

In this thesis, the paraffin cut was used to study the flower bud differentiation morphological characteristics of Oncidium'milliongolds', and the changes of physiology-biochemistry was determined during flower bud differentiation. The changes rhythm of the flower bud differentiation process was probed. Then, the effects of spraying treatments with different kinds and concentrations of plant growth regulators on Oncidium florescence were studied. The main study results were as follows:1. The results showed that flower bud differentiation process could be divided into six phases:initial differentiation phase, inflorescence priomdium differentiation phase, flower primordium differentiation phase, sepal primordium differentiation phase, petal primordium differentiation phase, and column and pollinia differentiation phase.2. During flower bud differentiation, the content of soluble sugar, soluble protein and nucleic acid in the leaves were determined. The results were as follows:The soluble sugar content in leaves decreased remarkably till reaching its minimum value at flower bud differentiation period, a stable increase was observed afterwards. Soluble protein content in the leaves decreased sharply and then increased, and the maximum of protein content occurred in the new bud sprouting period. Overall, the content of nucleic acid declined.3. The changes of sugar and protein during the development of flower bud were studied by slicing up and histochemistry coloration. The results showed that the polysaccharide and protein were mainly in or around the primordium. In inflorescence primordium differentiation phase, the content of polysaccharide was little, while protein was rich and distributed uniformly. With the continued differentiation of the flower bud, polysaccharide and protein occurred abundantly in sepal primordium differentiation phase, and they decreased as a visible grads in petal primordium differentiation phase. The polysaccharide and protein focused on column and pollinia during column and pollinia differentiation phase.4. Changes in soluble polysaccharide and soluble protein content of Oncidium buds during flower bud differentiation were studied. The results showed that the content of polysaccharide began to increase and declined in petal primordium differentiation phase, then gradually increased till rising to a peak. The content of soluble protein showed great changes during flower bud differentiation.5. The effects of spraying treatments with different kinds and concentrations of plant growth regulators on Oncidium florescence were studied. The results showed that the blossom date was significantly accelerated by spraying 200 mg·L-1 GA3 and oGA3(200mg·L-1)+6-BA (25mg·L-1), compared with the control treatment (no spraying growth regulators). Single treatments with 6-BA could improve the rate of flower bud differentiation but cause the flower getting smaller. When spraying GA3+6-BA, it was not only to enlarge the flowers size, but also to prolong stalk length. It was significantly prolonged the blossom time under the treatments by spraying 200 mg·L-1 and 250 mg·L-1 PP333, while the 250 mg·L-1 treatment was the best. Under the treatment by different concentration of PP333, the stalk length was decreased. There was no remarkably effect on first internode width of pedicle in all growth regulators treatments.