| Plumbago auriculata Lam.is the perennial evergreen shrubs and its origin is in southern South Africa,which is more than a year season flowering plants and flowers in four seasons in source area,so the types of flower bud differentiation is differentiation many times in one year.But after its introduction China especially in sichuan and in northern city,under the influence of the external environment,the flower bud differentiation time is only in summer and autumn,so flowering time is shorten,ornamental value is greatly reduced.Temperature plays a crucial role in the growth and development of plants,and it is one of the most important factors for plant growth.Studies have shown that it can influence the possibility of flowering and the rate of flower bud differentiation,which is an important node for plants to change from vegetative growth to reproductive growth.In this study,six-year-old plumbago auriculata seedlings and pot cuttings as the research object.Through phenological observation,the biological characteristics of cyanophora were understood,and the morphological structure of flower bud differentiation of cyanophora was studied by paraffin section method,and the changes of physiological substances in the process of flower bud differentiation were analyzed.At last,the optimum temperature of flower bud differentiation was found by temperature gradient treatment.The main results of this study are as follows:(1)After the introduction of plumbago auriculata into China,the evergreen plant has become a semi-dormant deciduous plant in sichuan basin.And the pattern of flower bud differentiation changed from several times a year to twice a year.(2)The branches of plumbago auriculata have one level,two level and three level branches respectively,and the flower buds are formed at the top of the first,second and third level branches.(3)The flower bud differentiation of plumbago auriculata process can be divided into: undifferentiated period,the early stage of the flower bud differentiation,flower primordium differentiation,sepal primordium,petal primordium,stamen primordium differentiation stage and pistil differentiation stage,pollen formation,ovary enlargement stage nine differentiation stage,which has certain correlation with its external form,can establish relevant relationship.(4)With the increase of temperature,the flower bud differentiation and flowering were faster.In the temperature range(25/21-31/27 ℃),as temperatures rise,the faster the vegetative growth of plumbago auriculata,flower bud differentiation began earlier,flower bud differentiation was faster and the beginning of flower is earlier.But leaves have pathological phenomenon under 31/27 ℃,the phenomenon of flower bud blasting appears and flowering time is short.So 28/24 ℃ should be a better choice.In the temperature range,too low or too high temperature will have negative effects on flowers bloom quality of plumbago auriculata,ornamental value of plant under 28/24 ℃ is the best.(5)The content of soluble sugar in leaves increased first and then decreased in the whole flower bud differentiation stage.The total consumption of soluble sugar was similar to that in leaves,but the change trend of soluble sugar in flower buds was different from that in leaves.The starch content in leaves and flower buds showed an irregular change trend,which first decreased,then increased,and then increased.The starch content in leaves was higher than that in flower buds.The content of soluble protein in leaf and flower bud was similar to the trend of change,basically the same,and both increased first and then decreased. |
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