| The tree peony originated in our country. As an ornamental plant, it has a history of 1600 years or so from wild to cultivated species. At present, the tree peony is an especially important resource of the tourism and sight-seeing agricultural industry. It has mainly two uses. First, a large number of seedling trees are exported to be used in the building of ornamental gardens of tree peony in alien land; Second, a lot of strong seedlings of tree peony are needed to force flower anti-season, especially on the Spring Festival, to meet the ornamental demand. There are about 1,000,000 tree peony in the market of the whole country during the Spring Festival every year, which can gain an output value of about 200 million yuan annually. Viewing and admiring the tree peony on the Spring Festival has already become a kind of elegant fashion.Using the traditional technology of forcing flower anti-season, people can force "the untimely flower" on the Spring Festival. But because people fail to have a full understanding of the ecological habits, the biological characteristics and the law of the physiological and biochemical changes during the process of forcing flower, especially the mechanism of forcing flower of tree peony, the quality of the forced flower is low, and the blossoming is not on schedule and even the failure of the forced flower is sometimes inevitable. So, for the practice of forcing flower anti-season of tree peony it is an important subject to be solved to build a general technological systems of forcing flower anti-season by studying the law of growing of tree peony, the biology characteristic of blooming and probing the mechanism of forcing flower anti-season in winter, which is also urgent for developing the industrialization of tree peony.The main purpose of this research is to probe the law of growth and the biology characteristic of the blooming of tree peony, focusing on 3 key links of forcing flower anti-season of tree peony, the forming of strong tree peony seedling—the dormancy and its' removing of tree peony'-th'e techniques of artificial forced cultivation in protecting field. Firstly, researching the growth of tree peony during the process of forming Strong seedlirigs and strong buds, from the building of form of tree peony bud, the photosynthetic characteristics during the process of tree peony growing in field and the dynamic accumulation of the photosynthetic production, the main nutrimental material and of the hormone material, to offer the theoretical foundation for establishing the measures of cultivating the strong seedling of tree peony; Then, study the dormancy of tree peony ,the chilling requirement of breaking dormancy and the changing law of the various kinds of nutrition materials and hormone materials in the process of breaking dormancy during the process of blooming of forcing flower anti-season of tree peony, to offer the theoretical foundation for'building the technology of forcing flower anti-season of tree peony; Finally, study the technology of prolonging the florescence of tree peony in the process of forcing cultivating, in order to increase the ornamental quality of tree peony and build a scientific technology system of forcing flower anti-season in winter. The following are the main results of the study: I. Form occurring of tree peony bud and its life cycleThe bud of tree peony is mixed bud by observation. And its process of differentiation begins from the original body of axillary bud and ends with the blooming and bearing fruit. It lasts three annual periods, actually 25 months. During the first annual stage, mainly the young' generation of axillary bud primitive body is produced, the Second annual periods the flower primitive body, and the third annual bloom arid bear fruit.The growth of mixed bud of tree peony includes two stages: the nutrition grow and the reproduction grow. And the critical point of qualitative change is from the organization of dividing of primitive body to the end of formingleaf primitive body. If the condition of nutrition and hormone is suitable, from the nutrition growth it will turn to the reproduction growth, and then form the flower primitive body. Otherwise, the growth will stop at the stage of forming leaf primitive body, and can only form leaf bud. So, not every axillary bud primitive body can form mixed bud.Take the mixed bud in the second annual periods as maternal generation bud, the top dividing organization of maternal generation bud mainly produces leaf primitive body, first filial generation mixed bud primitive body and flower primitive body during this year. The growth of first filial generation mixed bud primitive body is during the second annual periods next year, and then produce the second filial generation bud primitive body in the axilla of the leaf primitive body; and in the second annual periods of the second filial generation bud primitive body, it produces the third filial generation bud primitive body; it will cycle to-and-fro until the death of tree peony plant.The best time of the tree peony transplantation is September - October, for it's just the right moment when the maternal generation mixed bud is forming the flower primitive body, and the embryonic form of the young flower bud has already been established. It can unquestionably blossom and bear fruit the next year after transplanting and surviving. But because the first filial generation bud primitive body is in the second annual periods at this moment, and because the root system can be damaged by transplanting, it is unfavorable for the growth of the first filial generation bud primitive body and the growth will stop at the stage of leaf primitive body only to form leaf bud in the end. That's also the reason why tree peony seldom blossoms next year after grafting.According to the law the growth of mixed bud, the management of cultivation, such as applying fertilizer and watering can be used to promote the formation of vigorious seedling, and strong buds, thus achieve the best result of blooming. There are direct relations between the life periods of mixed bud and the forced cultivation anti-season. Only when the transplantation occurs after the flower bud differentiation has finished can we achieve successful forced flower.II. Photosynthetic characteristics of tree peony leavesThis paper studied the photosynthetic characteristics of two tree peony variety, cv. Dahuhong and cv. Wulongpengsheng, under the condition of field cultivation. The result shows: the chlorophyll content of these two tree peony varieties during the growth process is about 1 mg. dm"2, and its changing trend appeared increasing from the early April to June. At the early June, the chlorophyll content of cv. Dahuhong reaches the supreme value, and at the late June, does the chlorophyll content of cv. Wulongpengsheng. After that, the chlorophyll content of these two varieties begins to decrease gradually. But there is a difference that the decreasing of the chlorophyll content of cv. Dahuhong is earlier and faster than that of cv. Wulongpengsheng and the chlorophyll content of cv. Wulongpengsheng is slightly higher than that of cv. Dahuhong.Under the condition of field cultivation, generally the net photosynthetic rate of tree peony leaf is about 12|jmol. m"2. s*1. During the annual periods of tree peony, the persistent period of high photosynthetic rate and the accumulation period of photosynthetic production of leaf usually falls in April, May and June. So, strengthening management, such as fertilizer and watering during this period, to increase the accumulation of photosynthetic production is important to promote the division and growth of flower bud, cultivate strong seedling and strong flower bud, force flower anti-season, and to improve the quality of blooming. In mid-June, as the environmental condition worsened, the photosynthetic capability of tree peony reduces dramatically. But different tree peony varieties still have differences, compared with cv. Dahuhong, the photosynthetic capability of cv. Wulongpengsheng is higher.We studied the diurnal variation in the photosynthetic efficiency and fluorescence parameters in leaves of field tree peony by using gas exchange observation and the technology of analyzing chlorophyll fluorescence. The results indicated that the curve of diurnal variation of tree peony net photosynthetic rate (Pn) was demonstrated two peaks in clear day and appearedmidday depression of photosynthesis at about 12:00 o'clock, and the apparent quantum yield (AQY) displayed a significant midday decline but the carboxylation efficiency (CE) would enhanced when light intensity increased, and chlorophyll fluorescence parameters Fv/Fm and FO demonstrated single peak, which decreased obviously in the midday and was different from the curve of FO. These results showe that PS II reaction center exhibits a dynamic change on revisable inactivation and PS II function exhibits obvious down-regulation and photoinhibition under strong midday light. Under the condition of strong light, high temperature and low humidity, the photoinhibition is the important reason of influencing the photosynthetic ability of mesophyll cell.For the photoinhibition of tree peony leaves, we studied the effects of shading on photosynthetic characteristics of field tree peony leaves. The results indicated that the net photosynthetic rate (Pn), apparent quantum yield of photosynthetic (AQY) and carboxylation efficiency (CE) of the shaded tree peony leaves were higher than those in the field. Shading made photosynthetic active radiation (PAR), air temperature (Ta) and leaf temperature (Tl) decrease, and stomatal conductance (Cs) and leaf temperature (Tr) and the internal leaf C02 pressure (Ci) increase. The chlorophyll fluorescence parameters Fv/Fm and Fm of the shaded tree peony leaves changed slightly. Shading hardly affected the FO. This indicates that shading can lessen the photoinhibition caused by strong light and high temperature. Under the condition of high temperature, low humidity and strong light, shading can alleviate the decomposition of the chlorophyll level of tree peony and improve the net photosynthetic rate properly, which is important to promote the accumulation of photosynthetic production, the dividing and forming of flower bud, and the forming of strong seedlings and strong buds of tree peony. So shading the field of tree peony in every June is a new measure for the cultivation of tree peony with high quality and high yield. There is no report on the biological characteristics of tree peony, so this research and be regarded as an creative research. III. Dynamic changes of the accumulation of nutrition material and hormonematerial of tree peony in the fieldThis thesis studies the dynamic changes of soluble sugar, starch, free amino acid, and soluble protein, etc. in the organs such as leaves, the root systems, the branches and the flower buds during the nearly 6 months after blooming in the tree peony annual periods of these two varieties. The results show there is an increasing trend of accumulation of soluble sugar and starch in the leaves, the root systems, the branches and the flower buds, accumulating slowly before August and faster after August. The accumulating rate of soluble sugar and starch in flower buds is obviously faster than that in any other organs. And these two varieties appear the same trend. But there are slight differences in the accumulation of leaves. The accumulation of soluble sugar and starch can reach the maximum at the end of August for these two varieties, but it is not until September that the accumulation of soluble sugar of cv. Wulongpengshengreaches its maximum and then decreases gradually.The accumulation trend of free amino acid and protein of the two varieties is unanimous, accumulating slowly in prophase, accelerating in metaphase and slowing down and reducing content in anaphase. The accumulating dynamic of the branches, the root systems and the flower buds is roughly similar. The content in the leaves reaches the maximum at the end of August and reduces later.From the analysis of the dynamic changes of photosynthetic capability of tree peony leaves, it is can be concluded that the persistence period of the high photosynthetic rate is from April to June. During this period the accumulation of the photosynthetic production should be fast too. But according to the accumulating dynamic changes of starch, soluble sugar, free amino acid and protein, it is slow on the contrary. This indicates that the photosynthetic production is used mainly for the growth of each organs of tree peony. This period is the chief period of the growth of each organ in tree peony, and the photosynthetic production is used mainly for growth while the accumulation is little.Before August, the metabolism of different materials in each organ of treepeony is centered on growth. After August, with the changing of the weather, the metabolism of different materials changes into the center of storing materials. And with the leaves and branches stop growing and the leaves senescence, the macromolecule material in the leaves are,changed into small molecule material transported to the branches, the root systems and the flower buds and stored there, which makes preparations for blooming in the process of growth in the coming year.In the annual growth period, after tree peony bloomed, the dynamic changes of the content of IAA, GA3 and CTK accumulated in the various organs accords with the growth trend in the yearly growth period of tree peony.With the dynamic change of the content of GA3 and the pattern observation of the growth and development of tree peony, the leaves of tree peony nearly stopped growing in the late June , the.growth of branches nearly completed in the late August , the pattern of flower buds nearly formed in September , and after August , the roots entered growth peak. The dynamic change of the content of GA3 was identical with the growth of tree peony.IAA demonstrated similar change trend withGA3, which was also identical with the trend of growth and development of tree peony.The dynamic accumulation of CTK was also similar with GA3. Dahuhong and Wulongpengsheng demonstrated same change trend. The results indicate that IAA, GA3 and CTK produced in tree peony are of positive regulation function to the growth of the plant.From the analysis of the change trend of content of ABA in the above two varieties, the high content of ABA in the various organs, especially in leaves before July, was related to the stomata movement in leaves under high temperature, draught and strong light in growth seasons. Under these conditions, stomata made shutting regulation in order to adapt to the adversity. ABA switched on and took part in the process. In the later period, the content and compound rate of ABA decreased maybe because rainy season increased the air humidity. With the temperature becoming lower after late August, the content of ABA increased again,which was related to the physiological process, including switching on and regulating the leaves dropping, finishing yearly growth period and entering dormancy period, etc. Compared with Dahuhong, the growth of Wulongpengsheng was better, its leaves getting yellow and dropping about half month later and increasing again later, too. But during the period, the content of IAA, GA3 and CTK was very low. These results further showed that ABA switched on and took part in the senescence and dropping of leaves, and the end of yearly growth period and the dormancy of flower buds in tree peony IV. Mechanism of forcing flower anti-season of tree peonyThe research indicated that the natural low temperature around 0-10°C is most suitable to the breaking of dormancy. Chilling requirements during dormancy release by low temperature were studied on Paeonia suffruticosa cv. Da Hu Hong. The results showed that the estimated chilling requirement by Utah model was 650c. u, and the accumulation of low temperature had decisive effect on the growth of tree peony flower buds, and the process of dormancy released by low temperature is also the "later-growth' process of tree peony. The nutrient substance also has important influence on tree peony pressing for flower.The content of soluble sugar, starch, soluble protein and free amino acid of tree peony flower buds during dormancy release in low temperature environment were constantly measured. The change in nutrition can reflect the process of domancy release. When there is an insufficient nuturtion, it is hard for the bloosm to occur even if the domancy has been released. Therefore, the content of nurtrituion elements is of critical importance to the bloosming of the tree penoy.At the same time, the content of GA3, ABA, IAA and ZR during dormancy release in low temperature environment were determined. The results showed that GA3 was the positive hormone factor, while the function of ABA was contrary to GA3, and ZR also had a certain positive function during the process of dormancy release, but the function of IAA was not obvious. The function of adjusting and controlling dormancy release that hormone has may depend on the balance of all the hormones.V. Study on the florescence prolonging of tree peonySome physiological and biochemical changes of petals during the process of senescence of tree peony were studied. These results showed that during the period of blooming and senescence of tree peony the soluble protein content in both petals and leaves increased at prophase, then began to decrease at anaphase. The content of MDA and 02~, and the membrane permeability was increasing with the senescence of petals, and the activity of SOD was reducing. The trend of the quantity of ethylene release was high-low-high, and petals fluctuated more obviously than leaves, which corresponded to the result of morphologic observation. Relative analysis showed that soluble protein content didn't correlate to concentration of free amino acid, probably because of nutrient transportation. Soluble protein content and membrane permeability for petals obviously correlated to MDA, SOD and 02~ etc., which was not the same as those of leaves. Two peaks of ethylene release rate nearly correlated to senescence of tree peony flowers, but had no correlation with other indexes. Therefore, senescence for tree peony was caused by programmed cell death for universal action of many factors.The effects of Calcium on photosynthesis characteristics of tree peony were studied by using the Arnon and Hoagland nourishing liquid containing calcium 80mg/L—240mg/L The results indicated that the saturation light of photosynthesis in tree peony was around 750pmol ? m"2 ? s\ the light compensation point was 80pmol ? nf2 ? s"'; C02saturation was around 1500|jl ?!/"', C02compensation point was 50jj1 ? L~'; carboxylation efficiency was 0.0402-0.0586pmol CO2 ? mg"'Protein ? min"'. In addition, it was found that Calcium of proper content may improve the leaves' stomatal conductance, transpiration rate, activity of RuBPCase, carboxylation efficiency and photosynthetic rate. And the results showed that it's better to use nourishing liquid contained calcium 160mg/L.The physiological and biochemical changes during the senescence of tree peony flowers were studied with different Ca2+content. It showed that with the increase of Ca2+ content, group blossom period could be prolonged for 1-2 days,...
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