| Paeonia ostii is a famous ornamental and medicinal peony in China, is also an excellent bickiron of ornamental peony, so it has an important position in the industrialized production of the peony seedlings. However, Paeonia ostii seeds have a deep dormancy trait, which restricts the seedling production rate seriously. At present, there has been a lot of research on the use of gibberellic acid (GA3) and moist chilling to break the epicotyl dormancy of Paeonia ostii seeds, but the study of the other stage on Paeonia ostii seed germination is much less and the mechanism of various stages on Paeonia ostii seed germination has not carried out systematically.In this research, effects of the after-ripening and hypocotyl germination processes with constant-temperature stratification and different concentrations of GA3treatment, effects of breaking the epicotyl dormancy with moist-chilling treatments and different concentrations of GA3on Paeonia ostii seeds, and the effect of the seedling quality by these measures were studied. And the research analyzed the dynamic changes of internal nutrients and endogenous hormone content in the germination process on Paeonia ostii seeds, in order to reveal the physiological metabolic mechanism in the various stages of Paeonia ostii seeds, find a method which can break the dormancy quickly and access to high-quality seedlings, and provide a technical support for the production of cultivating high-quality and strong seedlings quickly. The main results are stated as below:1. Effects of constant-temperature stratification and different GA3concentrations on the physiological metabolism in the after-ripening process on Paeonia ostii seeds:The changes of nutrient content and rising and decliningand the balance of endogenous hormones in the after-ripening-related process of full Paeonia ostii seeds with constant-temperature stratification and different concentrations of GA3treatments were studied. The results were as follows:GA3could accelerate the conversion of starch and protein for providing adequate nutrients for the embryo growth; improve ZR, IAA and GA content, reduce ABA content, and increase ZR/ABA, IAA/ABA and GA/ABA ratio. So it was effective on promoting embryo growth and reducing the after-ripening time, and the higher the concentration was, the more obvious the effect was. While the nutrients had a slow transformation after the constant-temperature stratification and the increasing amplitude of endogenous hormones was inferior to the control, it went against the after-ripening process of Paeonia ostii seeds.2. Effects of constant-temperature stratification and different GA3concentrations on the physiological metabolism in the rooting process on Paeonia ostii seeds:The changes of the physiological metabolism in the rooting process on Paeonia ostii seeds with constant-temperature stratification and different GA3concentrations were studied. The results were as follows:All GA3treatments could take the rooting time in advance, they were also helpful to improve the rooting rate and the percentage of main root length≥4cm, and the rooting quality was better; while the constant-tempreture stratification went against. In addition, GA3treatments could improve the CAT activity, enhance the metabolic activity of Paeonia ostii seeds, accelerate the transformation of nutrients, improve the absolute content of ZR, IAA and GA (in particular, the content of GA and ZR), reduce ABA content, and increase GA/ABA and ZR/ABA ratio. So it was an effective method of shortening the rooting time, and the higher the concentration was, the more obvious the effect was. While the constant-tempreture stratification had a poor result.3. Effects of moist chilling and different GA3concentrations on the physiological metabolism and seedling quality during the process of breaking the epicotyl dormancy on Paeonia ostii seeds:The changes of the physiological metabolism during the epicotyl-dormancy-breaking process on the seeds of main root length≥4cm with moist chilling and different GA3concentrations were studied. The results were as follows:during the epicotyl-dormancy-breaking process, the nutrients and endogenous hormones contents had some big changes, for example, a significant decline in starch and protein content, while the soluble sugar content increased significantly; the content of ZR, GA, IAA increased to varying degrees, while ABA content continued to decline, and the higher the concentration or the longer the moist-chilling time was, the more obvious the effect was. Furthermore, ZR/ABA, GA/ABA, IAA/ABA ratio continued to grow, which ZR/ABA>1, so it is possible that during the epicotyl-dormancy-breaking process, ZR antagonistic effect of ABA was the most remarkable. And all treatments could shorten the epicotyl germination time, among them, moist chilling28days was the shortest, followed by moist chilling21days and300mg·L-1GA3treatment; and moist chilling21days got the highest germination index and rate. The study on Paeonia ostii seedling growth of various treatments showed that, GA3treatments increased the plant heights, petiole elongation and leaf area, and were helpful to the seedling biomass and the leaf soluble protein and soluble sugar accumulation, of which300mg·L-1GA3treatment had the best effect. Second, moist chilling21days also got a good effect, and its root shoot ratio was the biggest in all treatments, it can be inferred that moist chilling21days may cause the most potential follow-up growth on Paeonia ostii seedlings. So it is considered that300mg·L-1GA3treatment and moist chilling21days were both effective methods of breaking the epicotyl dormancy on Paeonia ostii seeds and also suitable for the seedling growth. |
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