| Heracleum moellendorffii Hance is a perennial herbaceous herb of the umbelliferae,and it belongs to Heracleum L.,which is also known as mountain celery,short fruit celery,and large-leaved celery.Heracleum moellendorffii Hance was a shade-tolerant plant,which was mostly distributed in coniferous and broad-leaved mixed forests,wood forests,and in the valley wetlands.It is one of the major mountain wild vegetable species in the northeast forest region.Heracleum moellendorffii Hance whole plant can be used as good feed and it also has certain health care value as be used as medicine,such as promoting gastrointestinal movements,cleaning up the gastrointestinal garbage,etc.And it can also treat some diseases,such as rheumatoid arthritis,headache,hypertension,hyperglycemia and hyperlipidemia,etc.As a wild plant,the seeds of Heracleum moellendorffii Hance have dormancy characteristics.Due to the dormancy characteristics of Heracleum moellendorffii Hance seeds,some problems are encountered in the production such as lower and irregular germination rate,and longer periods of seedling growth,etc.And in order to solve these problems in production,four kinds of variable temperature stratifications were designed.The embryo development was observed,the morphological,physiological and biochemical indexes of seeds were measured by periodic sampling.Futhermore,the dynamic changes of these indexes and their relationship with afterripening of seeds were analyzed.This study provided a theoretical basis and technical support for revealing the dormancy mechanism of Heracleum moellendorffii Hance seeds,breaking the dormancy of seeds,developing its production in agriculture and adjusting the economic structure of forest area.The main results were as followed:(1)The embryo of Heracleum moellendorffii Hance seeds gradually developed from heart-shape embryo in late stage to torpedo-shaped embryo and finally formed the cotyledon embryo by the variable temperature stratification,and that indicated the achievement of morphological after-ripening.(2)Compared with the other three kinds of variable temperature stratification,the pattern of the third stratification(20°C,10 d→4°C,90 d→ 20°C,5 d)was more effective in promoting the completion of Heracleum moellendorffii Hance seed embryos,The seed embryos entered cotyledon stage firstly under the third pattern which was a cost-effective seed treatment method.(3)The seed of Heracleum moellendorffii Hance was treated with the model of the thrid(20°C,10 d→4°C,90 d→ 20°C,5 d),the length of embryo increased by 119.6% from 0.51 mm to 1.12 mm and the rate of embryo increased by 14.9% from 12.6% to 27.5%.In the process of variable temperature stratification,the duration of low temperature at 4°C had the greatest influence on the development of embryo,and the longer the time was,the better the seed embryo development was.(4)In the growth process of Heracleum moellendorffii Hance seed embryos accompanied by changes in nutrients.Although the specific process of nutrient changes in different variable temperature stratification was different,the overall trend was basically identicial.The content of soluble sugar changed from decreasing to increasing and then declined,while the content of soluble protein,starch and crude fat decreased in general.(5)The specific process of enzyme activity changes in different variable temperature stratification was different,but they roughly with the same trend.The activity of protease and amylase showed a first upward and then an decreased trend,and after that a upward trend,while lipase gradually increased. |
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