| Acer yanjuechi is a deciduous and ancient relic tree of Aceraceae Acer,was originated in an altitude of 750?900 meters of subtropical evergreen,eciduous broad-leaved mixed forest,is one of the 2nd grade protected and endangered plants in China.It is of the great value in scientific researches and landscape application.In this paper,the habitat conditions,biological characteristics,female gametophyte,dormancy breaking ofseeds,was studed and the endangered mechanism,the scientific and reasonable conservation strategies was discussed.The main results are as follows:(1)The soil nutrient analysis and investigation of habitat conditions of artificial planting Acer yanjuechi in Nature Reserve of Tianmu Mountain,Provided a scientific basis for artificial planting of Acer yanjuechi.There exited larger amplitude of soil nutrientamong the different sites,which organic matter 52.4?217.25g·kg-1,alkali-hydrolyzed nitrogen 170.82?573.41mg-kg-1,available phosphorus 7.85?20.25mg·kg-1,rapidly available potassium 140?450mg·kg-1.Soil nutrients nitrogen,phosphorus and potassium imbalance,high nitrogen content,and lack of available phosphorus.acidic soil.The survey found that the Acer yanjuechi strong growth and good solid in sunny place,soil nutrient,pH,light condition and shade density of Acer yanjuechi could greatly influence the growth and development.(2)Acer yanjuechi buded in early April and flowered in mid-April,primary fruit in late April,fruit ripening by the end of September.Due to the genetic characteristics and its own ecological environment in which the same species exhibited variousblossom phenology in different distribution.As for the inflorescence,the apex of main axis inserted mostly of bisexual flowers,few of male flowers.(3)Development of female gametophyte:This paper studied the development of female gametophyte of Acer yanjuechi by using normal paraffin method.The ovary has two loculus with two anatropous ovules in each and the ovule is bitegminous,crassinucellate on the axile placentation.The megasporocyte divides into four megaspores in line type after meiosis and only one megaspore in chalaza end usually is the functional one.The embryo sac belongs to the polygonum type.Acer yangjuechi female gametophyte development period,ovary 2 indoor respectively can see 2 anatropous ovules,most of which only one in the late develop into seeds;megasporogenesis in Acer yanjuechi and embryological development,the emergence of ovule abortion,Pearl heart sac tissue degradation and cell death and,therefore,croissants maple serious reproductive disorders in female gametophyte development process,but also an important reason for its endangere.(4)Acer yangjuechi is on the extremely endangered situation.The seed development test of two different individuals planted in National Nature Reserve of Tianmu Mountain,Zhejiang province,was conducted in 3 continuous years.The seed dormancy mechanism and dormancy releasing techniques were studied.The results are as follows:embryo development rate is much lower and differentiated between the two different individuals.The average percentage of well-developed seeds floated from 7.81%to 31.81%and the average seed viability was 52.22%.The methanol extractants from testa and embryo had the higher inhabitation effect on seed germination of cabbage seeds than that of from endotesta.The germination rate increased significantly by moist storage of gtesta-removed seeds at 5?,and combined with exogenous hormone solution soaking of 100mg·L-1 GA3 or 200 mg·L-1 6-BA for 12 hours promoted the germination rate reaching to 46.67%and 43.33%respectively,over 80%seeds of viability germinating. |
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