Mechanism Of Selection For Stubbles And Their Adaptation In Domesticated Fritillaria Przewalskii Maxim

Fritillaria przewalskii Maxim.is one of the original plants of Fritillaria cirrhosa D.Don.It is a rare and endangered wild medicinal plant,wild breeding and domestication is the only way to protect its species diversity.In this study,based on the directedcultivation of Solanum tuberosum(MLS),Vicia faba(CD),Brassica campestris(YC),Angelica sinensis(DG)and Abandonment stubble(LH)in the alpine region,wild F.przewalskii was domesticated and cultivated for 3 years,and the selection of stubbles and ecological adaptation strategies for F.przewalskii with different growth years through phenology and growth adjustment,as well as internal relationship between soil microecology and phenological change,growth and bulb productivity were systematically studied.The aim is to explore the excellent stubble for domesticated cultivation of F.przewalskii,which is of great significance for the rational allocation of resources and cultivation of high-quality F.przewalskii.The main findings are summarized as follows:1.Compared with LH stubble,soil water content,p H,hydrolyzed nitrogen,available phosphorus,and available potassium content of DG and CD stubble were significantly increased,while the bulk density was decreased.As the depth of the soil layer increases,soil water content and bulk density increase,but the p H decreases.In the third year of domestication,the content of hydrolyzed nitrogen and available phosphorus decreased,and the total potassium,K⁺,Na⁺and Cl^-contents in each stubble soil were relatively stable.Compared with LH stubble,the activities of soil sucrase,urease,phosphatase,and catalase of CD stubble were significantly increased.During the prosperous period,the soil enzyme activity reached the highest value in each stubble.2.Before the domestication of F.Przewalskii,the soil basic bacterial richness(Sobs)of DG stubble was the largest,while the bacterial diversity(Shannon)and richness(Ace)of CD stubble in different years after establishment were the largest.The Shannon and Sobs indexes of fungi in CD,YC and DG stubbles were the largest in the second year of domestication.The main dominant bacterial communities in the soil of each stubble were relatively stable,and their relative abundance was in the order of Actinobacteria>Proteobacteria>Acidobacteria>Chloroflexi.The order of dominant fungal relative abundance was Ascomycota>Mucoromycota>Basidiomycota.Soil bulk density,sucrose and catalase activity are positively correlated with the abundance of Actinobacteria,and soil moisture,hydrolyzed nitrogen,urease and phosphatase activities are positively correlated with Proteobacteria abundance.Soil organic matter,p H,urease activity are positively correlated with the abundance of Ascomycota.Bulk density and urease,phosphatase,catalase activities are also positively correlated with the abundance of Mucoromycota.3.Compared with LH stubble,the SOD and POD activities of leaves and bulbs in DG and CD stubble were significantly enhanced.The content of MDA and the activities of SOD,POD and CAT in leaves were largest than those in bulbs.The SOD and POD activities of leaves were the largest in the vigorous growth period,while the CAT activities was the largest in the emergence and fall of the seedlings;the SOD,POD and CAT activities of the bulb were the largest in the falling seedling period.The three enzyme activities of leaves of each stubble were the largest in the third year of domestication.The TTC activity of the roots of each stubble was DG>LH>CD>MLS>YC,and they were the largest in the third year.4.Fritillaria przewalskii bulb rot disease aggravated with the increase of growth years.Four strains of F1,F2,F5,and F6(Accession:MH917682,MH917683,MH917686 and MH917687)were obtained from the isolating and identifying pathogens from the three-year pathogen isolation and identification,among which F2 and F5 were the main pathogenic bacteria,and the pathogenicity rates were as high as 95.0%and 94.8%,respectively.Through comprehensive morphological and DNA analysis,F1,F2,F5,and F6 were determined to be Clonostachys rosea,Fusarium oxysporum,Fusarium tricinctum,and Bionectria ochroleuca,respectively,and F1 was the asexual form of F6.The optimum temperature for growth and sporulation of F5 hyphae was 25?,while that of F2 hyphae was 25?and 30?.The optimum p H of F5 was 8,the lethal temperature of mycelium was 56?,and that of F2 was 6 and 61?,respectively.The most suitable carbon sources for F2 and F5 were sucrose and glucose,and the most suitable nitrogen sources were sodium nitrate.50%carbendazim was the most virulence to F2 and F5,with an EC₅₀of 0.01 mg?m L^-1,followed by 75%chlorothalonil and80%mancozeb.5.The emergence of F.przewalskii of each stubble seedlings to green and the fall of seedlings showed a dynamic trend of"slow-fast-slow",the emergence rate was DG>CD>LH>YC>MLS,the LH stubble felling was the earliest,but it was not significant between stubbles.Compared with 1-year-old,the time of turning green and falling seedlings of 2-and3-year-olds were 12 days and 20 days earlier,respectively.However,the rate of rejuvenation had been decreasing year by year,and the incidence rate had increased significantly.The morbidity rate of each stubble of 3-year-old students was MLS(5.58%)>DG(4.69%)>YC(2.55%)>LH(2.22%)>CD(1.97%).The content of alkaloids in each stubble increases with the increased in growth years.In the third year,the content of alkaloids in each stubble was DG(0.135%)>CD(0.130%)>LH(0.125%)>YC(0.122%)>MLS(0.119%).6.Based on the membership analysis of multiple indicators,the order of the comprehensive factors of each stubble was CD(0.84)>DG(0.57)>LH(0.52)>YC(0.38)>MLS(0.18).In summary,the domesticated F.przewalskii regulated its adaptation strategies to stubbles through phenology and growth and development.CD,DG and LH stubbles could optimize the rhizosphere micro-ecology,synergistically promoted its growth and development and the transformation and accumulation of internal qualities,enhanced its resistance to adversity,reduced the occurrence of diseases,and effectively improved the effectiveness of domestication.This study proposed an optimal stubble for F.przewalskii domestication and cultivation and its micro-ecological regulation mechanism,which could provide an important reference for the sustainable protection and utilization of F.przewalskii resources.