Preliminary Study On Population Restoration Of Endangered Plant Parrotia Subaequalis

Parrotia subaequalis is a tertiary relict plant endemic to China.It has been listed as a national Class I key protected plant and a protected species in The National Plan for Saving and Protecting Wild Plants with Minimal Population（2011-2015）.Due to the narrow and scattered distribution area,genetic difficulties,and human interference,the wild resources of this species are extremely rare,and the targeted conservation work is urgently needed.In order to better protect Parrotia subaequalis and increase its population,this study is carried out from seed germination,tissue culture and field regression of artificial population,in an attempt to provide basic data support for artificial breeding and population recovery of this species.The main test results are as follows:1.Seed germination experiment（1）The collection month had no significant effect on the germination rate and germination potential of seeds,but the sun drying treatment after seed collection could significantly improve the germination rate.Storage treatment is very important for the germination of Parrotia subaequalis,and the best way is cold storage,without storage treatment,the germination rate is 0.The germination rate and germination potential of seeds were significantly increased by soaking in water,under experimental conditions,the optimal germination rate and germination potential were 61.11%and 28.15%respectively with the optimal soaking time was 48h.（2）Substrate had significant effects on both seed germination rate,seedling growth and biomass accumulation.Under the experimental conditions,the matrix with the highest germination rate was perlite,which reached 83.33%.The growth potential and biomass accumulation of Parrotia subaequalis seedlings under peat soil substrate were the best.（3）The results of aseptic seed germination experiment showed that hormone concentration had a significant effect on seed germination rate.The germination rate of seeds reached 11.67%on MS+3%sucrose+0.9%AGAR was used as the basic medium,and2.0mg/L 6-BA and 1.0mg/L NAA were supplemented with.2.Stem tissue culture experiment（1）When explants were disinfected,0.1%Hg Cl₂ for 3min had the best effect.Under the experimental conditions,the pollution rate is 25.00%,and the survival rate is 46.47%.（2）The sampling time had a significant effect on the contamination rate of explants.October was the best sampling time,with pollution rate of 30.00%and induction rate of 21.67%.（3）The stem segment should be pretreated before inoculation.The time of low temperature pretreatment had no significant effect on the Browning rate of the explants,but had a significant effect on the induction rate of the explants.Dark pretreatment time had no significant effect on Browning rate and induction rate of Parrotia subaequalis.The pretreatment time of PVP had significant effect on the induction rate and Browning rate of the explants.The Browning resistance was the best when the temperature was 24h and PVP was3h.The Browning rate was 76.67%and induction rate was 13.33%under the experimental conditions.When 0.50g/L AC was added to the medium,the Browning rate was 48.33%and the induction rate was 25.00%.When 1.00g/L PVP was added,the Browning rate was 8.33%and induction rate was 80.00%.The induction rate and Browning rate of explants were significantly affected by adding different concentrations of AC in the medium.The induction rate and Browning rate of explants were significantly affected by different concentrations of PVP in medium.3.Return to the wildInvestigation was conducted on the growth of seedlings of 5 populations of Parrotia subaequalis returned to Jinzhai County Forestry Bureau in 2016,the results showed that the survival rate of the seedlings was 82%after five years of field return,and the growth potential of abandoned land was the best overall.The average ground diameter and height of the regression population were 4.55cm and 3.90m after 5 years of growth.