Establishment Of Rapid Propagation Of Heuchera Micrantha Tissue Culture And Response Of Asexual Seedlings To Drought Stress

Heuchera micrantha is a foliage flower with high ornamental value and a promising market.In this paper,the rhizome of Heuchera micrantha was used as the explant,and different sterilization times and hormone concentrations were used to screen out the best medium formulation for each stage of tissue culture of Heuchera micrantha,and to establish a rapid propagation system for Heuchera micrantha.At the same time,PEG-6000 was used to simulate drought stress in Heuchera micrantha seedlings,and PEG-6000 at different concentrations(5%,10%,15%and 20%)was used as the control to determine the changes of growth,physiological and photosynthetic indicators of Heuchera micrantha under different degrees of drought stress.This study was conducted to investigate the drought resistance of Heuchera micrantha and to provide a theoretical basis for the introduction of Heuchera micrantha in Northwest China and to determine the water management methods.The main results of the study are as follows:1.Establishment of a rapid propagation system for Heuchera micrantha tissue cultureExplant sterilisation:The explants were selected from the rhizome of alum root,and when sterilized with 0.1%HgCl2 for 14 min,the survival rates of Heuchera’Cracked Ice’,Heuchera ’Caramer’and Heuchera’Cherry Cola’ were the highest,which were 35.64%,39.76%,and 38.90%respectively;when sterilized with 0.1%HgCl2 for 16 min,the survival rates of Heuchera’Miracle’,Heuchera’Jiuhong’ and Heuchera’Pistache’ were the highest,39.98%,37.82%,and 43.94%respectively.Cluster bud induction:The cluster bud induction was carried out on the medium of MS+0.5 mg/L 6-BA+0.15 mg/L NAA,the induction rate was the highest and the cluster bud growth condition was good,Heuchera’Miracle’,Heuchera’Jiuhong’,Heuchera’Cracked Ice’,Heuchera’Pistache’,Heuchera ’Caramer’and Heuchera’Cherry Cola’were 80.35%,85.90%,69.76%,76.18%,73.65%and 71.69%respectively.Proliferation culture:when the subculture medium was MS+0.5 mg/L 6-BA+0.2 mg/L NAA,the multiplication ratio is the highest,and the multiplication ratios of Heuchera’Miracle’,Heuchera’Jiuhong’,Heuchera’Cracked Ice’,Heuchera’Pistache’,Heuchera ’Caramer’ and Heuchera’Cherry Cola’ were 8.47、7.7、6.62、6.94、6.81 and 7.63 respectively.Rooting induction:When the medium was 1/2MS+0.1mg/L NAA+1.5 mg/L IBA,the rooting rate of the six varieties of Heuchera micrantha reached 100%,and the average rooting number and longest root length reached the maximum value.The rooting numbers of Heuchera’Miracle’,Heuchera’Jiuhong’,Heuchera’Cracked Ice’,Heuchera’Pistache’,Heuchera’Caramer’and Heuchera’Cherry Cola’ were 13.1、12.6、11.5、10.8、10.5 and 11.4 respectively,and the longest root lengths were 4.11 cm、4 cm、3.61 cm、3.84 cm、3.63 cm and 3.25 cm.2.Drought resistance study of Heuchera micranthaWith the intensification of drought stress,the growth and physiological indicators of the 6 varieties of Heuchera micrantha varied:Heuchera’Cracked Ice’,Heuchera’Pistache’,Heuchera’Cherry Cola’,Heuchera’Jiuhong’,Heuchera ’Caramer’ and Heuchera’Miracle’ Plant height,fresh weight above ground,fresh weight below ground,leaf relative water content,chlorophyll a,chlorophyll b,chlorophyll a+b,carotenoid content,net photosynthetic rate,transpiration rate and stomatal conductance all decreased gradually;POD activity,CAT activity and SOD activity all increased first The trend of high and then decreased;Pro content,MDA content,soluble sugar content,soluble protein content and relative conductivity increased significantly;the intercellular CO2 concentration showed the law of first decreasing and then increasing.3.Using fuzzy membership function method and principal component analysis method to comprehensively evaluate various physiological indicators,the results obtained by the two analysis methods were consistent.The order of drought resistance of six Heuchera micrantha was:Heuchera’Jiuhong’>Heuchera’Cracked Ice’>Heuchera’Cherry Cola’>Heuchera’Miracle’>Heuchera’Pistache’>Heuchera ’Caramer’.