A Comparative Study On Rapid Propagation In Vitro And Salt Tolerance Of Three Species Of Portulaca

Portulaca pilosa L.,Portulaca grandiflora Hook and Portulaca oleracea L.belong to the genus Portulaca.They have high ornamental value and certain medicinal value because of its gorgeous color and long flowering period.They can be widely used in landscaping.In recent years,three species have strong adaptability to the environment and strong resistance to stress,which can be more used for ecological environment restoration.Previous researches mainly focused on the research of P.oleracea,while there were few comparative studies on different species of Portulaca.In this paper,tissue culture techniques and salt tolerance of two other spesis of Portulaca were compared.Based on this,study on the best explants disinfection method,induction and proliferation medium,rooting medium screening,Shoot organogenesis and plant regeneration technology,rooting culture,seedling refining,tissue culture seedling transplanting technology.At the same time,the salt resistance of three species of Portulaca was compared.The tissue culture system of three species of Portulaca was established,and the stress resistance of three species of portulaca was compared,so as to provide technical support for the large-scale production of portulaca seedlings,and the restoration of island ecosystem.（1）Optimal explants disinfection method:The disinfection steps of young stem section of P.pilosa are mainly as follows:the stem explants were wiped with 75%alcohol cotton wool on the surface,then soak the explant in 75%alcohol for 30 s,and treat it with 0.1%HgCl₂ for 9 min+6 min+2 min,respectively,for the most optimal and the success percentage of 87.5%.The disinfection steps of young stem section of P.grandiflora and P.oleracea are mainly as follows:the explants were wiped with 75%alcohol cotton wool on the surface,and then the explants were soaked in 75%alcohol for 30 s and treated with 0.1%HgCl₂ for 27 min or 25 min respectively,with the most optimal.The success percentage was 77.1%and 79.8%,respectively.（2）Optimum shoot proliferation medium and optimum pH:The optimal shoot proliferation medium of P.pilosa was MS+3.0μM BA with a proliferation ratio of 6.2.The optimal shoot proliferation medium of P.grandiflora was MS+5.0μM 2-ip with a proliferation ratio of 12.1.The optimal shoot proliferation medium of P.oleracea was MS+3.0μM 2-ip with a proliferation ratio of 4.0.The best pH range for P.pilosa is5.0–6.0.P.grandiflora,P.oleracea is best suited to a pH of 5.0.（3）Optimum rooting medium:Optimum rooting medium NAA and IBA were used to enhance root formation.Different species had different optimum rooting media.All three species of portulaca were easy to develop roots and the highest rooting percentage was up to 100%.The optimum medium for rooting of P.pilosa and P.oleracea was free-PGR MS medium.The optimum medium for rooting of P.grandiflora was MS medium supplemented with 1.0μM NAA.（4）Shoot organogenesis and plant regeneration:The optimal callus induction medium for P.pilosa leaves was MS+1.0μM TDZ+0.1μM NAA.Adventitious buds were induced in the leaves by indirect organogenesis,and the proliferation factor was3.8.The optimal callus induction medium of P.grandiflora leaves was MS+1.0μM TDZ+0.1μM NAA.Adventitious buds were induced by in the leaves by indirect organogenesis,and the proliferation factor was 10.7.The optimal callus induction medium of P.oleracea leaves was MS+1.0μM BA+0.1μM NAA.Adventitious buds were induced in the leaves by indirect organogenesis,and the proliferation factor was5.7.（5）Seedling transplanting:In the transplanting stage,the plant survival percentage of P.pilosa was 90.3%in the substrate with perlite:marine sand（1:1）.P.oleracea in peat soil:sand:perlite（1:1:1）matrix survival percentage is high to 93.5%.P.grandiflora has a high survival percentage of 92.0%in a substrate with perlite:marine sand（1:1）.（6）Comparative study on salt tolerance:Three species of portulaca,were treated with single salt NaCl,composite salt（NaCl:NaHCO₃:Na₂SO₄:Na₂CO₃=1:1:1:1）and PEG stress.The comparison of the salt stress tolerance of three species of Portulaca plants showed that under NaCl stress,the stress resistance was from high to low is as follows:P.pilosa>P.grandiflora>P.oleracea.Under the stress condition of composite salt,the stress tolerance from high to low is as follows:P.pilosa>P.grandiflora>P.oleracea.Under the conditions of PEG simulation drought,the stress resistance from high to low is as follows:P.pilosa>P.grandiflora>P.oleracea.Generally,the salt tolerance from high to low is as follows:P.pilosa>P.grandiflora>P.oleracea.