Studies On Emei Yellow Ginger Shoot Tip Culture And Virus-free Propagation

Emei yellow ginger,a local ginger variety introduced and selected by farmers,characterized by its adaptability,high yield and resistances,is one of the most important commercial crops.Ginger,as all other crops vegetative propagated,is susceptible to various viruses,which leads to variety degression and thus reduce the productivity.This situation got much harder for Emei yellow ginger,due to higher temperature and moisture environment during growth of ginger.In order to establish the techniques of virus eliminating and virus-free seedling propagating:stem apexes were stripped from tips heat-treated(to deactivate viruses),and virus-free plantlets were verified by enzyme-linked immuno sorbent assay(ELISA);effects of plant hormones(most of which are plant growth regulators,PGRs)and combinations of PGRs on induction,proliferation of adventitious buds(multiple shoots)and induction of adventitious roots were investigated,as well as effects of culture substrates on transplanted plantlets.The main results and conclusions are as following.1.Rates of virus elimination.Results of ELISA indicated that 56.3%plantlets derived from stem apexes stripped from heat-treated tips were free of mosaic virus,tobacco mosaic virus and ginger mosaic virus,and are capable of applied in further virus-free propagation.2.Effects of PGRs on induction and proliferation of shoots.There were significant(P<0.01)among PGRs combination on survival rates of apexes and induction rates of shoots;both the highest apex survival rate(77.5%)and shoot induction rate(92.5%)were acquired on medium containing higher(0.2 mg.L-1)6-BA and lower(0.1 mg.L-1)GA3 concentration,which were significantly(P<0.05)higher than the other 3 PGRs combinations applied in this experiment.To be concluded,the most suitable shoot induction medium for Emei yellow ginger is MS+6-BA 0.2 mg.L"1+NAA 0.05 GA3 0.1 mg.L-1.Shoots were sub-cultured on the same medium for 30d proved that it also be suitable for proliferation of shoots induced.3.Effects of PGRs on induction and proliferation of multiple shoots.Analysis of variance(ANOVA)showed that induction rate of multiple shoots and average number of shoots formed were significantly(P<0.01)among PGRs combinations tested,while growth rates and qualities of shoots varied among PGRs combinations;with the combination of higher(0.5 mg.L-1)NAA and lower(0.1 mg.L-1)6-BA level,the highest multiple shoots induction rate and average shoot number were gained,which were 92.5%and 12.4 shoots respectively,and were significantly(P<0.05)higher than other PGRs combinations tested.Shoots on the medium of this PGRs combination were proved to grow faster and better.In general,MS+6-BA 0.1 mg.L-1+NAA 0.5 mg.L-1 is the suitable adventitious shoots induction medium for Emei yellow ginger.Approving results were obtained by using it as sub-culture PGRs combination for shoots acquired.4.Effects of PGRs on induction of adventitious roots and quality of plantlets.100%adventitious root induction rate were obtained on all media with 5 PGRs combinations,while average numbers of roots differed from media significantly(P<0.01),16.3 and 17.6 roots-were formed on two applied PGRs combinations,higher(0.5 mg.L-1_IBA and lower(0.1 mg.L-1)IBA+0.5 mg.L-1 NAA,respectively,and were significantly(P<0.05)higher than other combinations of PGRs.Further investigations on root growth rate and quality of plantlets showed that growth rate(average root fresh weigh,average root length and root vigor more specifically)were significantly different among media,among which added with 0.1 mg.L-1 IBA and 0.5 mg.L-1 NAA was superior to other 4 media.With respect to content of chlorophyll(chla and chlb),fresh weight and average length of leaves,the best results obtained on the same PGRs once again.It was also the medium that gave rise to plantlets showed the highest activities of SOD,POD and CAT enzymes,this suggested that those plantlets might be more vigor physiologically,and have higher ability to repair any mightbe damages.To sum up,MS+IBA 0.1 mg.L-1+NAA 0.5 mg.L-1 is suitable for induction of adventitious roots and growth of plantlets.5.Effects of culture substrates on transplanted plantlets.Significant(P<0.01)differences were revealed among 7 substrates applied for transplanted plantlets growth,among those substrates,the highest survival rate(98.3%),plant height(13.89cm)and root length(6.87cm)was acquired on A2(50%vermiculite+50%humus soil),thus it is capable of being suitable culture substrate for plantlet transplant.In conclusion,a series of elementary techniques necessary for virus elimination and virus-free plantlet propagation(including induction and proliferation of adventitious shoots,induction of adventitious root,proliferation of plantlets and culture substrates for plantlet transplanting)were established based on experiments implemented,it should be valuable for virus-free seedling propagation.Analysis of PGRs effects also provided a reference for studies on virus-free seedling of any other ginger varieties.