Breeding And Cultivation Of Three Species Of Bletilla

The seeds of Bletilla striata,B.ochracea,B.formosana,Cymbidium kanran and Dendrobium officinale were served as the experiential materials,the seed morphological characteristics and changes of seed vigor during storage was compared to study preliminarily the reason why the Bletilla seeds were easy to germinate.NAA,6-BA and AC were used as the three factors to design orthogonal experiments at 3 levels which screens the suitable medium for axenic germination in Bletilla.Sawdust,mushroom dregs,and cow dung were used as the three factors to design three levels of orthogonal experiments which screens the substrate ratio for natural germination of Bletilla.The endophytes were isolated from Bletilla,to study its effect on seed germination and the growth of Bletilla in symbiotic culture.3 kinds of B.striata seedlings obtained by aseptic germination were used as experiential materials,to study the effect of different concentrations of sucrose,macronutrients and uniconazole on tubers expansion of Bletilla.The Bletilla tubers were used as materials to study the effects of different temperatures and GA₃ concentrations on the release of dormancy of Bletilla.1.Compared with the seeds of C.kanran and D.officinale,Bletilla seed was short,and seed coat ornamentation was shallow?or its surface was smooth?.The structure was simple,and the embryo was large with a high degree of development.It was indicated the reason of easy germination was related to its simple seed coat in construction and large embryo with a high degree of development.The seed vigor gradually decreased with the prolongation of storage time,and the seed vigor was the strongest at the time of picking.B.striata,B.ochracea,B.formosana,Cymbidium kanran and Dendrobium officinale were 98.54%,87.97%,98.09%,96.62%and 91.74%respectively.After storage of 14 days,the activity decreased fastest,and the seed vigor of the five plants fell below 80%.It was the best choice to finish the seed within 14 days after picking.There was no significant difference in seed vigor of the five plants when it was just picked.The findings suggest that there was no direct relationship between seed vigor and degree of seed germination.2.AC had significant effects on the aseptic germination of Bletilla seeds,and the suitable medium for seed germination was 1/2MS+1.0 mg/L 6-BA+0.5 g/L AC.The germination rates were highest in using this medium and B.striata,B.ochracea and B.formosana were 92.90%,92.09%and 82.34%,respectively.NAA and 6-BA had no significant effect on seed germination.It indicates that exogenous hormones had little effect on the germination of Bletilla seeds.The optimum ratio of mushroom residue and cow dung in natural germination was 2:1,the highest germination rate of three species of 3 Bletilla seeds which include B.striata,B.ochracea and B.formosana were 96.43%,88.59%and 83.17%,respectively.There was no significant difference in germination rate between aseptic germination and natural germination,but the seedling growth rate of natural germination was lower than those of aseptic germination.3.The plating efficiency of endophytes isolated from root segment was higher than those from grinding fluid of roots,and it decreased with the increase of disinfection time.A total of 63 fungi were isolated,of which 7 species could simultaneously promote the germination of Bletilla seed.Among them,the endophytes coded B21 could promote seed germination and seedling growth.It indicates that the endophytes that promote seed germination and seedling growth have no specificity.4.Different concentrations of sucrose,MS macroelement and uniconazole had a significant effect on Bletilla tuber enlargement.The optimal concentration of sucrose was 50 g/L,and the expansion coefficients of three Bletilla species were1.450,1.375 and 1.582 respectively;the optimal MS macroelement concentration was 5/2MS,and the expansion coefficients were 3.026,3.303,and 3.192respectively.The optimal uniconazole concentration was 0.1 mg/L,and the expansion coefficients were 5.206,4.902,and 5.077,respectively.Uniconazole had the most significant effects on Bletilla tuber enlargement in the three factors.5.Low temperature and a certain concentration of GA₃ play an important role in relieving dormancy of Bletilla.Whether it is a low temperature of 5°C or a high temperature of 25°C,the time of breaking the dormancy was decreased with the increase of GA₃ concentration.It indicates that the high concentration of GA₃ was more important than temperature in relieving dormancy.However,the high concentration of GA₃ would cause the excessive growth of seedlings.Thus,25°C,90 mg/L GA₃ soaking for 24 h was the optimal operation for relieving dormancy of Bletilla.