Optimization Of Production Technology System In Tissue Culture Seedling Of Carica Papaya

Papaya has three main problems in production process:papaya ringspot leaf virus(PRSV,PLDMV),complex species(female 20-30%,male 3-5%,hermaphrodite 60-70%),and intolerance of storage and transportation.This topic mainly focuses on the related research work on the problems of sex in papaya.The rountine papaya breeding is mainly produced by seed reproduction.The papaya of hermaphrodite has commercial value in female,male and hermaphrodite,so the cost of using seed propagation is very high.and the production system of existing tissue culture seedling is hard to meet the actual needs of large-scale production.Above these reasons,it is good for cultivating high survival rate,good quality of commercial seedlings through orthogonal experiments and comparative experiments.Adult lateral buds of Shuluo and Mihong of papaya were used to optimize system of tissure culture seedings in this study.First,Shuluo,non transgenic papaya variety was used as test material,disinfection of explants was carried out by combination of the detergent"5%sodium hypochlorite(5min)+ sterile water +0.15%mercuric chloride(5-7 minutes)+ sterile water".MS was used as the basic culture medium.In the design,growth regulator combinations contain IBA,NAA,KT,the orthogonal experiment was used with the different ratio of growth regulator for rooting medium screening.The results showed that the optimum combining concentration of root growth regulator was IBA0.75mg/L,NAA0.05mg/L and KTO.Olmg/L and the rooting percentage was 66.7%.Secondly,the non root seedlings of Shuluo were respectively soaked in the nutrient root water with 10mg/L,25mg/L,50mg/L and 75mg/L for 6 hours.Then concentration of the highest seedling rate was 50mg/L and the seedling rate was 86.1%.According to the concentration,the soaking time of different gradients was tested with 2 hours,4 hours,6 hours,8 hours,respectively.Without regard for time cost,finally,the highest highest seedling rate was 8 hours for soaking,and reaching 87.5%.The experimental results of above the root rate and the transplanting survival rate were compared and verified with the Mihong.The results showed that using the optimum combination concentration of growth regulator of IBA NAA,KT:0.75mg/L,0.05mg/L,0.01mg/L,the rooting percentage of Mihong was 46.7%.Then dealing with the best rooting agent concentration of 50mg/L and soaking time of 8h,the transplanting survival rate of Mihong was 85%.These showed that the same root formulation was used to deal with two different varieties of mature bud subculture seedlings,their root rates had great difference,however,there were small differences in using rooting water treatment to the transplanting survival rate.In this study,a set of rapid propagation system of tissue culture seedlings was also established by using two papaya varieties.The outer epidermis of fruits was treated with 5%sodium hypochlorite aseptic water,and the seeds were harvested.After sterile breeding,the seedlings were identified as hermaphrodite plants by PCR technique.The optimum concentration of growth regulator and the best concentration of rooting agent and soaking time were used in the experiment.The results were as follows:the rooting rate was 81.1%,and the survival rate of transplanting was 91.1%.The rate of promoting root was 60%,while the survival rate of transplanting was 86.7%.It can be seen that this result is basically the same as that of plantlets in tissue culture of adult lateral buds,but the rate of promoting roots is similar to that of plantlets in tissue culture.The rate and survival rate of transplanting have been greatly improved and reached the level of commercial production.Therefore,the techniques of rapid propagation of lateral buds and hermaphroditic plants of adult hermaphrodite plants were gotten,which not only proved the gene or variety dependence of papaya plantlets in the process of cultivation,but also a new tissue culture system was established.It is of great significance to the development and application of papaya tissue culture seedlings,and also provides a reference for the study of other plant tissue culture techniques.