Studies On The Technology System Of In Vitro Rapid Propagation Of Carica Papaya L.

In this study, a series of experiments were designed to find out the optimal procedure of the key steps in the system of in vitro rapid propagation of carica papaya, basically solved the two main obstacles which were high contamination rate of explants and low rooting percentage of in vitro papaya plantlets in carica papaya tissue culture propagation production, established an efficient and practical system of in vitro rapid propagation of carica papaya.In the system of in vitro rapid propagation of carica papaya, the lateral buds were taken as explants, a great deal of cluster buds were induced from carica papaya lateral shoots,then were induced for rooting to get carica papaya tissue culture seedling. This paper studied several steps of in vitro rapid propagation, such as obtaining sterile explants, inducing the adventitious buds, proliferation of adventitious shoots, sound seedling culture, plantlets rooting and transplantation, primarily probed the key technical points of in vitro papaya propagation.The results showed that the best time to derive lateral buds is April or so, the best diameter of the explants is 0.6¹.0cm.the best disinfection procedure of mature papaya explants is: pretreatment with 1% xiao-jia-jing solution soaking for 5 min, then using 1333mg/L chlorine dioxide disinfecting for 6 min or using 0.2% mercuric chloride solution disinfecting for 8 min.The best induction medium of papaya lateral bud explants is: MS + sucrose 30g / L + carrageenan 4.7g/L + BA 0.5mg/L + NAA 0.1mg/L; the most appropriate medium of subculture proliferation is: MS + sucrose 30g/L + carrageenan 4.7g/L + BA 0.5mg/L + NAA 0.1mg/L + GA3 0.2mg/L + AD 2.0mg/L, which produced the highest proliferation rate of 6.7. The most suitable culture temperature of proliferation is at 29℃, light intensity is 2000Lx, and illumination time is 12h/d. The best sound seedling culture medium for proliferated buds is: MS + sucrose 30g/L + carrageenan 4.7g/L + BA 0.1mg/L + NAA 0.02mg/L + GA3 0.5mg/L + AD 2mg/L + VB₂ 2.5mg/L. the best culture medium for proliferation and sound seedlings culture is: MS + sucrose 30g/L + carrageenan 4.7g/L + BA 0.3mg/L + NAA 0.08mg/L.This study used"rooting in one step","rooting in two steps"and"cuttage rooting"as the three methods for rooting. The results showed that the most appropriate medium for"rooting in one step"is: MS + sucrose 30g/L + carrageenan 4.7g/L + IBA 1 mg/L + NAA 0.1 mg/L + AC 0.02%, with the rooting rate of 67.6%. The most appropriate procedure for"rooting in two steps"is: first step cultured on the induction medium of MS + sucrose 30g/L + carrageenan 4.7g/L + IBA 2 mg/L,after 3 days transferred to the second medium of MS + sucrose 30g/L + carrageenan 4.7g/L + VB₂ 2 mg/L + AC 0.02%,with the rooting rate of 78.6%.the best inducer for"cuttage rooting"is the mixed solution of IBA 100 mg/L and 0.1% a-mi-xi-da solution. The three methods have their own advantages and disadvantages, so the most appropriate method of rooting in production should be choosen according to specific circumstances.