Plant Regeneration In Pitaya (Hylocereus Undatus Costaricensis)

In this study, Pitaya (Hylocereusndatus) as material, different types of explants by plant growth regulators concentration ratio selected for pitaya calluses and adventious bud indutiong medium, in order to establish a stable, rapid and regeneration system in pitaya. Conclusions of the study are as follows:1、Regeneration system of calluses and adventitious shoots stem segmentsThe most suitable surface disinfection method for Pitaya stem segments:followed by rinse in 75% alcohol for 30s+0.1% mercuric chloride for 8min, and then rinsed with sterile water 3-6 times.The best way for inoculation of explants:2cm stem segments were cut and longitudinally inoculated in the medium.The optimal medium for callus induction:MS+2,4-D 1.0 mg·L-1+TDZ 0.4 mg·L-1+NAA 0.5 mg·L-1, and adventitious shoot differentiation:MS+2,4-D 1.0 mg·L-1+TDZ 0.4 mg·L-1+NAA0.5 mg·L-1,in which 89.1% of callus induction and 94.0% of adventitious shoot regeneration were obtained, the callus showed yellow green, finely granular, dense.2、The regeneration system for calluses and adventitious shoots from mature embryosThe optimum culture medium for embryo culture was 1/2MS medium, in which seed germination rate and rooting rate reached 100%.Calluses could be obtained from cetyledons, stem section 1 and hypocotyls, The callus induction rate of stem section 1 can reach 93%, but the calluses were yellow green in colour, loose in texture and prone to browning and death. Cotyledons resulted in callus induction rate as low as 25.3% and prone to browning and death. The hypocotyl callus induction rate was up to 93.3%, and the induced calluses showed yellow dense granular and free from browning and death. The optimal callus induction medium was MS+6-BA 2.0mg·L-1+2,4-D 0.5 mg·L-1,adventitious shoot differentiation:MS+2,4-D 0.5mg·L-1+TDZ 0.4 mg·L-1+NAA 0.5 mg·L-1But the adventitious shoots induced from hypocotyl calli showed poor growth and root formation in rooting culture.3、Rooting and transplanting of tissue culture seedingsThe optimal medium for root induction was MS+CCC 0.5 mg·L-1+6-BA 3.0 mg·L-1+AC 200 mg·L-1, in which the rooting rate was as high as 94.7%, the average root number was 6.7 and the average root length was 10.1cm. Activated charcoal (AC) effectively inhibited browning and promoted root formation.The suitable matrix formula for Pitaya tissue culture seedling transplanting was organic fertilizer:garden soil:vermiculite (1:1:2), in which the survival rate was as high as 97%, and under proper management the plantlets grew strongly with good growth potential.