Propagation In Vitro Of Erycina Pusilla

Erycina pusilla is a native orchid from Subribe Oncidiinae with flabellifoliate petite plants and flat slender leaves.Apart from fast growth and short juvenile stage,its adults can put forth big and special-shape bright yellow flowers incessantly all the year round uninfluenced by seasons.That makes it a perfect candidate for commercial bottled ornamental flowers.In this paper,we explored the propagating system of Erycina pusilla from the aspects of in vitro asymbiotic seed germination,rooting and strong seedling cultivation,flower induction in bottles,PLBs induction and proliferation,pollination and fruit development in bottles,and found out the system of its entire^[1]life cycle in vitro,which provided not only the foundation for industrial production of Erycina pusilla as commercial flowers,but also technical support for researches on it as a model Orchidaceae plant with a short life cycle.The main findings are as follows:1)The environment during its fruit development had a great effect on the seed maturity of Erycina pusilla.The deviation was large with DAP as the criterion,so it was difficult to determine the suitable DAP for sowing.However,it was of strong operability and high accuracy to combine DAP with morphological indicators and choose those after more than110 DAP of fruit development when their outside edges turned brown.2)Natural additions had a great effect on the germination of Erycina pusilla.Among the three natural additions of coconut milk,banana juice and potato juice,potato juice had the most significant effect.As a convenient water-soluble fertilizer,Peters No.2 had a better effect than the traditional MS and Hyponex No.1 that was frequently used for orchids.Through intuitive analysis of the orthogonal experiment data,we found from their ranges that the main effects of various factors were shown as natural additions>protein hydrolysate>basic medium>sucrose concentration,and inferred that the optimal condition for in vitro seed germination was 3 g/L Peters No.2+25 g/L sucrose+2 g/L casein hydrolysate+10%potato juice.The optimal medium components in the orthogonal experiment were as follows:3 g/L Peters No.2+20 g/L sucrose+2 g/L casein hydrolysate+10%potato juice.Its seed germination rate was 35.31%.3)Coconut milk had a better effect on the rooting and strong seedling cultivation of Erycina pusilla than potato and banana.The better medium components were as follows:1/2MS+20g/L sucrose+0.5 mg/L NAA+10%coconut milk+1 g/L activated carbon+4.5 g/L agar.Its survival rate was 93.75%in 60d;and in 100d,the average fresh weight of Erycina pusilla increased to 34 times,from the original 5.70 mg/plant to 194.80 mg/plant.4)Erycina pusilla PLBs induction was relatively easy and there was a certain induction rate even without PGRs.1 mg/L IBA+1 mg/L NAA had the highest induction rate and the lowest death rate.The suitable PLB induction was as follows:3 g/L Peters No.2+25 g/L sucrose+10%coconut milk+2 g/L soybean protein hydrolysate+1 g/L activated carbon+4.5 g/L agar+1 mg/L IBA+1 mg/L NAA.Its induction rate was up to 50%,20%higher than that of the blank control and its death rate was 30%,5%lower than that of the blank control.5)As a convenient water-soluble fertilizer,Hyponex No.1 had a better effect in Erycina pusilla flower induction than MS medium and had a certain flowering rate in 8 months after sowing.The suitable medium for in vitro flowering was 3 g/L Hyponex No.1+1 mg/L 6-BA+1 mg/L ABA+40 g/L sucrose with a bud induction rate of 20%and a flower induction rate of 5.56%.6)Light intensity had a great effect on the flowering of Erycina pusilla.The light intensity too high or too weak would reduce its flowering rate while 63μmol/m²s was the most suitable for its in vitro flowering with a flowering rate of 23.33%.7)The better medium components for Erycina pusilla fruit development were 3 g/L Peters No.10+0.5 mg/L NAA+30 g/L sucrose+10%potato juice+1 g/L activated carbon+4.5g/L agar,and they could be sown when they were cultured at 25°C under the light of 63μmol/m^-2s^-1 12 h/d for 130 d after pollination.