Detailed Explanation of Efficient Production Technology for Phalaenopsis Test-Tube Plantlets

Phalaenopsis is an orchid with high ornamental value, known as the "Queen of Orchids." Its plant form is very peculiar, being a monopodial epiphytic orchid, with roots that prefer to be exposed above the potting medium or extend out of the bottom of the pot, absorbing water and nutrients from the air. The flower stalk emerges from the leaf axil, curving in an arc, possessing great curvilinear beauty. The stalk has nodes, and flowers bloom on the upper nodes, opening one after another in succession. Flower colors vary endlessly, including crimson, pure white, light purple, goose yellow, and azure blue, among others; some varieties have bicolor or tricolor flowers with stripes or variegation, brilliantly colorful. Each stalk can bear 7-12 flowers, with the maximum reaching 70. However, because the plant rarely develops lateral branches, conventional asexual propagation is difficult, making it hard to meet the growing demand of Phalaenopsis enthusiasts. After years of research and practice, a complete set of rapid propagation and efficient production technology processes for Phalaenopsis has now been established, and success has been achieved in the test-tube plantlet production of the excellent large-flowered Phalaenopsis varieties "Jubaohong Meigui," "Huolong," and the small red-flowered variety "Mantianhong," gradually forming a scale of annual production of several hundred thousand seedlings of various specifications and one hundred thousand flowering plants.

I. Technical Process: Mother plant selection → Primary induction → Cluster shoot differentiation → Subculture proliferation → Seedling strengthening and rooting → Seedling hardening → Out-of-bottle transplanting.

II. Initiation and Induction (1) Mother plant selection. Since tens of thousands of tissue-cultured plantlets all originate from the same explant, the selection of the mother plant should be particularly cautious, following three basic principles: 1. The entire population exhibits the typical traits of the variety. 2. The population grows and develops well, without widespread infection by specific diseases such as Cymbidium mosaic virus and Odontoglossum ringspot virus. Mixed infection by these two viruses is very common, so the mother plant must first undergo virus testing. 3. From populations meeting the above conditions, select robust individual plants with excellent traits as mother plants. (2) Primary induction. Use the dormant buds at the lower end of flower stalks that have already bloomed as material. Cut the flower stalk with the upper inflorescence removed into 5-7 cm stem segments, rinse under running water for 1-2 hours, then on a laminar flow bench soak in 75% alcohol for 1 minute, rinse with sterile water, then place in 0.1% mercuric chloride solution for about 10 minutes, rinse again with sterile water 3-4 times, peel off the bracts of the dormant buds on a sterile inoculation tray, then place in 0.05% mercuric chloride solution for 4-5 minutes, and rinse again with sterile water 3-4 times. The treated flower stalks are cut into 3-4 cm stem segments, each with one lateral bud, inserted base-downward into the induction medium, then placed in a culture room for cultivation, with a light intensity of 2000 lux, a photoperiod of 12 hours per day, and a culture temperature of 25°C. The lateral buds begin to sprout after 10 days, with an induction rate reaching 90%. After 30 days, the lateral buds can grow into plantlets. During the induction process of dormant buds on flower stalks, a few dormant buds after sprouting grow into slender stalk-like stems similar to lateral branches of the flower stalk. When they reach 3 cm with 2-3 buds, cut them away from the flower stalk and re-cut into segments, each with one bud, placed base-downward into the induction medium again, where they can continue to induce sprouting plantlets.

III. Differentiation and Proliferation After the lateral buds of the flower stalk are induced into plantlets, cut the plantlets away from the flower stalk and inoculate them into the differentiation medium. Then place them in a culture room for cultivation, with a light intensity of 2500-3000 lux, a photoperiod of 10 hours per day, and a culture temperature of 25°C. Subculture every 45-50 days; after 2-3 subcultures, cluster shoots can be differentiated. Carefully separate the differentiated cluster shoots, inoculate them into the proliferation medium, then place them in a culture room for cultivation, with a light intensity of 3000 lux, a photoperiod of 10 hours per day, and a culture temperature of 25°C. Subculture every 50 days, with a proliferation rate of more than 3 times. As the number of subcultures increases, although high concentrations of 6-BA will increase the proliferation rate, they will also cause variation in the plantlets. After 10 generations of proliferation or after variant plants begin to appear, only lower concentrations of 6-BA can be used to promote the growth of cluster shoots, and variant plants should be eliminated promptly. The proliferation and growth of cluster shoots have a certain population effect; when cluster shoots are cut into segments with only 1-2 buds, the proliferation of cluster shoots is greatly reduced, and after one subculture cycle most show almost no proliferation, with the plantlets merely growing slightly larger. When cluster shoots are cut into segments with 3-5 buds, the proliferation of cluster shoots is relatively normal. When cutting cluster shoots, only gently separate the cluster shoots; do not cut around the periphery of the cluster shoots, otherwise the excessive cutting wounds will cause the medium to brown quickly, which is detrimental to the growth and differentiation of cluster shoots and may even cause the death of cluster shoots. For some larger cluster shoots (shoot height above 1.5 cm, monopodial stem diameter above 0.5 cm), cross-cutting can greatly increase the proliferation rate. After cross-cutting, a new round of cluster shoots will grow from the base of the cluster shoots, and the proliferation rate can be increased by 5 times. Because the monopodial stem of Phalaenopsis is relatively short and small, the cutting position must be accurately controlled during cutting, otherwise the bud will be cut to death or the expected proliferation rate will not be achieved because the apical bud has not been removed.

IV. Rooting and Hardening When the shoots grow to 1.5 cm in height with 2-3 leaves, transfer them to the rooting medium, then place them in a culture room for cultivation, with a light intensity of 3000 lux, a photoperiod of 12 hours per day, and a culture temperature of 25°C-28°C; rooting begins after 20 days. After rooting, place the plantlets under an environment with a light intensity of 8000-10000 lux and a photoperiod of 12 hours per day for about 20 days, which can significantly improve the quality and survival rate of the plantlets in the culture bottles. When the plantlets reach 4 cm in height with 3-5 leaves, they can be taken out of the bottles for planting.