Auxiliary techniques to enhance the survival rate of transplanting test-tube seedlings have become increasingly important in recent years. With the growing application of rapid propagation methods, a wide variety of plant species and cultivars are being cultivated. However, differences in climate, equipment, and environmental conditions across regions often lead to challenges during the transplanting process. As a result, several effective strategies have been developed to improve the success rate of this critical stage.
One key issue is the susceptibility of test-tube seedlings to wilting and death under low humidity conditions. This is primarily due to the lack of functional root systems or weak connections between roots and stems, which limits their ability to absorb water and nutrients. To address these problems, various measures can be applied to support the transition from in vitro to ex vitro environments.
Several effective methods are available:
1. Promote recovery and functional development of test-tube seedlings. Some plant species struggle to develop strong root systems in the test tube, or their roots may not properly connect with the vascular tissue of the stem. This leads to poor nutrient uptake, making survival after transplantation difficult. Using tools like a chlorophyll meter can help monitor leaf health, as low chlorophyll levels indicate stress and the need for external rooting techniques.
(1) Miniature cuttings. Some plants can be propagated using micro-cuttings taken directly from test-tube shoots. These can be planted in soil and rooted successfully, though hormone treatment is recommended for better results. For example, rhododendron cuttings tend to root well both inside and outside the test tube. Some labs estimate that inducing rooting in test tubes accounts for 35% of total costs, but many seedlings die when transplanted without roots. Using an outdoor rooting method allows for combined rooting and acclimatization, reducing costs and increasing survival rates.
(2) Rooting and refinement in a rooting chamber. This involves creating a controlled environment without agar or sucrose, using substrates such as peat, perlite, or moss. Temperature and light are manually regulated, and misting systems are used to maintain high humidity without wetting the foliage. Stems are placed into the chamber, and after 3–4 weeks, they develop strong, absorbent roots suitable for greenhouse planting. While this method is effective and easy to control, it requires more space and resources.
(3) Transplanting seedlings with early root primordia. If the roots are too long, they risk damage during handling and transport, lowering survival rates. Seedlings with short, developing roots are more resilient and easier to transplant. The process involves cutting strong buds (3 cm or longer) into a rooting medium. After 7–10 days, the roots begin to form, and within 5–6 days, they develop root hairs and improved absorption capacity. This technique boosts survival rates and reduces production time, making it ideal for long-distance shipping.
(4) Bottle or pot insertion. Small containers filled with peat, humus soil, and fine sand can be used to insert 20–30 rootless seedlings per container, with a depth of 0.3–1.2 cm. Adding half-strength MS mineral elements and IBA or IAA rooting solution at 1.0–5.0 mg/L helps stimulate root growth. Under controlled temperature, humidity, and light conditions, new roots appear after 20 days, and secondary roots reach 8–12 cm in 30 days. At this point, the seedlings can be transplanted successfully. More instrument information: Chlorophyll meter http://Instrument_more/yq_85_1.html
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