"Hubei Larch Pine Fast-growing and High-yielding Forest Cultivation Technique" Eight

**II. Collection of *Larix principis-rupprechtii* Seeds** To ensure a large supply of high-quality seeds, it is essential to determine the right time for seed collection. Collecting too early can result in immature seeds that do not germinate well, while collecting too late may lead to seed loss due to natural shedding. Therefore, timing is crucial for successful seed harvesting. **(i) Seed Maturity and External Features** Seed maturity can be divided into physiological and morphological stages. Physiological maturity occurs when the embryo is fully developed and capable of germination, while morphological maturity refers to visible changes in the seed’s appearance. For most tree species, including *Larix principis-rupprechtii*, seeds are collected when they reach morphological maturity. At this stage, internal nutrients are accumulated, moisture content decreases, respiration slows down, and the seed coat becomes dense and resistant to damage, making the seeds more suitable for storage. When *Larix principis-rupprechtii* seeds mature, their cones change from green to yellow-brown, indicating readiness for collection. **(ii) Seed Production Period** The timing of seed collection significantly affects seed quality. Once the cones of *Larix principis-rupprechtii* mature, the scales open easily, and the seeds—light and winged—are quickly scattered. From the time the cones turn color to full seed dispersal, there is typically only 15 to 20 days, so prompt collection is necessary to avoid losses. In the Mengzi Forest Management Bureau area, the seed maturation period for *Larix principis-rupprechtii* generally occurs between late August and early September. **(iii) Seed Collection Methods** Collecting seeds from felled trees is a simple and cost-effective method that allows for the collection of high-quality seeds from the canopy top. However, this approach is only feasible if the harvesting and seed collection periods align. For tall mother trees, tools like ladders, ropes, and seed-picking hooks can be used. It's important to avoid damaging the mother tree by limiting branch cuts to those with a diameter less than 1.5 cm and ensuring no more than one-third of the canopy is pruned. Over-pruning can affect future seed production and increase the interval between harvests. In seed orchards, manual collection using ladders is preferred, and any damage to branches must be strictly avoided. **III. Preparation and Storage of *Larix principis-rupprechtii* Seeds** Preparation involves processes such as drying, threshing, cleaning, and grading to make seeds suitable for planting or storage. Prompt sowing after collection helps prevent issues like mold and reduces seed quality loss. **(a) Threshing** Threshing *Larix principis-rupprechtii* seeds begins with drying the cones to allow seeds to fall out naturally. Two methods are commonly used: natural drying and artificial heating. While artificial drying requires a controlled environment, it is often expensive. Natural drying is more practical. Cones are placed in sunny areas, turned several times daily, and left for 5–7 days until they crack open. The seeds are then separated, cleaned, and stored. The purity should be at least 95%, with moisture content below 10%. Due to the presence of hollow seeds, the fineness is usually around 60–70%. **(b) Seed Storage** Proper storage ensures that seeds remain viable during storage. Larch seeds, which are planted in spring, must be stored properly after autumn collection. Some years may have low seed yields, so storage is essential to maintain germination rates for future use. The longevity of seeds depends on factors like moisture content and temperature. If kept at 8–9% moisture, larch seeds can last 2–3 years in a dry, ventilated storage facility and up to 3–4 years in a cold store. **IV. Seed Quality Testing** Seed quality includes both genetic and sowing qualities. Testing focuses on sowing quality, such as clarity, weight, moisture, and germination rate. These tests help determine the best use of seeds and reduce waste in production. **(i) Sampling** Accurate sampling is critical. A representative sample of at least 50g is needed. Tests include clarity, 1000-seed weight, moisture content, germination rate, and vitality. **(ii) Clarity** Clarity measures the percentage of pure seeds in a sample. High clarity indicates good quality. For *Larix principis-rupprechtii*, clarity is generally above 95%. **(iii) 1000-Seed Weight** This is the weight of 1000 air-dried seeds. For *Larix principis-rupprechtii*, it ranges from 5.3g to 6.9g, with seed orchard seeds being slightly heavier. **(iv) Moisture Content** Optimal moisture content is 8–9%. Too much or too little moisture can harm seed viability. **(v) Germination Test** Germination rate and potential are tested by soaking seeds and observing sprouting. A germination test is conducted at 25°C for about three weeks. **(vi) Pests and Diseases** Seeds are inspected for wormholes, pests, and diseases through visual and laboratory methods. **(vii) Seed Quality Assessment** Experienced technicians can assess seed quality visually. High-quality seeds have a shiny surface, full shape, and strong aroma. The quality of seeds produced by the Mengzi Forestry Bureau is generally above 70%. After testing, seeds are bagged and labeled with details such as origin, germination rate, moisture content, and national standard level. They are then stored in the seed bank for distribution. **Chapter III: Nursery Management** **Section 1: Nursery Site Selection and Zoning** **I. Operating Conditions** Nurseries should be located near afforestation areas or urban outskirts for easy transportation and access to resources. They should avoid areas with pollution, poor drainage, or unsuitable soil conditions. **II. Natural Conditions** 1. **Topography**: Choose flat or gently sloping land (less than 3°). 2. **Soil**: Loamy or sandy loam soils with a pH of 6.5–7.0 are ideal. 3. **Water Supply**: Ensure a reliable irrigation source, avoiding deep groundwater. 4. **Pest and Disease Control**: Avoid areas with high pest activity and infectious diseases. **III. Land Division** Nursery land should be divided to optimize resource use. Key considerations include minimizing irrigation distances, arranging roads and facilities efficiently, and planning for production and auxiliary areas. **(1) Production Area Zoning** - **Sowing Area**: Located in fertile, well-drained soil. - **Transplantation Area**: Suitable for container-grown seedlings. - **Vegetative Propagation Area**: Requires good drainage and water availability. By following these guidelines, nurseries can effectively produce healthy seedlings for reforestation and ecological restoration.

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