What are the planting methods for osmanthus seeds?
How do you plant osmanthus seeds? Osmanthus seeds are drupes, long and oval, with ridges, and generally mature in April to May. When mature, the outer skin turns from green to purplish black and falls from the tree. The seeds can be picked from the tree or gathered from the ground, but they must be collected as soon as they fall. Otherwise, the dry spring climate can easily cause the seeds to lose water and become worthless for sowing. Let us take a look below at the planting methods for osmanthus seeds!
Pre-sowing treatment of osmanthus seeds
1. Seed preparation: After osmanthus seeds are collected, they must be prepared immediately. The outer seed coat of mature fruit is relatively soft, so it can be washed immediately with water. Wash the fruit skin clean, remove the empty and small seeds floating on the water surface, pick out impurities, and then place them indoors in the shade to dry. Be careful not to dry them in the sun, because there is no waxy layer on the seed coat of osmanthus seeds, so they easily lose water and shrivel, thereby losing physiological activity.
2. Seed storage: Osmanthus seeds have the characteristic of physiological after-ripening, so they must undergo proper storage and germination promotion before sowing and raising seedlings. Osmanthus seed storage generally has two methods: sand storage and water storage.
① Sand storage means covering the seeds layer by layer with wet sand. The site for sand storage of seeds should preferably be a cool, ventilated place first, and they should be stacked on soil or sandy ground, not on concrete ground.
② Water storage means putting the seeds in a bag that is breathable but not easily rotted, tying the bag tightly, and placing it in cold water, preferably running water. Check frequently to see whether the seeds have lost water or become moldy and deteriorated. The seed bag in water storage should not be exposed above the water surface. In summer, the seed bag should be kept away from the high-temperature water layer near the water surface, so as to prevent the seeds from germinating and rotting from heat.
3. Seed inspection and disinfection
① Inspection: Before sowing, seed inspection should be carried out, removing empty-shelled seeds and deteriorated seeds. Then use a small knife to randomly cut open several plump seeds and observe whether the kernel is fresh and whether it has viability. Generally, the kernel of good seeds is milky white.
② Disinfection: First wash the seeds clean with water, then soak them in a 0.5% potassium permanganate solution or a 1% bleaching powder solution for 15 to 20 minutes, then filter off the residual disinfectant liquid and residue. After the seeds are rinsed with water, dry them and sow; or soak the seeds in a 0.5% formalin solution for 15 minutes, pour off the liquid, seal and fumigate the seeds for half an hour, then rinse with water, dry, and sow.
4. Germination promotion treatment: In order to make the seeds germinate quickly and uniformly, the disinfected seeds can be soaked in warm water at about 50°C for 4 hours, then taken out and placed in a bamboo basket, covered with a wet cloth or straw, and kept at 18 to 24°C for germination promotion. When half of the seeds have cracked seed coats or slightly exposed radicles, they can be sown. During the germination promotion process, the seeds should be turned frequently so that the temperature and humidity of the upper and lower layers remain consistent, so as to achieve uniform sprouting.
Sowing methods for osmanthus seeds
In early February to April of the following year, sowing and seedling cultivation can begin when the seeds crack and show white. Generally, the drill sowing method is used, that is, making horizontal or vertical furrows on the seedbed, with a furrow width of 12 cm and a furrow depth of 3 cm; sow 1 germinated seed every 6 to 8 cm in the furrow. When sowing, place the hilum sideways to avoid bending the radicle and young stem, which would affect the growth of the seedlings. In the Guilin area, wide-row drilling is usually used, with a row spacing of 20 to 25 cm and a width of 10 to 12 cm, sowing 20 kg per mu, which can produce 25,000 to 30,000 seedlings.
After sowing, cover immediately with fine soil. The suitable soil covering thickness is no more than 2 to 3 times the transverse diameter of the seed; after covering with soil, level the bed surface to avoid water accumulation; then cover with a thin layer of straw, to the extent that the soil is not visible, and stretch ropes to press it tightly to prevent the covering straw from being blown away by the wind; then use a fine-hole watering can to water thoroughly until the soil is soaked through. Covering with straw and watering can keep the soil moist, avoid soil compaction, and promote early seed germination and early emergence.
Post-sowing management of osmanthus seeds
After the seeds germinate, management work should follow promptly in order to cultivate robust seedlings. For the growth and development of the seedlings, the following six tasks should be done well in actual operation:
1. Removing the covering straw and shading: After the seeds germinate and emerge from the soil, the straw should be removed appropriately on cloudy days or in the evening. Removing the straw too early fails to achieve the purpose of covering with straw; removing it too late can break the young shoots or form leggy seedlings. The straw should be removed in stages, and part of the covering straw can be left between the seedling rows to keep the seedbed moist, reduce water evaporation, and prevent weed growth. After removing the straw, as the high-temperature summer season arrives, shading frames should be built promptly, keeping the shading shed at about 40% light transmittance. The daily shading time is generally covered in the morning and uncovered in the evening; covered on sunny days and uncovered on cloudy and rainy days. By early to mid-September, the reed curtains used for shading can be collected and stored.
2. Loosening the soil and weeding: Loosening the soil should be carried out promptly, with a depth of 2 to 3 cm. It should be shallow rather than deep to prevent root damage. Weeding can be combined with soil loosening, and every effort should be made to remove weeds early, when small, and completely. In addition, weeds along ditches, paths, and field ridges should also be removed completely, so as to clean the nursery land and eliminate places where diseases and insects breed.
3. Thinning and filling in seedlings: Osmanthus seedlings are relatively shade-tolerant and slow-growing, so generally thinning is not necessary; appropriately moving dense seedlings to fill gaps is sufficient. When moving seedlings, do not damage the root systems of the retained seedlings. After moving seedlings, irrigate once so that the seedling roots bind closely with the soil.
4. Irrigation, drainage, and fertilization: In dry summer and autumn seasons, attention must be paid to drought resistance and seedling protection. Irrigation is best carried out in the morning or evening. Use the method of rapid irrigation and rapid drainage. Water should be applied thoroughly and evenly. In the rainy season, ditch cleaning and drainage should be strengthened to avoid waterlogging of the seedlings. One month after the seedlings emerge, they enter a period of vigorous growth. Once a month, apply a fully decomposed dilute barnyard manure liquid or nitrogen fertilizer. The concentration is 10 kg of barnyard manure liquid per 100 kg of water, or 150 to 200 g of urea, or 300 to 400 g of ammonium sulfate. As the seedlings grow, the fertilization concentration can be appropriately increased. After autumn begins, stop topdressing to prevent excessive vegetative growth of the seedlings and frost damage. When topdressing, do not let the fertilizer liquid adhere to the seedlings, so as to avoid injuring them.
5. Pest and disease control: Continuous cropping nurseries of osmanthus are prone to brown spot disease and damping-off disease, causing large numbers of leaves to turn yellow and fall, or the root collar and root cortex of the seedlings to rot, leading to the death of the whole plant. At the same time, aphid damage is also likely to occur during the seedling stage. Therefore, pest and disease control work cannot be ignored.
6. Timely transplanting: One-year-old sown osmanthus seedlings are 20 to 30 cm tall and are transplanted in early spring of the following year. Two-year-old seedlings are about 60 cm tall, and when three-year-old seedlings are about 1 m tall, they need to be transplanted again. If used as courtyard shade trees or trunk-road trees, they generally need to be cultivated for 8 to 10 years, reaching a height of 2 to 3 m and a diameter of 8 to 10 cm, before they are favorable for maintenance and management after planting.