Orchid Cultivation, Fresh-Keeping, Storage and Transportation, and Edible Fungus Fertilization Techniques and Methods
The medium for growing orchids sours very easily. How can this be overcome?
When sphagnum moss is used to grow orchids, after a few days the moss becomes contaminated by acid-producing bacteria and turns sour, and then black tip symptoms (Fusarium infection) tend to develop in the orchid root zone.
When the orchid growing medium is boiled in water or sterilized at high temperature in an autoclave, why can the orchid black tip problem not be completely overcome?
Some orchid nurseries boil the sphagnum moss or sterilize it at high temperature before growing orchids. Although this can temporarily kill bacteria and insect eggs, after planting, the moss still turns sour, causing black tip symptoms to develop easily in the orchid root zone. This is because after the orchids are planted, they are still contaminated by acid-producing bacteria.
How can the black tip problem be reduced when growing orchids?
Black tip symptoms in the orchid root zone occur mainly because the medium, such as sphagnum moss, is contaminated by acid-producing bacteria, causing the medium to turn sour and leading to massive reproduction of Fusarium (Fusarium grows best at around pH 4). Therefore, raising the pH of the medium can reduce Fusarium infection.
How can the black tip problem be effectively reduced?
Applying small-molecule water-soluble chitin and actinomycetes diluted 2000 times with water to irrigate orchids can effectively reduce black tip symptoms in orchids. Media such as sphagnum moss should be soaked in small-molecule water-soluble chitin and actinomycetes diluted 1000 times for 1-5 minutes, then drained before planting.
What is small-molecule water-soluble chitin? What benefits does it have for orchids?
Chitin is extremely widely distributed in nature. For example, the shells of crustaceans (shrimp, crabs, etc.), the shells of insects (cockroaches, butterflies), and the shells (clams, oysters) and internal skeletons (squid) of mollusks all contain chitin. After acid and alkali treatment to remove calcium and protein, chitin is obtained. After chitin is treated with high temperature and strong alkali for deacetylation, chitosan is obtained. Chitin and chitosan are collectively called chitin.
Advantages of using chitin on orchids:
1. Enables continuous cropping of the medium - chitin can increase beneficial microorganisms in the medium, such as actinomycetes, reduce harmful bacteria such as Fusarium, and eliminate root-knot nematodes, reducing the troubles of continuous cropping obstacles in the medium.
2. Promotes healing and development of root wounds, increases root hairs, and enhances nutrient absorption. Promotes plant growth.
3. Induces the production of phytoalexin, improves crop disease resistance and antibacterial ability, thereby reducing the amount of pesticides used.
4. Increases the calcium content of orchids, which can increase stem rigidity.
5. Enhances the absorption of trace elements, thereby increasing the reducing sugar content of leaves, advancing harvest, improving quality, and extending the fresh-keeping period.
Actinomycetes are Gram-positive bacteria that are extremely common in soil in nature. More than 400 species are known. Since most have the ability to produce antibiotics, their application in crop disease control has continued for more than half a century since Waksman's report in 1943. Similar successful developments have mostly focused on the production of antibiotic preparations. The best known is streptomycin, used to control bacterial diseases in many fruits, vegetables, and flowers. In addition, actinomycetes can decompose organic matter and produce extracellular enzymes to break down proteins, cellulose, lignin, and chitin, so this property can be used against microorganisms with chitin cell walls. For example, adding chitin to soil can control Fusarium, mainly because the chitinase secreted by actinomycetes can cause lysis of pathogenic hyphae.
What are the benefits for orchids of using small-molecule water-soluble chitin and actinomycetes at the same time?
When chitin and actinomycetes are used simultaneously to irrigate orchids, chitin has an antibacterial effect and can promote the growth of actinomycetes, inhibit the growth of Fusarium, and promote wound healing. For example, it is very effective against anthracnose, which causes black leaf spots.
What effect does ethylene have on orchids?
Orchids are quite sensitive to ethylene. Just 0.01 ppm of ethylene can cause Vanda flowers to wilt. Next in sensitivity are orchids from Southeast Asia. Dendrobium, Phalaenopsis, and Paphiopedilum are next. Oncidium is not sensitive to ethylene. Province-grown Phalaenopsis treated with 0.09 ppm ethylene can be induced to age, producing symptoms such as flower drop and dehydration-induced wilting. Ethylene causes the tips of orchid sepals to wither and the lip to turn red. The early symptoms of aging are transparency of the sepals and petals, followed by prominent veins and the formation of an abscission layer, leading to floret drop.
In addition, as flowers mature or after dehydration, high temperature, or disease, their sensitivity to ethylene increases.
Why do budded potted orchids turn yellow and drop buds during storage and transportation?
Long-distance transport of budded potted orchids causes yellow leaves and bud drop mainly because of the effects of excessively high ethylene concentration and bacterial infection.