How to choose eucalyptus seedlings? You need to know these selection tips
How to choose eucalyptus seedlings? What seedling-raising methods are there for eucalyptus seedlings? What varieties of eucalyptus are there? Please give an introduction. Eucalyptus seedlings can be selected from the following points for reference. Selecting by seedling-raising method: 1. Tissue-cultured seedlings: also called gene seedlings, refers to those produced using modern technology in the laboratory by utilizing cell totipotency through asexual reproduction...
How to choose eucalyptus seedlings? What seedling-raising methods are there for eucalyptus seedlings? What varieties of eucalyptus are there? Please give an introduction.Eucalyptus seedlings can be selected from the following points for reference.
Selecting by seedling-raising method:
1. Tissue-cultured seedlings:Also called gene seedlings, refers to those produced using modern technology in the laboratory by utilizing cell totipotency through asexual reproduction methods. The production environment is controlled, and by renewing propagation materials every year, the excellent traits of quality and the best genetic gain are retained. The characteristics of tissue-cultured seedlings are a longer cultivation time, relatively complete seedling development, a well-developed root system, a main root system, stronger stress resistance than cuttings, a higher survival rate after afforestation, and relatively greater growth.
2. Cuttings:Generally refers to seedlings cultivated by taking side branches with relatively high vigor from specially cultivated eucalyptus mother plants and soaking them in rooting powder to promote root growth from the cortex tissue. The characteristics of cuttings are low cost, short cultivation time and simple operation. Overall, their growth vigor and growth amount are slightly inferior to those of tissue-cultured seedlings.
3. Seedlings grown from seed:Refers to eucalyptus seedlings cultivated from eucalyptus fruit. Seedlings grown from seed are simple to produce and low in cost, but because their genetic traits are unstable and variation is relatively great, the vigor of the seedlings is also relatively lower, thus affecting the overall growth amount and the rate of trees reaching maturity. Seedlings grown from seed are gradually no longer adopted.
Recommendation: In most cases, the growth of tissue-cultured seedlings is more advantageous than that of cuttings and seedlings grown from seed. Especially under poor growing conditions, such as relatively late planting time, high temperature, little water, poor soil, and places with frequent termite activity, the survival rate of tissue-cultured seedlings is greater than that of cuttings and seedlings grown from seed.
Selecting by eucalyptus variety:
DH3229：A hybrid bred with Eucalyptus urophylla as the female parent and Eucalyptus grandis as the male parent. Its excellent characteristics are obvious, and its cold tolerance is better than that of Guanglin No. 9. The growth amount per unit area can reach 45 cubic meters/year*HM. It is resistant to bacterial wilt and dieback, and the stump has strong sprouting ability. Generally, it can close its canopy and become a forest in about one year. As a short-term industrial timber raw material, it provides relatively fast economic returns. It is suitable for planting in areas with high temperatures year-round, such as Guangdong and Guangxi.
Guanglin No. 9:A hybrid bred with Eucalyptus grandis as the female parent and Eucalyptus urophylla as the male parent, possessing the excellent characteristics of both parents. It has good wind resistance. The growth amount per unit area can reach 45 cubic meters/year*HM. It is resistant to bacterial wilt and dieback, and the stump has strong sprouting ability. Generally, it can close its canopy and become a forest in about one year. As a short-term industrial timber raw material, it provides relatively fast economic returns. It is suitable for planting in areas with high temperatures year-round, such as Guangdong and Guangxi.
Eucalyptus wetarensis x Eucalyptus camaldulensis No. 3:A new fast-growing, cold-tolerant variety developed through natural hybridization of Eucalyptus wetarensis and Eucalyptus camaldulensis followed by further selection. It can withstand low temperatures of minus 10 degrees Celsius. The growth amount per unit area can reach 45 cubic meters/year*HM. It is resistant to bacterial wilt and dieback, and the stump has strong sprouting ability. Generally, it can close its canopy and become a forest in about one year. As a short-term industrial timber raw material, it provides relatively fast economic returns. It is suitable for planting in areas with long frost periods.
Precautions:
Eucalyptus seedlings are prone to dieback and bacterial wilt, so when choosing eucalyptus seedlings they need to be identified to avoid buying diseased seedlings. Dieback often occurs in cutting nurseries and damages tender leaves, tender branches and tender shoots. When infection is severe, the seedlings quickly wither and die. Dieback mainly appears as lesions on branches and leaves that are light brown to brown, round or irregular. When humid, the edges of the diseased parts are water-soaked, and the lesions look as if they have been scalded by boiling water; when dry, the boundaries of the lesions are obvious, and the downy mildew-like substance on the back is not easy to see. Dieback mostly occurs in hot and humid seasons, and cuttings are more susceptible because in the seedbed the temperature is high and the relative humidity is great, making the disease more likely to spread.
Eucalyptus dieback and bacterial wilt can also be prevented and controlled:
1. Choose a good nursery site: The nursery site should be set up in a place with good air circulation, and dense planting is not advisable.
2. Strengthen management: Control the moisture in the seedbed. In summer, provide appropriate shading and cover with grass to lower soil temperature, and appropriately increase fertilizer application to promote seedling growth and improve disease resistance. In hot and humid summers, spray 0.5-1% Bordeaux mixture once a week to protect the seedlings, or 75% chlorothalonil 600-800 times solution. Cuttings should be disinfected. Generally, soak them in 0.2-0.3% potassium permanganate for 6 hours, then wash them clean with clear water before inserting them into nutrition bags. On the second day after being put into the bags, begin the first application: first disinfect with 0.2% potassium permanganate, then wash the seedlings with clear water, and then spray with 75% chlorothalonil 600-800 times solution once a week.
3. Promptly handle diseased plants: If diseased seedlings are found, they should be promptly removed, and 0.2-0.3% potassium permanganate should be sprayed on the seedlings to inhibit the disease from continuing to spread. After spraying, wash the seedlings with clear water.
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