Poplar is a fast-growing poplar species, mainly suitable for road greening, garden landscape, ecological shelter forest, three north shelter forest, agricultural forestry shelter forest and industrial timber forest, has become an important source of raw materials for processing in the veneer layer timber, fiberboard, particle board, plywood, papermaking, furniture, matches, sanitary chopsticks and packaging industry. For poplar cultivation, the selection of high-quality poplar seedlings is the first step, the selection of seedlings of the right size is the second step, how to choose seedlings has become the most headache for new users.
1. In desert edges and arid areas with severe water shortage, it is appropriate to choose annual poplar saplings. The root width of annual poplar seedlings produced by high-quality nurseries generally reaches 30-50 cm, and the sandy loam soil with good water and fertilizer conditions can cultivate robust seedlings with root widths of 60 cm and rhizomes of 1-1.5 cm, which can be completely planted and is the seedling age with the highest survival rate.
After purchasing saplings and transporting them to the cultivation site, cut off the aboveground part in time, and seal the shear part with paraffin wax, etc., and then transplant, and the root part after transplanting depth is consistent with the original. This practice is similar to nursery land for one-year stubble, which can effectively increase the height of the trunk, reduce the amount of pruning, and obtain more wood.
The biggest advantage of choosing an annual poplar sapling is that the cost of the sapling is low, the transportation cost is low, and the survival rate of transplanting is high, but it is necessary to dig large holes, apply plantar fertilizer and protect the integrity of the root system to ensure that the root system is stretched.
2. Self-propagating and self-breeding growers, growers who purchase seedlings at close range and growers with irrigation conditions generally choose biennial poplar seedlings. The root system of the biennial poplar seedlings is developed, the rhizome usually reaches more than 3 cm, and the stubble has been flattened in the nursery, and the saplings are very tall, which can shorten the growth period. However, the biggest disadvantage of biennial seedlings is that the root system is too large, and it is easy to damage the root system and stem in the process of mining and transportation, resulting in the occurrence of large-scale diseases and insect pests, the survival rate of transplanting is low, and a lot of watering is required to make the root system and soil dense.
The biggest disadvantage of the low survival rate of transplanting is the increase in cost, coupled with the replanting of seedlings in the same plot, there are obvious differences in growth rate, and the total growth amount will be reduced, resulting in reduced economic benefits and poor greening effects.
Why are they said to be good for two-year poplar saplings? That is the result of deliberate publicity by the nursery, it is impossible to sell all the annual seedlings; some nurseries have not reached the standard of strong seedlings due to management reasons; the seedlings of the second-year seedlings have good economic benefits; the seedlings that are replanted will also choose their own seedlings, and they can sell more money.
3. Unless it is a roadside tree, poplar seedlings of 3 years or more will generally not be selected. Poplar trees are originally very fast-growing tree species, and some areas begin to be thinned in 4-6 years, and excessive damage to the root system, bringing serious diseases and insect pests, it is more than worth the loss.
It should be noted that the depth of poplar transplanting is also exquisite, suitable for deep planting in areas such as the Three North Shelter Forest, and black poplar poplar trees are suitable for deep planting, which can increase multi-layer root system, increase water absorption capacity and windproof sand resistance, and the specific transplanting depth is: 40 cm for soil with strong stickiness, and more than 80 cm for sandy soil. Poplar poplars only need to be planted 30-40 cm.
Transplanting poplar trees needs to be classified, and seedlings with consistent root sizes and seedlings with consistent rhizome sizes are selected for transplanting to ensure the consistency of seedling growth. If dead seedlings are found, transplant older seedlings in the autumn. If small zombie trees or poorly grown plants are found, timely control of pests and diseases or increase the amount of fertilizer alone.
Poplar trees can have been propagated by cuttings, only need to soak the branches for 5-7 days after direct nailing into the soil to survive, but the main reason for the low survival rate of transplanted saplings is that the root system is too long in the transportation process or the root system is damaged, etc. The root system is water-scarce, and when transplanting, it is necessary to dig a large hole, apply sufficient fertilizer, irrigate enough water at one time, and cover the black mulch film around the rhizome for moisturizing. Larger saplings need to be fixed with triangular support to prevent high winds or human and animal shaking of the root system, resulting in a decline in survival rate.