Intensive cultivation of fast-growing poplar industrial timber forest needs clonal seedlings first, that is, only one clonal seedling is used for afforestation. Mixed clone seedling afforestation is easy to cause stand differentiation, increase the difficulty of tending management, and reduce stand yield and quality. Therefore, it is necessary to be able to identify different cultivated species very clearly in the nursery.
Because the morphological characteristics between varieties are sometimes very close, and often only specialized technicians can distinguish them, they must be placed separately, and their positions should be recorded in the seedling register and vertical map immediately after emergence or transplantation. Seedlings should be inspected regularly, and mixed species must be corrected if found. In order to avoid confusion, 1 year-old seedlings can be painted with various identification colors. In addition, using cutting seedlings provided by cutting nursery is the most reliable means to ensure the purity of clones. In areas where cutting seedling has not been established, seedling technicians should strictly control the selection of cuttings to prepare cuttings, pay attention to observation during the growth of seedlings, dig out mixed clones as much as possible or make obvious marks, and pick out these mixed clones for other use when raising seedlings to ensure the clone purity of seedlings.
(2) Health status of seedlings
Many diseases and insect pests of fast-growing poplar trees should be effectively controlled at seedling stage, which can reduce the control cost after afforestation. In the classification investigation of seedlings leaving the nursery, it is necessary to check the diseased plants, and immediately pick out the diseased plants and insect pests that were missed in the past and deal with them centrally. Seedbed seedlings are not allowed to be sold if there are a certain number of infected seedlings in the seedbed. The most serious disease is the disease that leads to premature defoliation, which makes the seedlings defoliate 1 month in advance, resulting in insufficient lignification and insufficient accumulation of nutrients and water necessary for healthy development, which is an important reason why they cannot take root after transplantation.