What is the effect of seedling density on seedling growth?

Seedling density refers to the number of seedlings per unit area (or unit length). In order to achieve high quality and high yield of seedlings, the maximum seedling yield per unit area (or unit length) must be obtained on the basis of ensuring the healthy growth and development of seedlings per plant. Therefore, seedling density plays an important role in the yield and quality of seedlings. The density of seedlings is too high, the nutritional area of seedlings is insufficient, the ventilation is poor, the illumination is poor, the seedlings are thin, the leaves are few, the terminal buds are not full, the root growth is limited, the root width is small, the lateral roots are few, the dry matter weight is small, the seedlings are susceptible to diseases and insect pests, and the survival rate of transplanting is low. If the density of seedlings is too small, it will not only affect the yield of seedlings per unit area, but also cause too large open space between seedlings, low land utilization rate, easy to breed weeds, increase the loss of water and nutrients in the soil, and make it difficult to manage. Therefore, to determine the reasonable density should be to obtain the maximum number of seedlings per unit area or unit length under the premise of ensuring the healthy growth and development of individuals. Seedling density should be determined according to the biological characteristics of tree species, growth rate, environmental conditions of nursery, seedling years and seedling technical requirements. With fast growth, strong growth, superior nursery environmental conditions, long seedling years and high seedling technology level, sowing should be sparse, otherwise it can be dense. One year after sowing, the transplanted tree species can be densely planted, and the rootstock seedlings directly used for grafting can be sparsely planted to speed up the thickness and length of the seedlings and facilitate the grafting operation.

The density of seedlings is reflected in the row spacing, especially the row spacing. The general row spacing of seedbed seedlings is about15 ~ 25 cm; Generally, the row spacing of field seedlings is 40 ~ 60 cm. The range of seedling yield per unit area in production is generally as follows: conifer annual sowing seedlings 150 ~ 300 plants/m; Fast-growing conifers can reach 600 plants/meter. The annual sowing seedlings of broad-leaved trees are: large seeds or fast-growing trees 25 ~ 120 plants/m; 60 ~ 160 plants/m, medium growth rate.