Seed stage (embryonic stage)
Plants start from the fertilization of eggs to the formation of zygotes until the seeds germinate. Embryonic stage is mainly to promote seed formation, safe storage, sowing in suitable environmental conditions, and make it germinate smoothly. The length of embryonic period varies from plant to plant. Some plant seeds will germinate as long as there are suitable conditions. Some plant seeds can not germinate immediately after being given suitable conditions, but only after a period of dormancy.
initial stage
From seed germination to the first flowering of plants. Childhood is a period when the overground and underground parts of plants grow vigorously by centrifugation. Plants grow rapidly in height, crown width, root length and root width. And gradually accumulate a lot of nutrients in the body to prepare for the transition from vegetative growth to reproductive growth in morphology and internal substances.
The length of young age varies with the species, varieties, environmental conditions and cultivation techniques of garden trees.
The cultivation measures in this period are to strengthen soil management, fully supply water and fertilizer, promote the healthy and balanced growth of vegetative organs, lightly cut and leave more branches, deep roots and many leaves, form a good tree structure, produce and accumulate a lot of nutrients, and lay a good foundation for early fruit. It is necessary to promote the reproductive growth of ornamental flowers and fruits. In the early stage of planting 1 ~ 2 years, when the new shoots grow to a certain length, appropriate inhibitors can be sprayed to promote the formation of flower buds and shorten the young stage.
At present, large-scale perennial seedlings are widely used in landscaping, so they spend their infancy in garden nurseries. It should be noted that trees should be cultivated according to different greening purposes.
mature period
From the first flowering of plants to the senescence of trees.
Youth: from the first flowering of plants to the end of a large number of flowering. It is characterized by the accelerated expansion of crown and root system, which is the fastest period of centrifugal growth and can reach or approach the maximum nutrient area. Plants can blossom and bear fruit every year, but the quantity is small and the quality is not high. Cultivation measures in this period: to give good environmental conditions and strengthen fertilizer and water management. For trees with the purpose of viewing flowers and fruits, light cutting and heavy fertilization are the main measures to make the crown reach the predetermined maximum nutritional area as soon as possible; At the same time, we should relax the tree potential and promote the growth of trees and the formation of flower buds. If the growth is too strong, nitrogen fertilizer can be applied less, phosphorus fertilizer and potassium fertilizer can be applied more, and chemical inhibitors can be used appropriately when necessary.
Maturity: from a large number of trees began to blossom and bear fruit to a sharp decline in bearing capacity, branches outside the crown dried up. It is characterized by fully developed flower buds, enlarged flowering and fruiting parts and increased number. The shapes of leaves, buds and flowers all show stereotypes. After the centrifugal growth of the backbone branches stops and the crown reaches the maximum, it often shrinks again due to the decline or contraction pruning of the terminal branchlets. The fibrous roots at the end of the root system also died, and a small number of vigorous regenerated branches began to appear in the inner cavity of the crown.
The cultivation measures in this period should strengthen the management of water and fertilizer; Apply base fertilizer early and topdressing by stages; Only by carefully renewing and pruning can we continue to grow vigorously and avoid premature aging. At the same time, some backbone roots are cut off to promote root regeneration.
Maturing period
The main branches and roots gradually declined, and the growth was obviously weakened until the plant died. It is characterized by a large number of deaths of backbone branches and roots, fewer and fewer vegetative branches and fruiting mother branches, slender branches, small growth, serious damage to tree balance, weak ability of crown regeneration and rejuvenation, obvious reduction of stress resistance, wood rot, bark peeling, tree aging and gradual death.
The cultivation techniques and measures in this period should be different according to different purposes. For common flowering shrubs, they can germinate and regenerate, or they can be cut down and replanted; For ancient and famous trees, various rejuvenation measures should be taken to prolong their life cycle as much as possible. Only when they are irretrievable and lose any value can they be cut down.
For the life cycle of asexual trees, except the seed stage, there may be no juvenile stage or the juvenile stage is relatively short. Therefore, the age period in the life cycle of clonal trees can be divided into three periods: infancy, maturity and senescence. The characteristics and management measures of each age group are basically the same as those of the corresponding period of seedlings.