The maturation process of Shanghai plant rental seeds is mainly the development of embryo and endosperm
What is the maturation process of Shanghai Plant Rental Seeds?
(A) Seed maturity
The maturation process of Shanghai plant leased seeds is mainly the development of embryo and endosperm. After fertilization, the eggs gradually develop into embryos with radicles, hypocotyls, germ and cotyledons. At the same time as the seed embryo is formed, the endosperm formed by the combination of polar nuclei and sperm will gradually accumulate and store nutrients. Seed maturity includes two processes: physiological maturity and morphological maturity:
In the early stage of seed development, the ovary swells quickly. The seed coat and peel are thin and tender. The color is light and the internal nutrient sites are increasing, but the speed is slow. There is a lot of water and it is mostly transparent liquid. When the seed develops to a certain degree, it shows that the tissue is full, the degree of lignification is strengthened, the internal nutrient accumulation speed is accelerated, the concentration is increased, the water is reduced, and the transparent liquid is changed to a cloudy latex state. It gradually condenses to a solid state. The inside of the seed is almost filled with hardened synthetic products. This is a series of biochemical changes. When the nutrients of the seeds are stored to a certain degree, the seed embryo is formed, and the seeds have the ability to germinate, which is called physiological maturity. The physiologically mature seeds have high water content. The nutrients are in a soluble state, and the seed coat is not dense. Not yet. It has the characteristics of protecting seed kernels. It is not easy to prevent water loss. The seeds collected at this time. Their kernels shrink sharply. It is not conducive to storage, will soon lose germination ability, and has poor resistance to the adverse external environment, easy to be attacked by microorganisms. Therefore, the collection of species f is not at this time. get on. For some deep dormant trees (such as long dormant and difficult to break dormant) such as forged trees, mountain inspection, manchurian ash, etc., physiologically mature seeds can be harvested. Sowing immediately after harvesting. This can shorten the dormant period and improve Germination rate.
2. Morphological maturity
When the seed completes the development of the seed embryo. When the accumulation of nutrients ends, the water content decreases. The nutrients are converted from the soluble state to the insoluble fat, protein and starch, and the weight of the seed itself no longer increases or increases very little. Respiration is weak, the seed coat is dense, solid, and resistance is enhanced. After entering the dormant state, it is resistant to storage. At this time, the external shape of the seed shows mature characteristics, which is called morphological maturity. Most garden tree seeds are collected at this time. The seeds of most tree species have physiological maturity first. Morphological maturity can be reached after a period of time. There are also some tree species. The physiological maturity and morphological maturity of the seeds are almost the same, with a short time interval, such as early willow, Baiyu, Paulownia, Schima superba, Mocha, Taiwan Acacia, Leucaena. The seeds of these tree species fall off on their own when they reach physiological maturity. Therefore, they should be harvested in time. There are also a few tree species whose seeds reach physiological maturity after morphological maturity, such as ginkgo. When the seeds reach morphological maturity, the germ coat becomes yellow and soft and falls off from the tree. But at this time the seed embryo is very small. It has not yet developed. The seed embryo develops only after a period of time after harvest. Normal germination ability, this phenomenon is called physiological post-ripening. Some people believe that when the gingko seeds mature, the pollen tube has not reached the ovule, and fertilization can be completed after a period of time. Gradually re-form the embryo. Therefore, seeds with physiological post-ripening characteristics cannot be sown immediately after harvesting. They must be stored under appropriate conditions. Certain protection measures can be used to germinate normally.
From physiological maturity to morphological maturity, a series of biochemical changes are performed inside the seeds. This creates certain conditions for the dormancy of the seeds. The dormancy of seeds is the inheritance of some tree species. It is also a characteristic of adapting to external environmental conditions during long-term individual development.