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Gibberellins cause also seed germination by breaking the seed's dormancy and acting as a chemical messenger. Its hormone binds to a receptor, and calcium activates the protein calmodulin , and the complex binds to DNA, producing an enzyme to stimulate growth in the embryo.
Germination is the early growth of a plant from a seed. Meanwhile, dormancy precedes germination and serves to preserve a seed until conditions are receptive towards growth. The transition from dormancy to germination seems to depend on the removal of factors inhibiting growth. There are many models for germination which may differ between species.
It is a measure of germination time course and is usually expressed as a percentage, e.g., an 85% germination rate indicates that about 85 out of 100 seeds will probably germinate under proper conditions over the germination period given. Seed germination rate is determined by the seed genetic composition, morphological features and ...
Within the spermosphere, a range of complex interactions take place among the germinating seed, the soil, and the microbiome. [3] [1] Because germination is a brief process, the spermosphere is transient, but the impact of the microbial activity within the spermosphere can have strong and long-lasting effects on the developing plant. [3]
In addition to the mentioned seed pretreatments, seed germination is also assisted when a disease-free soil is used. Especially when trying to germinate difficult seed (e.g. certain tropical fruit), prior treatment of the soil (along with the usage of the most suitable soil; e.g. potting soil, prepared soil or other substrates) is vital.
Seed vigor is a measure of the quality of seed, and involves the viability of the seed, the germination percentage, germination rate, and the strength of the seedlings produced. [ 47 ] The germination percentage is simply the proportion of seeds that germinate from all seeds subject to the right conditions for growth.
The seeds of many Australian plants and plants from southern Africa and the American west require smoke or fire to germinate. Some plant species, including many trees, do not produce seeds until they reach maturity, which may take many years. Seeds can be difficult to acquire, and some plants do not produce seed at all.
There are at least three stages of plant development where photomorphogenesis occurs: seed germination, seedling development, and the switch from the vegetative to the flowering stage (photoperiodism). [2] Most research on photomorphogenesis is derived from plants studies involving several kingdoms: Fungi, Monera, Protista, and Plantae. [3]