What are the common seed germination methods?

Germination is through artificial measures, so that the seeds in a dormant state, especially long-term dormant seeds, under certain conditions and physical and chemical methods of stimulation, to break the seed dormancy, to promote the rapid germination of seeds, germination neat process.

Seeds through germination can not only lift the dormancy, but also can make the young shoots out of the soil at the right time, germination quickly and neatly, shorten the period of seedling emergence, and improve the germination rate of the nursery. At the same time can also enhance the resistance of seedlings, improve the yield and quality of seedlings. Germination treatment before sowing is the main measure of nursery work. Production of commonly used germination methods are the following:

(a) water immersion germination:

Water immersion germination is aimed at softening the seed coat, so that the seed absorbs water and expands, which is conducive to the enzyme activity, and promotes the hydrolysis of the storage material for the seed germination needs. At the same time, dipping seeds, washing seeds can also be dissolved within the seed inhibitor leaching, is conducive to breaking seed dormancy.

The water temperature and time for seed dipping varies according to the size of the seed, the thickness of the seed coat and the chemical composition. General seed grain size, thick seed coat, soak the seed water temperature can be higher. Such as acacia, soapberry water temperature up to 80 ~ 90 ℃, and small seeds, thin seed coat poplar, willow, elm, paulownia, etc. are more cold water soaking. When the water temperature is high, the duration should not be too long, the volume ratio of seeds and water to 1:3 is appropriate, while pouring water and stirring, so that it naturally cools. Soak the seeds for more than 12 hours, to change the water, to ensure that there is enough oxygen in the water, conducive to seed germination. How much water absorption of seeds, mainly depends on the seed characteristics and soaking time, generally more fat-containing seeds than protein-containing seeds absorb more water; protein-containing seeds more than starch-containing seeds absorb more water, the general water absorption of seeds to reach the dry weight of the seed itself 25% to 75% can begin to germinate. More water absorption prevents seed respiration but is unfavorable to seed germination.

Through the soaking of seeds and fully absorb water after expansion of the seeds, a little drying can be sown (that is, only soaking the seeds without germination), or mixed with 3 times the wet sand, or put into a container with a wet cloth or moss cover, placed in a warm place to germinate. On the method should pay attention to the temperature and aeration condition of the regulation, when the seed cracked mouth white accounted for 30% can be sown.

Production of forced dormant seed germination, can be netted after the seed to let it fully absorb water to soak the seed, and then piled up in a warm place, covered with plastic film, warming and moisturizing, when there is a 1/3 of the seed whitening when sowing, both germination neat, rapid, and simple and practical.

(ii) layer germination:

This method is widely used in production, the effect is good, especially for physiological dormant seeds, more need to use layer germination, the disadvantage is that germination time is longer.

Layer germination is to put the seeds in a moist, low-temperature and aeration environment, gradually lifting the seed dormancy, after sowing to make the seeds germinate quickly and neatly.

The stratification of germination is carried out under certain temperature and moist conditions. First, the seed coat is softened and permeability is increased, which is conducive to the development of the embryo. At the same time so that inhibitors such as abscisic acid, phenolics, etc. gradually decomposed, and growth hormones such as gibberellins, cytokinins, etc. gradually increased to promote seed germination. The shift from inhibitor dominance to growth hormone dominance is the key change process to break dormancy. The germination process also promotes the growth and development of the seed embryo and metabolic activities, so that the enzyme activity is strengthened, complex insoluble organic matter such as proteins, fats, starch, etc. is converted into simpler soluble amino acids, glycerol and glucose for the growth of the embryo, for example, ginkgo seed embryo in the laminated significantly larger, and earlier completion of its physiological maturation process. Therefore, laminar germination is a simple and safe method of germination.

Schematic diagram of stratification germination

Schematic diagram of mixed sand germination

Specific methods are: outdoor selection of high and dry terrain, well-drained, loose soil and windy places, digging germination pits, the length and width of the seeds depending on how many, the depth according to the local temperature and water table, in principle, will be placed in the best seed above the water table, the frozen layer of the following, the depth of general 60 ~ 80 cm, the length and width of the seeds as much as the number of seeds, according to local temperature and water table. 80 centimeters, length and width depending on how many seeds. Soil pit dug, first in the bottom of the pit to lay a layer of gravel or coarse sand, about 10 ~ 15 cm, and then paved 5 ~ 6 cm thick moist fine sand, the center of the pit inserted a bunch of straw (such as the pit length of more than 2 meters, should be every 1 ~ 1.5 meters inserted a bunch of straw), so that the pit 20 cm above the surface in order to aerate. Then the seeds and wet sand mixed at 1:3 volume ratio stacked in the pit, or a layer of seeds a layer of wet sand alternating layers, the thickness of each layer of about 5 centimeters. The humidity of the sand to the hand into a ball without water, loosen the hand to touch to disperse (about 50% to 60% of the saturated water content) is appropriate. When the seed pile to the ground 10 to 30 centimeters until it is covered with wet sand, and then covered with soil piled into a ridge shape. Pit mulch thickness should be based on local climatic conditions, in the north should be thickened with the climate becomes colder and thicker soil layer. In order to prevent water in the pit caused by moldy seeds, the pit should be dug around the drainage ditch. If there is a rodent infestation, the pit can be surrounded by wire mesh.

Small seeds or more valuable species, such as the number is not large, the seed can be mixed with sand into a wooden box or bamboo basket and then buried in the pit. The wooden box should be drilled around some small holes to facilitate aeration.

In the stratification germination period should pay attention to regular inspection and management, to prevent seed mold or dry. When 30% to 50% of the seeds are cracked, they can be sown.

Different tree species seed stratification germination days are different, the same tree species and due to the different methods used, the germination date is also a big difference. Seed stratification germination days.

Seed stratification germination days

(3) chemical germination:

Seeds with wax, oil seed such as Sapium sebiferum, lacquer tree, pepper, etc. available 1% alkali solution or washing powder solution or grass ash solution soaked to remove wax, oil and then germination. For some seed coat does not have oil, wax seeds, such as ponytail pine, acacia, etc., with 1% of the soda soaked seeds also has a softening of the seed coat, to promote the role of the metabolism of the seed embryo. The seed coat is particularly hard seeds, such as soap pods, more than 60% of the concentrated sulfuric acid can be used to soak the seeds for half an hour, and then rinse with water, can greatly reduce the time of soaking.

In addition, also available plant hormones such as gibberellin fermentation solution (diluted 5 times) treatment, soak the seed for 24 hours, on the stinking toon, ash, acacia and other seeds, not only to improve seedling emergence, but also can significantly improve seedling growth potential. The use of plant hormone seed dipping, must master the appropriate solution concentration and seed dipping time, the concentration is too low, the effect is not obvious, the concentration is too high on the seed germination has an inhibitory effect.

In order to supply the seeds in the germination of nutrients needed, with ammonium sulfate, urea, calcium superphosphate, potassium chloride and other fertilizers and with trace elements such as calcium, magnesium, sulfur, iron, zinc, copper, manganese, boron, aluminum and other salts, to the appropriate concentration of the solution, can be a single or integrated immersed seeds, not only to improve the germination rate of the field nursery, but also to accelerate the growth of the seedling and the dry matter of the accumulation of seedlings, and to improve seedling on the adverse environment of the Resistance. But the concentration of trace elements should not be high, so as not to victimize the seeds. General copper sulfate available 0.05%, boric acid with 0.02%, zinc sulfate with 0.2%, remove the seeds after 24 hours of immersion, a little dry and then immersed in water for 24 hours, and then mixed with sand germination.

(D) physical methods of germination:

Physical factors such as sound, light, electricity and other physical factors to deal with the seeds, such as ultrasound, radioactive substances, laser irradiation, microwave treatment, low-frequency electric current and high-frequency electromagnetic wave treatment. To promote seed germination have significant effect. Such as the seeds of juniper with ultrasonic frequency 830 kilohertz, intensity of 18 watts/cm, time for 1 to 3 minutes, can improve the germination rate 4 to 5 times.