germination

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germination

 [jer″mĭ-na´shun]
the sprouting of a seed, spore, or plant embryo.
Germinationclick for a larger image
Fig. 171 Germination . A typical seedling.

germination

the beginning of the growth of a seed, spore or other structure that is dormant. Seed DORMANCY can be broken by several factors, depending on the species:
  1. the removal of a germination inhibitor which can be leached out by water.
  2. a period of cold temperature (STRATIFICATION).
  3. exposure to the correct wavelength of light to stimulate PHYTOCHROMES in the seed, for example, lettuce seeds require red light for germination and are inhibited by far-red light.
  4. rupture of a thick testa by (i) microbial breakdown, (ii) abrasive action of soil (as in desert plants), (iii) heat from bush fires, (iv) the effect of digestive juices (as when eaten by birds), (v) the softening action of water. Once dormancy is broken a regular sequence of events takes place: water is imbibed which hydrates the tissues increasing enzymic action in the ALEURONE layer (when present), a process aided by the release of GIBBERELLIN from the embryo; food stores are mobilized by production of enzymes in the ENDOSPERM or within the COTYLEDONS; AUXINS and CYTOKININS are formed which promote cell division and enlargement, causing the embryo to grow and burst through the testa. See Fig. 171 .

There are two main types of germination, depending on whether the seed cotyledons are carried above the soil (EPIGEAL) or remain below ground (HYPOGEAL).

References in periodicals archive ?
Fabiao, "Influence of mother plant and scarification agents on seed germination rate and vigor in Retama sphaerocarpa L., (Boissier)," IForest-Biogeosciences and Forestry, pp.
(2015) reported that both hydropriming and osmopriming improved germination and seed germination rate index of pepper seeds compared to unprimed seeds.
The crossed chemical treatment on the intact cypsela was effective to slow down just the central cypsela germination rate (b = -0.29 [+ or -] 0.10, t = 2.92, p = 0.03, Intact vs.
In contrast, the lowest germination rate (9.3%) was noted for Halilbey variety at 120 mM NaCl dose.
Optimal Cox proportional hazard model of germination rate in E.
The concentrations of clove oil of less than 1.5 mL negatively affected the vigor of the seedlings, contributing to its shorter length, due to the increased incidence of fungi in the seeds and thereby reduced germination rate (Figure 2).
The researchers calculated the germination rates as the number of germinated seeds per total number of seeds after two days.
SEED--LABEL ANALYSIS SEED AMOUNT GERMINATION RATE Weka White Clover 14.98% 85% Kotare White Clover 14.91% 90% Commander Chicory 04.97% 85% Medium Red Clover 04.96% 90% Sweet Clover 04.95% 85% Forage Chicory 04.94% 85% Other Crop Seed 00.05% -- Inert Matter 00.21% -- Weed Seed 00.03% -- Coating Material 50.00% -- Net weight: 25 Pounds TEST DATE: 5/17
Caption: Figure 6: Seed germination rate as a function of time at various treatments.
The germination energy (GE) was determined at the 15th day and the germination rate (GR) calculated on the 23th day (Gesch et al., 2016).
Finally, a drag chain covers the seed, and the rear wheel presses the soil around the seed to maximize the germination rate.