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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 ...
Growing degrees (GDs) is defined as the number of temperature degrees above a certain threshold base temperature, which varies among crop species. The base temperature is that temperature below which plant growth is zero. GDs are calculated each day as maximum temperature plus the minimum temperature divided by 2, minus the base temperature.
Maximum effect is achieved at 7 °C (45 °F). [4] Temperatures between 13 °C (55 °F) and 16 °C (60 °F) (the threshold between chilling and warm weather) have zero weight, and higher temperature have negative weights: they reduce the beneficial effects of an already accumulated chilling hours. [3]
Warm stratification requires temperatures of 15–20 °C (59–68 °F). In many instances, warm stratification followed by cold stratification requirements can also be met by planting the seeds in summer in a mulched bed for expected germination the following spring. Some seeds may not germinate until the second spring. [citation needed]
The germination percentage is simply the proportion of seeds that germinate from all seeds subject to the right conditions for growth. The germination rate is the length of time it takes for the seeds to germinate. Germination percentages and rates are affected by seed viability, dormancy and environmental effects that impact on the seed and ...
The soaking increases the water content in the seeds and brings them out of quiescence. After draining and then rinsing seeds at regular intervals, the seeds then germinate, or sprout. For home sprouting, the seeds are soaked (big seeds) or moistened (small), then left at room temperature (13 to 21 °C or 55 to 70 °F) in a sprouting vessel.
True dormancy or inherent (or innate) dormancy is caused by conditions within the seed that prevent germination even if the conditions are favorable. [7] Imposed dormancy is caused by the external conditions that remain unsuitable for germination [8] Seed dormancy can be divided into two major categories based on what part of the seed produces dormancy: exogenous and endogenous. [9]
Many plants grown in temperate climates require vernalization and must experience a period of low winter temperature to initiate or accelerate the flowering process. This ensures that reproductive development and seed production occurs in spring and winters, rather than in autumn. [3] The needed cold is often expressed in chill hours. Typical ...