Vocabulary Flashcards: Temperature Fluctuation and Germination (Eastern Tibet Plateau study)

Vocabulary flashcards drawn from the study on how diurnal temperature fluctuation vs. constant temperatures affect germination across 445 species on the eastern Tibet Plateau.

Germination

The process by which a seed begins to grow into a seedling, influenced by environmental cues such as temperature, light, and soil moisture.

Diurnal temperature fluctuation

Regular daily changes in temperature (day vs. night) near the soil surface that can cue seed germination.

Alternating temperatures (5/25°C and 10/20°C)

Two temperatures applied in a daily cycle to mimic field diurnal fluctuations (large amplitude 5/25°C and smaller amplitude 10/20°C).

Constant temperature (15°C)

A fixed incubation temperature used as a control in germination experiments.

Regeneration niche

The abiotic conditions that govern seed germination and regeneration, helping explain a species’ habitat and distribution.

Seed viability (TTC test)

The proportion of seeds capable of germination, assessed using the triphenyltetrazolium chloride test.

TTC test

Triphenyltetrazolium chloride test used to determine seed viability before germination experiments.

Germination percentage

The proportion of seeds that germinate under a given treatment.

Seed mass classes (≤1 mg, 1–2 mg, ≥2 mg)

Categories used to group seeds by mass for analyzing germination responses.

Life cycle type (annuals/biennials vs. perennials)

Categories distinguishing plants that complete their life cycle within one year or a few years from those that live and reproduce for multiple years.

Habitat categories

Five environments studied: alpine/subalpine meadow, disturbed ground, forest margin/scrub, marshland, and dry sunny slope.

Altitudinal distribution (≥2000 m vs. both above and below 2000 m)

Classification of species by elevation range used to analyze germination responses to temperature fluctuation.

Functional group (graminoids vs. forbs)

Two plant functional groups: graminoids (grasses and sedges) and forbs (non-graminoid herbaceous plants).

Germination response group I

Species with a negative germination response to temperature fluctuation.

Germination response group II

Species with a positive germination response to temperature fluctuation.

Germination response group III

Species that do not germinate well regardless of temperature fluctuation.

Germination response group IV

Species with high germination regardless of the magnitude of temperature fluctuation.

Friedman Test

A nonparametric test for comparing multiple related samples (used to analyze germination across temperature treatments).

Gap detection

A mechanism by which seeds use diurnal temperature fluctuations to detect vegetation gaps and time germination for favorable sites.

Depth sensing

A mechanism by which seeds sense burial depth through near-surface temperature cues to avoid deep germination.

Temperature amplitude

The magnitude of difference between high and low temperatures in a regime (e.g., 5/25°C vs. 10/20°C).

Maximum daily temperature cue

At high elevations, germination may be triggered by the highest daily temperature rather than the fluctuation itself.

Seed bank

A reservoir of viable seeds in the soil; temperature fluctuation–driven germination can contribute to seed bank dynamics.

Germination in darkness

Germination tests conducted with seeds kept in darkness, with brief light exposure during counting to fulfill possible light requirements.