Which environmental factor can influence seed germination in some species, aside from air, moisture, and temperature?

Which environmental factor can influence seed germination in some species, aside from air, moisture, and temperature?

• A. Light
• B. Gravity
• C. Sound
• D. Salt

Answer: (A)

Light can influence seed germination in some species because seeds use light as a cue about their surroundings. Some seeds are positively photoblastic and need light to begin germinating, while others are negatively photoblastic and germinate better in darkness. Plants have photoreceptors, like phytochromes, that detect red and far-red light; the light signals tell the seed whether it’s near the surface or shaded by vegetation, helping ensure germination happens under favorable conditions. In practice, surface-sown seeds or those that require light should be exposed to light to germinate, whereas seeds that prefer darkness should be kept covered lightly to maintain darkness. The other options don’t serve as germination cues in the same way: gravity mainly influences growth direction after germination, sound isn’t a recognized germination trigger, and high salinity can inhibit germination but isn’t a light-based cue.

Light can influence seed germination in some species because seeds use light as a cue about their surroundings. Some seeds are positively photoblastic and need light to begin germinating, while others are negatively photoblastic and germinate better in darkness. Plants have photoreceptors, like phytochromes, that detect red and far-red light; the light signals tell the seed whether it’s near the surface or shaded by vegetation, helping ensure germination happens under favorable conditions. In practice, surface-sown seeds or those that require light should be exposed to light to germinate, whereas seeds that prefer darkness should be kept covered lightly to maintain darkness. The other options don’t serve as germination cues in the same way: gravity mainly influences growth direction after germination, sound isn’t a recognized germination trigger, and high salinity can inhibit germination but isn’t a light-based cue.