• Home
• Science Strategy
• Science Teams
• Projects
  • Germination Micro-Site Perception: the Role of Light Quality and Quantity
• People
• Publications
• Acronyms

Germination Micro-Site Perception: the Role of Light Quality and Quantity

Recently emerged seedlings of Piper sp. (Piperaceae) in gap on forest floor

This project is one of a series in the theme 'Ecophysiology and Morphology'.

Germination is a high-risk phase in the life-cycle of plants. Consequently they exhibit specific adaptations to “cue” seed germination to either particular times of year or to particular micro-sites that are most suitable for both germination and onward seedling growth.

Whilst germination is high risk for all seeds it is particularly so for small seeded species since these only have the resources to emerge from a few millimetres depth in the soil, are unable to penetrate through leaf litter, are particularly sensitive to drought and have no capacity to recover from severe herbivory / trampling. Consequently small seeded species require mechanism(s) to carefully control, when and where germination occurs. Many small seeded species require light for germination to occur and this serves the purpose of ensuring that germination only occurs close to the soil surface. However, photo-responsive seeds also have the capacity to determine the quality (ratio of red : far red wavelengths) of intercepted light which can be used as a measure of the suitability of the environment for seedling growth – high ratios of red : far red light signal the absence of established vegetation and leaf litter both of which are potentially high risk for small seeds / seedlings.

However, while the responses of small seeds to the presence / absence of light have been comparatively well studied, little work has been conducted on the response of seeds to light quality. Consequently we are conducting comparative studies on the germination response to light quality for seeds of differing size and from different habitats to explore the role of light perception in determining both micro-site selection and regeneration success in situ. Currently we have found that for >20 Polish woodland herbs, there is a significant negative relationship between seed mass and the ratio of red : far red light required for germination, suggesting that small seeded species perform best in open micro-sites. However, this is in contrast to work by Pearson et al. in Functional Ecology (2003) from Central America which has shown the opposite relationship. We are currently working on trying to understand these potentially habitat-type driven differences in response.  See Annex 1 for information outputs associated with this project.

Kew Home | Science Directory | Copyright & Privacy