*2.1.4 Light*

The promotional effect of light in seed germination is through a single photoreaction controlled by the blue pigment phytochrome [26]. Seeds of many temperate tree species are known to be light sensitive, and their germination is promoted by red light and inhibited by far red light [27]. It is generally held that both light intensity (lux) and light quality 'colour and wavelength' influence seed germination. Germination is triggered by increases in light as well as by the ratio of red to far-red light and temperature [28]. However, while light has been reported to be a germination inhibitor i.e., show negative photoblastism in some Palmae as it's the case of *Sabal palmetto* [29] others are indifferent to light for their germination. Germination of seeds covered by soil suggests that seed of most species are indifferent to light [30].
