Role of the light factor in plant growth

Light plays a fundamental role in plant growth and development. It is estimated that 20-25% of turfgrass is maintained, to a greater or lesser degree, under shaded conditions either by buildings or by surrounding trees. (Jack fry and Bingru huang, applied turfgrass science and physiology, 2004)..

Plant growth and development will be affected by the quality, intensity and duration of light depending on the variety, species or cultivar.

Light quality: The energy produced by the sun is a mixture of electromagnetic radiation with different wavelengths. In photosynthesis, the sun's energy is converted into chemical energy by photosynthetic organisms called pigments which absorb only specific wavelengths between 400-700nm. Wavelengths between 700-800nm do not interfere with photosynthesis, but may affect germination, flowering and leaf stem growth.

Intensity Only 37% of the energy emitted by the sun has wavelengths usable for photosynthesis (400-700nm).62 % is infrared (<700nm) and the remaining 1% is ultraviolet (200-400nm). Generally, more light equals higher levels of photosynthesis. However, as light intensity increases, the rate of photosynthesis reaches a peak. This point is called light saturation point.

On cold climate turf the light saturation point is achieved with values between 534-1,072 µm per m² per second and in warm climate turfgrasses between 1,794-2,139 µm per m² per second (Jack fry and Bingru huang, Applied turfgrass science and physiology, 2004).

Duration of light The number of hours of light per day will depend on factors such as latitude, the time of year, the size of the structure that can provide shade... Increasing the hours of light can promote leaf growth and tillering of grasses, as well as increase resistance to stress caused by external factors. (Hay and Heide 1983, Aamlid 1992.).