Growth Factors II. Light

Light is another important factor for growth and the correct functioning of physiological processes in turfgrass.

Photosynthesis is the process by which energy from sunlight is converted into chemical energy, which can be used by plants. Atmospheric (inorganic) carbon is transformed to organic carbon using water and, as an energy source, light. The end products are Oxygen and Carbohydrates (energy). The reaction governing the process is as follows:

6 CO2 + 6 H2O >>> 6 O2 + C6H12O6

Light is electromagnetic energy made up of units called photons. The radiation used in photosynthesis is the band of sunlight with a wavelength frequency between 380 and 775 nanometres, which is called PAR(Photosynthetically Active Radiation) and its unit of measurement is micromol/m2 and second.

Therefore, depending on how sunny or shaded an area is, photosynthesis will take place and thus the formation of energy and ultimately the correct growth of the grass. The measurement of the amount of this energy that a surface can capture in a day is called the DLIDaily Light Integral, which is expressed in units of mol/m2 and day.

The range of values is between 0 and 60 mol/m2 and day.

Nowadays, there are different devices on the market capable of measuring these phenomena instantaneously and on a daily basis. The instantaneous measurement is given by the PFFDPhotosynthetic Photon Flux Density, and the unit is micromol/m2 y s. From this, we obtain the DLI of any area as a representative parameter, which will vary seasonally for the same area.

 Tiloom offers the necessary technology for daily, DLI and instantaneous metering, PPFD.

Based on recent studies at Clemson University (Bunnell, 2005), we recommend a DLI of 32, 6 mol/m2 and day for Bermuda Tifeagle greens. Other studies in Florida (Glenn, 2012), indicate minimum requirements for different Bermuda varieties (Celebration and Tifgrand) over 1 inch in height, around 20 - 25 mol/m2 and day.

On the other hand, C4 cultivars such as St Agustine and Zosiagrass are even less demanding in DLI, i.e. more shade tolerant.

C3 species will generally have lower requirements than C4 species, with Fescues being one of the most shade tolerant.

Strategies recommended by Tiloom are the increase of the cutting height and the use of artificial light in cases where demanding varieties are already established and it is not possible to achieve the necessary minimum DLI thresholds, as is often the case in football stadiums.