Increase of Efficiency of Horticultural Lighting

Technology of horticultural cultivation gives us a common knowledge that the production of all kind of crops directly depends on illumination level. It is obvious that uniform illumination level can be achieved by using lighting equipment with different parameters of spatial light distribution. Lighting system with wide light distribution provides "volumetric" irradiation when in one point of normalized plane rays fall from several (6-8) fixtures from different directions. In this case a minimum of shadow zones arises; leaves of all layers of a plant are better lit in comparison with light level provided by luminaires with semi-wide or narrow light distribution. In addition the "volumetric" irradiation is similar to natural conditions where the direction of solar rays falling on plants varies within a day. Long-term practice of growing cucumber in the LLC Greenhouse Combine "Maiski" has shown that at equal normalized light exposure (or specific electric capacity) productivity in case of use of fixtures with wide light distribution (alpha(max)=68 degrees) on 20-25% is higher in comparison with use of fixtures with semi-wide light distribution (alpha(max)=40 degrees). Increase of efficiency of plant growth due to change of spatial characteristics of radiation of horticultural lighting at preservation of power expenses for its functioning is the important argument for further research and practical experiments in the given direction.