The influence of a hybrid irradiation system on the growth, development and production process of tomato crops

Relevance. LED sources of plant irradiation, surpassing the level of sodium light sources in terms of energy efficiency, are superior to them in terms of the possibility of optimizing spectral characteristics. Therefore, the issue of wider use of LED light sources when growing plants under light culture conditions is relevant. Possessing significantly greater efficiency compared to high-pressure sodium lamps, LEDs are of great interest to greenhouse growers. However, the successful application of these new light sources requires new approaches. And the main thing is that LED sources of plant irradiation cannot be widely used without changing the technology for growing vegetable crops in protected soil, without introducing new, specially created hybrids. And direct replacement of sodium light sources with LEDs does not make sense.Methods. The studies were carried out in a modern greenhouse under controlled conditions of real light culture while growing a medium-fruited tomato F1 Bountis (DRS). The area of the registration plot was 326 m2. For phenological observations and crop recording, areas with the same number of plants were allocated in the center of the recording plot, leaving protective strips in one row of plants along the edges. The installed lighting power is 200 W/m2. The light source was high-pressure sodium lamps DNaZ/Reflux 600W 400V with a ZhSP25 Reflux lamp with electronic ballasts, as well as a LED greenhouse lamp 680W 400V.Results. When using a hybrid system, the total illumination in the PAR region is 40% higher compared to a sodium lighting system, and it would be expected that the yield of the tomato crop will change accordingly. In general, over the entire period of the experiment, the yield under hybrid lighting conditions was higher by only 3 kg/m2 or 5.5% and amounted to 58.3 kg/m2, and under the sodium system – 55.2 kg/m2. At the same time, under the conditions of the hybrid lighting system, plant growth was slightly behind the control: the length of the main stem was by 15%, the number of established leaves and their average length by 3%, the number of formed inflorescences by 5%, and the thickness of the leaf blade by 20%.Conclusion. An increase in light does not always lead to a similar increase in yield. Not just light is important for plants, it is important to correctly assess its productivity and spectral composition. The problem of assessing illumination taking into account the real interaction of light with the plant exists and must be solved.