Research

In the growing season 2022/ 2023 Plantalux together with Department of Vegetables and Medicinal Plants of Warsaw University of Life Sciences conducted a research “Effect of Plantalux LED lamps light supplementation compared to traditional light supplementation with sodium lamps on yield and quality of greenhouse cucumber grown in winter”. The cultivation compartments for research, were equipped with sensors monitoring microclimate data connected to a climate computer controlling climate parameters in each compartment, such as air temperature, air humidity and CO2 concentration in the air.

Greenhouse cucumber (Cucumis sativus L.) of the `Mewa` F1 variety from Rijk Zwaan was used for the study. The seedling was grown under HPS lamps (600 W) at an average light level of 170 µmol/m2/s PPFD for 16 h per day.

The ready cucumber seedlings were planted into mineral wool mats in three cultivation chambers, each with a usable area of 40 m2 . In the first compartment HPS lamps were installed as a control. In next two chambers Plantalux LED lamps were used – of broad spectrum (second) and narrow with dominant red and blue wavelengths (third).

The cultivation substrate for the cucumber was mineral wool. The density of plants planted was 2.7 plants / m2  of the growing area. Plants were fed with CO2 maintaining a concentration of 800 ppm CO2 in each growing compartment. Light conditions in terms of PAR were maintained in each chamber at approximately 320-330 µmol/m2/s PPFD. The lamps placed over the tops of the plants were automatically switched off at a solar radiation level of 250 W/m2.

Lamps energy consumption

Automatic energy consumption

Heat energy consumption

Above charts presents percentage consumption of energy (lamps, automation, heat) for the production of1 kg of cucumber fruit in cultivation chambers supplemented with broad spectrum LED and narrow spectrum LED lamps in relation to the energy consumption per 1 kg of fruit produced in the chamber with HPS lamps.

Conclusions

  • The highest weekly yield was harvested from plants grown under broad spectrum LED, which was, on average for the whole cucumber yield period, 1.94 kg/m2 . In the combination where plants were supplemented with narrow spectrum LED, the average weekly cucumber yield was 1.87 kg/m2 , and in the control (HPS-supplemented plants) it was 1.53 kg/m2.
  • Weekly growth of cucumber shoot length, depending on the week of the year and the type of lamps used for supplementation, ranged from 60 to more than 80 cm and was usually longer in plants grown under HPS lamps than those grown under LED lamps.
  • Plants grown under broad spectrum LED lamps had fruit with the highest sugar extract content and high total sugars. In contrast, fruit from plants supplemented with sodium lamps had the lowest sugar extract and total sugars content.
  • Electricity consumption for lamp operation was more than 50% lower in the chambers supplemented with broad spectrum LED and narrow spectrum LED lamps than in the chamber with HPS lamps.