Effect of lignite substrate compared to mineral wool and supplementary lighting with HPS and LED on growth, plant photosynthetic activity, yield and fruit quality of greenhouse cucumber

Abstract

The substrate in hydroponic cultivation is one of the basic factors for proper plant growth, and current environmental trends suggest replacing the previously used mineral wool with organic substrates. Light is also essential for proper plant growth, which is why LEDs (Light Emitting Diode) are increasingly used to provide plants with supplementary light, allowing, among other things, to control the spectral composition. The aim of this study was to determine the effect of lignite substrate and LED supplementary lighting on morphological and physiological parameters as well as quality and yield of cucumber (Cucumis sativus L.) in hydroponic cultivation compared to the cultivation in mineral wool substrate. Lignite mats applied in cultivation with LED supplementary lighting had a beneficial effect on cucumber plant growth and development and plant nutrition in Fe, K, P, Ca, Mg and Zn compared to cultivation in mineral substrate and HPS supplementary lighting. The combination of LED lighting and lignite mats also improved the physiological parameters of the cucumber plants, as well as fruit hardness. Fruits harvested from plants grown in lignite substrate and supplemented with LEDs had the lowest nitrate content and increased TSS value, as well as increased fruit firmness.