Growth and Quality of Hydroponic Cultivated Spinach (Spinacia oleracea L.) Affected by the Light Intensity of Red and Blue LEDs

Abstract

This study aimed to evaluate the effect of four light intensities (90, 140, 190 and 240 µmol m-2 s-1) provided by red-blue LED light (spectrum ratio: R660/B450 = 4/1) on the growth and quality of hydroponic cultivated spinach. The results showed that when the light intensity increased, plant height, leaf number, root length, leaf width, shoot fresh weight, shoot dry weight, root fresh weight and root dry weight were increased but specific leaf weight and shoot-to-root ratio did not increase. The highest values of growth parameters were observed under 190 µmol m-2 s-1 treatment, while the lowest values were observed under 90 µmol m-2 s-1 treatment. At higher light intensities, K+, oxalic acid and nitrate contents tended to decrease but not Ca2+ content. Meanwhile, the highest values of Fe2+, crude fiber, soluble-solids, total polyphenol and vitamin C contents were observed under 190 µmol m-2 s-1 treatment, but 190 µmol m-2 s-1 treatment showed the lowest organic acid content. Our results indicated that among all experimental lighting treatments, 190 µmol m-2 s-1 light intensity showed the best effect on the growth and quality of hydroponic cultivated spinach.

The Influence of the Spectral Composition and Light Intensity on the Morphological and Biochemical Parameters of Spinach (Spinacia oleracea L.) in Vertical Farming

“…As in an early study with plants of the Brassicaceae family [16], nitrate content in spinach plants (Figure 3) decreases with increasing light intensity [7,9]. It is worth emphasizing that in our case, more contrasting values of nitrate concentration with an increase in illumination from 120 to 180 µmol m −2 s −1 were observed in the control and V2 variants with spectral compositions; in other variants, the difference was not significant.…”

“…Optimal growth parameters were observed in the variant with 190 µmol m −2 s −1 . A decrease in potassium and oxalic acid was observed at higher light intensities [9]. When the effects of B, R, RB, and white (W) spectrum fluorescent lamps were studied at a PPFD of 300 µmol m −2 s −1 , it was found that blue spectrum irradiation was not suitable for growing spinach because of a sharp decline in shoot dry weight, although carotenoid content slightly increased, and R irradiation reduced nitrate content.…”

Defining growth requirements of microgreens in space cultivation via biomass production, morpho-anatomical and nutritional traits analysis

“…Leaf anatomical structure has a fundamental relationship with the plant photosynthetic performance, and usually a thicker and more dense tissue facilitates the transfer of gas and water among mesophyll cells ( Amitrano et al., 2022 ). Moreover, palisade cells are also known to concentrate more chloroplasts compared to spongy cells ( Nguyen et al., 2019 ), so one would expect ‘Saxa’ to have a higher photosynthetic pigment content. In our study, however, the content of both chlorophylls and carotenoids, as well as neoxanthin and lutein, was higher in ‘Vertus’ ( Table 5 ).…”

Effect of the Intensity and Spectral Quality of LED Light on Growth and Quality of Spinach Indoors

“…[14] observed that when photosynthetic photon flux density (PPFD) increased to 550 µmol m −2 s −1 , the specific leaf area (SLA) decreased in tomato plants. In another hydroponic spinach study, with the same light spectrum (R:B = 4:1) and different light intensities (90,140,190, and 240 µmol m −2 s −1 ), the authors observed that the highest values of growth parameters occurred in the variety of spinach PD512 when grown at 190 µmol m −2 s −1 , therefore producing a reduction in growth at the maximum light intensity (240 µmol m −2 s −1 ) [15]. On the contrary, low intensities can also cause changes in the morphology and physiology of the leaf.…”