Effect of light spectrum on growth, development, and mineral contents of okra (Abelmoschus esculentus L.)

Abstract

Influence of the light spectrum on growth, development, and nutrients contents of okra was studied by growing okra (Abelmoschus esculentus L.) under three different LED-based irradiations defined by their peak wavelength at 455.45 ± 1.80 nm (B455), 522.27 ± 1.46 nm (G522), and 635.03 ± 1.33 nm (R635), respectively in the blue, green, and red regions of the visible spectrum. The photosynthetic photon flux density (PPFD) of 200 μmol m−2 s−1 was provided by the LEDs for 18 h daily. Leaves macronutrients and micronutrients concentration and plant biometric parameters were measured 60 days after sowing; the evolution of biometric parameters was also monitored during the growing period. Results related to biometric parameters have shown that highest leaf area, plant height, and fresh and dry weight were achieved under B455 light; both R635 and G522 lights produce the highest quantity of leaves; and largest stem diameters were observed under B455 and G522 lights. Regarding mineral contents, highest calcium, phosphorus, and manganese concentrations were obtained under R635 light; highest sodium content was observed under G522 light; and the highest nitrogen content was obtained under both B455 and G522 lights. However, there were no significant differences observed for potassium, magnesium, and zinc concentrations among the three light treatments. These results revealed that selective spectrum in artificial lighting design can be strategically used to optimize the plant growth, development, and mineral contents uptake under controlled environments.

Productivity, photosynthetic light-use efficiency, nitrogen metabolism and nutritional quality of C4 halophyte Portulaca oleracea L. grown indoors under different light intensities and durations

“…The differential effects of PPFD and DLI on the mineral nutrient uptake exemplify that other lighting conditions such as light quality could have some effect on the uptake and allocation of specific dietary minerals. For instance, in the study with okra ( Abelmoschus esculentus L.), red light at 635 nm enhanced the accumulations of Ca and Mg while the highest N content was found in the plants grown under green light and blue light, respectively at 522 nm and 455 nm ( Degni et al., 2021 ). The effects of light intensity, quality, photoperiod and DLI on dietary mineral accumulation and the mechanisms involved are still largely unknown.…”

LED Illumination for High-Quality High-Yield Crop Growth in Protected Cropping Environments

“…The increase in leaf area is one of the most important physiological parameters used to estimate the effective photosynthetic rates per unit area. For example, it has been reported that the largest leaf area is typically produced under blue LED illumination [15,103]. Note that a large leaf area allows a higher light-plant interception [37].…”

Spectral composition of LED light differentially affects biomass, photosynthesis, nutrient profile, and foliar nitrate accumulation of lettuce grown under various replacement methods of nutrient solution

“…italica) cultivated under combined red and blue light (R/B = 1: 4), the amount of Ca, Mg, P, S, B, Cu, Fe, Mn, Mo, and Zn were increased (Kopsell et al, 2014). In a study by Degni et al (2021) on okra (Abelmoschus esculentus L.), results showed that red light increased absorption of Ca, P, and Mn, and blue light improved N content. Lettuce grown under recycled hydroponic subjected to combination of light quality (red + blue) increased the amount of nitrate (NO 3 − ) and nitrite (NO 2 − ) contents (Li et al, 2021).…”