Producing Enhanced Yield and Nutritional Pigmentation in Lollo Rosso Through Manipulating the Irradiance, Duration, and Periodicity of LEDs in the Visible Region of Light

Abstract

Pigmented food are an important part of the human diet, and anthocyanins have demonstrable protection against tumor production in mouse models and beneficial effects on human liver chemistry. As such, producing pigmented crops is important for a nutritionally diverse diet. Lollo rosso lettuce is a fast-growing pigmented plant, is rich in phenolic compounds, and represents a suitable system to test optimization strategies for yield and anthocyanin production. High-energy UV wavebands are often used to stimulate increased pigmentation; however, we hypothesized that optimizing visible wavebands would deliver both yield and quality improvements. Growing Lollo rosso under irradiances between 5 and 180 W m–2 using visible waveband LEDs produced 0.4 g fresh weight per W m–2 in the linear portion of the curve between 5 and 40 W m–2 and achieved an approximate asymptote of 20 g fresh weight at around 100–120 W m–2 for yield. Anthocyanin content increased linearly with irradiance. We attempted to optimize the visible wavebands by supplementing half the asymptotic energy for 15 days with supplemental red (R) or blue (B) wavebands in the peaks of photosynthetic activity (430–460 and 630–660 nm). R and B affected rosette morphology with no significant impact on yield, but B significantly increased anthocyanin content by 94% compared to R. We therefore focused on further optimizing B by shortening the daily duration of supplemental B. The minimum B treatment that lacked significant pigment induction was 1 h. We hypothesized that short durations would be more active at different times in the diurnal cycle. Supplemental B was applied for 2 h at four different times. A night-break with B produced the highest yield and anthocyanin content. Our research demonstrates new ways to efficiently use readily available LEDs within the PAR wavebands to increase both yield and crop quality in controlled environment agriculture.

Hybrid Genetic Programming and Multiverse-based Optimization of Pre-Harvest Growth Factors of Aquaponic Lettuce Based on Chlorophyll Concentration

“…Optimizing photosynthesis is vital in maintaining acceptable and marketable farm produce. Agricultural yield is dominantly driven by the combination of photosynthetic growth factors, namely carbon dioxide concentration, light intensity, temperature level [1], [2], photoperiod [3], vapor pressure [4], and the nutrients coming from soil and water resources that include nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S) as the macronutrients [5]. NPK, iron, and salinity concentration were previously optimized based on germination rate and root morphology for lettuce and rice [6]- [8].…”

“…Thus, leaf pigments are good visible indicators of the impact of abiotic stressors on plants concerning photosynthetic reactions. Leaf anthocyanin concentration is highest when low relative humidity and high irradiance [3], [4]. The use of a Sunlike light-emitting diode (LED) that mimics the natural solar spectrum (400 nm to 700 nm) proves that red and blue light of 9:1 ratio corresponds to better biomass production [19].…”

The Effect of Red & Blue Rich LEDs vs Fluorescent Light on Lollo Rosso Lettuce Morphology and Physiology

“…Optimized spectrum LEDs focused around the red and blue wavebands (red peaks at 634 and 665 nm and blue peak at 451 nm in our case) are highly efficient for plant growth ( Matsuda et al, 2004 ; Zheng and Van Labeke, 2017 ), and also impact photomorphogenesis ( Izzo et al, 2019 ). Rosette area (canopy cover) for example, a morphological adaptation supposedly resulting from the combination of multiple responses to light such as hypocotyl length, leaf angle and leaf shape ( Hoenecke et al, 1992 ; Cammarisano et al, 2020 ), responded mainly to light source and antithetically under the tested light sources. If under FL rosettes tended to expand with increasing irradiance, under LEDs increasing irradiance produced more compacted rosettes.…”

Photosynthetic Antenna Size Regulation as an Essential Mechanism of Higher Plants Acclimation to Biotic and Abiotic Factors: The Role of the Chloroplast Plastoquinone Pool and Hydrogen Peroxide

“…The problem of low photosynthetic efficiency of agricultural crops (e.g., of corn) when growing in the field is associated with the fact that most of the plant biomass is in shade [135]. Therefore, approaches to improve the acclimation of agricultural plants to suboptimal light conditions are being actively developed to improve their yield [136][137][138]. To increase crop yields a complex of approaches is required, including methods of biological protection of plants under stress conditions, under both biotic and abiotic environmental factors.…”