Seasonal Efficiency of Supplemental LED Lighting on Growth and Photomorphogenesis of Sweet Basil

Abstract

For decisions on supplemental lighting a quantitative knowledge of the plants' responses to light under varying conditions is fundamental. In this study, we developed light dose-response curves of growth and morphological traits for Ocimum basilicum L. and examined the effects of light color (blue, red, and white plus far-red) and natural environment (season) on these curves. Four greenhouse experiments were conducted throughout the year to determine the efficiencies of the light regimes on growth and their effects on plant morphology. A special aspect was the photosynthetic efficiency of far-red light. Linear and monomolecular relationships were found for the relationships between plant traits and supplemental light dose. Traits related to biomass productivity increased linearly with light dose whereas some morphological characters showed a saturation behavior. Red light and white plus far-red light were more efficient in plant dry weight production than blue light, and the plants adapted differently to the light qualities: higher biomass under red light was related to a plant architecture more favorable for light capture, i.e., taller plants and bigger leaves. White plus far-red light, on the other hand, increased leaf mass per area (LMA) and light use efficiency (LUE). Blue light resulted in lowest plant light interception and LUE. Considering photosynthetic effects of near-infrared light (PPFD800, 400–800 nm) instead of photosynthetic photon flux density (PPFD700, 400–700 nm) led to strongly reduced efficiencies. Traits related to photosynthesis such as dry weight, LMA and LUE were particularly affected by PPFD800. There were no interactions between the efficiencies of the different light colors and the seasons. Efficiencies of all light regimes were significantly lower during summer compared to spring and winter. Higher dry weight production during summer compared to winter and spring were a consequence of increased light interception rather than changes in LUE. The observed differences in seasonal efficiencies were directly linked to the amount of natural light present as indicated by changes in the ratio of supplemental to natural light.

Compensation of adverse growing media effects on plant growth and morphology by supplemental LED lighting

“…It was recently demonstrated that supplemental LED lighting efficiencies during greenhouse production are directly affected by the growing season. Supplemental lighting efficiencies are thereby lower during high light conditions compared to low light conditions [ 40 ].…”

“…[19,[28][29][30][31][32][33][34][35][36]). However, fewer studies investigated the interactions of supplemental lighting with other environmental factors such as air temperature, fertilizer concentration and growing season under controlled environments [37][38][39][40].…”

Effects of White and Blue-Red Light on Growth and Metabolism of Basil Grown under Microcosm Conditions

“…Small dimensions, high growth rate and short cultivation cycle make basil an interesting crop for indoor farming which can support year-round demand for basil as a fresh and dry herb, pesto sauce, extracts and essential oil. The scientific literature has clearly demonstrated that different lighting regimes affect downstream metabolic pathways which influence basil growth, development and metabolism, allowing one to tune basil metabolism by modulating light quality and intensity [ 14 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. Unravelling the huge amount of experimental literature results is, however, a very challenging task, as they were generated from research approaches which differ in many aspects, including experimental design and set-up, germplasm, plant developmental stages, duration of cultivation and growing methods, in addition to light supply.…”

Root-zone Temperature Effects on Spinach Biomass Production Using a Nutrient Film Technique System

“…The MAT inside the greenhouse varies with variations in outside climate. In addition, energy use efficiency, including light use efficiency (LUE), varies with the changes in the environment in greenhouses (Solbach et al, 2021). The cultivation of plants is just in such a synthetic environment.…”