Integrative Effects of CO2 Concentration, Illumination Intensity and Air Speed on the Growth, Gas Exchange and Light Use Efficiency of Lettuce Plants Grown under Artificial Lighting

Abstract

This study investigates and quantifies the integrative effects of CO2 concentration (500, 1000 and 1500 µmol mol−1), illumination intensity (100, 200 and 300 μmol m−2 s−1) and air speed (0.25, 0.50 and 0.75 m s−1) on the growth, gas exchange and light use efficiency of lettuce plants (Lactuca sativa L.) grown under artificial lighting. The results show that lettuce growth and gas exchange are closely related to CO2 concentration and illumination intensity, while air speed enhances CO2 transport during photosynthesis. The most influential two-way interactions were observed between CO2 concentration and illumination intensity on the fresh and dry weights of lettuce shoots with effect sizes of 34% and 32%, respectively, and on the photosynthesis, transpiration and light use efficiency, with effect sizes of 52%, 47% and 41%, respectively. The most significant three-way interaction was observed for the photosynthetic rate, with an effect size of 51%. In general, the fresh and dry weights of lettuce plants increased by 36.2% and 20.1%, respectively, with an increase in CO2 concentration from 500 to 1500 µmol mol−1 and by 48.9% and 58.6%, respectively, with an increase in illumination intensity from 100 to 300 μmol m−2 s−1. The photosynthetic rate was found to be positively correlated with CO2 concentration, illumination intensity and air speed. The transpiration rate and stomatal conductance increased by 34.9% and 42.1%, respectively, when the illumination intensity increased from 100 to 300 μmol m−2 s−1. However, as CO2 concentration increased from 500 to 1500 μmol mol−1 and air speed increased from 0.25 to 0.75 m s−1, the transpiration rate decreased by 17.5% and 12.8%, respectively. With the quantified data obtained, we were able to adequately determine how CO2 concentration, illumination intensity and air speed interact with their combined effects on the growth of lettuce plants grown in indoor cultivation systems with artificial lighting.

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

“…Moreover, efficiency of combined application of red and blue LED light on photosynthetic rate, leaf transpiration, and stomatal conductance in lettuce plants was recently reported by Ahmed et al. ( 2022 ) which agreed with our results. Blue‐light‐induced stomatal opening is mediated through activation of a plasma membrane (PM) H+ pump, later identified as the PM H+‐ATPase, in guard cells (Assmann et al., 1985 ; Matthews et al., 2020 ; Shimazaki et al., 2007 ).…”

“…The low values of photosynthetic characteristics of plants exposed to red LED light were due to deficiency or lack of nitrogen in plant leaves; as a result, the lower the leaf N content, the lower the content of chlorophyll and carotenoid (Kim et al, 2004). Moreover, efficiency of combined application of red and blue LED light on photosynthetic rate, leaf transpiration, and stomatal conductance in lettuce plants was recently reported by Ahmed et al (2022) which agreed with our results. Blue-light-induced stomatal opening is mediated through activation of a plasma membrane (PM) H+ pump, later identified as the PM H+-ATPase, in guard cells (Assmann et al, 1985;Matthews et al, 2020;Shimazaki et al, 2007).…”

Light use in the plant factory: changes in chlorphyll fluorescence and gas exchange parameters of two lettuce cultivars at LED spectra in floating hydroponics

“…It has been found that the combination of red and blue is used in commercial research and horticulture because these light wavelengths play an important role in photosynthesis and the e ciency of photosynthesis decreases if they are not used 34 . Ahmad et al, 41 reported that the use of red and blue lightemitting diodes increased the photosynthetic rate, transpiration rate, and stomatal conductance in lettuce plants. The researchers found that more than 90% of the blue and red light was absorbed by the plants.…”

Breeding Approaches for Controlled Conditions of Artificial Light Culture for Small Radish and Radish (Raphanus sativus L.)

“…This is one of the reasons why the range of crops grown in CEAL is still quite limited: it is determined primarily by economic efficiency. These are predominantly fast-growing green leafy vegetables, herbs, microgreens, and some fruiting crops [11][12][13][14]. The development and improvement of CEAL technologies requires the expansion of the range of crops and an increase in their adaptation to the controlled environmental conditions.…”