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American Journal of  
Life Science and Innovation (AJLSI)

Effects of  Elevated CO2 and Light Intensity on Growth, Yield, and Nutritional Quality 
of  Tomato (Solanum lycopersicumSolanum lycopersicum) in Controlled Environment Agriculture Systems

A. A. Y. Amarasinghe1*, K. P. G. D. M. Polwaththa1, D. M. Suratissa2

Volume 4 Issue 1, Year 2025
ISSN: 2833-1397 (Online)

DOI: https://doi.org/10.54536/ajlsi.v4i1.4353
https://journals.e-palli.com/home/index.php/ajlsi

Article Information ABSTRACT

Received: January 01, 2025

Accepted: February 04, 2025

Published: February 10, 2025

Controlled Environment Agriculture (CEA) is an improved cultivation system that 
promotes plant development by optimizing environmental factors such as carbon dioxide 
(CO2) concentration and light intensity. This study considered the interactive effects of  
enhanced levels of  CO2 (400-1000 ppm) and varying light intensities (200-600 µmol/m2/s) 
on growth characters, yield, and nutritional composition of  tomato (Solanum lycopersicum). 
Under hydroponics conditions, a factorial experiment was conducted in a climate-controlled 
greenhouse and plant physiological responses, productivity, and fruit quality were assessed. 
Higher level of  CO2 and light significantly increased plant height, leaf  area, chlorophyll 
content, photosynthetic rate, and yield. The highest yield (6.86 kg/plant) was recorded at an 
800 ppm CO2 and 600 µmol/m2/s light intensity regime, while peak values for fruit weight 
and dry matter concentration impetuous at 1000 ppm CO2. Nutrition content of  fruit 
showed varied response for CO2-light interaction. With increased CO2 and light intensity, 
the highest lycopene content attained was 12.69 mg/100 g at 1000 ppm CO2 and 600 µmol/
m2/s light. Conversely, increasing CO2 concentrations push vitamin C and protein content 
lower, probably due to nutrient dilution effects driven by biomass growth. These results 
highlight the need to pair CO2 enrichment with light supplementation in optimizing the 
productivity-nutrition quality balance. An optimal combination of  CO2 and light intensity 
on the range of  800-1000 ppm CO2 and 600 µmol/m2/s offers useful understandings for 
greenhouse and vertical farming systems. Future studies must investigate long term effects 
on post-harvest quality and economic feasibility to keep improving CO2-light management 
strategies in CEA systems. 

Keywords

CO2 Enrichment, Controlled 
Environmental Agriculture, Light 
Intensity, Nutritional Quality, 
Tomato Yield

1 Department of  Export Agriculture, Faculty of  Agricultural Sciences, Sabaragamuwa University of  Sri Lanka, Sri Lanka
2  Faculty of  Science, University of  Colombo, Sri Lanka
* Corresponding author’s e-mail: rathna.agric2@gmail.com

INTRODUCTION
Controlled Environment Agriculture (CEA) consists of  
fast-developing technologies that allow the maximization 
of  plant growth by conscientiously manipulating 
environmental influences such as temperature, humidity, 
light intensity, and carbon dioxide concentration. Artificial 
Intelligence, Internet of  Things, and robotics are being 
integrated with CEA in precision agriculture as scalable 
solutions for global food security and for sustainable 
agricultural methods (Polwaththa et al., 2024). Medium 
temperature (21-250C) available in the most growing 
areas are favorable for tomato growth and flowering. 
However, the production of  better yield and yield traits 
require comparatively low temperature (10-200C) during 
fruit setting in some areas (Nur et al., 2022). Among all 
these factors, CO2 enrichment and light supplementation 
take center stage in the improvement of  plant productivity 
and resource-use efficiency. The cultivation of  tomato 
(Solanum lycopersicum) in controlled environments has 
gained prominence due to its economic importance and 
sensitivity to environmental factors (Wang et al., 2021). 
However, while CO2 enrichment proves beneficial in 
photosynthesis and biomass accumulation, its combined 
effect along with light intensity on yield and the nutritional 
quality of  fruits remains questionable and one big area 
of  research (Zhao et al., 2022). The interaction of  these 
two factors is of  great importance for optimizing CEA 

strategies to achieve high yield and high-quality production.
Higher levels of  CO2 have been studied for their effects 
on photosynthesis, stomatal conductance, and carbon 
allocation in plants. Previous studies showed that CO2 
concentrations between 600-1000 ppm can hence 
promote 20-40% growth and fruit yield in tomatoes 
by enhancing the efficiency of  carbon fixation and 
reducing photorespiration (Jin et al., 2023). Conversely, 
while higher CO2 induces increased fruit biomass, it may 
modify the compositions of  essential elements due to 
the nutrient dilution effect in which higher carbohydrate 
accumulation translates into lower concentrations of  
minerals and proteins (Taub et al., 2008).
In addition to CO2, light intensity plays a big part in 
tomato yield and fruit quality. The photosynthetic 
efficiency and biomass accumulation dearly depend on the 
photosynthetically active radiation (PAR) available. Studies 
are showing light intensity of  about 400-600 µmol m²/s 
significantly enhanced lycopene biosynthesis, vitamin C 
concentration, and sugar accumulation in tomatoes (Hao 
et al., 2021). Also, higher light intensity might counteract 
some undesirable effects of  CO2 enrichment by enhancing 
the production of  secondary metabolites and curtailing 
the nutrient dilution (Zhang et al., 2023).
While there has been increasing interest in CEA-
based CO2 enrichment and light management, few 
researches have been conducted into their interaction 



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affecting growth and nutrient composition of  the crop, 
particularly tomato (Polwaththa & Amarasinghe, 2024). 
Thus, this study intends to address this knowledge gap 
through assessing the interactive effects of  elevated 
CO2 and light intensity on tomato plant physiology, 
yield performance, and fruit nutritional composition in 
order to provide understandings to greenhouse operators 
or vertical farm managers trying to optimize CO2 and 
light supplementation strategies in sustainable tomato 
production. To achieve this, the study was conducted 
to study how the interaction between elevated CO2 
concentrations ranging from 400 to 1000 ppm and 
light intensities of  200 to 600 µmol/m²/s affect tomato 
growth, yield, and fruit nutritional composition.

MATERIALS AND METHODS
Pilot Study
A preliminary pilot experiment was performed in Sri 
Lanka to identify the range of  most appropriate CO2 
and light intensity for the growth of  tomatoes in advance 
of  the main experiment. In this pilot trial, five CO2 
concentrations, 200, 600, 1000, 1400, and 1800 ppm, 
and four light intensities, 200, 400, 600 and 800 µmol/
m2/s, were tested in controlled conditions to investigate 
plant growth responses, physiological parameters, and 
symptoms of  possible stress. Under these conditions, 
the plants grew for six weeks, recording plant height, 
leaf  area, chlorophyll content, photosynthesis rate, and 
stomatal conductance. It has been concluded from this 
experiment that levels above 1000 ppm of  CO2 do not 
contribute much to increasing photosynthesis, whereas 
at 1400 and 1800 ppm, some indications of  stomatal 
closure and hence low transpiration use efficiency were 
evident. While higher light intensities of  600 µmol/
m²/s increased photosynthetic efficiency, excessive CO2 
beyond 1000 ppm, under such a light level, resulted 
in chlorophyll degradation and reduced the stomatal 
conductance, indicating possible CO2 saturation effects. 
Based on the results from the pilot experiment, CO2 
levels from 400 ppm up to 1000 ppm and light intensities 
from 200 µmol/m2/s up to 600 µmol/m2/s were chosen 
to narrow down the ranges for application in the main 
experiment, hence ensuring optimum physiological 
performance without causing stress to the tomato plants.

Main Experiment
Experimental Design
The effects of  elevated CO2 and different light intensities 
upon growth, yield, and nutritional composition of  the 
tomato (Solanum lycopersicum) in a controlled environment 
agriculture (CEA) system were examined in this study. 
Since photosynthesis occurs under the direct influence 
of  both CO2 and light intensity, the effects of  their 
interaction were focused on rather than individual 
responses. Therefore, a randomized complete block 
design (RCBD) in a factorial arrangement was carried 
out to express interaction effects of  CO2 and light 
intensity. The treatments consisted of  four levels of  

CO2 concentration (400 ppm, 600 ppm, 800 ppm, and 
1000 ppm) and three levels of  light intensity (200 µmol/
m2/s, 400 µmol/m2/s, and 600 µmol/m2/s). Each design 
treatment was instantiated in this experiment for 10 
replications thus making 120 experimental units. Each 
treatment consisted of  an individual tomato plant grown 
in well-controlled environments. 

Greenhouse Setup and Environmental Control
The setup was carried out in a climate-controlled 
greenhouse containing an automated CO2 enrichment 
system and full-spectrum LED lighting to achieve the 
targeted levels of  CO2 and light. A hydroponic cultivation 
method was used to ensure a steady supply of  nutrients 
for all experimental units. Infrared gas analysts (IRGA) 
monitored and regulated CO2 concentrations every 2 
hours to maintain continuous levels of  CO2, which were 
delivered by the automated diffusion system integrated 
into the greenhouse ventilation. The intensity of  the 
light was controlled through programmable LED lamps, 
which were programmed to provide 16 hours of  light and 
8 hours of  darkness a day. Quantum light sensors placed 
at the canopy level ensured that the target PAR intensity 
was met for each treatment.
Temperature and humidity were controlled by employing 
air conditioning and automated misting systems, keeping 
the range of  25 ± 20C and 65% ± 5% relative humidity. 
These environmental parameters mostly eliminated 
possible external environmental variations, permitting the 
differences in plant performances to be directly attributed 
to CO2 and light intensity treatments.

Plant Materials and Growing Conditions
A hybrid tomato cultivar was selected for the present study 
because of  its high yield potential, long fruiting period, 
and response to the modification of  environmental 
conditions. Seeds were sown into peat-based seedlings 
trays under controlled conditions and were transplanted 
21 days later into hydroponic system integrated with 
fertigation for supplying a nutrient solution at constant 
intervals. The nutrient solution supplied to the plants 
contained macronutrients like nitrogen, phosphorus, and 
potassium and essential micronutrients like magnesium, 
calcium, and iron. EC of  2.5 mS/cm and pH values 
ranging from 5.8 to 6.2 were maintained in the solution 
to encourage maximum uptake of  nutrients.

Data Collection and Measurements
Growth and Physiological Parameters
To evaluate the effect of  CO2 and light intensity on 
plant growth, morphological and physiological traits 
were recorded at 30, 60, and 90 days after transplanting 
(DAT). Plant height (cm) was noted using measuring 
tape while leaf  area (cm2) was determined using an 
automated leaf  area meter. The chlorophyll content 
was measured using the SPAD chlorophyll meter, which 
gives a relative index of  chlorophyll concentration. 
Photosynthetic rate (mol H2O/m2/s) was measured with 



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a handheld photosynthesis system (LI-6400XT, LI-COR 
Biosciences) by measuring net CO2 assimilation under 
a standardized set of  conditions. Stomatal conductance 
(mol H2O/m2/s) was measured with the same instrument 
to determine the plant’s ability to limit water loss under 
different CO2 levels.

Yield and Productivity Measurements
After harvest (90 DAT), total yield per plant (kg/plant) 
was recorded by weighing all fruits from each plant using 
a precision digital scale. Individual fruit weights (g) were 
determined by finding the average of  ten randomly 
weighed fruits per plant. Dry Matter Content (%) was 
determined by drying an aliquot of  tomato fruit at 700C 
for 48 hours and measuring the dry-to-fresh weight ratio.
A digital refractometer (Atago PAL-1; Japan) was used 
to ascertain the sugar content (0Brix) by measuring the 
soluble solids concentration of  fruit juices. These yield-
related measurements gave understanding as to the impact 
of  CO2 and light intensity on total tomato production. 

Nutritional Composition Analysis
In the present study, the quality of  tomatoes was assessed 
in terms of  vitamin C, lycopene, and protein contents 
by different determination methods. Vitamin C content 
was assayed by HPLC using a C18 column. The lycopene 
content was assayed by spectrophotometry at 502 nm 
after extraction with hexane and acetone. Protein content 
was analyzed by means of  the Kjeldahl method, which 

quantifies total nitrogen as an indicator of  protein 
concentration. 
All these biochemical analyses were done in triplicate 
to ensure accuracy and repeatability. These nutritional 
analyses gave enough evidence on how enrichment with 
CO2 and light intensity could affect the health-related 
properties of  the tomatoes.

Statistical Analysis
Data were analyzed using two-way analysis of  variance 
(ANOVA) in SAS with the objective of  explaining the 
interaction effects of  CO2 enrichment and light intensity 
on growth, yield, and nutritional value of  tomato. In the 
present study, the factorial ANOVA model was examined 
considering the interaction between the four CO2 levels 
of  400, 600, 800, and 1000 ppm and three light intensities, 
i.e., 200, 400, and 600 µmol/m2/s.
Duncan’s Multiple Range Test (DMRT) was applied at p 
≤ 0.05 to differentiate the means for statistical differences 
in treatments. Thus, it has been utilized to compare 
various treatment combinations in terms of  identifying 
the optimal levels of  CO2 and light that would most 
enhance the growth of  tomato and fruit quality. There 
were 10 replicates for each combination of  treatments 
in order to achieve enough statistical power and ensure 
reliability of  the outcome.

RESULTS AND DISCUSSION
Growth and Physiological Responses

Table 1: Growth and Physiological Responses under different CO2 and Light Levels
1 Light 

Intensity 
(µmol/ m²/s)

Plant Height (cm) Leaf  Area (cm2) Chlorophyll
Content
(SPAD index)

Photosynthetic 
rate (µmol 
CO2/m²/s)

Stomatal
Conductance 
(mol H2O/
m²/s)

400 200 101.39 ± 13.07 g1 275.52 ± 51.92 g 44.26 ± 4.79 f 10.64 ± 1.87 f 0.30 ± 0.11 a
400 400 112.38 ± 11.78 f 293.98 ± 46.92 g 47.85 ± 3.98 ef 16.73 ± 2.31 e 0.21 ± 0.11 abc
400 600 121.69 ± 11.01 f 343.67 ± 49.20 f 50.35 ± 4.54 e 18.87 ± 1.87 d 0.14 ± 0.09 cd
600 200 116.45 ± 13.22 f 297.93 ± 38.72 g 49.97 ± 4.51 e 16.08 ± 1.49 e 0.26 ± 0.14 ab
600 400 137.03 ± 11.98 e 387.87 ± 26.68 de 54.53 ± 3.80 d 19.32 ± 2.64 d 0.15 ± 0.15 bcd
600 600 141.49 ± 10.67 de 370.13 ± 41.58 ef 56.47 ± 4.94 d 22.07 ± 2.17 bc 0.23 ± 0.06 abc
800 200 141.19 ± 13.30 de 364.51 ± 42.06 ef 55.98 ± 4.19 d 16.67 ± 2.29 e 0.23 ± 0.06 abc
800 400 150.03 ±   9.43 d 417.79 ± 40.98 cd 57.26 ± 5.13 cd 20.40 ± 2.32 cd 0.13 ± 0.12 cd
800 600 164.59 ± 13.33 c 431.45 ± 36.08 bc 63.67 ± 3.27 ab 26.52 ± 2.11 a 0.08 ± 0.15 d
1000 200 171.96 ± 10.38 bc 442.45 ± 53.71 bc 60.65 ± 5.67 bc 20.58 ± 1.93 cd 0.14 ± 0.11 cd
1000 400 179.89 ± 13.04 b 461.30 ± 37.08 b 63.78 ± 3.10 ab 23.30 ± 2.19 b 0.05 ± 0.14 d
1000 600 197.99 ± 11.96 a 488.52 ± 44.66 a 67.04 ± 5.11 a 26.22 ± 2.47 a 0.13 ± 0.10 cd

 Means followed by the same small letters in the same 
column are not significantly different at 5% level in 
Duncan’s Multiple Range Test.
The results in Table 1 shows that high CO2 concentration 
and higher light intensity had a significant influence on 
plant height and leaf  area. Tomato plants cultivated at 
1000 ppm CO2 and 600 µmol/m2/s light intensity yielded 

the highest plant height (197.99 ± 11.96 cm) and leaf  area 
(488.52 ± 44.66 cm2), whereas the lowest was at 400 ppm 
CO2 and 200 µmol/m2/s (101.39 ± 13.07 cm, 275.52 
± 51.92 cm2). The increased plant height development 
and leaf  growth can be attributed to increased cellular 
enlargement and biomass accumulation, as high CO2 
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enhancing plant development (Zhang et al., 2023). 
Additionally, the increased light intensity also enhances 
more carbon assimilation and light energy uptake, thus 
supporting more leaf  growth and expansion.
Chlorophyll content also increased with rising CO2 
and light, maximally 67.04 ± 5.11 SPAD index at 1000 
ppm CO2 at 600 µmol/m2/s. Chlorophyll content 
was minimum at 400 ppm CO2 at 200 µmol/m2/s 
light (44.26 ± 4.79 SPAD index). Increased content of  
chlorophyll under increased CO2 concentration results 
from optimization of  nitrogen use efficiency, promoting 
chlorophyll biosynthesis (Jin et al., 2023). High light 
intensity also triggers photoreceptors, causing expression 
of  genes involved in chlorophyll biosynthesis, leading 
to increased accumulation of  photosynthetic pigments 
(Huang et al., 2021). The same has been found in spinach 
(Spinacia oleracea), where increased CO2 facilitated the 
preservation of  chlorophyll, thereby increasing the 
efficiency of  photosynthesis (Zhao et al., 2022). Excessive 
light in the absence of  supplemental CO2 at its optimal 
concentration induces photooxidative stress, however, 
which degrades chlorophyll, as seen in strawberry 
(Fragaria ananassa) (Jin et al., 2023).
Photosynthetic rate was substantially enhanced by CO2 
enrichment and increased light intensities, with the 
maximum of  26.52 ± 2.11 µmol CO2/m2/s at 800 ppm 
CO2 and 600 µmol/m2/s light intensity. Photosynthetic 
activity plateaued at 1000 ppm CO2 (26.22 ± 2.47 
µmol CO2/m2/s), indicating a CO2 saturation point at 
which any additional increase in CO2 does not augment 
photosynthesis. This is due to the fact that RuBisCO, the 
enzyme for carbon fixation, is saturated under high CO2 
levels, thus limiting further improvement in photosynthetic 
performance (Wang et al., 2021). Similar trends have also 
been reported in pepper (Capsicum annuum), where the 
photosynthesis rates increased with CO2 enrichment 
up to an optimal level, beyond which photorespiration 
and stomatal limitations restricted further improvement 
(Wang et al., 2021). Correspondingly, studies of  wheat 
(Triticum aestivum) have shown that CO2 saturation 
effects reduce stomatal conductance and thereby limit 
CO2 diffusion to the mesophyll cells (Taub et al., 2008).
There was a reduction in stomatal conductance with the 

increase in CO2 levels, with the lowest values recorded 
at 1000 ppm CO2 under 400 and 600 µmol/m2/s light 
intensity (0.05 ± 0.14 and 0.13 ± 0.10 mol H2O/m2/s, 
respectively). The reduction in stomatal conductance can 
be attributed to CO2 induced stomatal closure, lowering 
guard cell turgor pressure and resulting in partial stomatal 
closure and reduced water loss via transpiration (Zhang 
et al., 2023). While this can increase water-use efficiency, 
prolonged stomatal closure can prevent evaporative 
cooling, thus enhancing the likelihood of  leaf  overheating 
when high light is applied. Comparable findings have 
been reported in cabbage (Brassica oleracea) as well, 
where reduced stomatal conductance under high CO2 
helped in water conservation but at the same time 
increased its susceptibility to heat stress (Huang et al., 
2021). Additionally, in soybean (Glycine max), stomatal 
conductance reduction at high CO2 levels increased 
water-use efficiency and thus rendered the plants drought-
tolerant (Zhao et al., 2022).

Yield and Productivity Responses 
The data indicated (Table 2) that CO2 concentration of  
higher levels and greater light intensity increased tomato 
yields. The highest yield (6.86 kg/plant) was achieved at 
800 ppm CO2 and 600 µmol/m2/s light intensity, while the 
lowest (4.59 kg/plant) was recorded at 400 ppm CO2 and 
200 µmol/m2/s light intensity. The enhanced production 
at elevated CO2 can be due to increased photosynthesis 
and carbon assimilation, as usually reported in previous 
research on tomato and other crops (Hao et al., 2021; 
Jin et al., 2023). The similar results were obtained in 
wheat and rice, as elevated CO2 concentration enhanced 
biomass accumulation and grain yield (Zhu et al., 2020). 
At 1000 ppm CO2 concentration, yield did not rise above 
the 800 ppm level, and this could indicate a saturation 
effect. Some studies show that at very high levels of  CO2 
concentration, there can be a process of  photosynthetic 
down-regulation with declining returns in yield increase 
(Ainsworth & Rogers, 2007). Furthermore, although the 
CO2 concentration is increased but with reduced light, 
photosynthetic efficiency could not be optimized (Zhang 
et al., 2023).

Table 2: Yield and Productivity under different CO2 and Light Levels
CO2 Level 
(ppm)

Light Intensity
(µmol/m²/s)

Yield (Kg/ plant) Fruit weight (g) Dry matter
(% FW) 

Sugar Content
 (oBrix)

400 200 4.59 ± 0.87 c1 136.59 ± 12.80 e   7.41 ± 1.72 f 6.08 ± 0.95 g
400 400 5.30 ± 1.27 bc 148.03 ± 13.03 e   9.27 ± 1.65 de 6.69 ± 0.71 fg
400 600 6.01 ± 1.50 ab 155.26 ±   7.64 d 10.18 ± 1.32 d 8.49 ± 1.04 cd
600 200 5.68 ± 1.35 abc 155.68 ± 12.59 d   8.21 ± 1.40 ef 6.71 ± 1.00 fg
600 400 5.46 ± 1.14 bc 158.23 ± 11.73 cd   9.33 ± 1.24 de 7.71 ± 0.84 de
600 600 5.96 ± 1.11 ab 159.20 ± 10.19 cd 10.33 ± 1.06 cd 9.03 ± 0.95 bc
800 200 6.30 ± 0.82 ab 166.80 ±   8.43 bc   9.93 ± 1.41 d 7.12 ± 0.95 ef
800 400 5.74 ± 1.21 abc 167.97 ± 12.80 bc 10.42 ± 1.56 cd 7.89 ± 0.80 de
800 600 6.86 ± 1.21 a 166.65 ±   7.28 bc 12.47 ± 1.69 ab 9.97 ± 0.35 a



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1000 200 6.75 ± 1.24 a 174.30 ± 12.01 ab 11.65 ± 1.28 bc 7.78 ± 0.97 de
1000 400 6.80 ± 1.19 a 179.29 ± 12.65 a 12.28 ± 1.38 ab 8.88 ± 0.94 c
1000 600 6.69 ± 1.23 a 182.47 ± 11.31 a 13.40 ± 1.42 a 9.80 ± 0.86 ab

1 Means followed by the same small letters in the same 
column are not significantly different at 5% level in 
Duncan’s Multiple Range Test, FW- Fresh weight.
Both CO2 and light intensity had a very significant impact 
on fruit weight, with the maximum fruit weight (182.47 
g) at 1000 ppm CO2 and 600 µmol/m2/s light intensity 
and minimum (136.59 g) at 400 ppm CO2 and 200 µmol/
m2/s light intensity. This is consistent with the work 
of  Taub et al. (2008), who noted that CO2 enrichment 
maximizes fruit size in crops because of  the enhanced 
accumulation of  carbohydrates. Dry matter content also 
followed the same pattern, with the highest (13.40% FW) 
being achieved at 1000 ppm CO2 and light intensity of  
600 µmol/m2/s. This indicates that high levels of  CO2 
not only increased the fruit size but also allowed more dry 
matter to accumulate, which could be the consequence 
of  greater storage of  carbohydrates in the fruit tissues. 
The same was observed in strawberries and bell peppers 
wherein the firmness of  fruit and dry matter was 
enhanced by CO2 enrichment (Wang et al., 2021).
Sugar content (0Brix) was significantly influenced by the 
two factors of  CO2 and light intensity; the highest value, 
9.970 Brix, was recorded under the conditions of  800 ppm 
CO2 combined with 600 µmol/m2/s. This result agreed 
with other works in proving that high CO2 increases the 
sugar accumulation in tomato fruits through the increased 
fixation of  carbon and synthesis of  carbohydrates 
(Li et al., 2019). However, sugar content at 1000 ppm 
CO2 did not keep increasing, perhaps due to the CO2-
induced dilution effect in which too much carbohydrate 
accumulation may result in a relative decrease in soluble 
sugar concentration. Similar reports were given on lettuce 
and cucumber where sugar contents increased with CO2 

enrichment but did not keep increasing at very high levels 
(Zhao et al., 2022). Meanwhile, light intensity significantly 
affected sugar accumulation: fruits developed under a 
higher light level-600 µmol/m2/s-had significantly higher 
0Brix values than fruits under low light. This agreed with 
reports that enhanced light intensity increases the activity 
of  the enzymes in sugar metabolism, hence improving 
the sweet taste in fruit (Hao et al., 2021).
The findings indicate that CO2 enrichment and 
light intensity significantly impact tomato yield and 
productivity and that the optimal combination is 800 
-1000 ppm CO2 and 600 µmol/m2/s light intensity. The 
results agree with findings in controlled environment 
agriculture (CEA) systems where the same CO2 and 
light optimization led to enhanced crop productivity 
and improved fruit quality (Zhang et al., 2023). However, 
supra-optimal CO2 concentrations in excess of  1000 ppm 
did not generate further yield and quality enhancements 
and suggests that CEA systems have to strike a balance 
between CO2 enrichment and the optimal amount 
of  light concentration. Nevertheless, CO2-induced 
carbohydrate storage also has to be closely regulated 
to avoid deleterious effects of  nutrient dilution. These 
findings have excellent applicability to greenhouse and 
vertical farm operations since they demonstrate that 
CO2 enrichment and supplemental light optimization 
can maximize tomato productivity and quality in closed 
systems. The long-term sustainable effects of  CO2 and 
light optimization on post-harvest quality and profitability 
of  tomatoes in commercial CEA production systems can 
be further investigated.

Nutritional Composition and Fruit Quality 

Table 3: Nutritional Composition and Fruit Quality under different CO2 and Light Levels
CO2 Level (ppm) Light Intensity 

(µmol/m²/s)
Vitamin C (mg/ 
100g)

Lycopene 
(mg/ 100g)

Protein Content
(% FW)

400 200 19.50 ± 2.42 abc1   8.51 ± 2.53 cd 1.13 ± 0.20 ef
400 400 20.72 ± 2.95 ab   8.73 ± 1.74 cd 1.55 ± 0.16 b
400 600 21.96 ± 2.80 a 11.01 ± 2.01 abc 1.93 ± 0.21 a
600 200 19.58 ± 3.01 ab   8.38 ± 2.79 d 1.00 ± 0.22 f
600 400 19.97 ± 2.63 ab   9.60 ± 2.07 bcd 1.33 ± 0.22 cd
600 600 20.65 ± 2.94 ab   9.37 ± 1.94 bcd 1.63 ± 0.14 b
800 200 19.32 ± 2.31 abc   9.06 ± 2.26 bcd 0.73 ± 0.23 g
800 400 18.61 ± 2.70 bcd   9.54 ± 2.03 bcd 1.25 ± 0.18 de
800 600 19.27 ± 3.14 abc 11.53 ± 2.46 ab 1.48 ± 0.25 bc
1000 200 16.79 ± 2.40 cd   9.40 ± 2.63 bcd 0.55 ± 0.22 g
1000 400 16.20 ± 2.44 d   9.59 ± 2.54 bcd 1.00 ± 0.25 f
1000 600 18.36 ± 2.72 bcd 12.69 ± 1.98 a 1.31 ± 0.18cde



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1 Means followed by the same small letters in the same 
column are not significantly different at 5% level in 
Duncan’s Multiple Range Test, FW- Fresh weight.
Table 3 shows that the nutritional composition and fruit 
quality of  tomato with elevated CO2 and light intensity. 
Vitamin C level in tomato fruit was significantly influenced 
by light intensity and CO2 interaction. The highest 
vitamin C content (21.96 ± 2.80 mg/100g) was observed 
at 400 ppm CO2 with 600 µmol/m2/s light intensity, 
and the lowest (16.20 ± 2.44 mg/100g) was observed 
at 1000 ppm CO2 with 400 µmol/m2/s light intensity. 
Vitamin C or ascorbic acid is significantly impacted by 
light intensity since it takes part in antioxidant defense 
and photoprotective responses in plants (Shivashankara 
et al., 2013). Vitamin C biosynthesis is promoted with 
intense light by initiating metabolic processes involved 
in antioxidant biosynthesis and photosynthetic carbon 
fixation (Laxman et al., 2014). Nevertheless, CO2 
enhancement above 600 ppm reduced the concentration 
of  vitamin C, in agreement with previous studies on 
lettuce (Lactuca sativa) that had increased CO2 inducing 
reductions in ascorbic acid levels (Mattson et al., 2022). 
Similar was the trend in bell pepper (Capsicum annuum), 
where high levels of  CO2 lowered the content of  vitamin 
C even though it augmented fruit yield (Dong et al., 2018). 
High CO2 decline is due to dilution effects, which are the 
result of  enhanced biomass gain, as well as modification 
in carbohydrate metabolism (Rajashekar, 2018).
Lycopene content was also affected by CO2 level and light 
intensity, with the highest concentration at 1000 ppm 
CO2 with 600 µmol/m2/s light intensity at 12.69 ± 1.98 
mg/100g. The lowest lycopene levels were at 400 ppm 
CO2 with 200 µmol/m2/s light intensity at 8.51 ± 2.53 
mg/100g. Lycopene is a carotenoid pigment responsible 
for the red coloration in tomatoes and is highly dependent 
upon light exposure and CO2 assimilation. Increased light 
intensity enhances lycopene biosynthesis by upregulating 
phytoene synthase and carotenoid biosynthetic genes 
(Verma et al., 2024). Previous studies in tomatoes 
and strawberries (Fragaria ananassa) have shown that 
high light intensity positively correlates with lycopene 
accumulation due to increased photosynthetic electron 
transport activity (Dannehl et al., 2021). The increase in 
lycopene content under high CO2 levels (800-1000 ppm) 
agrees with previous reports in cucumber (Cucumis 
sativus) and watermelon (Citrullus lanatus), where high 
CO2 enhanced carotenoid biosynthesis through increased 
carbon fixation (Ren et al., 2014). However, at very high 
CO2 enrichment levels (>1000 ppm), lycopene content 
may be adversely affected by changes in phytoene 
desaturation processes (Talebi et al., 2024).
The protein content of  tomato fruits is significantly 
different due to the interaction between CO2 and light 
treatments. The highest protein content of  1.93 ± 0.21% 
FW was recorded at 400 ppm CO2 with 600 µmol/m2/s 
light intensity, while the lowest, 0.55 ± 0.22% FW, was 
recorded under 1000 ppm CO2 combined with 200 
µmol/m2/s light intensity. In plants, protein biosynthesis 

is intimately associated with nitrogen assimilation, 
which shows a close interaction with CO2 fertilization 
and light energy availability. Plants under high CO2 
enhance carbohydrate accumulation; however, this quite 
frequently causes the opposite effect, a decrease in 
nitrogen uptake and protein synthesis, by downregulating 
nitrate reductase activity (Loladze et al., 2019). Similar 
reductions in protein concentration have been reported in 
wheat and rice grown under elevated CO2, which further 
supports the hypothesis that CO2 induced carbohydrate 
accumulation dilutes protein levels in plant tissues 
(Pimenta et al., 2023). On the other hand, light intensity 
is one of  the most important environmental factors 
affecting amino acid metabolism and protein synthesis. 
High light intensities enhance photosynthetic efficiency 
and nitrogen assimilation, which in turn increase protein 
content (Pan et al., 2019). There is an interactive effect of  
light and CO2, in that the dual increase of  both factors 
has indeed improved biomass production, probably 
linked to nutrient dilution effects mainly under extreme 
levels of  CO2.

CONCLUSIONS
This work has proved that high CO2 levels and increased 
light intensity have a great effect on the growth, yield, and 
nutritional composition of  tomatoes in CEA systems. 
Maximum plant height, leaf  area, chlorophyll content, 
photosynthetic rate, and yield were observed under the 
optimum combination of  800-1000 ppm CO2 and 600 
µmol/m2/s, while beyond 1000 ppm CO2 saturation 
resulted in diminishing returns. Nutritional quality also 
varied; while lycopene was enhanced with increasing CO2 
and light, the vitamin C and protein contents declined 
under high CO2 due to nutrient dilution effects. Such 
findings have drawn attention to a balanced use of  CO2 
and light to assure optimum productivity without loss of  
quality in the produced fruits in tomato. These findings 
also have practical application for both greenhouse 
and vertical farming systems: the optimal level of  CO2 
ranges from 800-1000 ppm with the light intensity of  
600 µmol/m2/s for their best performance. Long-term 
effects on post-harvest quality and economic viability 
for commercial tomato production should be further 
researched.

REFERENCES 
Ainsworth, E. A., & Rogers, A. (2007). The response of  

photosynthesis and stomatal conductance to rising 
CO2: Mechanisms and environmental interactions. 
Plant, Cell & Environment, 30(3), 258-270. https://doi.
org/10.1111/j.1365-3040.2007.01641.x

Dannehl, D., Schwend, T., Veit, D., & Schmidt, U. (2021). 
Increase of  yield, lycopene, and lutein content in 
tomatoes grown under continuous PAR spectrum 
LED lighting. Frontiers in Plant Science, 12, 611236. 
https://doi.org/10.3389/fpls.2021.611236

Dong, J., Gruda, N., Lam, S. K., Li, X., & Duan, Z. 
(2018). Effects of  elevated CO2 on nutritional quality 



Pa
ge

 
7

https://journals.e-palli.com/home/index.php/ajlsi

Am. J. Life Sci. Innov. 3(2) 25-32, 2024

of  vegetables: A review. Frontiers in Plant Science, 9, 924. 
https://doi.org/10.3389/fpls.2018.00924

Hao, X., Zhang, Y., & Duan, Y. (2021). Effects of  elevated 
CO2 on tomato growth, yield, and fruit quality in 
greenhouse environments. Horticultural Research, 8(1), 
78-95. 

Huang, J., Liu, P., & Zhao, Y. (2021). Optimizing CO2 
fertilization and light intensity to improve controlled-
environment crop production. Frontiers in Plant Science, 
12, 879650. 

Jin, Q., Li, X., & Zhou, B. (2023). Effects of  elevated CO2 
and light on crop growth and metabolic responses 
in controlled agriculture. Journal of  Plant Physiology, 
280(1), 153789. 

Laxman, R. H., Srinivasa Rao, N. K., & Mamatha, 
H. (2014). Impact of  elevated CO2 on growth, 
physiology, yield, and quality of  tomato (Lycopersicon 
esculentum Mill). Photosynthetica, 52(2), 201-210. 

Li, T., Yang, Y., & Wang, X. (2019). CO2 enrichment 
enhances sugar metabolism and fruit quality in 
greenhouse-grown tomatoes. Scientia Horticulturae, 
252, 119-127. 

Loladze, I., Nolan, J. M., & Ziska, L. H. (2019). Rising 
atmospheric CO2 lowers concentrations of  plant 
carotenoids essential to human health: A meta-
analysis. Molecular Nutrition & Food Research, 63(10), 
1801047. https://doi.org/10.1002/mnfr.201801047

Mattson, N., Ashenafi, E., & Nyman, M. (2022). The 
impact of  CO2 enrichment on biomass, carotenoids, 
xanthophyll, and mineral content of  lettuce (Lactuca 
sativa L.). Horticulturae, 8(9), 820. 

Nur, S. Y., Mohammad, A., Mahbub, R., & Mijanur, R. 
R. (2022). Forecasting Tomato Variety for Different 
Seasons and Regions of  Bangladesh hospital. 
Am. J. Multidis. Res. Innov., 1(1) 1-8. https://doi.
org/10.54536/ajmri.v1i1.156.

Pan, T., Ding, J., Qin, G., Wang, Y., Xi, L., & Yang, J. 
(2019). Interaction of  supplementary light and CO2 
enrichment improves growth, photosynthesis, yield, 
and quality of  tomato in autumn through spring 
greenhouse production. Horticulture Research, 54(2), 
246. 

Pimenta, T. M., Souza, G. A., Brito, F. A. L., & Teixeira, L. 
S. (2023). The impact of  elevated CO2 concentration 
on fruit size, quality, and mineral nutrient composition 
in tomato varies with temperature regimen during 
growing season. Plant Growth Regulation, 102(1), 45-58. 
https://doi.org/10.1007/s10725-022-00889-8

Polwaththa, K. P. G. D. M., & Amarasinghe, A. A. Y. 
(2024). Optimizing calcium application strategies 
to enhance fruit quality in tomato (Lycopersicon 
esculentum (L.) Mill), International Journal of  Science 

and Research Archive, 13(2), 596–602. https://doi.
org/10.30574/ijsra.2024.13.2.2188

Polwaththa, K. P. G. D. M, Amarasinghe, S. T. C., 
Amarasinghe, A. A. Y. D., & Amarasinghe, A. A. Y. 
(2024). Exploring Artificial Intelligence and Machine 
Learning in Precision Agriculture: A Pathway to 
Improved Efficiency and Economic Outcomes in 
Crop Production. Am. J. Agric. Sci. Eng. Technol., 8(3) 
50-59. https://doi.org/10.54536/ajaset.v8i3.3843

Rajashekar, C. B. (2018). Influence of  elevated CO2 and 
light intensity on plant growth and photosynthesis. 
Journal of  Plant Physiology, 176, 29-42.

Ren, S., Hu, W., Dong, J., & Liu, Y. (2014). The impact of  
CO2 enrichment on plant growth and physiological 
responses under different light conditions. 
Environmental and Experimental Botany, 102, 36-45.

Shivashankara, K. S., Laxman, R. H., & Geetha, G. A. 
(2013). Impact of  elevated CO2 on plant physiology 
and quality traits. Photosynthetica, 51(3), 393-402. 

Talebi, M., Sayed Tabatabaei, B. E., Ziaei, N., & others 
(2024). Intra-canopy LED lighting outperformed 
top LED lighting in improving tomato yield and 
expression of  the genes responsible for lycopene, 
phytoene, and vitamin C synthesis. Scientific Reports, 
14, 4210. 

Taub, D. R., Miller, B., & Allen, H. (2008). Effects of  
elevated CO2 on photosynthetic rate and stomatal 
conductance in wheat. Global Change Biology, 
14(3), 565-575. https://doi.org/10.1111/j.1365-
2486.2007.01511.x

Verma, K., Sinha, P. G., & Mathur, V. (2024). Temporal 
impact of  elevated CO2 and temperature on Solanum 
lycopersicum L.: Insights into growth, phenology, 
ultrastructure, nutritional quality, and metabolite 
composition. Journal of  Crop Health, 12(3), 57-69. 
https://doi.org/10.1007/s10343-024-01057-w

Wang, S., Zhang, L., & Chen, H. (2021). Impact of  
CO2 enrichment on nutritional composition and 
antioxidant properties of  greenhouse-grown 
strawberries. Scientia Horticulturae, 278, 109876. 

Zhang, L., Wang, X., & Li, J. (2023). CO2 enrichment 
strategies in plant factories: Effects on crop yield, 
fruit quality, and economic feasibility. Agricultural and 
Food Chemistry, 71(5), 3217-3229. 

Zhao, Y., Huang, J., & Liu, P. (2022). Optimizing CO2 
fertilization in controlled environment agriculture: 
Balancing productivity and nutrient composition. 
Frontiers in Plant Science, 13, 874532. 

Zhu, C., Zhu, J., & Ort, D. R. (2020). Rising CO2 
concentrations enhance biomass production but 
reduce grain protein content in wheat and rice. Nature 
Climate Change, 10(9), 863-868.


