Effects of Different Treatments of Supplemental Light on Tomato

Growth and Fruit

Guangnan Zhang

1,a

, Xiangyun Lou

2,b

, Fei Xie

2,c

and Qiwen Zhong

1, d*

Horticultural Research Institute, Qinghai University (Qinghai Academy of Agriculture and Forestry Sciences),

Xining Qinghai, China

College of Agriculture and Animal Husbandry, Qinghai University, Xining, Qinghai, China

Keywords:

LED, Tomato, Growth and Development, Fruit Quality.

Abstract:

In exploring the effects of light supplementation measures on the growth and development, yield and quality

of tomatoes, this study used 'Gassina' tomatoes as the test material and set up CK (no light supplementation),

RGB treatment (Red: Green: Blue = 3:1:1, top-lighting), RGB + FR treatment (adding far-red light based on

the RGB treatment, top-lighting), RGB+UV1 treatment (adding ultraviolet light based on the RGB treatment,

filling light from the top), and RGB + UV2 treatment (adding ultraviolet light based on the RGB treatment,

inner-lighting) to analyze the changes of morphological and physiological indices as well as fruit yield and

quality of tomato plants under different fill light treatments. The results showed that the supplemental light

promoted the growth of tomato and improved the yield and quality of tomato. Under different light treatments,

RGB+UV2 interplant supplementation significantly promoted the growth of tomato plants compared with

other treatments, and RGB treatment significantly improved the fruit quality and yield of tomato.

1 INTRODUCTION

The plant growth and development are affected by

light, temperature, humidity, nutrients and other

environmental factors, among which light is one of

the important environmental factors for plant growth

and development. Light provides energy for plant

photosynthesis, and in combination with other

environmental factors regulates plant life activities

such as plant morphogenesis, photoperiodic reactions

and metabolic substance synthesis. Light is also

involved in the entire physiological process of crop

seed germination (Li, 2009), stem and leaf growth

(Liao, 2001), chlorophyll synthesis (Zhang, 2005 ),

induction of flower opening (Wan, 2018; Zhang,

2020) and fruit growth (Qian, 2018), which are

essential environmental factors for plant growth and

development and yield quality formation. Facility

agriculture, also known as environmentally regulated

agriculture, is an artificially created microclimate that

provides suitable environmental conditions for all

stages of vegetable, fruit, flower and other

horticultural products production as well as free from

the constraints of the natural environment. In facility

cultivation, light directly determines the thermal

environment of the greenhouse, thus affecting the

growth and development, yield and quality of the

facility as (Sun, 2014) For sustainable development

and high economic benefits, light quality, light

intensity, and photoperiod are needed to meet the

needs of the crop. However, often in the process of

facility cultivation, covering materials such as plastic

films and insulation facilities, continuous rain and

snow as well as short light hours in winter cause the

phenomenon of light deficiency in facilities, such as

insufficient light intensity and light hours, which

seriously affects the growth and development of

facility crops and high quality and efficient

production, limiting the production potential of

facility agriculture (Hu, 2016; Li, 2020; Choi, 2021).

Greenhouse light environment regulation through

artificial light sources to improve the efficiency of

light utilization by crops has become one of the most

common light environment regulation measures at

present.

At present, the application of artificial light

sources in China's facilities has been very common,

but the late start of facility agriculture in Qinghai

Province, the relative backwardness of the facility

industry, and the slow update of production

technology and supporting facilities. Especially in

winter and spring greenhouse insulation is covered

Zhang, G., Lou, X., Xie, F. and Zhong, Q.

Effects of Different Treatments of Supplemental Light on Tomato Growth and Fruit.

DOI: 10.5220/0012000500003625

In Proceedings of the 1st International Conference on Food Science and Biotechnology (FSB 2022), pages 8-13

ISBN: 978-989-758-638-5

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

mostly from 16:00 to 10:00 the next day, the light

intensity and time is seriously insufficient, which

seriously affects the production of winter and spring

facility crops (Ji, 2013). Reasonable light

supplementation measures can meet the

photosynthetic requirements of vegetable crops,

improve the energy utilization efficiency of vegetable

crops, achieve high yield, high efficiency and high

quality production of facility vegetable counter-

seasonal cultivation, and meet the counter-seasonal

vegetable supply in Qingha (Wang, 2019), which is

of great significance for winter-spring facility

vegetable cultivation in the alpine region of Qinghai.

Therefore, in this study we regulated the light

environment of greenhouses in Qinghai plateau based

on artificial supplemental LEDs, and investigated the

effects of LEDs on the growth and development and

quality of tomato plants by using different light

treatments to understand the effects of different

supplemental light measures on tomato growth and

fruit yield and quality in order to improve the yield

and quality of tomatoes and provide technical support

for the cultivation theory of annual production of

facility tomatoes in Qinghai region.

2 MATERIALS AND METHODS

2.1 Experiment Materials

The Glorioso tomato is used throughout the

experiment. The LED bar lights, provided by the

Xiaotaiyang Agriculture High-tech Co., Ltd. in

Zhejiang Province, are adopted as the source of the

supplemental light.

2.2 Experiment Settings

The experiments were carried out in the greenhouse

of the horticultural innovation base of Qinghai

Academy of Agriculture and Forestry Sciences,

Chengbei District, Xining City, Qinghai Province.

The length, span, height, and height of the solar

greenhouse are 40 m, 8 m, 3 m, and 50 cm,

respectively. The covering material of the greenhouse

is po film. Seedlings were raised on February 25,

2020, and seedlings with the same growth were

selected and planted by the trough cultivation in the

solar greenhouse on April 7, 2020. Five lighting

treatments were used in the experiment, which are

denoted as CK (no supplemental light), RGB (Red:

Green: Blue = 3:1:1, top-lighting), RGB + FR (adding

far-red light on the basis of the RGB treatment, top-

lighting), RGB + UV1 (adding ultraviolet light on the

basis of the RGB treatment, top-lighting), and RGB

+ UV2 (adding ultraviolet light on the basis of the

RGB treatment, inner-lighting), respectively. There

are 3 replicates for each treatment, and 15 seedlings

are used in each replicate. The light duration is 5 h

per day, and lighting starts before the open of the heat

preservation quilt (10:00) and ends after the cover of

the heat preservation quilt (16:00). The beginning and

the end of the lighting were controlled by the time

relay.

2.3 Measurement Items and Methods

For each treatment, 6 plants were randomly selected

as sample plants to measure the growth indexes of the

tomato plants and the fruit quality.

Following procedures were used to estimate the

growth indexes of the tomato plants. In detail, the

plant height is measured with a ruler from the plant

rhizome boundary to the plant growth point. The stem

diameter is the averaged value of two measures of the

stem under the cotyledon from two directions by

vernier caliper. The level of Chlorophyll (SPAD

value) is measured by a handheld chlorophyll meter.

The fruit quality is determined by the procedures

described below. The fresh fruit weight is weighed

with a one-tenths balance. The sugar content is

determined by Japan ATAGO digital Brix meter.

Soluble sugar content is quantified by anthrone

colorimetry. The soluble protein is estimated by

Coomassie Brilliant Blue G- 250 staining method.

The content of the organic acid is measured by the

high-performance liquid chromatography method

with the column temperature being 35℃, the volume

ratio of mobile phases being 9 over 1 between

KH2PO4 and methanol, flow rate being 0.8mL•min-

1, and the sample injection volume being 20 μL. The

composition and content of sugar are estimated by the

high-performance liquid chromatography method.

Specifically, the column temperature is 80℃. The

water is used as the mobile phase with the flow rate

being 1ml·min-1. The sample injection volume is 5

μL.

2.4 Data Analysis

The basic data were processed and analyzed using

Microsoft Office Excel 2010 software, and statistical

analysis of data was performed using SPSS 26.0

software to determine the significance of differences

between treatments by analysis of variance

(ANOVA), Duncan multiple range test and the

significant tests with the significant level being 0.05.

Origin 2019 was used for graphing.

Effects of Different Treatments of Supplemental Light on Tomato Growth and Fruit

3 RESULTS

3.1 Effects of Different Treatments of

Supplemental Light on Tomato

Growth

It can be seen from Table 1 that different

supplemental lighting treatments have different

effects on tomato growth. The plants with the RGB +

UV2 treatment have the highest plant height (324

cm), which was significantly higher than that of the

CK. The plants with other lighting treatments were

higher than that of the CK, but there was no

significant difference among them. The stem

diameter and the number of leaves of the plants with

the RGB + UV2 treatment were highest. But there

was no significant difference compared to that of CK.

Plants with RGB and RGB + FR treatment have the

least number of blades, which are significantly lower

than that of CK. With respect to the pitch, the RGB +

UV1 group takes the largest value. Moreover, the

pitch of the other groups utilizing lighting treatment

is significantly higher than that of CK.

3.2 Effects of Different Treatments of

Supplemental Light on Tomato

Leaves

It can be seen from Table 2 that, the leaf length and

width of the plants with lighting treatments are higher

than that of the groups without supplemental light

(the CK group). While no significant difference is

observed among the groups with lighting. The

chlorophyll level is highest in the RGB group and the

lowest in RGB + FR group. Moreover, no significant

difference is observed among the groups with other

treatments.

3.3 Effects of Different Treatments of

Supplemental Light on Tomato

Fruit Quality

It can be seen from Figure 1 that different

supplemental light treatments do affect the fruit

quality of tomatoes. Except for the fruit from the

plants with RGB + UV2 treatment, the sugar contents

of fruits from the other groups were higher than that

of CK, and the RGB + FR group takes the highest

value of being 6.28 as shown in Figure 1A. The

soluble sugar content of the fruit from the RGB group

Table 1: Effects of different treatments of supplemental light on tomato growth.

Treatment Plant height/cm Stem diameter/mm Internode length/cm

Numbers of

leaf blades

CK 299 ± 22.41b 11.8 ± 0.67ab 7.3 ± 0.67c 45 ± 6ab

RGB 305 ± 4.23b 11.27 ± 0.78ab 8.8 ± 0.55b 39 ± 4c

RGB + FR 302 ± 8.52b 10.99 ± 0.64ab 8.7 ± 0.79b 39 ± 4c

RGB + UV1 301 ± 13.65b 10.83 ± 1.30b 10.1 ± 1.09a 43 ± 4abc

RGB + UV2 324 ± 18.02a 11.96 ± 0.76a 8.4 ± 0.55b 46 ± 1a

Note: CK (no light supplementation), RGB treatment (Red: Green: Blue = 3:1:1, top-lighting), RGB + FR treatment

(adding far-red light based on the RGB treatment, top-lighting), RGB+UV1 treatment (adding ultraviolet light based on the

RGB treatment, filling light from the top), and RGB + UV2 treatment (adding ultraviolet light based on the RGB treatment,

inner-lighting). The data followed by different lower-case letters within the same column are significantly different at 0.05

level. The same as below.

Table 2: Effects of different treatments of supplemental light on Tomato Leaves.

Treatment

Leaf length /cm Leaf width/cm Chlorophyll/SPAD

CK 26.76 ± 3.55ab 25.80 ± 3.23a

34.93 ± 4.77ab

RGB 29.13 ± 3.75ab 25.92 ± 2.46a

39.17 ± 2.10a

RGB + FR 28.37 ± 1.88ab 28.48 ± 4.38a

25.93 ± 6.71c

RGB + UV1 32.29 ± 4.36a 30.12 ± 3.11a

32.94 ± 4.05bc

RGB + UV2 32.23 ± 3.02a 28.48 ± 1.54a

33.42 ± 2.61ab

FSB 2022 - The International Conference on Food Science and Biotechnology

Figure 1: Effects of different treatments of supplemental light on tomato fruit quality. A: Sugar degree; B: Soluble sugar

content; C: Soluble protein content; D: Sucrose; E: Glucose; F: Fructose; G: Malic acid; H:Citric acid.

was highest (increased by 58% compared with that of

CK), followed by that of the RGB + UV2 group

(increased by 28% compared with that of CK).

Although the soluble sugar content of other

treatments was higher than that of CK, there was no

significant difference among those groups with

lighting as shown in Figure 1B. The soluble protein

content of fruit under each treatment was increased

by 42%, 28%, 18%, 21% compared with that of CK,

respectively. Except for the RGB treatment, the other

treatments were not significantly different from CK

(Figure 1C). This demonstrates that the supplemental

light treatment can improve the quality of tomatoes.

It can be seen from Figure 1D-F that the glucose

content in tomato fruit is highest, and the sucrose

content is the least. Different supplemental light

treatments have no significant effect on the content of

the sucrose. The glucose content of the RGB + UV2

treatment was significantly higher than that of CK,

and there was no significant difference between other

treatments and CK (Figure 1E). The fructose content

of RGB + UV2 treatment was the highest at

183.1μg/g, followed by RGB + FR treatment, and

RGB + UV1 treatment was the lowest at 151.5 μg/g

(Figure 1F). It can be seen from Figure 1G-H that the

supplemental light treatment can increase the content

of malic acid in tomato fruits, but it is not significant

compared with that of CK. The citric acid content of

RGB + UV1 treatment was the highest at 2415.3

µg/g, followed by RGB + FR at 2090.6 µg/g, and

RGB was the lowest at 1821.9 µg/g.

3.4 Effects of Different Treatments of

Supplemental Light on Tomato

Yield

From Table 3, the following can be observed: (1) the

fruit from the plant with RGB + UV1 treatment has

the largest single fruit weight; (2) the fruit from the

plant with RGB + UV2 treatment has the largest fruit

quantity; (3) the fruit weight of fruit from the plant

with RGB + FR treatment is the smallest, but the fruit

quantity is significantly higher than that of CK. In

other words, the supplemental light treatment can

significantly increase tomato yield. Moreover, the

RGB treatment increases the yield most (increased

41% compared to that of CK), followed by the RGB

+ UV1 strategy (39% higher than that of CK).

Effects of Different Treatments of Supplemental Light on Tomato Growth and Fruit

Table 3: Effects of different treatments of supplemental light on tomato yield.

Treatment

Single fruit weight/g Fruit quantity/g Yield/kg

CK 35.09 ± 6.45a 56 ± 10.67b 1965.04 ± 110.5bc

RGB 34.74 ± 7.59a 80 ± 24.83a 2779.2 ± 240.32a

RGB + FR 30.81 ± 4.83a 72 ± 22.03ab 2218.32 ± 300.96b

RGB + UV1 38.87 ± 4.25a 70 ± 15.51ab 2720.9 ± 309.8a

RGB + UV2 30.42 ± 8.81a 88 ± 17.39a 2676.96 ± 350.9a

4 DISCUSSIONS

Plant growth is a quantitative change, which is mainly

manifested by plant height, stem diameter, leaf

growth, etc. When the external light quality or

wavelength is different, the growth effect of the plant

is also different (Xu, 2015). Cui’s research shows that

the red light plays an important role in promoting

stem extension and accumulation of dry matter (Cui,

2009). It can be concluded from Yang's research that

the mixing red and blue light can effectively optimize

tomato leaf structure and chloroplast ultrastructure,

thereby promoting the accumulation of dry matter of

tomato seedlings (Yang, 2018). In this experiment,

different supplemental light treatments can affect the

growth and development of tomatoes. The plant

height, leaf length and width of the plants with all

supplemental light treatments are higher than that of

the plants without lighting, which is consistent with

the results of previous studies. Meanwhile, the

chlorophyll content of the tomato plants with RGB +

FR treatment was significantly lower than that of CK,

and the yield was the lowest among all supplemental

light treatments. This is consistent with the research

results of Huang (Huang, 2017): increasing the ratio

of far-red light will reduce the chlorophyll content

and yield per plant. Plant height, stem diameter,

number of leaves, and leaf area of the plant with the

RGB + UV2 treatment are the highest. This may be

because the inter-lighting supplements the light of the

middle and lower leaves of the plant, which promotes

the photosynthesis of the middle and lower leaves,

and then promotes the growth of the plant (Yan, 2018;

Hovi-Pekkanen T, 2008). The above results

demonstrate that LED supplemental light can

promote the growth of tomatoes, and the combination

of red and blue light can promote the growth of

tomatoes significantly, which is important to promote

the formation of late yield.

The soluble sugar content reflects the metabolic

capacity of the plant， and it is one of the main

products of plant photosynthesis metabolism. Light

quality not only affects the growth and development

of tomato plants, but also affects fruit quality

formation (Chen, 2016; Sha, 2021). Ding found that

the mixing red and blue light can significantly

increase the soluble solid content and soluble sugar

content of tomatoes (Ding, 2016). In this experiment,

the soluble sugar and soluble protein of the fruit with

each supplemental light treatment were higher than

that of CK, indicating that the red and blue light can

effectively improve the quality of tomato fruit. The

effect of different light quality on fruit yield is also

very significant. Sun et al. applied the red light and

the mixing red and blue light to tomatoes in the solar

greenhouse, and found that the yield of tomatoes was

significantly increased (Sun, 2014). In this

experiment, the yield of fruits treated with

supplemental light was significantly increased, and

the effect of RGB treatment was the most significant.

The above results demonstrate that red and blue light

mixing can increase the accumulation of sugar

substances in tomato fruits, which has a significant

effect on yield and quality improvement.

However, since this study is the first exploratory

experiment in Qinghai, due to the limited conditions

and relatively simple experimental setup, there are

problems such as relatively few experimental

treatments, a single variety, and fewer measurement

indexes, etc. Moreover, since there are many other

influencing factors in the greenhouse, the final results

may have certain deviations and fail to scientifically

and rationally explain the scientific problems of the

effect of supplemental light on tomato growth and

yield, which is limited. In the future, we will focus on

the scientific aspects of the effects of LED

supplemental lighting on the growth and

development of tomato seedlings and the fruit

formation process during the growth period in

Qinghai.

5 CONCLUSIONS

In summary, different light supplementation

treatments had different effects on tomato growth,

with RGB+UV2 (red: green: blue:

ultraviolet=3:1:1:1) interplant supplementation

FSB 2022 - The International Conference on Food Science and Biotechnology

treatment having the most significant effect on

tomato plant growth than the other treatments, and

RGB (red: green: blue=3:1:1) top supplementation

treatment significantly improving tomato fruit quality

and yield. This result can provide a theoretical basis

for green, high yield and high quality cultivation in

Qinghai. This result can provide a theoretical basis

for green, high-yielding and high-quality tomato

cultivation in Qinghai.

ACKNOWLEDGMENTS

This article is the Qinghai Province Science and

Technology Achievement Transformation Special

Project (2020-NK-121), Qinghai Province

Agriculture and Forestry Science Innovation Fund

(2019-NKY-02), Qinghai Province Science and

Technology Department Key Laboratory Project

(2020-ZJ- Y02) One of the phased results.

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Effects of Different Treatments of Supplemental Light on Tomato Growth and Fruit