*Corresponding author: fjrincon@espam.edu.ec

Jennifer Alexandra Orejuela-Romero

Juan Gabriel Chipantiza-Masabanda

Pablo Danilo Carrera-Oscullo

Ana Ximena Salguero-Cajo

Rev. Fac. Agron. (LUZ). 2023, 40(2): e234012

ISSN 2477-9407

DOI: https://doi.org/10.47280/RevFacAgron(LUZ).v40.n2.02

Crop production

Associate editor: Dr. Jorge Vilchez-Perozo

University of Zulia, Faculty of Agronomy

olivarian Republic of Venezuela

Keywords:

Water stress

Thermography

Plant physiology

Eect of decit irrigation on Helianthus annuus L. plants in containers

Efecto del riego decitario en plantas de Helianthus annuus L. en contenedores

Efeito da irrigação decitária nas plantas de Helianthus annuus L. em contentores

Group YASUNI-SDC, Escuela Superior Politécnica de

Chimborazo, Sede Orellana.

Group Causana Yachay-Escuela Superior Politecnica de

Chimborazo, Sede Orellana Ecuador.

Received: 31-01-2023

Accepted: 22-03-2023

Published: 06

-04-2023

Abstract

In order to evaluate changes related to plant physiology, infrared

thermography has been chosen as a non-invasive complement. The research

objective was to analyze the eect of decit irrigation on Helianthus

annuus L. plants in containers by means of IR thermography in a controlled

experimental population at the University of Seville.

The experiment consisted

of three irrigation treatments to sunower plants; one treatment received full

irrigation (C-100) and two treatments received decit irrigation: 70 % (R-70)

and 50 % (R-50). A randomized block design was used. In the initial stage,

polystyrene seedling trays of 54 cells (square) were used for the cultivation

of sunowers. The dimension of the trays was 700 x 400 x 70 mm. The cell

size was 65 x 70 mm and the capacity was 135 cm

. For the development

stage, plastic pots with a capacity of 4 L and a dimension of 21 x 16.4 cm

were used. The sunower plants used in this study did not exhibit signicant

dierences in temperature and physiological analyses as a function of the

irrigation treatment applied. However, there was a strong tendency for

the plants to better resist water stress under a restrictive irrigation of 70 %.

This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.

Rev. Fac. Agron. (LUZ). 2023, 40(2): e234012 Abril-Junio. ISSN 2477-9408.

2-6 |

Resumen

Para evaluar los cambios relacionados con la siología de la

planta, se ha elegido la termografía infrarroja como complemento no

invasivo. El objetivo de la investigación fue analizar el efecto del

riego decitario en plantas de Helianthus annuus L. en contenedores

mediante termografía IR en una población experimental controlada

en la Universidad de Sevilla. El experimento consistió en tres

tratamientos de riego a plantas de girasol; un tratamiento recibió riego

completo (C-100) y dos tratamientos recibieron riego decitario: 70

% (R-70) y 50 % (R-50). Se utilizó un diseño de bloques al azar. En

la etapa inicial, se utilizaron bandejas de poliestireno de 54 celdas

(cuadradas) para el cultivo del girasol. La dimensión de las bandejas

era de 700 x 400 x 70 mm. El tamaño de las celdas era de 65 x 70

mm y la capacidad de 135 cm

. Para la fase de desarrollo se utilizaron

macetas de plástico con una capacidad de 4 L y una dimensión de 21 x

16,4 cm. Las plantas de girasol utilizadas en este estudio no mostraron

diferencias signicativas en temperatura y análisis siológicos en

función del tratamiento de riego aplicado. Sin embargo, se observó

una fuerte tendencia de las plantas a resistir mejor el estrés hídrico

bajo un riego restrictivo del 70 %.

Palabras clave: estrés hídrico, termografía, siología de las plantas.

Resumo

A m de avaliar as alterações relacionadas com a siologia

vegetal, a termograa infravermelha foi escolhida como um

complemento não invasivo. O objectivo da investigação foi Analisar o

efeito da irrigação decitária nas plantas de Helianthus annuus L. em

recipientes utilizando termograa IR numa população experimental

controlada na Universidade de Sevilha. A experiência consistiu em

três tratamentos de irrigação a plantas de girassol; um tratamento

recebeu irrigação completa (C-100) e dois tratamentos receberam

irrigação decitária: 70 % (R-70) e 50 % (R-50). Foi utilizado

um desenho de blocos aleatórios. Na fase inicial, foram utilizados

tabuleiros de poliestireno de 54 células (quadrado) para o cultivo de

girassóis. A dimensão dos tabuleiros era de 700 x 400 x 70 mm. A

dimensão da célula era de 65 x 70 mm e a capacidade era de 135

. Para a fase de desenvolvimento, foram utilizados vasos de

plástico com uma capacidade de 4 L e uma dimensão de 21 x 16,4

cm. As plantas de girassol utilizadas neste estudo não apresentaram

diferenças signicativas de temperatura e análises siológicas em

função do tratamento de irrigação aplicado. No entanto, houve uma

forte tendência para as plantas resistirem melhor ao stress hídrico sob

uma irrigação restritiva de 70 %.

Palavras-chave: estresse hídrico, termografía, siologia vegetal.

Introduction

To evaluate changes related to plant physiology, infrared

thermography has been chosen as a non-invasive complement,

because temperature is an important environmental parameter

(Tattersall, 2016). Being important to employ this system as it allows

timely detection of diseases, dehydration, in plants (Yang et al.,

2019); therefore, infrared thermography can be widely applied in the

non-invasive examination of seed vigor and allows fast and ecient

seed detection for agricultural and silvicultural purposes in the future

(Liu et al., 2020), in this sense, thermography has provided great

advances in eld applications and agriculture.

Due to what has been raised, surface temperature measurement

through thermographic cameras has been widely used in various

elds in recent years (Budzier and Gerlach, 2018). Among the various

benets provided by thermography, its easy handling at the time of

capturing the thermal image stands out, as well as its wide spatial

resolution in one or several objects simultaneously (Harrap et al.,

2018), this involves detecting plant water stress in time, a situation

that helps to optimize irrigation with the intention of enhancing the

plant to an optimal production, this in the medium term, leads to the

economic performance of the plantation, as well as sustainability

until the harvest is achieved (Al Aasmi et al. 2022).

In agreement, Shehzad et al. (2020), indicates that drought stress

is one of the extreme eects of climate change that causes great

losses in crop plant production, applying for sunower plants, foliar

spray K + Ct, (spray with chitosan nanoparticle properties to control

stress in plants ), helping to signicantly improve the gas exchange

characteristics of the leaf, which increased proline, soluble proteins

and free amino acids and increased the antioxidant defense system,

helping to maintain the water status of the plant in sunowers

exposed to drought stress, being functional in this case, to apply IR

thermography for the early detection of water stress in sunowers with

the intention of provoking a timely intervention where intervening

treatments can be applied for the repair of the plant.

It is important to note that water stress decreases growth rates,

photosynthetic pigments, osmoprotectants, yield components, oil

and carbohydrates (%) compared to 100 % irrigation requirements

(Abdallah et al. 2020). Being that the use of IR thermography

contributes to obtain accurate information on plant biology during the

process of water stress, being an important tool to know the impact

and possible consequences, being highly recommended its use,

especially in populations under controlled environments (Harrap and

Rands, 2021).

Based on the above, the research objective is to analyze the eect

of decit irrigation on Helianthus annuus L. plants in containers by

means of IR thermography in a controlled experimental population at

the University of Seville.

Materials and method

Experimental design

In 2020, an experiment was carried out under controlled conditions

in the plant physiology laboratory of the Faculty of Biology of the

University of Seville, Spain. The experiment consisted of three

irrigation treatments to sunower plants; one treatment received full

irrigation (C-100) and two treatments received decit irrigation: 70 %

(R-70) and 50 % (R-50). A randomized block design was used.

Experiment procedure

Sunower seeds (Helianthus annuus L.) of the dwarf variety were

planted under controlled conditions of humidity and temperature. The

culture chamber had an initial temperature of 16.02 ºC during the

rst week, when planting took place. In the following weeks it was

maintained at an average temperature of 24 ºC with slight variations

of ± 2 ºC. The average relative humidity was between 73 % - 84 %.

Peat was used as substrate for the cultivation of sunowers, due to

its chemical characteristics such as nutrient content, cation exchange

capacity (CEC), pH, electrical conductivity (EC) and C/N ratio.

Considering the importance of maintaining EC and pH in optimal

This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.

Orejuela-Romero et al. Rev. Fac. Agron. (LUZ). 2023 40(2): e234012

3-6 |

ranges to avoid low water potential, which could result in water loss

of the plant. The content of salts presents in the peat used was ≤ 2

dS.m

-1

and pH of 6.8 respectively.

In the initial stage, polystyrene seedling trays of 54 cells (square)

were used for the cultivation of sunowers. The dimension of the

trays was 700 x 400 x 70 mm. The cell size was 65 x 70 mm and the

capacity was 135 cm

. For the development stage, plastic pots with a

capacity of 4 L and a dimension of 21 x 16.4 cm were used.

The dry mass in grams of stems and leaves of the three treatments

was obtained, for which the fresh weight (FW) of the sample leaves

was recorded and then the leaves were immersed for 1h in distilled

water. The leaves were removed, and excess water was removed, and

the turgent weight (WW) was recorded. The samples were placed in

an oven at 70 ºC for 48 h to obtain the dry weight (DW). The same

procedure was used to calculate the values obtained in the treatments,

C-100 showed root dry mass values higher than R-70 but lower than

R-50.

According to Córdova-Téllez, (2018) between 60,000 and 70,000

seeds can be sown in one hectare, with a loss percentage of 10 %. Due

to the above, the water consumption was established based on the

water need of 55,000 L.ha

-1

considered 50,000 plants in 10,000 m

The

water demand per plant was established based on the calculated

eld capacity of 11 L in a complete cycle.

The initial seedling stage in the seedbed lasted 28 days, until a

minimum of three true leaves were obtained. Once the sunowers were

transplanted to the pot, the development stage lasted 35 days, where

the plants acquired more than 8 unfolded leaves. In the intermediate

stage of 24 days, the inorescence was produced and 26 days lasted

the nal stage where black seeds were evidenced inside the owers.

At the beginning of the experimental phase the sunowers were 85

days old and once concluded 113 days.

The photosynthetic activity (A) was measured through the

quantication of CO

and atmospheric w ater vapor using an open-

circuit infrared gas analyzer (IRGA) and to calculate the water use

eciency (WUE), the photosynthesis values obtained per treatment

and the stomatal conductance data (gs) were used in the formula:

WUE A.gs

-1

Five plants were used for each experimental unit, for a total of

15 plants in the experiment. The selected sunowers had between

9-12 leaves of similar shape and size. From the experimental

phase onwards, irrigation was programmed every three days. The

sunowers were supplied with water and fertilizer using a watering

can. The volume supplied was 300 mL for full irrigation (R-100).

Deficit irrigation of 70 % to 210 mL of water per sunflower and

deficit irrigation of 50 % to 150 mL respectively.

Allen et al. (1998), established the Kc of sunower at 0.35 in the

initial stage. With the development of the plant, the Kc increases until

it reaches a value of 1.15. After some time, the crop ages and withers,

producing a decrease in Kc to 0.35.

Viridis N30 mixed nitrogen fertilizer was used. With a formula

characterized by its high content of nitrogen, fulvic acids and

microelements that benets plant growth. With a pH of 7.5 according

to the manufacturer’s recommendations, 30 mL of fertilizer were

used for every 10 L of water (table 1).

Table 1. Fertilizers used for evaluation of eect of decit irrigation

on Helianthus annuus L. plants in containers.

Viridis N30 % weight.weight

-1

% weight.volume

-1

Total nitrogen 24.00 29.56

Ammonia nitrogen 6.00 7.31

Nitric nitrogen 5.00 6.27

Urea 13.5 14.9

Also contains: Boron (B); Cop-

per (Cu); Manganese (Mn);

Molybdenum (Mo) and Zinc (Zn).

≤ 0.1%

pH 7.8

Note: Fertilizers used in % weight and volume during the experiment.

Thermal Imaging

Thermographic images were recorded per individual of each

treatment, using a portable infrared thermal camera that was

incorporated into a Samsung Tablet model Galaxy Tab A (2019,

10.1”). The camera model used was FLIR ONE (Flir Systems,

Wilsonville, OR, USA). With resolution of 80 x 60 pixels, whose

spectral range is 8-14 μm. The temperature range measured by the

camera is -20 °C to 120 °C with a thermal sensitivity of 150 mK and

frame rate of 8.7 Hz. The thermal images were taken between 11:00 -

13:00 and were examined using the free software package “Flir One”

and then the data was analyzed by means of the Flir Tools application

for smartphones with Android operating system.

For temperature calculation, the emissivity was set to 1.0 based

on the radiation temperature of a crumpled aluminum foil sheet. The

emissivity for the sunower canopy was set to 0.95. The distance

between the camera and the target was less than 1 meter. Three areas

of dierent circumference were selected within each thermal image to

determine the average temperature per leaf. The selected areas were

exported to Excel to calculate the average temperature per treatment,

as well as the standard error of the data. The sampling days were

February 06, 12, 14, 18 and 27. The thermal images were taken under

the same conditions, except for February 12, when the images were

obtained prior to irrigation.

Statistical analysis

SPSS Statistics version 25.0 (IBM Corp., 2017) was used to

calculate the statistical analysis. They were processed by statistical

design of comparison of means, by application of Duncan’s method

at a margin of error of (p<0.05), which allowed comparison of all

pairs of means used in the experiment, supported by an ANOVA

analysis, after a review of the normal distribution of the data series

and homogeneous variance.

Results and discussion

From the temperatures obtained by thermography, no signicant

dierences (p=0.054) were found between the dierent treatments by

means of the analysis of variance. However, there was a tendency to

increase the temperature from the rst measurement in the treatments

subjected to decit irrigation. To which Iseki and Olaleye, (2020),

point out that through thermal imaging it is possible to determine

canopy and leaf surface temperatures.

Likewise, recent studies show that the plant hormone abscisic

acid (ABA) plays a central role in the regulation of stomatal

movements under water decit conditions (Hsu et al. 2021), ABA

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Rev. Fac. Agron. (LUZ). 2023, 40(2): e234012 Abril-Junio. ISSN 2477-9408.

4-6 |

is actively synthesized in the vascular tissues of roots and leaves

and transported to the protective cells. Consequently, when there

is water stress, stomatal closure occurs in the sunower leaf,

which generates an increase in its temperature, in addition to the

fact that plants detect the water decit signal mainly through the

leaves and roots. In consideration, gure 1 is presented, where

the leaf temperature obtained by IR thermography is identied.

Mean temperature per treatment per day on the x axis given to the

measurement periods.

Figure 2. Dierences were obtained for photosynthesis among

the dierent treatments. C-100: full irrigation (100%),

R-70: 70 % of irrigation, R-50: 50 % irrigation. Irrigation

was carried out every three days. The sampling days were

in February 1:06, 2:12 and 3:14. 5:27.

View complemented by the study of Killi et al. (2017), who

reported similar aectation in photosynthesis and growth of

sunowers directly by water decit and temperature. Although

temperatures were higher at R-70 photosynthesis is higher at R-50.

A peak is observed in the data for the third measurement and then

a steep drop for decit irrigation (both cases), with time as water

stress develops it becomes more accentuated. This may have

contributed to the degradation of physiology in the sunower plants

of the R-50 treatment.

Water use eciency for this experiment was not statistically

signicant (p=0.53). WUE was higher for the R-70 treatment, which

may be associated with the high temperatures exhibited by this

decit irrigation, possibly due to osmotic adjustment, as sunower

are consistent with an ABA-mediated hormonal stomatal response

to vapour pressure decit (VPD) rather than a hydraulically driven

stomatal response to VPD (Cardoso et al. 2020). The above is

presented in gure 3.

1 2 3 4 5

IR THERMOGRAPHY.

AVERAGE TEMPERATURE PER

TREATMENT

MEASUREMENT PERIOD PER DAY

C-100 R-70 R-50

Figure 1. Leaf temperature obtained by IR thermography.

C-100: full irrigation (100%), R-70: 70 % of irrigation, R-50: 50 %

irrigation. Irrigation was carried out every three days. The sampling

days were in February 1:06, 2:12, 3:14, 4:18 and 5:27.

The R-70 treatment, despite not being the most restrictive

irrigation, leads to a greater increase in leaf temperature on all

days sampled. This could indicate the tendency of sunowers to

regulate water loss by closing the stomata for a decit irrigation

of 70 % and resist water stress, which is similar to the study

conducted by Mostafa and Afy, (2022), where it was shown that

sunower plants are resistant and productive in the presence of an

intermediate irrigation. The plants that were subjected to the R-50

treatment presented temperatures between 1 and 2

C below the

R-70 treatment, but despite this dierence, two of the ve plants

died, which could indicate the low tolerance of sunowers to a

restrictive irrigation of 50 %.

Jones (2004), points out that, in the plant, the increase or decrease

of temperature are not limiting for biochemical interactions (around

the optimum temperature), but can become determinant under

severe restrictive conditions, although they are reected in small

variations of temperature.

At the beginning of the experimental phase, the sunower plants

were robust, with an intense green color in leaves and stem, with a

length of more than 40 cm. They had several leaves of appropriate

shape and size. Some plants had small owers, the rst temperature

data taken from the beginning of the experimental phase, under the

conditions mentioned above. Almost at the end of the experimental

phase, the plants had lost their vigor, which could be described as

the characteristic intense green color of leaves and stems. Leaf spots

and necrotic areas on the edges of the leaves were clearly visible in

the treatments subjected to decit irrigation.

Andrade et al. (2017), it is always related stomatal conductance

to leaf water status. As well as the opening and closing of the

stomata are regulated through the integration of environmental

signals and stimuli.

In this research, no signicant dierences were obtained for

photosynthesis among the dierent treatments (p=0.59). As leaf

temperature increased with decit irrigation in R-70 and R-50, so

did photosynthesis values, which may have been due to reductions

in CO

solubility. The above is presented in gure 2.

0,5

0,6

0,7

0,8

0,9

1,1

1,2

1 2 3

PHOTOSYNTHESIS AMONG THE

DIFFERENT TREATMENTS (P=0.59)

MEASUREMENT PERIOD PER DAY

C-100 R-70 R-50

0,1

0,2

0,3

1 2 3 4 5 6

DRY HIGHER ROOT DRY MASS

VALUES MASS IN GRAMS

MEASUREMENT PERIOD PER DAY

C-100 R-70 R-50

Figure 3. Water eciency. C-100: full irrigation (100%), R-70: 70

% Irrigation was carried out every three days. The sampling days

were in February 1:06, 2:12 and 3:14.

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Orejuela-Romero et al. Rev. Fac. Agron. (LUZ). 2023 40(2): e234012

5-6 |

Generating the best utilization of water content by plants exposed

to water stress under the R-70 treatment. Although the values fall in

the fourth sampling (R-70), they return to be the highest at the end of

the experiment. WUE for C-100 from the second data collection is

reported below the two decit irrigation treatments, which may have

been inuenced by external factors such as the location of the plants

in the growth chamber. Both WUE and biomass of the R-70 treatment

were the highest recorded, which relates to the research of Killi et

al. (2017), where he points out that WUE is associated with biomass

production in sunowers and can be seen to inuence it directly.

Once the experiment was concluded, the dry mass in grams

of stems and leaves of the three treatments was obtained. In the

statistical analysis, there were no signicant dierences (p=0.971)

in the root biomass of the dierent irrigations applied. It is possible

that the number of individuals per treatment may have caused non-

determinant results. The above is presented in gure 4.

1 2 3 4 5 6

DRY MASS IN GRAMS

MEASUREMENT PERIOD PER DAY

C-100 R-70 R-50

Figure 4. Dry mass in grams of stems and leaves of the three

treatments. C-100: full irrigation (100%), R-70: 70 %

Irrigation was carried out every three days. The sampling

days were in February 1:06, 2:12, 3:14, 4:18 and 5:27.

Of the values obtained in the treatments, C-100 presented higher

root dry mass values than R-70 but lower than R-50. According to

Killi et al. (2017), sunowers under water stress present an increased

investment in root systems, propitiating a greater use of available soil

water. What could have generated the increase of the root system in

R-50 due to the high decit irrigation to which it had been subjected.

A more extensive root network can cause plants to make better use of

the available water. The above is presented in gure 5.

Therefore, periods of drought will have a negative impact on the

growth of sunower crops, being that García-Tejero et al. (2017),

reported relationships between thermal indicators and physiological

parameters in plants. What would be correlated in our experiment

by manifesting elevated temperatures in sunower plants and

physiological parameters reported in plants. While R-70 had the

highest values in stem biomass, followed by C-100 and nally R-50.

Dierences in stem biomass were not signicant (p=0.745) for the

three treatments.

Conclusions

The temperatures obtained by thermography; no signicant

dierences (p=0.054) were found between the dierent treatments by

means of the analysis of variance. However, there was a tendency to

increase the temperature from the rst measurement in the treatments

subjected to decit irrigation. The R-70 treatment, despite not being

the most restrictive irrigation, leads to a greater increase in leaf

temperature on all days sampled. This could indicate the tendency of

sunowers to regulate water loss by closing the stomata for a decit

irrigation of 70 % and resist water stress.

Generating the best use of water content by plants exposed to

water stress under the R-70 treatment, sunowers under water stress

show an increased investment in root systems, leading to a greater

use of available soil water. This may have led to an increase in the

root system in R-50 due to the high decit irrigation to which it had

been subjected. A more extensive root network may cause the plants

to make better use of the available water.

Having an eect that R-70 had the highest values in stem biomass,

followed by C-100 and nally R-50. The dierences in stem biomass

were not signicant (p=0.745) for the three treatments.

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1 2 3 4 5 6

DRY HIGHER ROOT DRY MASS

VALUES MASS IN GRAMS

MEASUREMENT PERIOD PER DAY

C-100 R-70 R-50

Figure 5. The treatments, C-100 presented higher root dry mass

values than R-70 but lower than R-50. C-100: full

irrigation (100%), R-70: 70 % Irrigation was carried out

every three days. The sampling days were in February

1:06, 2:12, 3:14, 4:18 and 5:27.

This scientic publication in digital format is a continuation of the Printed Review: Legal Deposit pp 196802ZU42, ISSN 0378-7818.

Rev. Fac. Agron. (LUZ). 2023, 40(2): e234012. Abril-Junio. ISSN 2477-9408.

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