Effect of three biostimulants and three doses on
the production and quality of watermelon (Citrullus Lanatus L.) crops
Efecto de tres bioestimulantes y tres dosis en la
producción y calidad del cultivo de sandía (Citrullus Lanatus L.)
Ángel Adolfo Mejía Chica
Agustín Hugo Álvarez Plúa
Published Instituto
Tecnológico Superior Corporativo Edwards Deming. Quito - Ecuador Periodicity January - March Vol. 1, Num. 28, 2026 pp. 45-54 http://centrosuragraria.com/index.php/revista Dates of receipt Received: September 02, 2025 Approved: November 25, 2025 Correspondence author angel6529@unesum.edu.ec Creative Commons License Creative Commons License,
Attribution-NonCommercial-ShareAlike
4.0 International.https://creativecommons.org/licenses/by-nc-sa/4.0/deed.es
[1] Agricultural Engineer, Master's student in
Agriculture at the Graduate Institute of the State University of Southern
Manabí, Jipijapa, Ecuador.mejia-angel6529@unesum.edu.ec https://orcid.org/0009-0007-0600-5637 Research Professor in the
Agricultural Science Degree Programme and
Master's Degree in Agricultural Science at the Postgraduate Institute of
the State University of Southern Manabí, Jipijapa,
Ecuador.agustin.alvarez@unesum.edu.ec
, https://orcid.org/0000-0002-4213-1493
Keywords: experimental design,
biostimulants,
production variables, fruit quality, application dose.
Resumen Con el objetivo de evaluar el efecto de los
bioestimulantes en la producción y calidad del cultivo de sandía (Citrullus
lanatus L.) en el cantón Montecristi, se implementó una parcela experimental en
campo en un diseño experimental de bloques completamente aleatorio (DBCA) en
arreglo factorial de 3 x 3 +1, donde los factores de estudio fueron: Factor A
(bioestimulantes) y Factor B (dosis), con 9 tratamientos, un testigo y 3
repeticiones. El experimento fue implementado a una densidad de 0,50 m entre
plantas y 4 m entre hileras, en una superficie total de 412 m2, con 120
plantas. Las variables evaluadas fueron: la longitud de guía (LG), días de
inicio de la floración (DIF), número de frutos por tratamiento (NFRU), longitud
de fruto (LFRU), diámetro de fruto (DFRU) y peso de fruto por planta (PFRU).
Los resultados determinaron que los bioestimulantes utilizados fueron mejores
para el largo de fruto de 41,31 cm y un peso de fruto de 7,15 kg por planta,
con una dosis de 2 L/ha.
Palabras clave: diseño experimental, biostimulantes, variables
productivas, calidad de fruto, dosis de aplicación.
Introduction
Watermelon (Citrullus lanatus L.) originated in the Kalahari Desert in Africa, where it
still grows wild, and there is evidence that modern domesticated watermelon is
more closely related genetically to the Sudanese Kordofan melon than to other
varieties (Renner et al., 2021). According to the FAO
(2019), the
largest producer of watermelons is China, with an annual production of more
than 60 million tonnes, followed by Turkey with 3.7
million tonnes, and India and Brazil with 2 million tonnes each. Watermelons are sold in numerous markets, but
the main export markets in Central America are the United States (56%), the
Netherlands (25%), the United Kingdom (9%) and Belgium (3%) (Cervantes et al., 2022).
The lack of organic matter exacerbates the situation, as it causes
nutrients to leach out quickly. This
highlights the importance of conducting a thorough soil analysis and choosing
crops that optimise available resources. In this
regard, watermelon (Citrullus lanatus) has shown promise as a crop
thanks to its heat tolerance and adaptability. However, to achieve good
results, proper soil management is crucial, including the use of organic
amendments and effective irrigation systems (Melendres et al.,
2025).
This crop does not require very
specific soils due to its ability to adapt to arid conditions, however, better
results have been observed in soils that have a high organic matter content,
good porosity and sandy loam texture. For growing watermelons in clay soils, it
is crucial that the soil allows for good drainage. It is best for the field
capacity to be around 70%, as the root system shows optimal development within
this range (Díaz, 2024).
To improve both national and global
production, different management and treatment programmes
have been established, involving the use of various horticultural products such
as biostimulants (Muñoz
& Brainard, 2022). Currently, there are biostimulants
available on the market, generally in the form of concentrated liquid
substances of plant origin, such as fulvic acid, which contain different
concentrations. These products can improve nutrient absorption and help plants
obtain better yields, while meeting the needs of crops during the energy demand
phase. They offer advantages in terms of the physicochemical properties of the
colloidal active components, biological characteristics thanks to the
maintenance of the carbon-nitrogen ratio, and stimulation of the root system (Atlántica 2020).
This research was carried out
because it is necessary for farmers to learn about new products such as biostimulants that stimulate plant growth to generate good
productive development and obtain high-quality commercial fruit. The purpose of
this research was to evaluate the responses of watermelon crops (Citrullus
lanatus L) to the application of three biostimulants,
since watermelon producers in the Santa Rita area of the Montecristi
canton use excessive amounts of chemicals that affect the soil, degrading it at
the expense of good production. Therefore, the objective of this research was to
evaluate the effect of biostimulants on the
production and quality of watermelon (Citrullus lanatus L.) crops in the
Montecristi canton.
Methodology
Location
The research was carried out in the
canton of Montecristi, in the Santa Rita area of the
canton of Montecristi, Manabí province. Montecristi is located at 1°02′44″ south latitude,
80°39′32″ west longitude
at an altitude of 135 metres above sea level, and the
temperature varies from 24° to 28°C (PDOT, 2019).
Two factors were studied: Factor A: biostimulants (A1: Activer, A2: Aminocrop SL, A3: Humega) and
Factor B: application dose (B1: 1 L/ha, B2: 2 L/ha, B3: 3 L/ha).
Specific management of the
research
The germination trays were cleaned
using a 1% chlorpyrifos-based product to prevent any microorganisms that could
harm the germination process. A mixture of peat soil (organic material formed
by the slow decomposition of plant matter) was prepared. The germination trays
were then filled to sow the seeds. The seedbed was watered by micro-sprinkling
using a portable pump, twice a day, once in the morning and once in the
afternoon. To prepare the soil, weeds were removed, and then the soil was
harrowed twice to loosen it and encourage plant root growth. A drip irrigation
system was installed, with the tape placed at a distance of four metres apart. Once pre-transplant irrigation was carried
out, the plants were sown at a distance of 0.50 m between plants. Each experimental
unit had an area of 12 m2. Biostimulants
were applied every two weeks after transplanting, at 15, 30, and 45 days,
according to the treatments and doses indicated in the materials and methods.
Drip irrigation was performed three times a week until field capacity was
reached. Weed control was carried out manually, and the herbicide Gramoxone
(Paraquat) was applied at a dose of 1 L/ha. Solaris (Spinotoram)
was used to control insect pests at a dose of 10 cc/20 L, plus Abertiicc (abamectin) at a dose of 25 cc/20 L. Hammer (Mancozeb
+ Cymoxanil) was applied to control diseases at a dose of 10 g/20 L every 5
days. Basic fertilisation was carried out with three
nutrients that are essential for cultivation: nitrogen, phosphorus and
potassium. The fertilisers used were urea 165 kg/ha,
triple superphosphate 105 kg/ha and potassium muriate 250 kg/ha. Harvesting
took place between 65 and 75 days after transplanting (ddt).
The fruits were harvested and the number of watermelons per treatment and the
average weight were recorded.
The research was implemented in a completely randomised block design (CRBD) in a 3 x 3 +1 factorial
arrangement with 9 treatments, a control and 3 replicates (Gabriel et al., 2022).
The
following response variables were evaluated: Guide length (GL). A tape measure was
used, extending from the neck of the plant to the main guide. It was evaluated three
times (15, 30, and 45 ddt).
Days to flowering onset (DIF ). The days from transplanting until 50% plus one of all plants
were in bloom were counted. Fruit diameter cm (DFRU ). The
centre of the fruit was measured using a tape
measure. The diameter was calculated by dividing the number of fruits harvested
to find the average diameter per treatment.
Fruit length cm (FLF) . The length was measured in centimetres using a tape measure, then added up and divided
by the total number of fruits to find the average fruit length per treatment. Fruit weight per plant kg (PFRU) . This
was measured in kilograms using a digital scale, then divided by the total
number of fruits harvested to calculate the average weight per treatment . Number of fruits per treatment (NFRU)
. To record this variable, the number of fruits harvested was
counted according to the treatments.
Based on the defined model, analyses
of variance (ANOVA) were performed to test hypotheses about fixed effects, as
well as comparisons of treatment means using Tukey's test at a 5% probability
level. The ANOVA was also used to estimate the variance components for random
effects. The analyses indicated were performed using Infostat
software (Infostat, 2020).
Analysis of
normality and homogeneity of variance
The data for the variables evaluated
were not significant (P<0.05) with the Shapiro-Wilks test. Likewise, no
significance (P<0.05) was observed with the Levene test, showing homogeneity
of variances. The analysis suggested continuing with the ANOVA and the
comparison of means of the variables evaluated.
Results
Table 1 shows
the analysis of variance for the variables evaluated, determining that there
were no significant differences (P<0.05) for any of the variables. The
coefficients of variation (CV) ranged from 5 to 36%.
Table 1. Analysis of variance for evaluated
variables.
|
gl |
Mean squares |
|
|
||||||
|
|
|
LG15 |
LG30 |
LG45 |
DIF |
DFRU |
LFRU |
PFRU |
NFRU |
|
Rep |
2 |
0.0004 |
0.06 |
0.10 |
0.90 |
5.83 |
9.75 |
0.20 |
1.23 |
|
Treatments |
9 |
0.01 |
0.28 |
0.42 |
7.35 |
14.97 |
14.08 |
1.72 |
4.17 |
|
Biostimulant |
2 |
0.01 ns |
0.18 ns |
0.62
ns |
5.33
ns |
22.62 ns |
9.69 ns |
1.50 ns |
4.70 ns |
|
Dose |
2 |
0.01 ns |
0.26 ns |
0.49 ns |
7.11 ns |
12.85 ns |
35.85* |
4.93* |
7.26 ns |
|
Bioes
per dose |
4 |
0.01 ns |
0.38 ns |
0.26 ns |
5.11 ns |
14.06 ns |
8.16 ns |
0.63 ns |
4.31 ns |
|
Test vs.
rest |
1 |
0.02 ns |
0.11 ns |
0.55 ns |
20.83 ns |
7.54 ns |
3.14 ns |
0.09 ns |
5.35 ns |
|
Error |
18 |
0.0003 |
0.15 |
0.30 |
8.86 ns |
11.42 ns |
7.28 |
0.73 |
4.16 |
|
Total |
29 |
|
|
|
|
|
|
|
|
|
CV |
|
32.09 |
24.09 |
19.18 |
7.54 |
5.27 |
6.89 |
13.41 |
35.57 |
DIF: Fruit diameter, LFRU Fruit length, PFRU: Fruit weight, NFRU: Number
of fruits, LG15: Length of shoots at 15 days, LG30: Length of shoots at 30
days, LG45: Length of shoots at 35 days, DIF: Day of flowering onset.
The analysis of means using Tukey's
multiple test did not detect significant differences (P<0.05) for the biostimulants used in any of the variables evaluated.
However, a higher value was observed for Activer in
all variables and a lower value for Aminocrop SL
(Table 2).
Table 2. Analysis of means using
Tukey's multiple test for biostimulants.
|
LG15 |
LG30 |
LG45 |
DIF |
DFRU |
LFRU |
PFRU |
NFRU |
|||
|
0.24 |
1.70 |
3.03 |
40.22 |
65.82 |
39.70 |
6.75 |
6.33 |
|||
|
Humega |
0.22 |
1.60 |
2.84 |
40.22 |
64.38 |
39.53 |
6.32 |
5.56 |
||
|
Aminocrop SL |
0.19 |
1.42 |
2.51 |
38.89 |
62.66 |
37.83 |
5.94 |
4.89 |
||
|
Tukey
0.05% |
0.12 |
0.46 |
0.66 |
3.58 |
4.08 |
3.24 |
1.02 |
2.45 |
||
|
|
ns |
ns |
ns |
ns |
n/a |
ns |
ns |
ns |
||
|
Dosage |
|
|
|
|
|
|
|
|
||
|
2L/ha |
0.21 |
1.58 |
2.99 |
40.67 |
65.54 |
41.31a |
7.15a |
6.56 |
||
|
1L/ha |
0.25 |
1.74 |
2.86 |
39.78 |
64.14 |
37.64b |
6.15ab |
5.44 |
||
|
3L/ha |
0.20 |
1.40 |
2.53 |
38.89 |
63.17 |
38.11ab |
5.70b |
4.78 |
||
|
Tukey
0.05% |
0.12 |
1.11 |
0.66 |
3.58 |
4.08 |
3.25 |
1.03 |
2.45 |
||
|
|
ns |
ns |
ns |
ns |
n/a |
* |
* |
ns |
||
|
Biostimulant
per dose |
|
|
|
|
|
|
||||
|
Activer
1L |
0.28 |
2.01 |
3.23 |
38.67 |
67.27 |
38.80 |
6.71 |
7.67 |
||
|
Aminocrop
2L |
0.28 |
1.86 |
3.06 |
41.00 |
66.37 |
41.67 |
7.07 |
6.00 |
||
|
Humega
2L |
0.17 |
1.53 |
2.98 |
40.67 |
65.67 |
41.70 |
7.26 |
4.33 |
||
|
Activer
3L |
0.27 |
1.75 |
2.95 |
40.67 |
65.60 |
38.80 |
6.71 |
5.33 |
||
|
Activer
2L |
0.17 |
1.34 |
2.91 |
41.33 |
64.60 |
40.57 |
7.12 |
6.00 |
||
|
Humega
1L |
0.31 |
1.88 |
2.97 |
40.67 |
64.23 |
37.03 |
5.82 |
6.33 |
||
|
Humega
3L |
0.19 |
1.40 |
2.55 |
40.33 |
63.23 |
39.87 |
5.88 |
6.00 |
||
|
Aminocrop
1L |
0.16 |
1.33 |
2.38 |
38.33 |
60.93 |
36.17 |
5.93 |
5.67 |
||
|
Aminocrop
3L |
0.14 |
1.06 |
2.10 |
37.33 |
60.67 |
35.67 |
4.81 |
3.00 |
||
|
Tukey
0.05% |
0.29 |
1.10 |
1.57 |
8.51 |
9.71 |
7.72 |
2.44 |
5.83 |
||
|
|
ns |
ns |
ns |
ns |
n/a |
ns |
ns |
ns |
||
|
Treatment
vs. contrast |
|
|
|
|
|
|
|
|||
|
Control
vs. rest |
0.02 |
0.11 |
0.55 |
20.83 |
7.54 |
3.14 |
0.09 |
5.35 |
||
|
|
ns |
ns |
ns |
ns |
n/a |
ns |
ns |
ns |
||
ns: not significant, FDR: fruit diameter, FLDR: fruit length, FWR: fruit
weight, NFR: number of fruits, FL15: length of shoots at 15 days, FL30: length
of shoots at 30 days, FL45: length of shoots at 35 days, DIF: days to
flowering. DSH: honest significant difference
The analysis of means using Tukey's multiple test (P<0.05) for the
treated doses determined significant differences for the LFRU variable, where
the best treatment was for the 2 L/ha dose with a mean of 41.31 cm and for the
PFRU with a mean fruit weight of 7.15 kg (Table 3).
The comparison of means using Tukey's multiple test (P<0.05) for the
interaction between biostimulants and dose showed no
significant interaction for any of the variables evaluated (Table 3).
The contrasts performed using the F test at P<0.05 probability (Table
3) showed no significant differences for any of the contrasts performed.
Discussion
The
findings of this study indicate that the biostimulants used did not show differences
between the different treatments. However, they did promote positive
characteristics in the plants and fruits of the watermelon crop, with the
treatments outperforming the control, although this was not statistically
significant. This coincides with the findings of Vélez (2010), who points out
that biostimulants did not increase production
yields. This contrasts with the findings of Villamar (2012), who mentions that
products with a 100% biodegradable natural organic concentrate, when applied to
the leaves, promote plant growth by activating their physiological processes.
In this research, significant differences were determined for the LFRU
and PFRU variables, where the best treatment was for the dose of biostimulants (Activer, Humega, Aminocrop) with 2L/ha.
The results agree with Cervantes (2018), showing the best averages in terms of
root mass volume, with the highest weight obtained by treatment 2 (Humitrex 2 kg·ha-1 + Radix 2 L·ha-1) treatment, with an
average weight of 208.3 g, while treatments T1 (Humitrex
2 kg·ha-1) and T3 (Radix 2 L·ha-1) achieved lower values with averages of 180.4
and 156.33 g/plant, respectively, while the control was 139.4 g/plant. These
results coincide with those reported by Pazmiño
(2021), who states that the DFRU of the fruit is due to the fact that biostimulants help the plant absorb nutrients and thus
stimulate growth.
Similar results were reported by Veobides et
al. (2018), who mention that biostimulants
incorporate minerals into the stem and leaves, thus increasing yields and
improving fruit quality. The DFRU increases in thickness and volume and is also
beneficial to the environment as it does not pollute or leave residues. The
main action of foliar biostimulants is to moisten and
absorb water and solutes through the leaves, incorporating them into the plant
and thus providing adequate nutrition. In this regard, Pazmiño
(2021) indicates that the leaves act as water and mineral capturers. This is
due to the chemical composition of the biostimulants,
which allow for easy foliar penetration through the stomata, as these are very
important for the survival and growth of the plant.
In this study, comparisons of means for biostimulant
interaction by dose showed no significance, which contrasts with Zaldivar
(2012), who reports that all treatments in his study based on the substances
applied significantly outperformed the control ( ), with the treatment
combining botanical products, the biological medium and the biostimulant,
which significantly outperformed the rest of the treatments. There were no
statistical differences between treatments 2, 3 and 4, which are the treatments
based on plant extracts + the biostimulant or the
biological medium + the biostimulant.
Conclusions
It was determined that the biostimulants used in this research had an impact on the
characteristics of the plants and the fruit production of the watermelon crop,
although no significant differences were observed. However, the doses used did
show significant differences for the LFRU of 41.31 cm and a PFRU of 7.15 kg per
plant, with Humega at a dose of 2 L/ha.
Acknowledgements
To the Universidad Estatal del Sur
de Manabí and the Instituto de Posgrado, to the
Master's Degree in Agriculture for their support and valuable contribution to
my academic training.
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