ISSN: 0215-0212 / e-ISSN: 2406-9574 Pelita Perkebunan 41.
Ai108 and watering frequency on the growth The effect of cocoa seedlings DOI: 10.
22302/iccri.
The Effect of Melatonin Application and Watering Frequency on the Growth of Cocoa Seedlings (Theobroma cacao L.
Fakhrusy Zakariyya.
Eka Putri Novelia.
Gatot Subroto.
, and Sholeh Avivi.
* Pusat Penelitian Kopi dan Kakao Indonesia.
Jl.
PB Sudirman No.
Jember.
Indonesia Program Studi Ilmu Pertanian.
Fakultas Pertanian.
Universitas Jember.
Jl.
Kalimantan Tegalboto No.
Jember.
Indonesia Corresponding Author: savivi.
faperta@unej.
Received: January 14, 2025 / Accepted: July 6, 2025 Abstract Watering is one of the keys to cocoa plant growth, where proper watering enhances plant development, while infrequent watering can lead to drought stress.
Melatonin can help mitigate the negative impacts caused by drought stress.
Melatonin is a hormone that regulates various physiological processes and is believed to enhance plant tolerance to stress while stimulating growth.
The purpose of this study is to investigate the effect of melatonin application on the growth of cocoa seedlings under different watering frequency.
The study was arranged by randomized complete block design with a split-plot arrangement, consisting of two factors with three replications.
The main plot represents watering frequency of 3 days, 6 days, and 9 days.
The subplot represented melatonin concentrations of 0 AM, 50 AM, 100 AM, and 150 AM.
Observational parameters included plant growth based on plant height, stem diameter, leaf number, and leaf area, as well as plant dry weight based on the dry weight of the shoot, roots, and total plant.
The results showed that at the 3-day irrigation frequency, melatonin concentrations of 50-100 AAM enhanced plant growth parameters including plant height, stem diameter, leaf area, as well as shoot dry weight and total plant dry weight.
At the 6-day frequency, melatonin application up to 150 AAM reduced growth and had no effect on total plant dry weight, but increased root dry weight.
At the 9-day irrigation frequency with application of 150 AAM melatonin improved all growth parameters and total plant dry weight.
Therefore, melatonin can enhance drought tolerance and promote plant growth under limited irrigation conditions.
Keywords:
Melatonin, watering frequency, growth, cocoa
INTRODUCTION
Cocoa (Theobroma cacao L.
) is one of the key export commodities from the plantation sector, playing a significant role in IndonesiaAos economy as a source of foreign exchange revenue alongside oil.
The development of IndonesiaAos cocoa production saw a decline during the period from 2021 to 2022.
In 2021, cocoa production decreased to 50 thousand tons, followed by another drop in 2022, reaching 667.
30 thousand tons (BPS, 2.
The decline in cocoa production can be attributed to global climate change.
Climate change affects weather patterns in Indonesia, causing drought in certain regions.
This phenomenon is a result of the El Niyo event.
Cocoa is a crop highly sensitive to climate changes, particularly drought.
Originating from the tropical rainforests of the Americas, cocoa cultivation is influenced by critical climatic and soil factors, such as rainfall, temperature, and sunlight.
Cocoa plants rely heavily on moderate but evenly distributed rainfall throughout the year, which is crucial PELITA PERKEBUNAN.
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for the flowering process (Boer et al.
, 2.
Based on these considerations, it is essential to adapt cocoa cultivation to changes in weather patterns, particularly through irrigation techniques.
Watering management is a critical aspect of plant maintenance, especially during the early growth stages when cocoa seedlings require adequate water to support root development and overall plant growth.
Both water deficiency and excess during the initial growth phase can induce stress in cocoa Therefore, proper management of watering frequency is essential in nursery management, as it can affect soil moisture stability, water absorption efficiency, and seedling resistance to environmental stress (Zakariyya & Indradewa, 2.
Determining the optimal watering frequency aims to maintain a balance of water in the soil, prevent damage caused by over-irrigation or underirrigation, and ensure that seedlings receive sufficient water for their growth.
A watering interval of every 3 days is considered the most optimal, as it maintains a balance between water availability and soil aeration.
Daily or every-2-day watering, while capable of keeping the soil moisture high, poses a risk of water saturation in the growing media, which can inhibit root respiration and increase the likelihood of root diseases.
In contrast, watering every 3 days provides sufficient water for plant growth without causing excessive soil moisture, while also allowing time for partial drying of the media, thereby promoting healthy root development.
Sulastri et al.
reported that a 3-day watering interval resulted in greater plant height and dry weight of cocoa seedlings compared to 1-day and 2-day intervals.
Meanwhile, a 6-day watering interval begins to show signs of water stress, especially if not supported by external interventions such as the application of bioactive compounds that enhance drought tolerance.
Under such conditions, plants generally expe- rience a reduction in leaf number and slower Watering intervals longer than 7 days can cause significant water deficits, inhibit photosynthesis, and drastically reduce both dry weight and plant height.
This lowfrequency watering is not recommended, as it may lead to increased seedling mortality in cocoa nurseries (Djoah et al.
, 2.
cocoa nurseries, the application of appropriate watering strategies that align with local climatic conditions can enhance nursery success and influence the future productivity of cocoa plants.
One approach to mitigating drought-induced stress involves the application of hormones, compounds, substances, or specific proteins to help meet the plantAos nutritional needs and enhance its resilience.
The application of exogenous growth regulators, such as melatonin, has been proven to enhance drought tolerance in plants (Arnao & Hernandez-Ruiz, 2.
Melatonin itself is a natural pleiotropic biomolecule widely found in both plants and animals, and it has been shown to improve productivity (Ren et al.
, 2.
Melatonin belongs to the class of tryptophan derivatives and functions as a potent antioxidant.
As an alternative to mitigating stress in cocoa plants, the use of melatonin can be considered.
The purpose of this study is to examine the effects of exogenous melatonin application on growth and stress tolerance under different irrigation MATERIALS AND METHODS The research was conducted from April to July 2024, a period that includes the transition from the rainy season (Apri.
, with maxium temperatures 26.
5 AC and minimum 2 AC, to the early dry season (MayAeJul.
, during which maximum temperatures 30.
8 AC and minimum temperatures 2 AC.
The study took place in the greenhouse PELITA PERKEBUNAN.
Volume 41.
Number 2.
August 2025 Edition The effect of melatonin application and watering frequency on the growth of cocoa seedlings of the Indonesian Coffee and Cocoa Research Institute.
Kaliwining.
Jember.
East Java.
The cocoa seedlings used in this study were ICCRI 06H variety, 6 months old after planting.
The planting medium was prepared using 25 x 25 cm polybags, with a mixture of soil, manure, and sand in a 2:1:1 ratio (Sugianto & Jayanti, 2.
, with each polybag weighing 2.
5 kg.
The experimental design used was Completely Randomized Design (CRD) with split plot design consisting of two factors: watering frequency and melatonin concentration.
The combination of treatments was repeated three times, resulting in 36 experimental units.
The main plot was watering frequency, which included three treatments: watering every 3 days, 6 days, and 9 days, with 450 mL of water applied every polybag (Indri, 2.
each The sub plot was melatonin concentration, with four treatments: 0 AAM .
, 50 AAM, 100 AAM, and 150 AAM.
The melatonin solution was prepared by first creating a stock solution with DMSO as the solvent and stirring until fully dissolved.
Then, a liter of distilled water .
was added, and the solution was diluted to the desired concentrations.
Melatonin was applied foliar spraying the solution onto the cocoa leaves, with a volume of 10 mL per plant every two weeks in the morning.
The seedling growth includes plant height, stem diameter, and leaf number were observed every 9 days over the 3-month experimental period.
Other measurements, such as leaf area and the drymass of the plant .
ncluding shoot, roots, and total dry weigh.
, were taken at the end of the study.
Stress tolerance index was calculated by using formula ), where Ypi represents the seedling dry weight of 3-days watering frequency.
Ysi represents the seedling dry weight of 6and 9-days watering frequencies, and Yp represents the average cocoa dry weight of 3-days watering conditions (Bhandari et al.
Soil moisture was measured using a moisture meter both before and after watering to determine changes in soil water content as a result of the watering treatments.
Data obtained from the research then was analyzed using analysis of covariance (ANCOVA), and if significant differences were found between treatments, a DuncanAos Multiple Range Test will be performed at a 5% significance level.
RESULTS AND DISCUSSION
Plant growth variables, including plant height, stem diameter, and leaf number, were observed 10 weeks after treatments (WAT).
Increasing the watering frequency from every 3 days to every 6 days and 9 days suppressed plant growth in terms of height, stem diameter, and the number of leaves at the end of the observation period.
The increase in watering frequency from every 3 days to every 6 days and 9 days reduced plant height by 19.
9% and 28.
9%, respectively.
ANCOVA results showed an interaction between water frequency with melatonin application in the plant height, stem diameter, number of leaves, and leaf area.
All of growth variables includes plant height, stem diameter, number of leaves, and leaf area showed polynomial pattern.
At the 3-day watering frequency, the application of 100 AAM melatonin enhanced plant height and stem diameter.
Meanwhile, at the 9-day watering frequency, the application of 150 AAM melatonin significantly improved all growth variables of the plants.
The role of melatonin, as shown in Figures 1a, 1b, 1c, and 1d, at a 9-day watering frequency with the addition of 150 AAM melatonin, indicated that melatonin can enhance the growth of plants under drought stress.
This finding was in line with research by Arnao & HernyndezRuiz .
, who reported that melatonin application at concentrations ranging from PELITA PERKEBUNAN.
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y3-d = -0.
RA = 0.
y6-d = -0.
0003x2 - 0.
RA = 0.
y9-d = -0.
RA = 0.
Stem diameter .
Plant height .
Number of leaves .
Number .
y6-d = -0,0002x2 - 0,0152x 29,79 RA = 0,61* y9-d = -8E-05x2 0,02x 18,2 RA = 0,82** Note:
6 days 9 days The mean value followed by the same letter is not significantly different according to Duncan Test at the 0.
05 significance level.
y3-d = 0,0007x2 - 0,0631x 41,613 RA = 0,94** y6-d = 5E-05x2 - 0,0478x 29,558 RA = 0,97** y9-d= 0,0003x2 - 0,0201x 18,924 RA = 0,86** Melatonin concentration (AAM) 3 days 6 days 9 days Note:
3 days Melatonin concentration (AAM) y3-d = -0,0001x2 0,0117x 29,435 RA = 0,2381 9 days The mean value followed by the same letter is not significantly different according to Duncan Test at the 0.
05 significance level.
Leaf area .
m Note:
6 days y9-d = 1E-05x2 - 0,004x 11,261 RA = 0,89** Melatonin concentration (AAM) 3 days y6-d = 3E-05x2 0.
RA = 0.
y3-d = -5E-05x 2 0,0138x 13,225 RA = 0,90** The mean value followed by the same letter is not significantly different according to Duncan Test at the 0.
05 significance level.
Melatonin concentration (AAM) 33 days Note:
66 days 99 days The mean value followed by the same letter is not significantly different according to Duncan Test at the 0.
05 significance level.
Figure 1.
Analysis of covariance (ANCOVA) to the growth variables: plant height .
, stem diameter .
, number of leaves .
, and leaf area .
100 AAM to 200 AAM increased plant drought resistance, including in Arabidopsis thaliana and Oryza sativa.
Another study by Zhang et al.
also demonstrated that melatonin at concentrations of 100 AAM to 150 AAM improved growth in Oryza sativa under drought stress by increasing chlorophyll content and improving cell turgor.
Additionally.
Tan et al.
reported that melatonin application could enhance the drought tolerance of Arabidopsis thaliana by increasing antioxidant capacity and improving hormone regulation, supporting the finding that higher melatonin doses are more effective under severe drought conditions.
The application of various concentrations of melatonin and watering frequencys showed different effects on seedling dry weight variables, depending on the applied drought At a 3-day watering frequency, the addition of melatonin at 50 AAM to 100 AAM increased the dry weight of the shoots and total plant dry weight but reduced root dry weight.
This suggested that melatonin stimulates the growth of the shoot parts .
eaves and stem.
, which is associated with enhanced photosynthesis and other metabolic However, the decrease in root dry weight may be attributed to an imbalance between shoot growth and the root systemAos PELITA PERKEBUNAN.
Volume 41.
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August 2025 Edition The effect of melatonin application and watering frequency on the growth of cocoa seedlings ability to expand, as more frequent watering .
very 3 day.
supports faster above-ground growth than root development.
At a 6-day irrigation, the addition of melatonin up to 150 AAM had no effect on the total drymass of the plants and actually reduced growth .
lant height, number of leaves, and leaf are.
as shown in Figure 1.
However, concentrations ranging from 100 AAM to 150 AAM resulted in an increase in root dry weight (Figures 2.
This indicates that melatonin can stimulate root development in response to moderate drought.
The increase in root dry weight reflects the role of melatonin in modulating various plant hormones involved in stress responses, particularly by enhancing the activity of growth hormones like auxins, which support root cell division and elongation (Yang et al.
, 2.
y6-d= 0,0006x - 0,0946x 41,376 RA = 0,58* y3-d = 0,0001x2 0,0555x 50,091 RA = 0,99** a Root drymass .
Shoot drymass .
At a 9-day watering frequency, the application of melatonin at concentrations ranging from 50 AAM to 150 AAM increased the total plant drymass, shoot drymass, and root drymass, indicating that melatonin is effective in stimulating overall plant growth under more severe drought stress conditions.
Although, the soil moisture at a 9-day watering interval .
,6 %) was slightly higher than that of the 3-day .
,4%) and 6-day .
,1%) treatments, the prolonged interval between water applications likely imposed cumulative water stress over time.
This indicates that the observed increase in root drymass was not solely attributable to soil moisture levels at a single time point, but rather to physiological adjustments triggered by the extended intervals between These conditions also suggest that y9-d = 3E-05x2 0,0286x 27,337 RA = 0,53* y6-d = -0,0001x 0,0308x 10,256 RA = 0,97** y9-d = 9E-05x2 - 0,0025x 8,6126 RA = 0,98** 3 days 6 days 3 days 9 days The mean value followed by the same letter is not significantly different according to Duncan Test at the 0.
05 significance level.
Note:
6 days 9 days The mean value followed by the same letter is not significantly different according to Duncan Test at the 0.
05 significance level.
Total drymass .
Melatonin concentration (AAM) Melatonin concentration (AAM) Note:
y3-d = -0,0004x2 0,0612x 12,535 RA = 0,98** y = -0.
RA = 0.
y6-d = 0,0004x2 - 0,0638x 51,632 RA = 0,44 y9-d = 0,0001x2 0,026x 35,949 RA = 0,65** Melatonin concentration (AAM) 3 days Note:
6 days 9 days The mean value followed by the same letter is not significantly different according to Duncan Test at the 0.
05 significance level.
Figure 2.
Analysis of covariance (ANCOVA) to the biomass: shoot drymass .
, root drymass .
, and total drymass .
PELITA PERKEBUNAN.
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August 2025 Edition Stress tolerance index Stress tolerance index Zakariyya et al.
Figure 3.
Stress Tolerance Index: .
6 days watering frequency and .
9 days watering melatonin may enhance the plantAos water uptake efficiency by promoting root development, which constitutes a critical adaptation for survival under long-term drought stress.
This study was consistent with the research by Arnao & Hernyndez-Ruiz .
, who found that melatonin application could improve drought tolerance by enhancing root function and increasing overall plant dry Similarly, a study by Zhang et al.
showed that melatonin concentrations of 100 AAM to 150 AAM increased the dry weight of Oryza sativa plants subjected to drought stress.
The stress tolerance index was calculated based on the dry weight under three watering conditions: every 3 days, every 6 days, and every 9 days, as shown in Figures 3a and Soil moisture levels prior to irrigation showed a decreasing trend with increasing irrigation intervals, measured at 46.
8% for the 3-day, 42.
8% for the 6-day, and 33.
for the 9-day.
Following irrigation, soil moisture increased significantly to 100.
1%, and 101.
6% for the 3-day, 6-day, and 9-day watering intervals, respectively.
Under the 6-day watering frequency, the application of melatonin did not significantly affect the stress tolerance index.
However, the effect of melatonin became evident under the 9-day watering frequency.
The application of 150 AAM melatonin signi-ficantly increased the stress tolerance index from 0.
51 to 0.
This demonstrated that melatonin can help plants better withstand more extreme drought conditions, where plants must cope with longer periods of stress due to less frequent This result aligned with the research by Arnao & Hernyndez-Ruiz .
on Arabidopsis thaliana, which showed that melatonin plays a role in enhancing plant resistance to abiotic stress, including drought, by regulating hormone balance and increasing antioxidant activity in plants.
Another study by Zhang et al.
also reported that melatonin application in drought-stressed plants could improve their physiological condition and enhance their adaptive capacity to water stress.
Melatonin functions as a protective molecule that helps plants survive drought conditions through various mechanisms, including reducing oxidative stress, regulating hormones involved in stomatal opening, enhancing photosynthetic efficiency, increasing osmolyte content, and improving root structure (Arnao & Hernyndez-Ruiz, 2.
Drought stress induces oxidative stress, which damages plant cells, including membranes, proteins, and nucleic acids, due to the presence of free radicals.
Melatonin acts as an antioxidant by enhancing the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (Sharma et al.
, 2.
, as well as increasing ascorbic acid and glutamine content in plants (Huang et al.
, 2.
In this way, melatonin helps protect plant cells from oxidative damage during drought stress.
PELITA PERKEBUNAN.
Volume 41.
Number 2.
August 2025 Edition The effect of melatonin application and watering frequency on the growth of cocoa seedlings Additionally, melatonin works by modulating various plant hormones involved in stress responses, such as auxins to promote root growth, cytokinins to maintain cellular metabolic balance, and gibberellins.
Moreover, melatonin increases the production of abscisic acid (ABA), a key hormone in drought response, which regulates stomatal closure and reduces water evaporation, thus helping the plant conserve water during drought (Sharma et al.
, 2.
Institute for providing the essential facilities and resources that were vital to the smooth progress of this research.
Special thanks are also due to Sulistyani Pancaningtyas.
MSi.
for providing melatonin compound used in this research.
We also acknowledge the technical support provided by Hikmatullah Adicahyo.
Tr.
and Herwanto, which was crucial for the successful execution of the CONCLUSIONS
REFERENCES