Research, Articles, Design
[Research] The Effect of Synthetic Fertilizer and Organic Fertilizer on Plant Growth (Green ribbon)
INTRODUCTION
Cityfarm Malaysia contain 2 different type of fertilizer mainly the synthetic fertilizer which is composed of the Fertilizer A&B and the organic fertilizer which contain seaweed extracts.In hydroponic cultivation, plants require significant quantities of the three primary macronutrients, namely nitrogen, phosphorus, and potassium. Additionally, they also require the following essential micronutrients: calcium, magnesium, sulfur, iron, manganese, copper, zinc, molybdenum, boron, and chlorine(Sánchez, 2023).
As the trend shifts towards organic farming, an increasing number of individuals are opting for organic fertilizers when cultivating their crops. However, there exists a common concern among farmers and gardeners that using organic fertilizers may not yield the same results as synthetic fertilizers. Their concerns include not having the same yield, quality, size as well as overall health of the vegetables is not as good as compared to vegetables planted using synthetic fertilizers.
To address this issue, CityFarm Malaysia has initiated a small-scale experiment aimed at scrutinizing the disparities in the growth of vegetables, with a primary emphasis on the Green Ribbon lettuce, when nurtured using synthetic and organic fertilizers.
METHODOLOGY
To commence this experiment, we selected "green ribbon" vegetables, which were initially planted on 10/7/2023, making them approximately 3-4 weeks old at the outset. We established two distinct Nutrient Film Technique (NFT) systems, each equipped with its own water tank containing a different type of fertilizer. Specifically, System A was supplied with organic fertilizer, while System B received synthetic fertilizer, denoted as Fertilizers A&B. The duration of the experiment spanned approximately 5 weeks, culminating in the harvesting phase. Throughout this period, we meticulously recorded the weight, height, and leaf count of each vegetable on a weekly basis.
To ensure consistent conditions, we maintained nearly identical Electrical Conductivity (EC) values in both tanks. Additionally, we aimed to keep the pH levels within the range of 5.5 to 6.5. However, an unforeseen pH drop occurred in the organic tank due to the introduction of mosquito bti. The pH dipped to approximately 4, prompting us to rectify the situation by employing calcium carbonate powder to raise the pH back within the desired range. The data collected is then tabulated and a paired T-test is then run in order to identify if there is significant difference between the 2 batches of vegetables growing from synthetic and organic fertilizer.
RESULT
Table 1 Raw data for the weekly measurement for weight,height and leave number for the lettuce
Average Weight (g) | Average Height (cm) | Leaf Number | ||||
Row A | Row B | Row A | Row B | Row A | Row B | |
1 | 21 | 20 | 2.8 | 2.2 | 8 | 5 |
2 | 21 | 20 | 3.0 | 2.1 | 7 | 6 |
3 | 20 | 20 | 4.0 | 2.5 | 5 | 5 |
4 | 21 | 18 | 3.5 | 2.1 | 7 | 7 |
5 | 21 | 19 | 3.0 | 3.1 | 6 | 4 |
6 | 22 | 18 | 3.3 | 4.0 | 5 | 5 |
7 | 22 | 20 | 3.2 | 3.5 | 7 | 7 |
8 | 21 | 18 | 3.0 | 2.5 | 7 | 5 |
9 | 23 | 18 | 2.0 | 3.5 | 6 | 5 |
10 | 22 | 19 | 2.7 | 2.5 | 5 | 6 |
11 | 20 | 20 | 4.2 | 2.4 | 4 | 4 |
12 | 20 | 20 | 3.1 | 3.0 | 5 | 4 |
13 | 23 | 22 | 6.5 | 4.5 | 11 | 8 |
14 | 22 | 21 | 5.4 | 4.8 | 9 | 9 |
15 | 24 | 21 | 6.0 | 5.0 | 13 | 6 |
16 | 23 | 21 | 6.7 | 5.5 | 9 | 6 |
17 | 23 | 21 | 3.5 | 6.5 | 9 | 11 |
18 | 24 | 21 | 5.0 | 7.0 | 10 | 8 |
19 | 23 | 23 | 5.0 | 7.8 | 8 | 10 |
20 | 23 | 21 | 3.0 | 6.0 | 10 | 9 |
21 | 25 | 24 | 4.0 | 6.4 | 8 | 9 |
22 | 24 | 22 | 4.5 | 4.0 | 9 | 8 |
23 | 23 | 21 | 6.0 | 5.3 | 7 | 8 |
24 | 21 | 21 | 4.3 | 5.4 | 8 | 7 |
25 | 25 | 22 | 10.5 | 5.5 | 17 | 10 |
26 | 26 | 25 | 7.0 | 7.0 | 13 | 12 |
27 | 27 | 26 | 11.2 | 8.0 | 23 | 11 |
28 | 31 | 23 | 10.3 | 8.2 | 15 | 9 |
29 | 26 | 26 | 9.0 | 9.0 | 13 | 9 |
30 | 28 | 26 | 8.9 | 11.0 | 15 | 12 |
31 | 30 | 28 | 10.2 | 10.9 | 14 | 14 |
32 | 27 | 24 | 9.6 | 7.5 | 14 | 12 |
33 | 31 | 31 | 10.5 | 10.0 | 13 | 15 |
34 | 31 | 25 | 10.3 | 8.5 | 14 | 10 |
35 | 29 | 25 | 10.3 | 7.4 | 12 | 11 |
36 | 23 | 25 | 8.0 | 7.5 | 13 | 10 |
37 | 40 | 38 | 13.0 | 12.0 | 26 | 11 |
38 | 41 | 46 | 12.5 | 13.0 | 16 | 14 |
39 | 54 | 54 | 15.0 | 14.0 | 30 | 17 |
40 | 52 | 45 | 13.2 | 12.8 | 21 | 13 |
41 | 42 | 53 | 12.5 | 13.8 | 20 | 18 |
42 | 45 | 47 | 13.5 | 15.0 | 20 | 16 |
43 | 51 | 41 | 14.5 | 14.4 | 21 | 14 |
44 | 47 | 46 | 13.0 | 13.6 | 18 | 17 |
45 | 55 | 59 | 14.2 | 16.5 | 20 | 17 |
46 | 50 | 40 | 12.0 | 14.5 | 18 | 14 |
47 | 59 | 43 | 15.5 | 15.0 | 19 | 13 |
48 | 36 | 45 | 12.5 | 14.0 | 16 | 17 |
49 | 57 | 56 | 13.4 | 14.9 | 35 | 18 |
50 | 56 | 70 | 16.5 | 13.7 | 26 | 20 |
51 | 77 | 85 | 16.5 | 15.5 | 46 | 19 |
52 | 74 | 70 | 14.0 | 15.2 | 35 | 18 |
53 | 54 | 82 | 14.6 | 15.3 | 27 | 23 |
54 | 66 | 73 | 16.0 | 16.7 | 37 | 21 |
55 | 80 | 61 | 18.3 | 15.7 | 31 | 19 |
56 | 72 | 68 | 16.2 | 16.8 | 32 | 24 |
57 | 91 | 86 | 17.2 | 18.3 | 31 | 22 |
58 | 73 | 56 | 14.5 | 17.3 | 28 | 20 |
59 | 86 | 63 | 17.4 | 18.2 | 28 | 18 |
60 | 51 | 67 | 14.3 | 16.0 | 23 | 21 |
T-Test for the weight of lettuce for both system A and B
H0: There is no significant difference between the means of the weight for both lettuce from system A and B .
H1: There is a significant difference between the means of the weight for both lettuce from system A and B .
P-value calculated : 0.153961112
P-value calculated is more than the alpha value which is 0.05 which indicates that the null hypothesis, H0 is accepted , there is no significant difference between the means of the weight for both lettuce from system A and B.
T-Test for the height of lettuce for both system A and B
H0: There is no significant difference between the means of the height for both lettuce from system A and B .
H1: There is a significant difference between the means of the height for both lettuce from system A and B .
P-value calculated : 0.969899
P-value calculated is more than the alpha value which is 0.05 which indicates that the null hypothesis, H0 is accepted , there is no significant difference between the means of the height for both lettuce from system A and B.
T-Test for the leave number of lettuce for both system A and B
H0: There is no significant difference between the means of the leave number for both lettuce from system A and B .
H1: There is a significant difference between the means of the leave number for both lettuce from system A and B .
P-value calculated : 0.00000017
P-value calculated is less than the alpha value which is 0.05 which indicates that the alternative hypothesis, H1 is accepted , there is a significant difference between the means of the leave number for both lettuce from system A and B.
Table 2 average mean for all the weekly measurements of the lettuce
Weight (g) | Height (cm) | Leaf Number | ||||
Row A | Row B | Row A | Row B | Row A | Row B | |
1st week | 21.2 | 19.2 | 3.2 | 2.8 | 6 | 5 |
2nd week | 23.2 | 21.6 | 5.0 | 5.7 | 9 | 8 |
3rd week | 27.8 | 25.5 | 9.7 | 8.4 | 15 | 11 |
4th week | 47.7 | 46.4 | 13.5 | 14.1 | 20 | 15 |
5th week | 69.8 | 69.8 | 15.7 | 16.1 | 32 | 20 |
Figure 2 line graph showing the average mean of the plant weight for the 5 weeks for both systems
Based on the graph displayed, it is apparent that the lettuces cultivated in System A, which utilizes organic fertilizer, initially exhibit greater weight compared to the lettuces grown in System B. However, over time, this weight disparity gradually diminishes, and ultimately, both groups converge to attain an equivalent average weight by the time of harvesting.
Figure 3 line graph showing the average mean of the plant height for the 5 weeks for both systems
The graph clearly illustrates that the lettuce plants in System A initially exhibit greater height than those in System B, particularly around the third week of growth. However, as time progresses, the height of the lettuce plants in System A levels off and appears to reach a plateau. Interestingly, by the time of harvesting, the lettuce plants in System B have managed to attain a slightly greater height compared to those in System A.
Figure 4 line graph showing the average mean of the leave number of the lettuces for the 5 weeks for both systems
The graph provides a clear visual indication that the lettuce plants cultivated in System A, which incorporates organic fertilizer, consistently display a higher number of leaves when compared to the lettuce plants in System B. The disparity between these two groups of vegetables is quite pronounced. In particular, the lettuce plants in System A eventually reach an average leaf count of approximately 31 leaves, whereas the lettuce plants in System B only manage to achieve an average leaf count of around 20 leaves.
DISCUSSION
Based on the data presented, it can be concluded that there is a subtle distinction between lettuce plants grown using organic fertilizers and those cultivated with synthetic fertilizers.The lettuce plants nurtured with organic fertilizers tend to have shorter stature but boast a higher leaf count in comparison to their counterparts grown with synthetic fertilizers. This indicates that while organic fertilizers may result in smaller plants, they compensate by yielding more leaves.
Besides, both sets of lettuce plants, whether cultivated with organic or synthetic fertilizers, appear to yield similar weights at the time of harvesting. This suggests that the choice of fertilizer does not substantially impact the overall weight of the lettuce. A notable discovery is that lettuces cultivated with organic fertilizers tend to possess a sweeter taste, while those grown with synthetic fertilizers may exhibit a more bitter flavor profile. This taste disparity is attributed to the potential overabundance of certain nutrients associated with chemical fertilizers, which can lead to bitterness in vegetables(Thomas, 2023).Another facts to take note is that It's essential to acknowledge that lettuces grown with organic fertilizers present certain challenges, such as smaller leaves and a softer plant texture. In contrast, lettuce nurtured with synthetic fertilizer is characterized by a crunchier and firmer texture. Another observable distinction lies in the coloration of the lettuce. Lettuce grown with synthetic fertilizer typically displays a lighter green hue and a fresher appearance, whereas lettuce cultivated with organic fertilizer tends to exhibit a darker green color and may not appear as fresh.
Figure 5 the difference in the size of the leaves growing from synthetic fertilizer(left) and organic fertilizer (right)
Figure 6 the difference in the overall size and color of the lettuces growing from synthetic fertilizer(left) and organic fertilizer (right)
In addition to its other attributes, an intriguing discovery is that CityFarm's organic fertilizer incorporates seaweed extract. This extract is derived from various brown seaweeds, including Sargassum, Laminaria, and Ascophyllum, and it boasts not only essential macro and micro nutrients, vitamins, and antibiotics but also a medley of growth hormones like auxin, gibberellin, cytokinin-kinetin, and cytokinin-zeatin. These growth hormones, richly present in seaweed extract, play a pivotal role in promoting plant growth by facilitating processes such as increased production, enhanced protein synthesis, cell division, and differentiation. Additionally, they contribute to fruit cell development and regulate overall plant growth, fostering optimal growth trajectories. Moreover, studies have demonstrated that the application of seaweed extract can augment nutrient content within leaves, ultimately leading to increased plant weight. This effect is attributed to the involvement of growth hormones in nutrient absorption and transportation processes within plants. Notably, seaweed extract also contains growth hormones like indole-3-acetic acid (IAA) and cytokinins, organic compounds known for stimulating growth through mechanisms such as protein synthesis, cell division, and nutrient metabolism. These findings underscore the multifaceted benefits of seaweed extract as an organic fertilizer, promoting robust plant growth and bolstering crop production (Yusuf et al.,2021) .
REFERENCES
R Yusuf et al 2021 IOP Conf. Ser.: Earth Environ. Sci. 828 012011
Sánchez, E. (2023). Hydroponics Systems and Principles Of Plant Nutrition: Essential Nutrients, Function, Deficiency, and Excess. Retrieved from https://extension.psu.edu/hydroponics-systems-and-principles-of-plant-nutrition-essential-nutrients-function-deficiency-and-excess
Thomas, R. (2023, May 7). 5 Reasons Organic Fertilizers Grow Better Vegetables. Dengarden. https://dengarden.com/gardening/Best-Garden-Fertilizer-For-Vegetables#:~:text=Chemical%20fertilizers%20can%20lead%20to,bland%20or%20bitter%2Dtasting%20vegetables.
- Tan Weng Hui (UM)
[ArtIcle] Urban Farming: Opportunities and Challenges
Traditionally, urban societies employed a variety of methods to cultivate food crops in their yards. Malaysian Agricultural Research and Development Institute (MARDI) and the Department Of Agriculture (DOA)'s introduction of innovative technology has enticed urban residents to adopt and utilize them in their home gardens or community farms. Aquaponics, aeroponics, hydroponics, and vertical farming are Malaysian communities' four most prevalent urban gardening technologies. Aquaponics is a technique that combines traditional aquaculture (raising fish and crayfish in tanks) and hydroponics (growing plants in water) in a symbiotic environment. Hydroponics and fertigation use nearly identical techniques to ensure that nutrients or fertilizers are delivered directly to the roots of the plants, hence preventing root infections. Hydroponics is one of the most popular techniques for quick and simple farming. Crops planted vertically are referred to as vertical farming. More crops can be grown on a smaller amount of land with this strategy. This means that more food can be produced with less land at the same time it opens many windows for urban citizens.
- Putera Muhammad Hazwan Hakim Bin Hamzah (UniSZA)
[Article] The Future of Indoor Vertical Farming
The future of indoor vertical farming looks bright, as this innovative method of growing crops continues to gain popularity and develop new technologies. Indoor vertical farming offers numerous benefits over traditional outdoor farming methods, including the ability to grow crops in urban areas, reduced water usage, and the ability to grow a wider variety of crops. As the world's population continues to grow and urbanization increases, the demand for fresh, local produce will only continue to rise, making indoor vertical farming an increasingly important part of the global food system.
One of the key developments that will shape the future of indoor vertical farming is the increased use of automation and data analytics. As indoor vertical farms become larger and more complex, automation will play a crucial role in managing and optimizing the growing process. For example, sensors and other technologies will be used to monitor and control factors such as temperature, humidity, and lighting, allowing for precise control over the growing environment. Data analytics will also be used to analyze vast amounts of data collected from sensors and other sources, helping farmers to make more informed decisions and improve their operations.
Another important factor that will shape the future of indoor vertical farming is food security. As the global population continues to grow, there will be increasing pressure on the world's food supply, and indoor vertical farming will play a crucial role in meeting this demand. Indoor vertical farms can produce fresh, healthy food even in areas where traditional outdoor farming is not possible, such as in cities and other urban areas. This will help to ensure that people have access to the food they need, even in regions where outdoor farming is not feasible.
The future of indoor vertical farming will also be shaped by advances in lighting technology. As we continue to develop new and more efficient lighting systems, indoor vertical farmers will be able to grow more diverse and nutritious crops, even in areas where sunlight is limited. For example, new LED lighting systems will allow farmers to simulate the natural light spectrum, providing plants with the specific wavelengths of light they need to thrive. This will help to improve crop yields and reduce the energy consumption of indoor vertical farms.
Finally, the future of indoor vertical farming will be influenced by advances in our understanding of plant biology and agriculture. As we continue to learn more about how plants grow and thrive, we will be able to develop new growing techniques and strategies that will allow us to grow even more diverse and nutritious crops in indoor vertical farms. This will help to further improve the sustainability and efficiency of indoor vertical farming, and will allow us to produce even more healthy, delicious food for people around the world.
Overall, the future of indoor vertical farming looks bright and full of promise. As technology continues to advance and our understanding of plant biology grows, indoor vertical farming will become an even more important part of the global food system, helping to feed a growing population and provide access to fresh, healthy produce in urban areas.
The contents of this article is generated by AI
- ChatGPT & DALL·E 2
[Research] The Effect of Water Temperature on Plant Growth
Introduction
The growth and development of plants can be influenced by water temperature in hydroponic cultivation. The physiological process of plants will be affected by the plant metabolic activities such as phenolic compounds, nutrient uptake, chlorophyll pigment formation, and photosynthesis. (Nxawe et al., 2011). The main function of plant roots is to absorb water and nutrients from the growing medium and later conduct them to the stem of the plant. Thus, besides electrical conductivity value, pH value and environment temperature, regulating water temperature is a crucial part in hydroponic cultivation because the temperature in the root zone may make a notable difference in plant growth.
- Lee Shen Ni (UPM)
[Article] Urban Farming in Malaysia
Urban Farming in Malaysia
Urban farming is becoming more popular in the agricultural field nowadays, plenty of groups and entrepreneurs started venturing into it in the agriculture market to seek more potential. What is so special about urban farming till it gains greater interest from the community over the year, let us learn about it!
- Backyard gardens
- Street landscaping
- Greenhouses
- Rooftop gardens
- Green walls
- Hydroponic
- Aquaponics
Excited to know more about urban farm culture in Malaysia?
- Lee Shen Ni (UPM)
[Research] Effects of Photoperiodism on Plant Growth
[Research] Effects of Photoperiodism on plant growth (single 12 hours session vs multiple sessions cumulatively 12 hours)
Introduction
Following the increasing interest in urban farming and hydroponics, many users are slowly looking to grow their own food with household farming setups. For these urban farmers, not all of them have sufficient outdoor spaces that provide sufficient natural sunlight to the plants, instead, they look towards artificial horticulture growlights as a substitute. In comparison, as natural sunlight is much stronger, plants only require approximately 8 hours of sunlight per day for healthy growth, whereas for artificial lighting, it is recommended that these indoor setups are exposed to at least 10 to 14 hours of lighting per day to achieve similar growth results (D’anna, 2021).
However, the usual concern with the statement above is related to none other than the expensive electricity costs that accompany the long hours of turning on the growlights. Additionally, following the Enchanced Time of Use (ETOU) tariff scheme launched by TNB which offers different tariff rates at different times of the day, urban farmers have a better chance at evaluating and reducing their operational costs while growing their passion (Tenaga Nasional Berhad, n.d.).
As seen below, Figure 1 shows the exact timing of the time zones for Peak, Mid-Peak and Off-Peak on weekdays, while Figure 2 shows the different charges for these respective time zones. Subsequently, the lighting requirement for indoor hydroponic farming can be carefully planned according to this information to achieve maximum energy savings without affecting the plant growth. This experiment is carried out to observe the practicality of splitting the lighting requirement for indoor plants into shorter periods, so that these plants have the same cumulative amount of lights across the day instead of a consecutive lighting for 10 hours a day to fit into the Off-Peak time zones. Thus, it is hypothesised that if the plants receive the same cumulative amount of lighting per day (despite splitting it into shorter, separate periods), the plants would have a similar growth rate.
Figure 1. TNB Enhanced Time of Use (ETOU) time zones
Figure 2. ETOU rate for different categories
Materials
- Digital Timers x 2
https://cityfarm.my/products/timer
- 4ft 2”x4” NFT Channels x 4
https://cityfarm.my/products/4-feet-120-cm-nft-channel
- Kintons 101 5W Pump
https://cityfarm.my/products/kintons-101-pump-5watt-1m-800l-h
- Hanna Instruments GroLine Monitor for Hydroponic Nutrients HI981420
https://cityfarm.my/products/groline-monitor-for-hydroponic-nutrients
- A & B Liquid Fertiliser for Leafy Greens
https://cityfarm.my/products/hydroponics-fertilizer
- 4ft Cityfarm Horticulture Full Spectrum T8 Growlights (Pin Connection)
Types of Vegetable Used
- Romaine Lettuce (germinated on 15/9)
- Half-Red Amaranth (germinated on 18/9)
- Hong Kong CaiXin (germinated on 18/9)
- Thai Basil (germinated on 11/9)
Methodology
This experiment started on the 29th of September and ended on the 30th of October. It was conducted in a City Vertical Farm M (Figure 3), which consists of 2 layers. The top layer was set up as the control plants, which the timer for the growlights were set to run for 12 consecutive hours every day from 6am to 6pm. On the other hand, the bottom layer was the experimental layer where the plants in this layer were exposed to 3 different sessions of 4-hour-period lighting throughout the day, these periods are 6am - 10am, 12pm - 4pm as well as 6pm - 10pm. It is important to note that both setups are still exposed to 12 hours of light per day.
Each layer holds two 4ft NFT channels which provide a total capacity of 32 plants for the experiment, 4 seedlings from each vegetable type were placed within the NFT channels as seen below in Figure 2. Aside from the lighting alterations made for the experiment, the remaining setup for the Vertical Farm M is identical to the usual hydroponic practices. The EC readings for the water tank was measured and maintained daily between 1.2 - 1.4 mS/cm, while the pH levels of the water was maintained above 5.5 to ensure the healthy growth for the plants.
Additionally, pictures of the plants were taken every 3 days from the start of the experiment to help visualise the differences between both setups as well as the differences between the locations of each plant within the same setup (due to the slight differences of light exposure from the plants’ positions). At the end of the experiment, the plant growth was measured using the fresh weight of the full plant after the harvest period, the mean weight of the plants were used to compare between both setups.
Figure 3. A 3D computer generated model of City Vertical Farm M
Results
Table 1. Post-experiment Fresh Weight Measurements
Plant Types |
|
Weight of Plants (kg) |
Mean Weight (kg) |
Half Red Amaranth |
Control |
0.04 |
0.051 |
0.046 |
|||
0.053 |
|||
0.065 |
|||
Experiment |
0.014 |
0.027 |
|
0.028 |
|||
0.034 |
|||
0.032 |
|||
Hong Kong Caixin |
Control |
0.015 |
0.0213 |
0.021 |
|||
0.03 |
|||
0.019 |
|||
Experiment |
0.012 |
0.019 |
|
0.018 |
|||
0.021 |
|||
0.023 |
|||
Romaine Lettuce |
Control |
0.085 |
0.068 |
0.07 |
|||
- |
|||
0.05 |
|||
Experiment |
0.081 |
0.07 |
|
0.084 |
|||
0.075 |
|||
0.041 |
|||
Thai Basil |
Control |
0.057 |
0.057 |
0.069 |
|||
0.064 |
|||
0.036 |
|||
Experiment |
0.03 |
0.042 |
|
0.055 |
|||
0.047 |
|||
0.035 |
As mentioned above, pictures of the plants were taken throughout the experiment, as there were a lot of pictures from the experiment, only the pictures from Day 1, Day 14, and Day 30 will be shown below to help visualise the differences of the plants.
Half Red Amaranth
Day 1 Control Day 1 Experimental
Day 14 Control Day 14 Experimental
Day 30 Control Day 30 Experimental
Hong Kong Caixin
Day 1 Control Day 1 Experimental
Day 14 Control Day 14 Experimental
Day 30 Control Day 30 Experimental
Romaine Lettuce
Day 1 Control Day 1 Experimental
Day 14 Control Day 14 Experimental
Day 30 Control Day 30 Experimental
Thai Basil
Day 1 Control Day 1 Experimental
Day 14 Control Day 14 Experimental
Day 30 Control Day 30 Experimental
Discussion
Photoperiodism, otherwise defined as the physiological reaction of organisms to the length of the dark period, is one of the most researched topics on both animals and plants. For plants, photoperiodism is particularly important as certain plant species require a specific duration of dark period in order to achieve their flowering and fruiting process.
In this experiment, it is observed that all control plants (aside from the Romaine Lettuce) grew slightly better when compared to its experimental counterparts. For the experimental plants, there is clear evidence of stem elongation throughout the growing phase, as seen in the pictures above. This is particularly visible for the Thai Basil as well as the Half-Red Amaranth plants. However, there were also slight differences between the experimental samples as some of the plants may not have received sufficient lighting due to its positioning in the NFT channels (especially around the edges of the NFT channels where the plants were not directly exposed to the lighting, which led to poor growth and stem elongation.
Additionally, it is also noted that most of the control plants managed to accumulate a higher biomass. Aside from the Romaine lettuces which showed little to no differences among the two setups, the remaining plant species recorded visible average weight differences. It is also important to note that there were cases of pest infestations during the experiment, which severely affected the Hong Kong Caixin plants. While immediate pest management measures were immediately taken once the issue was spotted, the end result still showed poor growth for both the control and experimental setups.
In a similar study conducted by Folta in 2019, the team experimented on ways to reduce energy requirements for farming in controlled environments. Rather than setting multiple 4-hour sessions of lighting, they experimented on various light-dark cycles, ranging from hours to seconds. Unfortunately, most of the longer cycles (6 hours, 3 hours, 1 hour, 30 minutes) showed that the plants grew as if they were in a light-deficient environment, thus the stems elongated to search for an alternative light source. However, when they further reduced the duration of light-dark cycles to approximately 5-20 seconds, the seedlings grew as if they had received 12 hours of regular lighting.
In conclusion, while the findings by Folta correspond to the findings in this experiment, it seems that it is difficult for everyday users or hobbyists to be able to tackle the energy cost without sufficient access to technology to alter the lighting cycles without affecting plant growth. As of now, in order to save on energy costs for indoor farms, the only method now would be to operate these farms during off-peak hours.
References
D’anna, C. (2021). The Basics of Hydroponic Lighting. Retrieved from https://www.thespruce.com/hydroponic-lighting-basics-1939224
Folta, K. (2019). Micro-naps for plants: Flicking the lights on and off can save energy without hurting indoor plants. Retrieved from https://explore.research.ufl.edu/micro-naps-for-plants-flicking-the-lights-on-and-off-can-save-energy-without-hurting-indoor-agriculture-harvests.html
Tenaga Nasional Berhad (n.d.). TNB Enhanced Time of Use (ETOU). Retrieved from https://www.tnb.com.my/faq/etou/
- Bryan Chan (Queensland University of Technology)