[Article] Urban Farming in Malaysia

[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)

https://cityfarm.my/products/new-2020-model-samsung-led-diodes-4-feet-cityfarm-horticulture-full-spectrum-led-t8-tube 

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

        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/ 

[Article] Get to know your lettuce!

Lettuce Categories

Cos lettuce

Also known as Romaine lettuce, it is medium to large in size and is believed to be one of the oldest varieties in the world. Its physical characteristics are elongated and stiff, with leaves averaging about 10-15cm in length and having a firm rib that runs down the centre. With red and green varieties, the intensity of the colours is strongest at the tip, displaying a dark red or green colour that fades into a near-white colour at the base of the leaf. The taste and texture of Cos lettuce are described as crisp, succulent, and crunchy with a mildly bitter taste.

Growing

Butterhead lettuce

Also known as Boston or Bibb lettuce, it is a medium sized lettuce. Its physical characteristics are short and attractively rose-like, with leaves averaging to about 10cm in length. With red and green varieties, the intensity of the colours is achievable with strong lighting. Red varieties are a blend of red, purple, and burgundy that slowly fade green at the base, whereas green varieties are intensely coloured that stays consistent from tip to base. The leaves are described as soft, loose, wavy, and wide growing in a rosette fashion, with taste and texture being described as lightly sweet and tender.

Growing

Lolla

Lolla lettuce, also known as coral lettuce, is a medium to large sized lettuce that is one of the most common lettuce seen in stores. Its physical characteristics are that it has extremely dense, soft, and wavy leaf tips, while having firm and fleshy ribs. It comes in red and green varieties, Lolla rossa and Lolla bionda respectively, that are intensely coloured. The taste is mild and texture is described to be smooth, crunchy, and light.

Growing

Oakleaf

Oakleaf lettuce is a type of looseleaf lettuce that does not form a compact head that grows large in size. As the category suggests, its physical characteristic is a loose, bushy bunch that extends out from a narrow base. Its leaves are described to be hook-shaped, tender, broad, and curled that are fragile and tear easily. Oakleaf comes in two colour varieties, red and green, with both colours not being very intense even when exposed to strong lighting. It’s taste is described to be nutty and mildly bitter or sweet depending on the variety.

Growing

Batavia

Batavia is a more heat tolerant lettuce that grows to a medium or large size. Its physical characteristics is a wide, wavy and dense leaf arrangement at the top that stems from a small base. As mentioned, its leaves grow out from the centre point at the bottom, spreading out large and having wavy tips. The intensity of the waves are dependent on the variety. Like other lettuces, Batavia comes in both red and green varieties. Red varieties are usually only red at the tips, with visible transitions to green 2-3cm from the tip. Its taste and texture is described to be earthy and smooth.

Growing

Special Varieties

Salatrio

Salatrio lettuce is not a specific variety of lettuce, but a special combination of three different lettuce varieties in one pot. Rijk Zwaan, one of the industry leaders in vegetable breeding, has specially selected combinations that grow well together. In total, there are 12 different combinations available worldwide. 

Eazyleaf

Eazyleaf is a category of lettuce varieties produced by Enza Zaden. The main attraction of these varieties is its ease of preparation. Eazyleaf plants are specially made for a one-cut preparation that will split the vegetable into many, equally sized leaves. These varieties are highly suitable for food processing and commercial use, where automation is common and operations are time sensitive.

Salanova

Salanova is a category of lettuce varieties produced by Rijk Zwaan. Varieties under the Salanova product line are specially produced for use in hydroponic systems, providing better taste, quality, and production. Benefits include 40% more yield, improved taste and texture, and increased shelf life. 

Types of Seeds

Unpelleted

Unpelleted seeds are your typical seeds you would buy or collect. These seeds have not been processed after harvest and come in its original shape and for, therefore managing these seeds may be a challenge, especially with machinery.

Pelleted

Pelleted seeds are coated to make them round, smooth, and uniform. This is done so that commercial growers can handle them easier. Certain plants produce very small seeds, and a commercial farmer may find it difficult to manage them at a small size. By coating them, all seeds are equal in size and round. This is especially useful when being used with machinery, such as a mechanical seeder.

[Research] Effects of Dissolved Oxygen (DO) on the Growth of Lollo Rossa in NFT Hydroponic System

The Effect of Dissolved Oxygen on the Growth of Lollo Rossa in Nutrient Film Technique (NFT) Hydroponic System

Objectives:

• To study the effect of dissolved oxygen on the growth of Lollo Rossa (red coral lettuce).
• To examine the level of dissolved oxygen in nutrient solution with and without aeration system.

Introduction:

Materials:

Methods:

Results:

[Guide] Microgreens Comprehensive Growing Guide

Microgreens Comprehensive Growing Guide

Including:

- Wheatgrass

- 13 types of microgreen

Table 1 is the suggested harvesting day printed on the packaging.

Apparatus and materials required:

-Microgreens seeds, Sprouting tray, Peat moss, Spray bottle

Step 1: Methods of Growing

There are media and media-less method when growing microgreens. Among them, wheatgrass can be grown using both method; other microgreens are suggested to be grown through media. Peat moss is the most suitable media in growing microgreens.

• Media-less (Wheatgrass only) Wheatgrass seeds will have to be pre-soaked for 2 to 3 days prior growing. In this case, an air-tight container will be required for soaking. Put the desired amount of seeds into the container, fill in water and close the lid. Soak for 24 hours. Rinse every 8 hours thereafter and invert the container to dry it using a mesh. The seeds will be sprouted and ready to be grow in 36 to 48 hours.

Some photos show the media-less wheatgrass growing process

[Research] Effects of Organic Matter on Plant Taste in NFT Hydroponics

Effects of Organic Matter on Plant Taste in NFT Hydroponics

Introduction

There are many factors contributing to flavor in vegetables such as plant biostimulants used, nutrient composition, growing temperature, harvest maturity and post-harvest handling (Diffley, 2012).

Organic matters such as humic acid and seaweed extract are among the most widely used plant biostimulants. A plant biostimulant is a substance or microorganism that, when applied to seeds, plants, or the rhizosphere, stimulates natural processes to enhance or benefit nutrient uptake, nutrient efficiency, tolerance to abiotic stresses, or crop quality and yield (Mattson & Shahid, 2021).

Plant biostimulants are available in different forms such as humic substances and seaweed extracts. The role of the plant stimulants is to enhance the plant growth and development and strengthen the plant’s defensive system to different environmental stresses (Mattson & Shahid, 2021). In this experiment, we mainly focus on the effects of plant biostimulant, Charbon (humic acid and seaweed extract) on plant taste.

Objective

The objective of this research project is to determine the effects of Charbon on plant taste.

Materials

 

The materials of this research project include:

• City Vertical Farm M
• Green coral’s seedlings (one-months-old)
• 4 feet CityFarm Horticulture Full Spectrum LED T8 grow lights
• Cooling fans
• EC meter
• pH meter
• Measuring cups
• Weighing scale
• Hydroponic fertilizers (A and B)
• Charbon (humic acid and seaweed extract)

Method

This experiment was carried out in the City Vertical Farm M (M farm) that consisted of 2 pieces of 4ft NFT channels at both levels. Each NFT channel was occupied by eight green coral seedlings and supplied with two 4 feet grow lights. Each level of NFT channels was occupied with 16 samples. The lighting duration was set to 12 hours per day. Both levels were equipped with one cooling fan respectively.

 

Figure 1: One-month-old green coral’s seedlings in the channels.

The nutrient tank for the upper level of M farm consisted of both hydroponic fertilizers (A and B) and Charbon, whereas the nutrient tank for the bottom level was only consisted of hydroponic fertilizers (A and B) and are served as the experimental control pool. 35g of Charbon was added every two weeks. Furthermore, EC and pH reading were taken from both tank at the beginning and the ending of the experiment.

There are a total of 16 samples of green coral’s seedlings at each level of M farm. The samples were harvested on day 52 along with flavor testing. The respondents randomly picked and tested five out of the 32 green coral samples. The taste of each samples was rated accordingly to the scale of 1-sweet, 2-little sweet, 3-no taste, 4-little bitter and 5-bitter.

In addition, the initial weight and final weight and final appearance of each sample were illustrated in Table 2 and Table 3 respectively. Also, the initial reading and final reading from both the EC and pH meters were recorded in Table 4. The results were recorded on 29th March of 2021 which is a total of 52 days from the stage of germination to the stage of harvest. 

Results

Flavor testing

 

Table 1 below showed the scores of flavor testing from 5 green coral samples of both Tank A and Tank B by 10 respondents.

Table 1: Flavor testing from samples of Tank A and Tank B

Tank A					Tank B
17	15	17	17	14	17	15	20	16	19
16	15	17	12	15	16	16	22	16	24
Mean: 3.1					Mean: 3.62

 

 

Table 2 below showed the initial weight and final weight of all 32 samples of green coral (with net pot) after 52 days.  

Table 2: Initial weight and final weight of samples (with net pot).

Sample (S)	Tank A		Tank B
	Initial weight (g)	Final weight (g)	Initial weight (g)	Final weight (g)
1	16	58	16	88
2	17	165	17	121
3	15	116	15	144
4	16	113	17	163
5	16	116	16	134
6	15	134	16	153
7	16	111	15	93
8	15	63	15	93
9	16	49	16	69
10	16	96	15	122
11	16	120	16	161
12	16	140	15	127
13	16	98	16	141
14	16	120	16	142
15	16	95	16	130
16	15	63	14	57
Average weight (g)	16	104	16	121

 

 

Table 3 below showed the final appearance of all 32 samples of green coral after harvested.

Table 3: Final appearance of green coral samples after harvested.

Samples from Tank A	Observation	Samples from Tank B	Observation
	Sample 1, 8, 9, 10, 16 - Elongated, slightly twisted and low number of leaves.		Sample 1, 8, 9,10, 16 - Elongated, and low number of leaves.
	Sample 5, 6 - Elongated and twisted.		Sample 2, 3, 5, 7- Elongated and slightly twisted.
	Sample 2, 3, 4, 7, 11, 12, 13 ,14, 15- Good in shape, compact and not twisted.		Sample 4, 6, 11, 12, 13, 14, 15 - Compact and slightly twisted.

 

Table 4 below showed the initial reading and final reading from both the EC and pH meters in both tank A and tank B.

Table 4: Initial reading and final reading from both the EC and pH meters.

	Tank A		Tank B
	EC (ms/cm)	pH	EC (ms/cm)	pH
Initial reading	1.67	6.39	1.58	6.25
Final reading	2.50	7.30	2.10	7.30

Discussion

Plant taste

According to the results obtained, most of the respondents rated the taste of the samples from Tank A and Tank B as no taste and little bitter respectively. Tank A consisted of both hydroponic fertilizers (A and B) and Charbon, whereas Tank B only consisted of hydroponic fertilizers (A and B). Charbon was made up of humate and seaweed extracts.

In terms of plant taste, sulfur is important in contributing to the flavor of the crops produced. Next, humate consisted of potassium. Potassium also proven have a crucial role in product quality parameter such as taste (Çalişkan & Cengiz Çalişkan, 2017). However, at the same time, humate also had the probability to decrease the amount of sulfur available to the plants (Rauscher, n.d.). Hence, if sulfur was unable to deliver to plant, this may results in no taste. Lastly, the reason of causing no taste in samples might be due to the humic acid in Charbon was chelated with the calcium in hydroponic fertilizers and resulted in precipitation. This makes the plants cannot absorb the nutrient such as potassium from humate.

Weight and final appearance of green coral samples

Results demonstrated that the samples with the addition of Charbon had a lighter weight as compared to the control. The average size of samples from Tank B was 104g which is 17g lesser than the samples from Tank A. Furthermore, result also showed that most of the samples from Tank A were good in shape, compact and not twisted whereas the samples from Tank B were compact and slightly twisted. This proved that the organic matter which is seaweed extracts in Charbon could lead to improved plant growth and quality.

EC reading and pH reading

EC stands for electrical conductivity. An EC meter measures the molar conductivity which is the potential for an electrical current to be transported through water (Klaassen, n.d.). Electrons are able to flow through the water due to the ions dissolved in the water (Klaassen, n.d.). The addition of the Charbon resulted in higher EC reading compared to the tank without Charbon. Hence, when Charbon was dissolved, the molar conductive potential for current through water was increased and thus increased the EC value.

Moreover, pH of a solution indicates the concentration of free hydrogen ions it contains (Andrew, n.d.). pH is related to nutrient availability (Andrew, n.d.). When the pH is within the optimum range, more nutrient was delivered and available to the plant roots. The result showed that the addition of the Charbon showed higher pH reading compared to the tank without Charbon. Hence, the tank consisted of Charbon had higher nutrient availability and this helped the plant to improve the nutrient uptake. However, when the pH of the nutrient solution was above 7, Ca2+, Fe2+, Mn2+, and Mg2+ would precipitate to the salts (Çalişkan & Cengiz Çalişkan, 2017). This means that the nutrients received by plants are restricted.

Conclusion

From this experiment, the results showed that the taste of the samples from Tank A and Tank B as no taste and little bitter respectively. Furthermore, the samples from Tank B are heavier than samples from Tank A. However, in terms of appearance, samples from Tank A with addition of Charbon have better appearance as compared to the control. This experiment is required to repeat for several times to obtain accurate results. Further studies need to be done on the effects of Charbon on plant taste in NFT hydroponics to support the hypothesis of this experiment.

References

Andrew. (n.d.). What is the best pH for hydroponics? Link

Çalişkan, B, & Cengiz Çalişkan, A. (2017). Potassium nutrition in plants and its interactions with other nutrients in hydroponic culture. Link

Diffley, A. (2012). Flavor – Growing vegetables. Link

Klaassen, P. (n.d.). Electrical conductivity, why it matters. Link

Mattson, N., & Shahid, M. (2021). Plant biostimulants as a tool for hydroponic vegetable production. e-Gro. 6(7), 1-7.

Rauscher, F. (n.d.). Which nutrients contribute to better-tasting homegrown fruits and vegetables? Link