Growth and Yield of Urban Farming Water Spinach ( Ipomea aquatica ) in Different Light Intensity Treatments

Water spinach ( Ipomea Aquatica ) is one of the superior commodities that is often used in urban farming cultivation models. The short lifespan and easy maintenance are the reasons water spinach is chosen for urban farming cultivation. One of the factors that must be considered when cultivating water spinach using urban farming is sufficient sunlight intensity for optimal growth of water spinach. This research aims to analyze the growth and yield of water spinach in the urban farming cultivation model using location placement treatments that have different sunlight intensities. The research method used for analysis of growth and yield which are presented in graphs and analyzed using t-tests. The results of plant growth urban farming water spinach for the parameters of plant height and number of leaves with different treatments of sunlight intensity showed that the values were not significantly different. However, water spinach plants in the unshaded treatment had a higher average plant height and number of leaves than those in the shaded treatment. Meanwhile, the fresh weight and dry weight of water spinach showed that plants with unshaded performance had a higher weight than shaded plants.


Introduction
The rapid growth rate of urban populations and global climate change conditions have encouraged people's interest in achieving sustainable food independence in urban environments.The urban farming cultivation model is an innovative solution to answer these challenges.Urban farming is an activity of growing and producing food in the city because food is one of the basic human needs for survival (Andini et al., 2021).
One of the popular plants cultivated in urban farming is water spinach (Ipomea Aquatica).Water spinach plants have the advantages of a short harvest time, easy to cultivate, and resistant to varying weather conditions.Apart from that, water spinach is a vegetable food commodity that is in demand by the public.Water spinach is rich in vitamins A, B1, C, protein, calcium, and phosphorus, and contains 2.5 mg of iron per 100g.Iron is important for the formation of red blood cells and can help treat anemia (Fevria et al., 2021).This is the reason why water spinach is in demand in urban farming cultivation.
Factors that can be a limitation in cultivating water spinach using urban farming are environmental conditions.Recognizing environmental conditions and potential is useful for minimizing the risk of failure in implementing urban farming (Tarigan & Suryandika, 2023).Adequate lighting is an environmental factor that must be considered so that the photosynthesis process takes place optimally.Plants carry out photosynthesis using carbon dioxide and water as raw materials to produce the sugar and oxygen needed for their nutrition (Suyatman, 2021).The environmental conditions for growing plants that are perfectly exposed to direct sunlight and environments without exposure to sunlight will have an effect on differences in plant growth (Maftukhah et al., 2023).The difference in sunlight intensity received by plants will differ depending on the cultivation environmental conditions.Therefore, the placement of urban farming is a factor that must be considered whether the placement supports sufficient light intensity for plants to carry out optimal photosynthesis.This research aims to analyze the growth and yield of water spinach plants in the urban farming cultivation model using location placement treatments that have differences in sunlight intensity.

Material and Methods
The research was carried out on Jl.Dupak Bangunsari III /5, Krembangan District, Surabaya City.The location was chosen because it represents the urban environment, so it meets the criteria to be called urban farming.The research was carried out on 25 May 2023 -7 June 2023 which included the planting and plant growth period.The treatment used in this research was a difference in light intensity.The technique for implementing the treatment is by placing urban farming cultivation locations in locations that have different light intensities.There were 2 treatments in this research, the first treatment was by placing water spinach plants on the terrace, hereinafter referred to as shaded treatment, while the second treatment was by placing water spinach plants on the roof, hereinafter referred to as unshaded treatment.Each treatment was carried out in 6 replications.
The second treatment carried out the same planting and care.Water spinach seeds are planted in the planting medium at a rate of 2-3 per polybag.Fertilization is carried out during media preparation, namely by mixing the soil with compost.Additional fertilization is carried out once a week using liquid organic fertilizer.Observation of the growth of water spinach plants was carried out by measuring the plant height and number of leaves once every week.Meanwhile, observations of the wet weight and dry weight of the plants were carried out after the plants were 2 weeks old, by taking 2 plant samples.
Analysis of plant growth and yield data is presented in graphs.Growth and yield data from the two treatments were analyzed using a two-independent sample t-test.The two-independent samples t-test is designed to assess the performance differences between two separate groups of independent samples, where observations in the first sample are independent of those in the second sample (Murwani et al., 2020).

Plant height and number of leaves
Observations of the growth of water spinach plants showed that at the beginning of the vegetative phase, water spinach plants in the shade grew faster than plants placed in full sunlight (Figure 1).This happens because it is influenced by the hormone auxin.Auxin as an acetate compound contained in indole, for plant parts such as stems that are not exposed to sunlight, will experience rapid growth (Sumiati & Sutoyo, 2021).
At the time of reaching the peak of the vegetative phase, plants placed in a shaded place show growth that is not maximized, marked by the increase in plant height which is below the value of plants that are not shaded.This shows that the difference in sunlight affects the photosynthesis process.Sunlight is needed by plants to carry out 2 stages, namely the bright reaction carried out in thylakoids and the Calvin cycle carried out in stomata (Yustiningsih, 2019).
The average number of leaves of water spinach plants in unshaded places has more leaves than in shaded places (Figure 2).This is because plants exposed to sunlight are able to carry out photosynthesis compared to plants that are not exposed to sunlight.Sunlight can cause an increase in photosynthetic products thus increasing the metabolic rate.Light intensity that is too low will affect the efficiency of photosynthetic production, while light intensity that is too high will affect the activity of stomata cells in the leaves by reducing transpiration levels which can inhibit plant growth (Kurniaty et al., 2010).Based on Table 1, it was found that the average height of water spinach plants in unshaded areas was faster, namely 21.75 cm.Meanwhile, plants placed in unshaded places have a lower plant height, namely 18 cm.This shows that plants placed in a shaded place do not experience etiolation.The risk of plants being in a state of lack of light is that the hormone auxin will stimulate the elongation of cells so that they grow longer (Ningsih, 2019).It can be concluded that urban farming water spinach plants that are planted in shaded conditions by placing them on the terrace of the house, can still grow normally because they do not experience etiolation.Plant height and number of leaves for the two treatments for differences in light intensity were then tested using the t-test to compare the differences between two independent samples.Based on the results of the t-test (Table 2), the t-stat value was obtained which was lower than the critical value of t, indicating that the observed difference in plant height was not statistically significant between the shaded and unshaded treatments.Likewise, in the number of leaves, there was no significant difference between the shaded and unshaded treatments (Table 3).

Yield
Plant biomass is the measure most often used to describe and study plant growth (Sayekti et al., 2016).Biomass observation results are shown in terms of fresh weight and dry weight parameters (Table 4).Based on Table 4 shown that the shaded treatment in the second week had an average fresh weight of 0.95 gr.Meanwhile, the unshaded treatment in the second week had a higher average fresh weight, namely 1.5 grams.These results indicate that plants grown in shaded conditions have slower growth compared to unshaded conditions.This shows that by the theory that limited sunlight can inhibit photosynthesis because low light intensity can interfere with the carbohydrate translocation process (Malik, 2014).In the third week of the shaded treatment, the average fresh weight of the plants increased to 1,255 gr.An increase also occurred in the dry weight of the plant, namely 0.06 gr.Meanwhile, for the unshaded treatment, there was also an increase, although not significantly, namely 1.535 gr, but there was a quite significant increase in dry weight, namely increasing to 0.08 gr.This shows that water spinach plants treated without shade have faster growth, reflecting higher productivity.
The increase in fresh weight and dry weight from the second week to the third week which showed insignificant values could be caused by factors other than sunlight.For example, this factor is due to a lack of other nutrients that come from soil or water.Figure 3 shows the difference between plants with high light intensity (unshaded) compared to plants with low light intensity (shaded).Shaded plants have stems with a smaller diameter and smaller leaf surface area.Meanwhile, plants that are not shaded have stems that tend to be thicker and fresher in color.

Conclusion
Water spinach plants (Ipomea Aquatica) in urban farming with cultivation placed on the rooftop (not shaded) have better growth than plants placed on the terrace of the house (shaded).This is indicated by the average plant height, number of leaves, fresh weight, and dry weight which are higher compared to the shaded treatment.However, based on the results of the t-test for the parameters of plant height and number of leaves for the two treatments, the differences in light intensity showed that the results were not significantly different.However, plants with unshaded treatment have.Meanwhile, the fresh weight and dry weight of water spinach plants showed that plants treated with no shade had a higher weight than shaded plants.

Figure 1 .
Figure 1.Graph of average plant height of water spinach

Figure 3 .
Figure 3. Water spinach in 3 weeks after planting (a) shaded and (b) unshaded

Table 1 .
Average plant height and number of leaves water spinach

Table 4 .
Fresh weight dan dry weight water spinach