Titin Apung Atikah*
| Abdul Syahid | Astri Widiarti
© 2023 IIETA. This article is published by IIETA and is licensed under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).
OPEN ACCESS
Utilization of biodiversity in the form of medicinal plants is an alternative to maintain health. Dayak onions as efficacious medicinal plants, have the potential to be developed. The optimal benefits of Dayak onions can be obtained if the raw materials used are of high quality. Environmental factors greatly affect the quality and quantity of tubers, including cultivation techniques and soil types. This research aims to study various cultivation techniques and soil types to improve the agronomical characteristics and flavonoid content of Dayak Onion. The study used a factorial randomized block design,3 repetitions. Factor I was the type of soil (T1=peat soil; T2=sandy soil). Factor II was the type of cultivation technique B0=without fertilization; B1=organic fertilization (chicken manure 20 t.ha-1); B2=inorganic fertilization (200 kg.ha-1urea,150 kg.ha-1 SP-36,200 kg.ha-1 KCl); B3=combination of organic+inorganic fertilization. The results showed that the interaction treatment of various cultivation techniques and soil types had a significant effect on plant height, number of leaves, number of saplings. The combination of organic+inorganic fertilizers (chicken manure 20 t.ha-1 and 200 kg.ha-1 urea+150 kg.ha-1 SP-36+200 kg.ha-1 KCl) planted on peat soil types gives the best results on tuber wet weight 48.27 g/clump, dry tubers 16.73 g (12 wap) The average content of flavonoids planted on peat soil was higher 64.75 compared to sandy soil 52.33.
Dayak onions, media growing techniques, soil type, agronomic characters, flavonoid
Indonesia is a country with a high level of biodiversity. One form of biodiversity in the form of medicinal plants as a source of biopharmaceuticals whose use continues to increase [1]. Dayak Onion is a local resource-based biopharmaceutical plant that has habitat suitability in Kalimantan [2], empirically and clinically proven as an efficacious medicinal plant that has the potential to be developed. Dayak onion bulbs contain compounds: alkaloids, glycosides, flavonoids, steroids, phenolics, quinones, tannins, triterpenoids [3], natural antioxidants, and vitamin C. Dayak onion tubers are useful as antiviral, antifungal, and anti-cancer [4], inhibitors of leukemia cell proliferation, anti-diabetics [5], antihypertensive [6], preventing heart disease, anti-bleeding agent and as an immunostimulant to boost immunity [7].
Several studies have been conducted including flavonoid compounds in onions proven to stimulate the immune system by increasing the activity of macrophages and T lymphocytes [8], ethanol extract of Dayak onions has the ability as an immunomodulator by increase Ig M in mice [9], immunostimulant in increasing the diameter of the germinal center in the lymph nodes and increasing serum IgG levels [10], inhibiting the growth of Staphyloccocus aureus with a minimum inhibitory concentration of 1% with an inhibitory diameter of 14.49 ± 0.51 mm and Trichophyton rubrum with a minimum inhibitory concentration of 15% with an inhibitory diameter of 15.06 ± 0.42 mm [11], has strong antioxidant activity or an inhibitor against free radicals with an IC50 value of 25.3339 µg/ml [12]. In addition, giving Dayak onion bulb extract had an effect on reducing total and LDL cholesterol levels in white male rats Wistar strain [13]. The Borneo Dayak tribe, Indonesia, uses the tubers of this plant to fight heart disease and as an anti-inflammatory [14], increase breast milk production and for the treatment of stroke, breast cancer and the treatment of sexual disorders [15].
The optimal benefits of onion bulbs can be obtained if the raw materials used are of the high quality. The quality of tubers is determined through how much production and content of bioactive compounds of tubers by factors: 1) plant physiology, 2) genetics, 3) geography and 4) environment [16]. Environmental factors that affect them are cultivation techniques and the type of soil used for plant cultivation. The agricultural system implemented by Dayak farmers in Central Kalimantan varies greatly, both in their cultivation techniques and the type of soil used. Peat soil and sandy soil is a type of soil that has differences in terms of quality and characteristics.
Based on the description above, the variety of cultivation techniques and different soil types causes unknown cultivation techniques and soil types that can show optimal agronomic character as a raw material for quality medicinal plants. Therefore, there needs to be research on the engineering of growing media and different soil types to improve the agronomic character and flavonoid compound content of Dayak onions.
2.1 Place and time
The research was conducted at a screen house, located in Petuk Katimpun Village, Central Kalimantan for ± 6 months. Soil and manure analysis is carried out in an integrated laboratory, at Palangka Raya University while the analysis of flavonoid compounds is carried out in the department of biochemistry and biomolecular, Faculty of Medicine, Universitas Lambung Mangkurat, Banjarmasin, South Kalimantan.
2.2 Materials and tools
Materials: onion bulbs obtained from farmers in Petuk Katimpun village, Palangka Raya city, Central Kalimantan, chicken manure organic fertilizers, inorganic fertilizers (Urea, SP-36, and KCl), dolomite, polybag 30 x 45 cm, peat soil taken from Kalampangan village, Sebangau District, Palangka Raya City, sandy soil taken from Petuk Katimpun village, Jekan raya District, Palangka Raya city, ethanol 70%, onion bulb powder, aquadest, NaNO2 5%, and AlCl3 20%. Tools: hoes, machetes, buckets, cameras, scales, filter paper, rotary evaporator, waterbath, test tube, UV-Vis spectrophotometer, 500 μ l micropipette and writing stationery.
2.3 Research methods
The study used a Factorial Random Group Design, 3 repetitions. The factor I consists of soil type (T1=Peat soil, T2=Sandy soil). Factor II consists of various cultivation techniques B0=No fertilization, B1=Organic fertilization (chicken manure doses of 20 t.ha-1), B2=Inorganic fertilization(200 kg.ha-1 urea+150 kg.ha-1 SP-36+200 kg.ha-1 KCl), and B3=Organic + inorganic fertilization combination (chicken manure doses of 20 t.ha-1 + 200 kg.ha-1 urea+150 kg.ha-1 SP-36 + 200 kg.ha-1 KCl).
2.4 Research implementation
2.4.1 The implementation of research in the laboratory
Analysis of soil and chicken manure was carried out to determine soil fertility status and nutrient content. Soil analysis includes pH using potentiometer method, C-organic using Walkey-Black method, N-total using Kjeldahl macro method, P-available using P-Bray method, K, Ca2+, and Mg2+ using 1 M NH4Oac method. Analysis of flavonoid compound content is carried out by analytical procedures including 1) the manufacture of onion extract, 2) the determination of flavonoid levels including sample preparation and standard curve making, and 3) the determination of total flavonoids including:
2.4.2 The implementation of research in the screen house
The planting media used is peat soil and sandy soil. In peat soil media: put 8 kg of soil into a 30 x 45 cm poly bag, then add 20 t.ha-1 organic chicken manure (130 g.polybag-1) and 5 t.ha-1 dolomite (32 g. poly bag-1). Sandy soil: 20 t.ha-1 organic chicken manure (100 g.polybag-1) and 5 ton.ha-1 (25 g.polybag-1) dolomite, except for the inorganic fertilizer treatment, chicken manure was not added. Organic fertilizer application is done 2 weeks before planting. While the application of inorganic fertilizers is given at a dose of 200 kg.ha-1 urea, 150 kg.ha-1 SP 36 and 200 kg.ha-1 KCl. Urea was given 2 times, ½ dose at planting and ½ dose at 30 days after planting. SP 36 and KCl fertilizers were applied at planting. Fertilizer combination of organic and inorganic fertilizers, namely organic chicken manure 20 t.ha-1 was applied 2 weeks before planting and inorganic fertilizers were applied at planting except for urea.
2.4.3 Variable measurements
Include Plant height (cm), Number of leaves, Number of saplings at the age of 6, 8, 10, and 12 wap, fresh weight of tubers, and dry weight of tubers (12 wap). The plant is harvested at an age of 12 wap (3 months) after planting. The data is analyzed with various analyses using the F 5% and 1% tests if there is a noticeable difference, followed by a medium value difference test using DMRT at the 5% level.
3.1 Results of soil analysis and chicken manure fertilizer
Based on the results of soil analysis in Table 1 shows that the degree of acidity (pH) of sandy soil is lower than peat soil which is 4.7. Similarly, when viewed from the nutrient content of N-total, P-Bray, K-dd, Ca-dd, and Mg-dd contained in sandy soils are lower than in peat soils. The characteristics of sandy soils that are easily leached quickly with porosity which is very easy to seep water which transports nutrients deep into the soil resulting in nutrients not being reached by plant roots which is a constraint in cultivating plants [17]. While the characteristics of peat soil other than has a high level of acidity, high Cation Exchange Capacity (CEC) with low Base Saturation (BS) is a constraint in its cultivation. Differences in characteristics and nutrient content in 2 different types of soil will affect the growth rate and yield of cultivated Dayak onion plants.
Table 1. Results of soil analysis and chicken manure fertilizer
|
No. |
Soil type |
pH H2O (1:2.5) |
C-organic (%) |
N-total (%) |
P-Bray I (ppm) |
K-dd (me/ 100 g) |
Ca-dd (me/100 g) |
Mg-dd (me/100 g) |
|
1. |
Peat soil |
4.93 |
49.11 |
1.06 |
488.55 |
2.72 |
8.77 |
2.22 |
|
2. |
Sandy soil |
4.7 |
4.3 |
0.28 |
8.76 |
0.01 |
2.78 |
0.31 |
|
3. |
Chicken manure |
7.51 |
23.88 |
0.93 |
491.92 |
10.78 |
28.38 |
1.90 |
Description: Analysis in integrated Laboratory, Palangka Raya University
3.2 Agronomic character of plants
a. Plant height
Based on the results of the various analysis and the test of the difference in the middle value to the height parameters of plants aged 6, 8, 10, and 12 wap obtained data as presented in the following graph:
(a) Without fertilization (B0)
(b) Organic fertilization (B1)
(c) Inorganic fertilization (B2)
(d) Organic + inorganic fertilization
Figure 1. The high growth of plants on the treatment of various cultivation techniques and soil types differs in plants aged 6, 8, 10, and 12 wap
Based on the data presented in Figure 1 above, it can be seen that the use of a combination of chicken manure and inorganic fertilizer shows an increase in plant height at the age of 6, 8, 10, and 12 wap on peat soil types. This shows the positive response of plants due to the addition of fertilizer. Whereas in sandy soil types, plant height tends to decrease slightly in plants aged 12 wap, especially in the combination treatment of organic and inorganic fertilizers.
Improvement of the plant environment due to the provision of chicken manure fertilizer through the improvement of the physical, chemical, and biological properties of the soil will support the absorption of nutrients more optimally. Nutrients available in sufficient quantities will encourage the process of photosynthesis to be more active which results in the formation of higher proteins to support the high growth of plants. In line with Ghaffoor et al. [18] that manure exerts a good influence on the physical and chemical properties of the soil through the improvement of soil structure, sources of nutrients for plants [19] and increases soil microorganisms [20].
Similarly, the addition of inorganic fertilizers through the provision of NPK fertilizers can support a faster rate of growth and development. In line with Gardner et al. [21] that with the fulfillment of the nutritional needs of cultivated plants will tend to invest partly in early growth.
b. Number of leaves
Based on the results of the various analysis and the middle-value difference test to the parameters of the number of leaves of plants aged 8 and 10 wap obtained data as presented in Table 2 and Table 3 below:
Table 2. The effect of various cultivation techniques and soil types on the number of leaves aged 8 wap
|
Soil Type (T) |
Fertilizer (B) |
|||
|
B0 |
B1 |
B2 |
B3 |
|
|
T1 |
5.50a |
31.67d |
16.50b |
31.17c |
|
a |
B |
B |
B |
|
|
T2 |
6.00a |
21.67b |
9.83a |
19.83b |
|
|
a |
A |
A |
A |
Description: The average value followed by the same letter in the same column or row means that it does not differ in effect according to dmrt 5%. B0=without fertilizer; B1=Chicken manure 20 t.ha-1; B2=NPK (200 kg.ha-1 urea, 150 kg.ha-1 SP-36 and 200 kg.ha-1 KCL; B3=Combination of Chicken manure +NPK; T1=Peat soil, T2=Sandy soil.
Table 3. The influence of various cultivation techniques and soil types on the number of leaves of plants aged 10 wap
|
Soil Type (T) |
Fertilizer (B) |
|||
|
B0 |
B1 |
B2 |
B3 |
|
|
T1 |
7.33a |
47.83c |
26.50b |
48.83c |
|
a |
B |
B |
B |
|
|
T2 |
8.67a |
33.67b |
14.00a |
29.50b |
|
|
a |
A |
A |
A |
c. Number of tillers
Based on the results of the various analysis and the test of the difference in the middle value to the parameters of the number of tillers aged 12 wap presented in Figure 2 obtained data as presented in the following graph:
Based on data on the number of leaves of plants aged 8 and 10 wap and the number of plant saplings aged 12 wap shows that the treatment of organic fertilization (chicken manure fertilizer) provides growth in the number of leaves and the number of saplings more than other treatments but does not differ markedly from the combination treatment of organic fertilizers + inorganic fertilizers grown on peat soil planting media. This is because organic fertilization treatment and a combination of organic + inorganic fertilization treatments both contribute nutrients, especially N nutrients that can support the vegetative growth of plants. Element N is an important ingredient in the constituents of amino acids, amides, nucleotides, and nucleoproteins but it is also essential for cell enlargement and division [21].
Figure 2. The number of saplings of the Dayak Onion plant in plants aged 12 wap on the treatment of such treatment technique cultivation and different types of soil
The use of chicken manure fertilizer has a positive effect in improving the structure and texture of peat soil so that water and nutrient need become more available to plants so that the growth process becomes improved. This can be seen in the growth in the number of leaves of 31.67 (8 wap) (Table 2) and 48.83 (10 wap) (Table 3). Likewise, the increase in the number of tillers was 18.33 (12 wap) in plants grown on peat soil types.
d. Fresh weight of tubers and dry weight of tubers
Based on the results of the analysis of variance and the test of the difference in middle values against the parameters of fresh weight of tubers and dry weight of plant tubers aged 12 wap (harvest) obtained data as presented in the following figure/graph.
Data on the wet weight of tubers and dry weight of tubers in Figure 3 shows that the fertilization treatment of organic + inorganic fertilizer combinations show the highest wet weight and dry weight of tubers on peat soil planting media. This is because the combination of organic + inorganic fertilizers is at a balanced dose in providing nutrients needed by Dayak onion plants. Balanced fertilizer delivery is the basis for producing more optimal crop output, where the nutrient content can meet the requirements of plant physiology to get the expected results [22].
The benefits of chicken manure fertilizer in addition to improving the physical, chemical, and biological properties of the soil are also able to prevent Fe and Al poisoning in peat soils that react sourly. In addition, manure is also able to increase the availability of phosphates and humus levels which in the end can increase the Cation Exchange Capacity [23]. Similarly, the provision of inorganic fertilizers in the form of urea, SP-36, and KCl in balanced amounts greatly affects the growth and yield of tubers. Element N in urea fertilizer is an important ingredient as a constituent of amino acids, amides, nucleotides, nucleoproteins, and essential elements in cell division and enlargement [21].
Element N (Nitrogen) is needed by plants, especially in the vegetative phase for the formation of leaves and stems. The high availability of element N will form more chlorophyll so that the absorption of sunlight is more optimal which ultimately increases the rate of photosynthesis of plants. Element P (Phosphorus) plays a role in increasing carbohydrates, lengthening the roots, and increasing the number and size of tubers so that plant yields increase [24]. While element K (Potassium) plays a role in the process of photosynthesis where organic compounds are transported to the tubers and tubers produced more quality [25].
(a) Treatment cultivation technique
(b) Treatment different types of soil
Figure 3. Wet weight and dry weight of the bulbs of the Dayak onion plant at the age of 12 wap on the treatment of such treatment cultivation technique and different types of soil
Figure 4. The agronomic character of Dayak onion plants aged 12 wap on treatment such as cultivation technique and different types of soil
Based on Figure 4, it can be concluded that the addition of chicken manure fertilizer in this study can improve the physical, chemical, and biological properties of the soil, and the addition of N, P, and K fertilizers can create better plant environmental conditions so that the nutrients needed by plants become more available in supporting agronomic character, namely growth and the formation of the yield of tubers. Increased vegetative growth due to the combination of organic + inorganic fertilization such as plant height, leaf count, and the number of saplings causes increased biomass formation which ultimately results in fresh weight and higher dry weight of plants [26].
3.3 Content of compound bioactive Dayak onion
a. Extraction results of Dayak onion bulbs
Table 4. The results of the extraction of onion bulbs in plants aged 12 wap due to the influence of treatment of various cultivation techniques and different soil types
|
Sample |
Simplisia Powder Weight (g) |
Condensed Extract Weight (g) |
Randemen Value (%) |
|
T1B0 |
15.0 |
1.1877 |
7.92 |
|
T1B1 |
15.0 |
1.0687 |
7.12 |
|
T1B2 |
15.0 |
1.4379 |
9.59 |
|
T1B3 |
15.0 |
1.6992 |
11.33 |
|
T2B0 |
15.0 |
1.7407 |
11.60 |
|
T2B1 |
15.0 |
1.6876 |
11.25 |
|
T2B2 |
15.0 |
1.0664 |
7.11 |
|
T2B3 |
15.0 |
1.4743 |
9.83 |
Description: B0=without fertilizer; B1=Chicken manure 20 t.ha-1; B2=NPK (200 kg.ha-1 urea, 150 kg.ha-1 SP-36 and 200 kg.ha-1 KCL; B3=Combination of Chicken manure +NPK; T1=Peat soil, T2=Sandy soil.
b. Test results of average flavonoid levels
Table 5. The results of the test of flavonoid compound content in the onion nut plant 12 wap due to the influence of treatment of various cultivation techniques and different types of soil
|
Treatment |
Flavonoid content |
|
T1B0 |
64.75d |
|
T1B1 |
50.75c |
|
T1B2 |
31.42a |
|
T1B3 |
52.92c |
|
T2B0 |
52.33c |
|
T2B1 |
44.92b |
|
T2B2 |
48.58bc |
|
T2B3 |
49bc |
Description: B0=The mean value followed by the same letter means that the effect is not significantly different according to the 5% DMRT. B0=without fertilizer; B1=Chicken manure 20 t.ha-1; B2=NPK (200 kg.ha-1 urea, 150 kg.ha-1 SP-36 and 200 kg.ha-1 KCL; B3=Combination of Chicken manure +NPK; T1=Peat soil, T2=Sandy soil.
Based on Table 4, it shows that the test results of the extraction of onion bulbs in the highest Dayak onion bulbs were in the treatment of plants grown on peat soil types with no fertilization treatment, which for the average flavonoid level was equal to 64.75 (Table 5) and the effect was significantly different from other treatments. Then followed by the treatment of organic + inorganic fertilization of 52.92 and fertilization with organic fertilizers of 50.75.
The above data shows that the difference in soil characteristics between peat soils and sandy soils also determines the content of flavonoid compounds in onion bulbs at the age of 12 wap. This shows that plant environmental factors also affect the synthesis of plant bioactive compounds in addition to heredity factors (genetic components) and ontogeny factors (developmental stages) [27].
Characteristics of sour peat soil media with higher nutrients (Table 1) in this study, it was not only able to improve the agronomic character of onion plants (growth and yield) but also able to stimulate the formation of flavonoid compounds that are higher than other treatments. This phenomenon proves that the same type of plant but planted at different locations or types of soil will produce secondary metabolic content that is not necessarily the same so this will affect its therapeutic effect. This study concluded that the characteristics of the soil with the nutrient content that is not necessarily the same between different soil types is one of the environmental factors that affect the growth, yield and content of bioactive compounds of the Dayak onion plant [28].
Media engineering grows in onion plants using fertilization techniques combination of organic + inorganic fertilizers with a dose of chicken manure fertilizer 20 t.ha-1 + NPK (200 kg,ha-1 urea + 150 kg.ha-1 SP-36 and 200 kg.ha-1 KCl) planted on peat soil type gives the best influence on the wet weight of tubers, which is 48.27 g per clump and the dry weight of tubers is 16.73 g per clump. While the average flavonoid content planted in peat soils is higher by 64.75 compared to sandy soils by 52.333.
This work is supported by the Community Service Research Institute, University of Palangka Raya, by providing financial support through Innovative Basic Research Grants for Fiscal Year 2021 No. 311/UN24.13/PL/2021.
[1] Andriani, S., Akbar A., Halwany, W., Lestari, I. (2010). Eksplorasi tumbuhan hutan khasiat obat di kalimantan selatan dan kalimantan tengah. Progra m Riset Terapan Intensif. Balai Penelitian Kesehatan Banjarbaru. https://www.yumpu.com/s/DhtXKcSxR2RwVsNO.
[2] Pusat Studi Biofarmasi LPPM IPB dan Gagas Ulang. (2013). Kesehatan Alami dengan Herbal. Bogor.
[3] Yusnita, R., Nahzi, M.Y.I., Diana, S. (2018). The effectiveness of Dayak onion bulbs extract (Eleutherine palmifolia (l) merr.) against root canal mixed bacterial (Preface study as root canal irrigation materials). Dentino: Jurnal Kedokteran Gigi, 3(2): 132-137. Yhttp://dx.doi.org/10.20527/dentino.v3i2
[4] Babula, P., Mikelova, R., Potesil, D., Adam, V., Kizek, R., Havel, L., Sladky, Z. (2005). Simultaneous determination of 1, 4-naphtoquinone, lawsone, juglone and plumbagin by liquid chromatography with UV detection. Biomed. Papers, 149(1): 25-28.
[5] Febrinda, A.E., Astawan, M., Wresdiyati, T., Yuliana, N. D. (2013). Kapasitas antioksidan dan inhibitor alfa glukosidase ekstrak umbi bawang dayak [antioxidant and alpha-glucosidase inhibitory properties of bawang dayak bulb extracts]. Jurnal Teknologi dan Industri Pangan, 24(2): 161-161. https://doi.org/10.6066/jtip.2013.24.2.161
[6] Insanu, M., Kusmardiyani, S., Hartati, R. (2014). Recent studies on phytochemicals and pharmacological effects of eleutherine americana merr. Procedia Chemistry, 13: 221-228. https://doi.org/10.1016/j.proche.2014.12.032
[7] Nur, A.M. (2011). Kapasitas antioksidan bawang dayak (eleutherine palmifolia) dalam bentuk segar, simplisia dan keripik, pada pelarut nonpolar, semipolar dan polar. Tesis. Fakultas Teknologi Pertanian. Institut Pertanian Bogor.
[8] Zalisar, L. (2013). Flavonoid of phyllanthus nururi as immunomodulator: A prospect to animal disease control. ARPN Journal of Science and Technology, 3(5): 529-530.
[9] Annisa, R. (2014). Uji efek imunomodulator ekstrak etanol umbi bawang dayak (Eleutherine americana (Aubl) Merr) pada Mencit (Mus musculus). Makasar: Fakultas kedokteran universitas hasanuddin.
[10] Carmelita, A.B. (2016). Pengaruh pemberian ekstrak etanol umbi bawang dayak (eleutherine palmifolia (l.) merr.) secara oral pada mencit balb/c terhadap pencegahan penurunan diameter germinal center pada kelenjar getah bening serta kadar igg serum. Jurnal Biosains Pascasarjana, 18(1): 1-12. http://repository.unair.ac.id/id/eprint/57810
[11] Puspadewi, R., Adirestuti, P., Menawati, R. (2013). Khasiat umbi bawang dayak (Eleutherine palmifolia (L.) Merr.) sebagai herbal antimikroba kulit. Kartika: Jurnal Ilmiah Farmasi, 1(1): 31-37. http://dx.doi.org/10.26874/kjif.v1i1.21
[12] Kuntorini, E.M., Astuti, M.D. (2010). Penentuan Aktivitas antioksidan ekstrak etanol bulbus bawang dayak (Eleutherine americana Merr.). Jurnal Ilmiah Berkala Sains dan Terapan Kimia, 4(1): 15-22. http://dx.doi.org/10.20527/jstk.v4i1.2043
[13] Jannah, N., Yustina, Y., Mahedra, D.N., Sumantri, T.S., Husna, R.A. (2018). Pengaruh pemberian ekstrak umbi bawang dayak (Eleutherine americana merr.) Terhadap penurunan kolesterol pada tikus jantan putih galur wistar. Al-Kauniyah, 11(1): 33-40. http://dx.doi.org/10.15408/kauniyah.v11i1.5656
[14] Kuntorini, E.M., Astuti, M.D., Nugroho, L.H. (2010). Struktur anatomi dan aktivitas antioksidan bulbus bawang dayak (Eleutherine americana Merr.) dari daerah Kalimantan Selatan. Berkala Penelitian Hayati, 16(1): 1-7. https://doi.org/10.23869/276
[15] Insanu, M., Kusmardiyani, S., Hartati, R. (2014). Recent studies on phytochemicals and pharmacological effects of eleutherine americana merr. Procedia Chemistry, 13: 221-228. https://doi.org/10.1016/j.proche.2014.12.032
[16] Francisco, M., Cartea, M.E., Butrón, A.M., Sotelo, T., Velasco, P. (2012). Environmental and genetic effects on yield and secondary metabolite production in Brassica rapa crops. Journal of agricultural and food chemistry, 60(22): 5507-5514. https://doi.org/10.1021/jf301070q
[17] Lingga, P. (2001). Petunjuk penggunaan pupuk. Niaga Swadaya.
[18] Ghaffoor, A., Jilani, M.S., Khaliq, G., Waseem, K. (2003). Effect of different NPK levels on the growth and yield of three onion (Allium cepa L.) varieties. Asian Journal of Plant Sciences, 2(3): 342-346. https://dx.doi.org/10.3923/ajps.2003.342.346
[19] Rosmarkam, A., Yuwono, N.W. (2002). Ilmu Kesuburan Tanah. Kanisius, Yogyakarta.
[20] Shereen, A., Ansari, R.U., Yasmin, S., Raza, S., Mumtaz, S., Khan, M.A., Mujtaba, S.M. (2007). Physiological responses of rice (Oryza sativa L.) to saline stress. Pak. J. Bot, 39(7): 2527-2534.
[21] Gardner, F.P., Pearce, R.B., Mitchell, R.L. (1991). Fisiologi Tanaman Budidaya. Penerjemah Herawati Susilo. Universitas Indonesia (UI-Press), Jakarta.
[22] Ryan, J. (2008). A perspective on balanced fertilization in mediteranean region. Turkish Journal of Agriculture and Forestry, 32(2): 79-89. https://journals.tubitak.gov.tr/agriculture/vol32/iss2/1.
[23] Nst, H.W.N.H.W., Nst, H.W., Lubis, A., Supriadi, S. (2013). Pemanfaatan limbah sargassum polycystum dari industri farmasi sebagai pupuk cair serta pengaruhnya terhadap sifat kimia tanah ultisol dan pertumbuhan tanaman sawi. Jurnal Agroekoteknologi Universitas Sumatera Utara, 1(3): 95456.
[24] Singh, J.V., Kumar, A., Singh, C. (2000). Influence of phosphorus on growth and yield of onion (Allium cepa L.). Indian Journal of Agricultural Research, 34(1): 51-54.
[25] Bai, B.A., Malakouti, M.J. (2003). Effects of iron, manganese, zinc, and copper on wheat yield and quality under saline condition. Olom-eAb Va Khak, 17(2): 48-59.
[26] Suwardi, Efendi, R. (2009). Efisiensi penggunaan pupuk n pada komposit jagung menggunakan bagan warna daun. Prosiding Seminar Nasional Serelia, Sulawesi Selatan. http://balitsereal.litbang.pertanian.go.id/wp-content/uploads/2016/12/disi20099new.pdf.
[27] Robbers, J.E., Speedle, M.K., Tyler, V.E. (1996). Pharmacognosy and Pharmaco biotechnology. Williams and Wilkins, Baltimore.
[28] Atikah, T.A., Wardiyati, T., Nihayati, E., Saputera. (2017). The growth patterns and eleutherine content of dayak onion (Eleutherine palmifolia Merr.) in sandy mineral soil and peat soil. Int. J. Biosci, 10(4): 222-231. http://dx.doi.org/10.12692/ijb/10.4.222-231
