Effects of Gibberellin on Physical and Chemical Quality of Oil Palm .......... Journal of Tropical Crop Science Vol. 10 No. 2, June 2023 www.j-tropical-crops.com 87 Effects of Gibberellin on Physical and Chemical Quality of Oil Palm (Elaeis guineensis Jacq.) Fresh Fruit Bunches Imelya RamanisA 0000-0002-3569-6939, Sudradjat*B 0000-0001-5824-8795, Deden SaprudinC 0000-0002-7758-9744 A Department of Agronomy and Horticulture, Graduate School, Faculty of Agriculture, IPB University, Bogor 16680, Indonesia B Department of Agronomy and Horticulture, Graduate School, Faculty of Agriculture, IPB University, Bogor 16680, Indonesia C Department of Biochemistry, Graduate School, Faculty of Mathematic and Natural Science, IPB University, Bogor 16680, Indonesia *Corresponding author; sudradjat@apps.ipb.ac.id RESEARCH ARTICLE Abstract The quality of crude palm oil (CPO) is influenced by the quality of fresh fruit bunches, crop culture, and postharvest handling. A delay in fruit processing can cause physical damages to the fresh fruit bunches. Gibberellic acid (GA3) can potentially reduce the physical damage due to delayed processing of the fresh fruit bunches. Our study aims to determine how GA3 affects the physical and chemical quality of oil palm fresh fruit bunches. The fresh fruit bunch samples were collected from the IPB-Cargill Palm Oil Education and Research, Jonggol, Bogor, Indonesia. This study used a randomized complete block design that consisted of four concentrations of GA3: 0, 12.5, 25 and 37.5 ppm. GA3 application reduced fruit loss, respiration rate, and maintain fruit moisture and firmness, increased the oil content, and stabilize the free fatty acid content. GA3 concentration of 12.5 ppm is the optimal concentration. Based on the correlation analysis, fruit softness has a strong correlation with free fatty acids. Keywords: crude palm oil, concentration, fresh fruit bunches, respiration. Introduction Palm oil (Elaeis guineensis Jacq.) is a very important crop in Indonesia. It is evident from the area of oil palm plantations which continues to increase every year, starting in 2012 with only 9,572,715 ha up to 15,380,981 ha in 2022 (Ditjenbun, 2022). The increase in area is in line with the increase in oil palm production. Production data for 2012 showed that the total crude palm oil (CPO) production was 26,015,518 tons, while in 2020 production was 48,235,405 tons (Ditjenbun, 2022). CPO is crude palm oil that is produced from extraction or from the pressing process of palm fruits and has not been refined. CPO is generally used as a raw material for a variety of products including cosmetics, chemicals, cooking oil, margarine, chocolate, ice cream, biscuits, and animal feed. In addition, CPO is an alternative biodiesel fuel (Depperin, 2007). Fresh fruit bunches (FFB) of oil palm are susceptible to bruising and other physical damages during harvest and at all stages of postharvest handling. The damage to the oil palm fruit results in an accelerated hydrolysis process so that the levels of free fatty acids (FFA) increase, whereas CPO with high FFA is considered as low-quality (Maulana and Susanto, 2015). The high content of FFA in CPO will cause various losses due to low refining value resulting in rancidity and odour (Fajri and Ihsan, 2019). The presence of oil FFA can cause side reactions through alkaline-catalyzed transesterification and can inhibit ester production and glycerol separation (Suriaini et al., 2021). According to SNI, the standard quality palm oil has an FFA content of <5% (SNI 01-2901- 2006). Good quality FFB should have an oil content of 22.1% to 22.2% with an FFA content of 1.7% to 2.1% during processing (Depperin, 2007). Oil palm fruit damages can occur during harvesting, transportation, loading and unloading. Several factors can accelerate the formation of FFA after the fruit bunches were harvested e.g., fruits injured by impact or hit by harvesting tools; drops of loose Journal of Tropical Crop Science Vol. 10 No. 2, June 2023 www.j-tropical-crops.com 88 Imelya Ramanis, Sudradjat, Deden Saprudin fruits; delays due to transportation, and delayed fruit collection (Pahan, 2008). Other factors that affects the delay in processing including shortage of manpower, particularly during periods of high production (April to July), and during long holidays. Therefore, it is crucial to streamline the postharvest handling to reduce physical damage of the FFB. One method to overcome this problem is to apply growth regulator gibberellic acid (GA3) immediately after FFB are harvested (Sudradjat, 2017). Gibberellic acid has been widely used to inhibit fruit ripening, and studies on the effect of GA3 on the physical quality of oil palm FFB was reported by Sudradjat in 2017. The current study is a methodological improvement from the previous study and was conducted on the actual storage condition of oil palm fruits in the field. Sudradjat et al. (2021) showed that the application of GA3 at 25 ppm can keep the physical quality of FFB by reducing fruit respiration rates, fruit weight loss, and by maintaining fruit mesocarp softness. The current study aims to determine the effect of GA3 in maintaining the physical and chemical quality of fresh oil palm fruits, and to determine the correlation between the measured variables. Material and Methods The study was conducted at the IPB-Cargill Palm Oil Education and Research Station, Jonggol, Bogor, Indonesia, the Postharvest Laboratory of the Department of Agronomy and Horticulture IPB, and the Biochemistry Laboratory of the Department of Biochemistry of IPB from January to March 2022. The study used FFB of the “D×P Dami Mas” variety from the IPB-Cargill oil palm plantation. GA3 hormone powder 10% (Sun Neo), PP indicator solution and 0.1N NaOH were used for field and laboratory works. This study was arranged using a randomized complete block design with four GA3 concentrations, i.e., 0 ppm as control or G0, 12.5 ppm as G1, 25 ppm as G2, and 37.5 ppm as G3) repeated three times. Each experimental unit consisted of 6 FFB, totalling 72 FFB. FFB used was fraction 2 with an average weight of 15-20 kg. Harvesting was conducted in the morning to reduce the transpiration rates. The harvested FFB was transported to an open field to dry. GA3 powder was dissolved in water to make the above concentrations. GA3 solution was sprayed to FFB that had been harvested at an approximate volume of 500 ml using a sprayer on the surface of the bunches. Oil extraction was carried out using a hydraulic bottle jack (Haisbuan, 2020) Measurement of physical quality consisted of the weight loss of fresh fruit bunches (%), fruit loss (kernel), and fruit mesocarp softness (mm.g-1.sec- 1) using penetrometer Stanhope-SETA, followed by physiological observations of fruit which was the fruit respiration rate (ml.CO2 -1.kg-1.hour-1) using a combustible gas detector XP-3140, mesocarp water content (%), and free fatty acid levels (%). All variables were measured at 6 DAA except for free fatty acid levels which were measured at 1, 3, and 5 DAA. Collected data were analyzed by analysis of variance (ANOVA) followed by the Duncan Multiple Range Test (DMRT) 5% for the significance. Correlation analysis was done between variables. The software used was Microsoft Office Excel 2010, R Studio ver. 9.1. and SAS 9.1 portable. In addition, a correlation test was also carried out between variables at 5 DAA, this was because the FFA was analyzed only up to 5 DAA. The correlation analysis was conducted with a simple correlation according to Pearson (Saidah et al., 2023) as follows: manpower, particularly during periods of high production (April to July), and during long holidays. Therefore, it is crucial to streamline the postharvest handling to reduce physical damage of the FFB. One method to overcome this problem is to apply growth regulator gibberellic acid (GA3) immediately after FFB are harvested (Sudradjat, 2017). Gibberellic acid has been widely used to inhibit fruit ripening, and studies on the effect of GA3 on the physical quality of oil palm FFB was reported by Sudradjat in 2017. The current study is a methodological improvement from the previous study and was conducted on the actual storage condition of oil palm fruits in the field. Sudradjat et al. (2021) showed that the application of GA3 at 25 ppm can keep the physical quality of FFB by reducing fruit respiration rates, fruit weight loss, and by maintaining fruit mesocarp softness. The current study aims to determine the effect of GA3 in maintaining the physical and chemical quality of fresh oil palm fruits, and to determine the correlation between the measured variables. Material and Methods The study was conducted at the IPB-Cargill Palm Oil Education and Research Station, Jonggol, Bogor, Indonesia, the Postharvest Laboratory of the Department of Agronomy and Horticulture IPB, and the Biochemistry Laboratory of the Department of Biochemistry of IPB from January to March 2022. The study used FFB of the “D×P Dami Mas” variety from the IPB-Cargill oil palm plantation. GA3 hormone powder 10% (Sun Neo), PP indicator solution and 0.1N NaOH were used for field and laboratory works. This study was arranged using a randomized complete block design with four GA3 concentrations, i.e., 0 ppm as control or G0, 12.5 ppm as G1, 25 ppm as G2, and 37.5 ppm as G3) repeated three times. Each experimental unit consisted of 6 FFB, totalling 72 FFB. FFB used was fraction 2 with an average weight of 15-20 kg. Harvesting was conducted in the morning to reduce the transpiration rates. The harvested FFB was transported to an open field to dry. GA3 powder was dissolved in water to make the above concentrations. GA3 solution was sprayed to FFB that had been harvested at an approximate volume of 500 ml using a sprayer on the surface of the bunches. Oil extraction was carried out using a hydraulic bottle jack (Haisbuan, 2020) Measurement of physical quality consisted of the weight loss of fresh fruit bunches (%), fruit loss (kernel), and fruit mesocarp softness (mm.g-1.sec-1) using penetrometer Stanhope-SETA, followed by physiological observations of fruit which was the fruit respiration rate (ml.CO2-1.kg-1.hour-1) using a combustible gas detector XP-3140, mesocarp water content (%), and free fatty acid levels (%). All variables were measured at 6 DAA except for free fatty acid levels which were measured at 1, 3, and 5 DAA. Collected data were analyzed by analysis of variance (ANOVA) followed by the Duncan Multiple Range Test (DMRT) 5% for the significance. Correlation analysis was done between variables. The software used was Microsoft Office Excel 2010, R Studio ver. 9.1. and SAS 9.1 portable. In addition, a correlation test was also carried out between variables at 5 DAA, this was because the FFA was analyzed only up to 5 DAA. The correlation analysis was conducted with a simple correlation according to Pearson (Saidah et al., 2023) as follows: ��� � 𝑛𝑛Ʃ𝑋𝑋𝑋𝑋𝑛𝑛𝑋𝑋 � �Ʃ𝑋𝑋𝑋𝑋��Ʃ𝑛𝑛𝑋𝑋�√�𝑛𝑛Ʃ𝑋𝑋𝑋𝑋� � �𝑋𝑋𝑋𝑋����𝑛𝑛Ʃ𝑛𝑛𝑋𝑋� � �𝑛𝑛𝑋𝑋��� R values of < 0 indicates that each variables have a close negative correlation, while the value of r > 0 indicates that each variables has a close positive correlation. The values of r = -1 ≤ r ≤ 1 (Saidah et al., 2023). Result and Discussion Weight Loss of Fresh Fruit Bunches GA3 treatment significantly reduced fruit weight loss starting one day after application (DAA, Table 1). The highest accumulative percentage of fruit weight loss at 6 DAA occurred in the control treatment, which was 29.82%. The treatment with the lowest weight loss was GA3 at 25 ppm, which was 23.45%. R values of < 0 indicates that each variables have a close negative correlation, while the value of r > 0 indicates that each variables has a close positive correlation. The values of r = -1 ≤ r ≤ 1 (Saidah et al., 2023). Result and Discussion Weight Loss of Fresh Fruit Bunches GA3 treatment significantly reduced fruit weight loss starting one day after application (DAA, Table 1). The highest accumulative percentage of fruit weight loss at 6 DAA occurred in the control treatment, which was 29.82%. The treatment with the lowest weight loss was GA3 at 25 ppm, which was 23.45%. Weight loss (WL) occurs due to physico-chemical changes in the fruits, including the loss of water during storage until the fruits ripened (Sutrisno et al., 2008; Aditama, 2014, Tarigan et al., 2019). Fruit Fall Fruit falling (FF) is reflected by the number of fall kernels (Table 2). Fruit ripening is influenced by lipase enzyme that plays important roles in oil synthesis, thus affecting free fatty acid (FFA) levels in the fruits. The fallen fruits contain higher FFA than the intact fruits Effects of Gibberellin on Physical and Chemical Quality of Oil Palm .......... Journal of Tropical Crop Science Vol. 10 No. 2, June 2023 www.j-tropical-crops.com 89 (Morcillo et al., 2013). Our study demonstrated that GA3 suppressed fruit loss from 2 to 6 DAA, whereas the control consistently had the greatest number of fall kernels (Table 2). GA3 at 12.5 or 25 ppm were effective to maintain kernels to remain intact until 6 DAA. In the final observation, the fallen fruits from GA3 at 12.5 or 25 ppm was 378 and 374 kernels, respectively, whereas without GA3 it was 399 kernels (Table 2). According to Manurung et al., (2022) application of GA3 at 15 ppm can reduce fruit loss rates. The process of fruit loss (abscission) is related to the ratio of auxin and ethylene content in the abscission zone, with low auxin and high ethylene resulted in senescence or abscission (Taiz and Zeiger, 2006). Ethylene induces the synthesis and secretion of cell wall-degrading hydrolases. Hydrolase enzyme may increase due to RNA transcription and cause damage to the cell walls of the abscission zone (Salisbury and Ross, 1996). GA3 roles is to delay the formation of the separating layer in the abscission zone (Tuan et al., 2013) and to promote carbohydrate mobilization to fruits, hence reducing fruit loss (Bons et al., 2015). Fruit Respiration Rate Table 3 showed that GA3 treatment can reduce fruit respiration rate (RR), except at 2-3 DAA. The highest respiration rate indicates the climacteric peak. According to Aditama (2014), climacteric fruits including oil palm experience a sudden increase in respiration rate before ripening, and the respiration rate decreases gradually after harvesting. GA3 can effectively delay fruit maturity by reducing the respiration rate, so the FFB can be preserved for longer during storage before further processing. Almost all GA3 treatments in this study reduced respiration rates compared to the control. Fruit respiration rate is influenced by various internal and external factors; included in the internal factors are stages of fruit development, skin layer, cohesiveness of the cells, and fruit’s physical damage Table 1. Effect of GA3 application on fresh fruit bunch weight loss GA3 (ppm) Fruit bunch weight loss with GA3 application at 1 2 3 4 5 6 days after application 0 kg 22.74 22.04 20.26 18.66 18.40 17.39 16.11 (%) 3.14a 11.00a 18.16a 19.27a 23.94a 29.82a 12.5 kg 22.49 22.16 20.60 18.99 18.16 17.10 16.63 (%) 1.51b 8.25a 15.45a 18.92a 23.51a 25.60a 25.0 kg 22.74 22.13 20.51 19.23 18.82 17.81 17.44 (%) 2.71a 9.84a 15.48a 17.31a 21.83a 23.45a 37.5 kg 22.42 21.74 20.66 19.24 18.80 17.36 16.29 (%) 3.10a 7.92a 14.43a 16.19a 22.73a 27.48a DMRT ** ns ns ns ns ns Note: Means in the same column followed by the same letter are not significantly different based on Duncan Multiple Range Test (DMRT); *=significant at α=0.05; **= highly significant at α=0.01; ns= not significant. Table 2. The effect of GA3 application on the loss of fresh fruit bunches GA3 (ppm) Number of fall kernels at 1 2 3 4 5 6 days after application 0 31a 131a 233a 274a 376a 399a 12.5 27a 113b 193b 267a 359b 378b 25.0 25a 110b 192b 269a 350b 374b 37.5 27a 76c 173c 245b 328c 382ab DMRT 5% ns ** ** * ** * Note: Means in the same column followed by the same letter are not significantly different based on DMRT at α=0.05. DAA=days after GA3 application. Journal of Tropical Crop Science Vol. 10 No. 2, June 2023 www.j-tropical-crops.com 90 Imelya Ramanis, Sudradjat, Deden Saprudin (Ahmad, 2013). Respiration rate is also highly affected by ethylene, that hormone is controlled by its immediate precursor, 1-aminocyclopropane- 1-carboxylic (Maduwanthi and Marapana, 2019). External factors that affect fruit respiration rates include ambient temperature, humidity, and air composition (Ahmad, 2013). Research by Marlina et al. (2014) demonstrated that salak fruits placed at different temperatures had different respiration rates; the higher the temperature, the higher the respiration rate. Fruit Mesocarp Water Content GA3 significantly affect fruit mesocarp water content (WC) at 3 DAA (Table 4). GA3 at 12.5 ppm was relatively better for reducing the water content of fruit mesocarp than the other treatments, especially at 4 DAA. In contrast, the control consistently had the highest water content. Higher GA3 concentrations resulting in higher water content of the fruit mesocarp. Hassan et al., (2009) reported that the water content of the fruit is related to the level of maturity of the fruit: ripened fruits have higher the water content. The increase in water content occurs because the respiration rate increases due to higher ethylene production (Sutrisno et al., 2008). According to Mulyadi et al., (2017), fruit water content is affected by plant genetics, humidity, fruit maturity, and post-harvest treatments. Loss of water can cause a decrease in cell turgidity which results in shrinkage and decrease in the quality of fruits (Aji, 2016). Fruit Mesocarp Firmness Fruit firmness (FFs) during the ripening changes cell wall composition due to changes in cell turgor (Winarno and Wirakatakusuma, 1979). GA3 treatment can maintain fruit firmness during the storage period. Fruit mesocarp firmness in the GA3 at 12.5 ppm was significantly different than those in other treatments (Table 5). According to Besada et al. (2008), application of GA3 before and after harvesting can maintain fruit firmness for up to several weeks compared to without GA3. The reduction of fruit firmness may be affected by several factors such as increased water content and ethylene level. Acuna and Mitcham (2008) reported that the decrease in pear hardness is affected by high ethylene levels and temperatures. It is also related to weight loss, water loss, and transpiration processes which cause the mesocarp to wither and wrinkle (Wills et al., 2007). According to Wang et al., (2018), increased fruit firmness not only relates to the rate of ethylene production but also the hydrolytic enzyme activities, degradation of pectin, cellulose, and hemicellulose. Table 3. Effect of GA3 application on fruit respiration rate GA3 (ppm) Respiration rate (ml.CO2 -1.kg-1.hour-1) 1 2 3 4 5 6 days after application 0 52.77a 34.36a 25.07a 33.94a 26.98a 21.80a 12.5 40.21b 33.42a 22.55a 17.94b 22.34b 14.05c 25.0 36.45c 32.26a 24.24a 17.44b 26.31a 18.75b 37.5 52.08a 31.98a 22.40a 19.65b 25.49a 18.27b DMRT 5% ** ns ns ** * ** Note: Means in the same column followed by the same letter are not significantly different based on DMRT at α=0.05. Table 4. Effect of GA3 application on fruit mesocarp water content GA3 (ppm) Fruit mesocarp water content (%) at 1 2 3 4 5 6 days after application 0 33.19a 30.54a 32.00a 33.18a 36.00a 39.31a 12.5 29.32a 30.73a 31.24a 28.11b 30.24b 33.49b 25.0 30.37a 31.56a 31.29a 32.15a 31.10b 38.37a 37.5 32.29a 31.67a 30.34a 33.26a 32.73ab 36.82a DMRT 5% ns ns ns ** * * Note: Means in the same column followed by the same letter are not significantly different based on DMRT at α=0.05; DAA: days after GA3 application Effects of Gibberellin on Physical and Chemical Quality of Oil Palm .......... Journal of Tropical Crop Science Vol. 10 No. 2, June 2023 www.j-tropical-crops.com 91 Free Fatty Acid Level FFA content is a quality indicator used to assess CPO quality. CPO quality decreases as FFA increases. GA3 treatment maintains CPO quality by reducing FFA, as shown in Table 6 that the control treatment had the highest FFA levels on each observation day. Increasing concentrations of GA3 reduced the FFA, and the differences between GA3 concentrations were significant at 5 DAA (Table 6). Our study demonstrated that G1 (GA3 at 12.5 ppm) is the best treatment and the mesocarp FFA with this treatment met the SNI- 01-2901-2006 standard of < 5%. Correlation between Variables There are several categories of correlation coefficient value e.g., very low (0.00 - 0.19), low (0.20 - 0.39), moderate (0.40 - 0.59), strong (0.60 - 0.79), and very strong (0.80 – 1.00). The results in Table 7 showed that the measured variables that have strong correlation are fruit mesocarp firmness, fruit respiration rate, mesocarp water content, and FFA levels. The correlation between these variables was positive/ unidirectional, which means that if one variable increases, the other variable will also increase. Based on Table 7, FFA levels and fruit respiration rate have a moderate unidirectional correlation. The strong, unidirectional relationship between variables consisted of FFs-WC, FFs-RR, and FFA- WC. Water serves as a catalyst in fat hydrolysis increase, so increases in the water content in the fruit mesocarp will promote hydrolysis that results in the increases in FFA levels as a breakdown of triglycerides by the lipase enzymes (Aji, 2016). FFA and FFs have a very strong unidirectional relationship: an increase in the fruit softness during the storage period indicates fruit ripening (Jiang et al., 2020), and FFA levels increased with fruit maturity (Hasibuan, 2020). Conclusion GA3 application can maintain the physical and chemical quality of oil palm fresh fruit bunches. GA3 at 12.5 ppm is the recommended concentration to minimize losses due to delays or waiting time in processing the oil palm fruit through reduction of fruit loss, fruit respiration rate, fruit mesocarp water content, and maintaining fruit firmness up to 6 DAA and FFA levels up to 5 DAA, hence prolonged the FFB shelf life. References Acuna, M.V., and Mitcham, E. J. (2008). Ripening of European pears: the chilling dilemma. Postharvest Biology and Technology 49, 187– 200. Table 5. Effect of GA3 application on fruit firmness between treatments GA3 (ppm) Fruit mesocarp firmness (µm-1.g-1.sec-1) 1 2 3 4 5 6 Days after application 0 71a 78a 82a 97a 98a 106a 12.5 48b 58b 60b 75b 74c 81c 25.0 64a 78a 79a 84a 87b 94b 37.5 68a 73a 77a 84a 98a 101ab DMRT 5% ** * ** * ** ** Note: Means in the same column followed by the same letter are not significantly different based on DMRT at α=0.05. Table 7. Correlation coefficient of GA3 application between variables at 5 DAA Variable WL FF RR WC FFs FF 0.241ns RR 0.010 ns 0.229 ns WC 0.276 ns 0.280 ns 0.479 ns FFs 0.091 ns -0.125 ns 0.681* 0.664* FFA 0.124 ns 0.093 ns 0.584* 0.651* 0.879* Note: *: significant α = 5%, ns: non-significant, WL: weight loss, FF: fruit fall, RR: respiration rate, WC: water content, FFs: fruit firmness, FFA: free fatty acid. Journal of Tropical Crop Science Vol. 10 No. 2, June 2023 www.j-tropical-crops.com 92 Imelya Ramanis, Sudradjat, Deden Saprudin Aditama, F.Z. (2014). “Pengaruh penggunaan KMnO4 Sebagai Bahan Penyerap Etilen Selama Penyimpanan Buah Alpukat (Persea americana, Mill)”. [Thesis]. Faculty of Agriculture, IPB University. Ahmad, U. (2013). “Teknologi Penanganan Pascapanen Buah-buahan Dan Sayuran”. 142 pp. Graha Ilmu. Aji, T.G. (2016). Karakteristik Buah Jeruk Pamelo (Cirus grandis (L.) Osbeck) ’Muria Merah’ Berbiji dan Tanpa Biji dan Upaya Memperbaiki Daya Simpannya. [Thesis]. Faculty of Agriculture, IPB University. Besada, C., Arnal, L., and Salvador, A. (2008). Improving storability of persimmon cv. Rojo brillante by combined use of preharvest and postharvest treatments. Postharvest Biology and Technology 50, 169–175. Bons, H.K., Kaur, N., and Rattanpal, H.S. (2015). Quality and quantity improvement of citrus: role of plant regulators. International Journal of Agriculture, Environment and Biotechnology 84, 33-447. Depperin] Departemen Perindustrian. [2007]. “Gambaran Sekilas Industri Minyak Kelapa Sawit”. https://kemenperin.go.id/. [November 25, 2021]. Ditjenbun] Direktorat Jenderal Perkebunan. (2022). “Statistical of National Leading Estate Crops Comodity 2020-2022”. https://ditjenbun. pertanian.go.id/. [February 17, 2023]. Fajri, R., and Ihsan, F.N. 2019. Pengaruh kadar free fatty acid (FFA) dalam bulk stronge tank (BST) terhadap kualitas crude palm oil (CPO) hasil produksi pengolahan kelapa sawit PMKS PT. Sisirau Aceh Tamiang. Jurnal Kimia Sains dan Terapan 1, 22-24. Fathurrohman, M. (2016). “Kajian Laju Respirasi Buah Jambu Kristal (Psidium guajava L.) pada Berbagai Suhu Penyimpanan dengan Pendekatan Model Arrhenius”. [Thesis]. Faculty of Agricultural Technology. IPB University. Hartmann, H.T., Flocker, W.J., and Kofranek, A.M. (2007). “Plant Science, Growth, Development, and Utilization of Cultivated Plants”. 594 pp. Prentice Hall Inc. Hasibuan, H.A. (2020). Determination of yield, quality and chemical composition of palm oil and palm kernel oil of fresh fruit bunches with variation maturity as a basic for determining harvest maturity standard. Jurnal Penelitian Kelapa Sawit 28, 123-132. Hassan, A.H., Jamil, H.M., Sulaiman, A.S., and Mokhtar, A.S. (2009). “Perusahaan Kelapa Sawit di Malaysia”. Institut Penyelidikan Minyak Kelapa Sawit. Jiang, L., Feng, L., Zhang, F., Luo, H., and Yu, Z. (2020). Peach fruit ripening: proteomic comparative analyses of two cultivars with different flesh texture phenotypes at two ripening stages. Scientia Horticulturae 260, 1-9. Maduwanthi, S.D.T., and Marapana, R.A.U.J. (2019). Induced ripening agents and their effect on fruit quality of banana. International Journal Food Science 2019, 1-8. Manurung, S., Roosmawati. F., Yosephine, I.O., and Kaharudding. (2022). Pengaruh aplikasi giberelin (GA3) terhadap perubahan mutu fisik tandan buah segar kelapa sawit (Elaeis guineensis Jacq). Jurnal Agroplasma 9, 76-81. Marlina, L., Purwanto Y.A., and Ahmad, U. (2014). Aplikasi pelapisan kitosan dan lilin lebah untuk meningkatkan umur simpan salak pondoh. Jurnal Keteknikan Pertanian 2, 65–72. Maulana, A.F., and Susanto, W.H. (2015). Pengaruh penyemprotan larutan kalsium propionat dan kalium sorbat pada pasca panen kelapa sawit (Elaeis guineensis Jacq.) terhadap kualitas CPO. Jurnal Pangan dan Agroindustri 3, 453- 463. Morcillo, F., Cros, D., Billotte, N., and Ngando- Ebongue, G.F. (2013). Improving palm oil quality through identification and mapping of the lipase gene causing oil deterioration. Nature Communication 4, 1-8. Mulyadi., Rasyad, A., and Isnaini. (2017). Perkembangan morfologi dan sifat fisik buah pada tanaman kelapa sawit. Jurnal Online Mahasiswa 4,1-11. Pahan, I. (2008). “Kelapa Sawit Manajemen Agribisnis Dari Hulu Hingga Hilir”. 412 pp. Penebar Swadaya. Effects of Gibberellin on Physical and Chemical Quality of Oil Palm .......... Journal of Tropical Crop Science Vol. 10 No. 2, June 2023 www.j-tropical-crops.com 93 Saidah, F.Y., Purnamawati, H., and Lubis, I. (2023). Evaluation of source and sink capacity of new cowpea varieties. Journal of Tropical Crop Science 10, 38-45. Salisbury, F.B., and Ross, C.W. (1996). “Plant Physiology” vol. 3. Brooks/Cole ISE. 682 pp.SNI] Standar Nasional Indonesia. (2006). “SNI 01-2901-2006 Minyak Kelapa Sawit Mentah (Crude Palm Oil)”. Badan Standardisasi Nasional Indonesia. Sudradjat., Sugianta., Siregar, H.A., and Purwanto, O.D. (2021). Effects of gibberellin (GA3) on the physical quality of oil palm fresh fruit bunches. IOP Conference Series: Earth and Environmental Science 694, 1-9. Suriaini, N., Arpi, N., Syamsuddin, Y., and Supardan M.P. (2021). Use of crude glycerol for glycerolysis of free fatty acids in crude palm oil. International Journal of Technology 12, 760-769. Sutrisno., Mahmudah, I., and Sugiyono. (2008). Kajian penyimpanan dingin buah manggis segar (Garcinia mangostana L.) dengan perlakuan kondisi proses penyimpanan In “Prosiding Seminar Nasional Teknik Pertanian” pp. 1-9. Taiz L, and Zeiger E. 2006. “Plant Physiology”. 4th ed. 565 pp. Sinauer Associates Inc. Publisher. Tarigan, S.M., Febrianto, E.B., and Cik, L.A. (2019). The effect of gibberellins (GA3) concentration with the time of application before harvest on the physical quality of oil palm fresh fruit bunches (Elaeis quineensis Jacq.). Agro Fabrika 1,61-68. Tuan, M., Nguyen., and Yen, C.R. (2013). Response of wax apple cultivars by applied GA3 and 2.4- D on fruit growth and fruit quality. International Journal of Agricultural and Biosystems Engineering 7, 23-31. Wang, D., Yeats, T.H., Uluisik, S., Rose, J.K.C., and Seymour, G.B. (2018). Fruit softening: revisiting the role of pectin. Trends Plant Science 23, 302-310. Wills, R., McGlasson, B., Graham, D., and Joyce, D. (2007). “Postharvest: An Introduction to the Physiology and Handling of Fruit, Vegetables and Ornamentals”. 227 pp. University of New South Wales Press. Winarno, F.G., and Wirakartakusuma, M.A. (1979). “Fisiologi Lepas Panen”. 97 pp. Sastra Hudaya.