International Conference on Science, Technology, and Environment 2020 Surabaya, December 2-3rd 2020 Growth and Quality Response of Potted Marigold (Tagetes erecta) by Applying the Method of Pinching and Retardant IRMA SANTI*, SITAWATI, NURUL AINI Department of Agronomy, Faculty of Agriculture, Universitas Brawijaya Abstract: Potted plants are generally used as interior decoration, and they require an ideal posture with lots of flowers to enhance sales This can be achieved by removing apical dominance and applying retardant This study examines the effect of pinching and paclobutrazol on growth and flowering of marigold pots This study uses factorial randomized block design with two factors Pinching (without pinching, single pinching, double pinching) was the first factor and paclobutrazol concentration (0, 15, 30, 45 ppm) was the second factor; both were repeated three times The results show that pinching and paclobutrazol affected growth and flower quality The quality of pinching and paclobutrazol plants decreased plant height and leaf area but increased plant dry matter and a number of flowers On the other hand, canopy increased on pinching and decreased on paclobutrazol Quality parameters were achieved on pinching with 45 ppm paclobutrazol indicated as a good fit in producing ornamental pot plants Keywords: Flowering, Paclobutrazol, Quality Introduction Marigold is an ornamental plant that is widely produced for landscaping, cut flowers, and decoration purposes As a potted flower, marigolds are increasingly in demand because they have flowers with attractive sizes, shapes, and colors The problem is that marigold cultivars generally grow tall so that it is difficult to meet the requirements as a potted ornamental plant It needs an adoption of technology in easy and profitable cultivation to produce quality potted marigolds A possible method to solve the problem is by applying the method of pinching and paclobutrazol The study was conducted to determine whether the type of pinching affects the concentration of paclobutrazol needed to improve the quality of potted marigold and whether different types of pinching and concentrations of paclobutrazol affect the growth and flowering of potted marigold *Corresponding author : irmasanti@student.ub.ac.id Electronic copy available at: https://ssrn.com/abstract=3810379 International Conference on Science, Technology, and Environment 2020 Surabaya, December 2-3rd 2020 The objective of this research was to investigate the effect of different types of pinching and concentration of paclobutrazol and to get the right type of pinching and concentration of paclobutrazol in influencing growth and flowering, thereby increasing the quality of marigold in pots Theoretical Framework and Hypothesis Development Ornamental plants have aesthetic values and are widely used to beautify the room, one of which is marigold Marigold is from the Asteraceae family and the most popular commercial flower and widely grown throughout the world It is able to widely adapt to various climatic and soil conditions, easy to cultivate, has bright colors ranging from yellow to orange with the best combination Attractive and brightly colored flowers are the most valuable economic part and widely used for making bouquets, religious offerings, exhibitions, decorations (Bhusari et al, 2017) In general, marigold is tall, erect-growing up to three feet in height The flowers are globe-shaped and large with measure up to inches across with yellow to orange and not include red colored marigolds, so this cultivar is suitable for bedding plants (Priyanka et al, 2013) The characteristics of potted ornamental plants that attract consumers are short and compact morphology, predictable flowering time, and high aesthetic value (Nordli et al, 2011) Therefore, the production of potted ornamental plants must be differently and carefully based on consumer preferences (Megersa et al, 2018) The improvement of visual quality is the main key and playing an important role to increase purchasing (Ferrante et al, 2015) Quality depends on the shape, size, color of flowers and leaves, and number of flowers (Noordergraaf, 1994; Wang et al, 2005) Yellowing of leaves, loss of flowers and leaves, low flower count and 50% of flowers per plant browning pot could reduce the quality of potted ornamental plants (Karimi et al, 2012; Ranwala et al, 2005; Williams et al, 2000) Thus, it takes efforts to increase it through pinching and paclobutrazol Pinching is a technique of cutting or removing terminal shoots to form a sturdy and tough plant, increasing branching, avoiding dominance of apical shoots and increasing the number of flowers on the plant In carnations, there are three types of 258 Electronic copy available at: https://ssrn.com/abstract=3810379 Santi, Sitawati pinching, namely: single pinching, 1½ pinching, and double pinching Single pinching is done only once by removing the apical shoots and leaving 5-6 leaves in the crown 1½ pinching is like a single pinching, then half of the growing lateral shoots are pinching back, leaving 2-3 leaves Double pinching begins with a single pinching, followed with pinching all the growing lateral shoots leaving 2-3 leaves (Wuryaningsih et al, 2008) Double pinching on potted Odontonema callistachyum was proven to produce the shortest plant compared to single pinching and without pinching (Rezazadeh et al, 2015) The application of retardant in potted ornamental plants is generally carried out to control plant height to obtain short and strong plants Retardants inhibit the synthesis of gibberellins so that the cell elongation function and the longitudinal growth rate of plants are inhibited (Krisantini and Tjia, 2011) Plant growth regulators have been shown to prevent excessive stem elongation and reduce internode lengths in plants (Kuehny et al, 2001) The retardant widely used to reduce stem elongation in ornamental plants is paclobutrazol It is an inhibitor that works physiologically in inhibiting the biosynthesis of gibberellins in the terpenoid pathway by inhibiting enzymes that catalyze the metabolic reaction process (Taiz et al, 2005) Its application by watering through the media is a better way than through the leaves because of the translocation of paclobutrazol through xylem (Whipker et al, 2003) The hypothesis was that pinching and paclobutrazol could control growth and improve the quality of pot marigold Research Method This research was carried out in the greenhouse “Angkasa” Abdul Rachman Saleh airbase, Malang from February until April 2020 It is located at an altitude of ± 500 m above sea, with the greenhouse’s temperature during the study of 23.5-30.93°C (minimum-maximum) and average humidity of 64.67%-75% This study used a factorial randomized block design with two factors Pinching is the first factor with levels of treatment including without pinching, single pinching and double pinching Paclobutrazol as the second factor consists of levels, namely 0, 15, 30, and 45 ppm 259 Electronic copy available at: https://ssrn.com/abstract=3810379 International Conference on Science, Technology, and Environment 2020 Surabaya, December 2-3rd 2020 The treatment was repeated times with 15 samples for each treatment; thus, there were 540 samples of the experimental pot Marigold that has been sown for 21 days is transferred to a pot with a diameter of 16 cm The media used consist of soil, husk charcoal, and cocopeat with a composition of 1:1:3 The treatment was started with single pinching on day 10, followed with double pinching after 20 days by pinching all the growing lateral shoots, paclobutrazol was applicated on day 22 Watering was carried out every day, fertilization of grams of NPK was given on days afterward, while pest control was done mechanically with insecticides Parameters observed included plant height, canopy width, leaf area, and flower parameters including flowering time and number of flowers The resulting data were analyzed using analysis variance (F) by 5% level, then BNJ by 5% level to see the difference between treatments Results and Discussion The present study investigated the effect of different types of pinching and concentration of paclobutrazol This result shows that the interaction between pinching and paclobutrazol causes a significant difference in plant height Pinching treatment affected the concentration of paclobutrazol needed to control plant height (Figure 1) Figure Effect of pinching on plant height in different concentration of paclobutrazol (Different latter is significantly different in the 5% BNJ test) 260 Electronic copy available at: https://ssrn.com/abstract=3810379 Santi, Sitawati The lower plant height was found in the double pinching with 30 and 45 ppm paclobutrazol On the other hand, the maximum high plant was found in the without pinching and paclobutrazol This result indicates that plant height can be controlled by pinching and paclobutrazol treatment Pinching reduced the need for paclobutrazol to produce shorter crops, this shows that there is a synergistic effect between pinching and paclobutrazol Pinching on apical buds cause inhibition of apical dominance so that axillary shoots to become free of correlative inhibition of apical dominance and begin to grow, more branching and the spread of plants, and finally reduced plant height in pinched plants (Rahman et al, 2008) Auxin synthesis in apical shoots to stop when there is inhibition of apical dominance so that the tips of active branches did not continue to grow, increased lateral branches, and decreased plant height (Rema and Khader, 1997) Reduced plant height due to double pinching has been demonstrated in Odontonema callistachyum (Rezazadeh et al, 2015) Paclobutrazol works physiologically in inhibiting gibberellin biosynthesis and inhibiting the oxidation of ent-kaurene to ent-kaurenoic acid which caused a decrease in the speed of cell division and inhibited plant elongation (Mansuroglu et al, 2009) Reduction in plant height due to paclobutrazol also been reported of Pelargonium zonal L (El Aal et al, 2017) and Lantana camara L (Muthahara et al, 2018), Pinching and paclobutrazol treatment statistically affected leaf area and canopy widht Table Table Effect of pinching and paclobutrazol on growth and flowering of Marigold Treatment Pinching P0 P1 P2 BNJ 5% Paclobutrazol ppm 15 ppm Leaf area (cm-2) Canopy width (cm) Dry weight (g plant -1) Days to flower bud initiation Number of flowers plant -1 1143,09 b 1070,56 ab 1016,79 a 86,56 34,03 a 35,35 ab 35,97 b 1,86 17,70 a 18,02 ab 18,99 b 1,09 27,08 a 27,25 a 31,25 b 1,48 5,42 a 7,25 b 7,77 c 0,52 1182,65 b 1088,59 ab 36,67 b 35,21 ab 17,22 a 18,17 ab 29,00 28,00 6,73 6,67 261 Electronic copy available at: https://ssrn.com/abstract=3810379 International Conference on Science, Technology, and Environment 2020 Surabaya, December 2-3rd 2020 30 ppm 1038,03 a 35,07 ab 18,58 b 28,22 6,96 45 ppm 997,98 a 33,51 a 18,99 b 28,89 6,89 BNJ 5% 110,47 2,37 1,39 ns ns CV (%) 7,84 5,16 5,82 5,07 7,38 The number followed by the same letter on the same treatment and parameters shows no significant difference based on the BNJ test by a 5% level ns = no significant show that leaf area decreased significantly in the pinching and paclobutrazol treatments However pinching treatment increased canopy width, but paclobutrazol decreased it (Table 1) Without pinching treatment produced maximum leaf area which was significantly different from double pinching However, the minimum canopy width was produced without pinching treatment and significantly different from double pinching On the other hand, without paclobutrazol produced maximum leaf area which was significant than 30 and 45 ppm paclobutrazol Similarly, maximum canopy widht was produced without paclobutrazol Paclobutrazol on 45 ppm decreased canopy width and was significantly different from without paclobutrazol Inhibition of apical dominance causes the plant to stop growing in height, so the shoots to grow sideways and produce flowers Pinching not only reduces plant height but also increase plant width and branching (Beniwal et al, 2003) Plant canopy that is carried out by pinching is getting wider due to growth on the stems, branches, and leaves Pinching affects plant metabolism from vertical to horizontal development and produces more branches (Salyh, 2013) The functions of paclobutrazol was to inhibit cytochrome P-450, this enzyme mediates oxidative dimethylation reactions, including those required for ergosterol synthesis and conversion of kauren to kaurenoic acid in the gibberellin biosynthetic pathway (Fletcher et al, 2000) Inhibiting gibberellin caused decreasing in the speed of cell division and inhibited plant elongation was thought to be related to reduced canopy width and leaf area The reduced leaf area has been proven in potted geranium due to paclobutrazol up to 60 ppm (El Aal and Mohamed, 2017) Retardant application has also been shown to reduce the diameter of the chrysanthemum crown (Kurnia, 2017) 262 Electronic copy available at: https://ssrn.com/abstract=3810379 Santi, Sitawati Table reveals that total dry plant weight was increased with pinching Plants with double pinching produced maximum plant dry matter per plant and were significantly different from without pinching However, single pinching produces total dry matter per plant was not significantly with without pinching and double pinching Besides, paclobutrazol increased dry matter, 45 ppm of paclobutrazol produced maximum dry matter per plant followed by 30 ppm paclobutrazol, and were significantly different from without paclobutrazol The increase in total dry matter of double pinching by 7.3% higher than that without pinching While the increase in dry matter in 45 paclobutrazol treatment by10.28% compared to without paclobutrazol The overall effect of the pinching generally practiced promoting bushy growth canopy with apical fight domination which plays a significant role in the production of potted plants It has direct relationship with plant form and subsequent potential for yield increment too (Martin, 1987) The increase in total plant dry weight indicates the efficiency of plant biomass formation due to photosynthesis In the previous study, it was reported that pinching and paclobutrazol could increase the chlorophyll content of geranium in pots Observed there is a relationship between pinching and paclobutrazol with an increase in cytokinins that stimulates chlorophyll synthesis (El Aal and Mohamed, 2017) The increase in chlorophyll content has the potential to increase the photosynthesis process so that more photosynthate is produced Table shows that time to flowering increased in the pinching treatment An early flower was recorded in control plants followed by single pinching which was significantly different from double pinching treatment Double pinching has maximum time to flower Similar to the time of flowering, a linear relationship between pinching treatment with the number of flowers observed Table shows that minimum flower was produced in the without pinching treatment and significantly different from all pinching treatment Double pinching produces maximum flower and significantly different from single pinching Double pinching produces flower by 43,36% than without pinching and 7,17% than single pinching In general, flowering time were delayed by pinching treatments that produced flower and onset to coloring later than without pinching treatment This delay in 263 Electronic copy available at: https://ssrn.com/abstract=3810379 International Conference on Science, Technology, and Environment 2020 Surabaya, December 2-3rd 2020 flowering seemed to be a result of pushing the plants back to the juvenile phase after pinching The later the pinching occurred, the later the plants flowered The precise cause of flowering delay may be attributed to the axillary shoots being in a less advanced physiological phase than the apical shoot, as they begin to develop only after pinching After pinching the plant will return to the juvenile phase so that it actively forms branches, leaves, and flowers In addition, the more branches that are produced, it takes longer to flower because the plants will return to the initial phase and delay the stimulation of plants to develop (Munir et al, 2006) The delay in flowering time after pinching occurs in Chrysanthemums (Ona et al, 2015) However, pinching has been shown to increase the number of flowers An increase in the number of flowers increases the value of the pot marigold and thus the higher quality In addition, the increase in the total dry weight of the plant causes energy sources in maintaining plant life, so that the marigold flowers delay in aging due to pinching and paclobutrazol Therefore, overall pinching and paclobutrazol enhancement the quality of potted marigold flowers Conclusion In general, the results obtained indicated 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Lemma and Banjawu 2018 Effect of plant growth retardant and pot sizes on the height of potting ornamental plants: a short review J .of Hort 5: 1-5 Munir, M and F Naz 2006 Growth and flowering of. .. Leaf and Flower Quality of Potted Oriental-Asiatic and LA-Hybrid Lily Cultivars Sci Hort.105: 383–392 Rema, M & Khader, M.A 1997 Effect of Leaf Plucking on The Growth and Grain Yield of Coriander