The Growth and Yield of Marigold Flowers (Tagetes erecta L.) on Gibberellins Concentration and Pinching Time

. Public awareness of beauty and environmental sustainability is getting better. The tropical climate in Indonesia allows many floricultural products to grow well. Considering that the potential is still very large but has not been fully exploited, efforts are needed to encourage floriculture to be more developed. We also need to focus on improving the method of cultivating plants in order to increase their economic value, without destroying the environment. Marigold is one of the most popular multifunctional ornamental plants. The problem in its cultivation is the presence of apical dominance which inhibits the growth of lateral shoots. Vertical growth will encourage flowering lateral shoots. Marigold flowering is affected by the number of flowering branches, so these branches need to be pruned. The aim of this study was to examine the interaction between GA3 concentration and pinching time on the growth and yield of marigold plants. This research was a field experiment with a split plot design consisting of two factors. The first factors as main plot, namely GA3 concentration (15, 200 and 250 ppm) and second factors as sub plot, namely pinching time (14, 21 and 28 days after planting). It was found that the interaction between gibberellins concentration of 200 ppm and pinching time of 14 DAP showed the fastest time of flower appearance. All concentrations of gibberellins gave the same good results for all parameters. Pinching time of 28 DAP gave the best results on plant height 35 DAP and number of flowers.


Introduction
Marigold is an ornamental plant that originated from Central America, particularly Mexico.This plant has spread throughout Indonesia due to its highly adaptive nature as well as the ability to grow in both lowland and highland areas [1].Marigold is a multifunctional plant that has high economic value and can be used for religious ceremonies, cut flower, ornamental garden plant, insect repellents, vegetable insecticides (marigold essential oil), natural dyes, and feed ingredients [2].Marigold flower industry in Bali is estimated to generate 100-200 billion rupiah per year, with a daily demand of 8 tons.In the Bandungan area of Semarang Regency and other highland regions, marigold is extensively cultivated for commercial purposes.These include flower and seed production, as well as garden flower in flower tourism destinations.In the main flower market in Bandungan, marigold is widely traded, particularly for flower arrangements such as flower boards [2].
The main issue related to marigold cultivation is apical dominance which delays growth of lateral shoots and inhibits flowering [3].Flower yield depends on the number of flowering branches and lateral shoot development can be promoted by restraining vertical growth.According to Khangjarakpam et al. [4], adjusting climatic conditions through site selection, employing appropriate cultivation techniques, ensuring balanced nutrition, and applying physiological manipulation techniques such as pinching or the use of Plant Growth Regulators (PGRs) can also enhance harvest yield.Therefore, it is recommended to apply PGRs and implement pinching as a practice to enhance growth and flower yield of marigold plant.
PGRs are organic compounds that are different from nutrients and in small amounts, they stimulate, inhibit, or modify various physiological processes in plant [5].At high concentrations, they can hinder growth, become toxic, and cause plant death.One widely used PGRs is gibberellin, which contributes to improved flower quality, enhanced plant growth, as well as increased primary and secondary branches.Gibberellin also helps in the maintenance of uniform flower size and number, thereby ensuring higher flower production [6].
According to Budiarto and Wuryaningsih [7], pinching method is effective in increasing crop yield, which involves the removal of the apical bud from the original seedling.This technique is employed to cease the dominance of the apical shoot to grow the seed and promote growth of lateral shoots that are further nurtured until flower buds are formed

Research methods
This research was conducted in October-November 2021 at Erista Garden, Pakem Sub-district.The area was located in the highlands with an elevation of 600 meters above sea level, with the highest and lowest temperature of 32°C and 18°C, respectively.The topography of the Pakem Sub-district consisted of undulating land, hills, and mountains.Furthermore, the materials used included 3 weeks old marigold maharani seedlings, soil, rice husk, goat manure, EM4, atonic, gromate, NPK, decis 25 EC, distilled water, and gibberellin.The tools used included a hoe, plastic sheets, polybags (sized 20x20), raffia string, labels, dibblers, watering cans, scissors, sprayers, measuring cups, calipers, pens, rulers, and notebooks.This research employed a field experiment using a factorial experimental design in split plot with 2 treatment factors.The main plot consisted of three levels of gibberellin (GA3) concentration, namely 150 ppm, 200 ppm, and 250 ppm.The sub-plot consisted of three levels of pinching time; 14 days, 21 days, and 28 days after transplanting (DAP).The data obtained from observations were analyzed using Analysis of Variance (ANOVA), followed by the Duncan's Multiple Range Test (DMRT) at a significance level of 5%.
The growing medium used was a mixture of soil, rice husk and goat manure in a ratio of 1:2:1.Subsequently, the medium was fermented by adding an EM4 solution (10 ml/L) and covered with plastic.After one week of fermentation, the mixture of the growing medium was placed into polybags measuring 20 cm x 20 cm.The polybags were punctured using a dibbler and filled with 1 seedling of 21 days old marigold after sowing.
Pinching was performed by cutting plant shoot with scissors, approximately 3-4 cm in length to promote branching in plant.This process was carried out when plant was 14, 21, and 28 days old after transplanting.Gibberellin (GA3) was applied by sparing evenly on all parts of plant one day after pinching.The preparation of GA3 involved creating a stock solution, followed by preparing solutions with concentrations of 150 ppm, 200 ppm, and 250 ppm.The dosage given per plant was 40 ml/plant and 8 parameters were observed.These included plant height, leaf count, branch count, stem diameter, time of flower emergence, number of flowers per plant, flower diameter, and color.

3
Results and discussion

Plant height (cm)
Plant height at 35 (DAP) had no significant difference among the treatment concentrations of G1 (150 ppm), G2 (200 ppm), and G3 (250 ppm).This suggested that the young stem played a crucial role in gibberellin production, where the endogenous hormone in plant was sufficient for stem elongation during the vegetative phase.Therefore, plant showed similar responses despite being subjected to different gibberellin concentrations.This aligned with Asra et al. [8], where endogenous gibberellin were found to be produced in the stem section.During vegetative growth, they stimulated cell division in the meristematic and cambium regions of the stem, leading to the elongation of plant.Pinching treatment at 28 DAP (P3) showed the highest average plant, while the lowest was observed at 14 (P1) DAP.According to Winardiantika et al. [9], earlier pinching led to a more significant shortening of plant.This was because pruning reduced the production of auxin in plant shoots, which inhibited plant height and encouraged the formation of lateral branches..62 q 46.03 p (-) Description: Numbers followed by the same letters in columns (a) and rows (p,q) show no significant difference and the (-) sign indicates no interaction.
The treatment concentrations of gibberellin and pinching time in terms of plant height at 49 DAP had no interaction.The combination of G3P2 did not show a significant difference compared to G1P3, but it resulted in significantly taller plant compared to others.This indicated that the appropriate concentration of gibberellin and pinching time can result in optimal plant height.According to Khangjarakpam et al. [4], physiological manipulation through pinching and appropriate PGRs application enhanced growth.In this research, plant height increased with higher GA3 concentration, thereby stimulating cell division and enlargement.Winardiantika et al. [9] stated that earlier pinching led to a greater reduction in plant height.This was because the pruning of the apical bud reduced auxin production, which inhibited an increase in plant height and promoted the formation of lateral branches.Similarly, pinching performed close to the generative phase hindered growth.

Total number of leaves
Total number of leaves at 35 (DAP) among the treatment concentrations of G1 (150 ppm), G2 (200 ppm), and G3 (250 ppm) had no significant difference.This suggested that the leaves served as the site of gibberellin synthesis during the vegetative phase, where gibberellin requirement of plant for leaf formation was already met.Appropriate gibberellin concentrations can actually help metabolism plant cell division for growth number of plant leaves [10].Therefore, plant exhibited similar responses despite being subjected to different gibberellin concentrations.This aligned with the statement by Salisbury and Ross (1995) cited by Farida and Rohaeni [11] that young leaves were the main site of gibberellin production.Gibberellin stimulated leaf growth, particularly during the vegetative phase, by promoting cell division and expansion, thereby contributing to the increase in number of leaves in plant.
There was no significant difference in number of leaves at 35 (DAP) between P3 (28 DAP) and P2 (21DAP), but both pinching treatments had significantly more leaves compared to P1 (14 DAP).The P3 (28 DAP) treatment had the highest leaf count because pinching at 28 DAP was the appropriate time to increase the number of leaves.Deden et al. [12] stated that pruning performed at the 27 DAP stimulated cell division, enlargement, and development, leading to the production of an optimal number of leaves.
-) Description: Numbers followed by the same letters in columns (a) and rows (p,q) show no significant difference and the (-) sign indicates no interaction.
There was an interaction between the treatment concentrations of gibberellin and pinching time in terms of number of leaves at 49 (DAP).The G3P3 treatment combination did not show a significant difference compared to G1P3, G2P3, and G3P2, however, it had significantly more leaves.This suggested that application of appropriate gibberellin concentrations followed by the right pinching time yielded the highest leaf count.According to Lakitan [13], direct application of gibberellin hormone to the leaves stimulated leaf growth, and plant with the right concentration enhanced phloem and xylem growth.This contributes to an increase in number of leaves.Plant that were pinched at an early stage focused their growth on branch formation, while those pinched at 28 DAP still have opportunity for vegetative growth, specifically leaf development.Winardiantika et al. [9] reported that pinching eliminated apical dominance and promoted the emergence of lateral branches.Apical dominance restricted vertical growth, leading to a reduction in the number of internodes on the main stem.Lateral branches appeared on the stem, and when the apical bud was pruned early, there was a decrease in the number of internodes, resulting in fewer leaves.

Total of branches (cm)
There was no significant difference observed in branch count at 35 DAP and 49 DAP among the treatment concentrations of gibberellin G1 (150 ppm), G2 (200 ppm), G3 (250 ppm), and pinching time P1 (14 DAP), P2 (21 DAP), and P3 (28 DAP), respectively.This suggested that the seedlings used originated from the same variety and possessed the ability to form branches equally, despite being subjected to different gibberellin concentrations and pinching time.Gardner [14] categorized factors influencing growth as external (environment) and internal (genetics).Among the interna factors, genetics played a direct internal role in determining growth and development, which were continuous processes throughout the life cycle.These factors depend on the availability of meristems, assimilation of hormones as well as other growth substances, and supportive environmental conditions.(-) (-) Description: Numbers followed by the same letter in the same column show no significant difference and sign (-) indicates no interaction between treatments..

Stem diameter(mm)
There was no significant difference observed in stem diameter at 35 and 49 DAP among treatment concentrations of gibberellin G1(150 ppm), G2(200 ppm), and G3(250 ppm).This suggested that plant stems produced sufficient endogenous gibberellin hormone for stem diameter development until harvest, hence, the exogenous application of gibberellin provided a similar response.Kusumawati [15] reported that gibberellin present in the stem enhanced the synthesis of RNA or enzymes during cell division in the meristematic region (such as in stem segments).This condition caused an increase in the number of cells in the stem, resulting in stem elongation.
There was no significant difference among pinching treatments in stem diameter at 35 (DAP).Therefore, the xylem tissue in the stem actively grew when the plant was young or during the vegetative phase, indicating that different pinching treatments resulted in similar responses.According to Pane et al. [16], an increase in stem diameter was due to xylem development in response to enhanced nutrient translocation by plant.In terms of stem diameter at 49 DAP, pinching treatment P3 (28 DAP) did not show a significant difference compared to P2 (21 DAP), but it did have a significantly larger stem diameter compared to P1 (14 DAP).The treatment with pinching at 28 (DAP) produced the largest stem diameter.Prayudi et al. [17] reported that plant subjected to early topping tended to focus their growth on early branch formation, while those topped at 30 (DAP) still have the opportunity for vegetative growth, such as increased plant height and stem diameter.(-) (-) Description: Numbers followed by the same letters in columns (a) and columns (p,q) show no significant difference and (-) indicates no interaction between treatments.

Flower appearance time (Days)
The treatment of gibberellin concentrations and pinching time on flower appearance parameter had an interaction.The combination of 200 ppm gibberellin treatment and pinching at 14 (DAP) (G2P1) resulted in the earliest flowering time, which was 40 days.This indicated that application of the appropriate concentration of gibberellin followed by the right timing of pinching accelerated the onset of flowering.Based on previous reports, it was suggested that the concentration of gibberellin used in the treatment met the requirements of plant for reproductive growth.According to Triani et al. [18], exogenous application of gibberellin can be effective when given according to the requirements of plant.Therefore, application of gibberellin at a low concentration was ineffective, while higher concentrations inhibited plant production.
Application of a 200 ppm GA3 concentration combined with pinching treatment 14 DAP positively affected the parameter of flowering time.This was because early pinching resulted in earlier flower initiation, while delay in treatment led to a longer [19].According to Kundu et al. [20], there was a significant delay in the number of days to flower and the duration of flowering in pinching treatment at 28 (DAP).This delay was caused by the removal of physiologically mature apical buds during pinching, and the developing branches in plant subjected to pinching treatment required more time for the initiation of the reproductive phase.Description: Numbers followed by the same letter show no significant difference in and the (+) sign indicates that there is an interaction between treatments.

Total number of flower
The average flower total of gibberellin concentration was significant different.This suggested that application of gibberellin at concentrations of 150 ppm, 200 ppm, and 250 ppm was suitable for plant requirement to form flower, resulting in similar responses in terms of flower quantity.According to Sundahri and Setiyono [21], effective application of gibberellin depended on meeting plant needs.Therefore, high concentrations and frequencies of gibberellin application were effective.Gardner (1991), cited by Widiwurjani and Arista [22], further added that appropriate concentrations of GA3 affected the biochemical processes in plant, leading to increased photosynthesis and the use of photosynthates in the formation of reproductive organs.Pinching treatment at 28 DAP (P3) was the highest of the total number of flower compared to treatments P2 and P1.According to Winardiantika et al. [9], early topping treatments led to a lower number of branches, which affected the total number of flower produced.During the early flowering stage, flower buds were found to emerge at the tips of the main stem and primary branches.

3.7
Flower diameter(cm) Table 9 showed that there was no significant difference in the parameter of flower diameter at 49 DAP among the treatments of gibberellin concentrations G1 (150 ppm), G2 (200 ppm), G3 (250 ppm), and pinching treatments P1 (14 DAP), P2 (21 DAP), P3 (28 DAP).This suggested that internal factors such as genetics played a more dominant role in determining flower diameter.Since the seedlings used were from the same variety, they exhibited similar flower diameters despite being subjected to different treatments of gibberellin concentration and pinching timing.According to Zahrah [23], each variety of plant exhibited different growth responses and production levels.Djumali [24] also stated that the genetic characteristics of each plant variety or cultivar influenced flower diameter of plant.(-) Description: Numbers followed by the same letters in columns and rows show no significant difference and sign (-) indicates no interaction between treatments.

Flower color
Based on Table 10, flower color of marigold plant in each treatment combination had the same category, which was 7.5 YR 7/10.This indicated that based on the functions of gibberellin and pinching, there was no direct correlation with flower pigments.The pigmentation in flower was influenced by genetic factors.Similarly, Triani et al. [18] stated that the addition of GA3 concentration significantly affected the timing of flower emergence, reduced shedding, and influenced the number of flower.According to Yuniza and Sitawati [19], pinching timing influenced the number of flowers and plant branches, as well as the timing of flower initiation.According to Kurniawan et al. [25], the color of marigold flower was caused by two main pigments, namely carotenoids, which provided yellow to red colors, and flavonoids, contributing to the yellow coloration.The genetic factor also affected the content of carotenoids in plant.This was because genetic differences in each plant had an impact on its ability to synthesize carotenoids.

Conclusion
This research demonstrated an interaction between the treatment of 200 ppm gibberellin and pinching at 14 (DAP) on the parameter time of flower appearance.Application of gibberellin treatment showed consistent results across all parameters.Moreover, pinching treatment at 28 (DAP) yielded the best results in terms of plant height at 35 DAP and the number of flower.

Table 3 .
Average Total Number of Leaves Age 35 DAP

Table 4 .
Average Total of Leaves Age 49 DAP

Table 5 .
Average Total of Branches aged 35 and 49 DAP

Table 6 .
Average Stem Diameter of 35 and 49 DAP (mm)

Table 7 .
Average Flower Appear Time (days)

Table 8 .
Average Flower Total 49 DAP Description: Numbers followed by the same letters in columns (a) and rows (p,q,r) show no significant difference in and sign (-) indicates no interaction between treatments.