The effect of AB mix fertilizer concentration on the yield of Marigold (Tagetes erecta) under hydroponic condition

In hydroponic substrate cultivation, nutrients are only sourced from fertilizers; therefore, fertilizer application must pay attention to concentration. The right concentration of fertilizer, namely AB Mix, affects the quality of marigold flowers (Tagetes erecta). The purpose of this study was to examine the effect of flower AB mix fertilizer concentration and obtain the best AB mix fertilizer concentration for marigold flower yields on cultivated hydroponic substrate. This research was carried out in May–July 2022 at the screen house of the Horticulture Industry Technology Study Program. The study used Group Randomized Design (GRD), with AB mix fertilizer treatment tested at a concentration of 1000; 1100; 1200; 1300; 1400; 1500; and 1600 ppm. The data obtained were analyzed with various fingerprints and continued with the honest significant difference (HSD) test level of 5% if there was a real effect. The parameters observed are the number of flowers, the diameter of the flower, and the fresh weight of the flower per plant. The results obtained are: 1. The concentration of AB mix fertilizer has a significant influence on the number of flowers, flower diameter, and fresh weight of flowers per plant). AB mix fertilizer with a concentration of 1,200 ppm is the best concentration because it produces marigold plants with the highest number of flowers (17.67 florets), the widest flower diameter (in the first harvest it was 79.31 mm, the second harvest was 78.12 mm, and the third harvest was 78.16 mm), and the heaviest flower weight (in the first harvest it was 15.11 g, the second harvest was 14.33 g, and the third harvest was 12.67 g).


Introduction
Marigold (Tagetes erecta) is a type of ornamental plant that smells distinctive with the beauty of the shape and color of the flower.Marigold flowers are used as cut flowers for flower krans, decorations of houses of worship, and religious activities, especially for Hindus.Marigolds are also used as natural food coloring and medicinal plants, such as for fighting free radicals, treating digestive problems, and sore throats, as well as poultry feed [1], because it contains carotene, xanthophylls, and carotenoids [2].Especially in Kupang City, marigold plants began to be in demand by the community in line with the development of cut flowers and flower krans, interior decoration, and religious ceremonies.Even the demand for marigold plants (flowers) tends to increase but is not balanced with production of around 89.9 kg/day [3], so marigolds were imported from outside the city.This condition is an opportunity to try to farm these crops.On the other hand, marigold cultivation in Kupang is also constrained by a lack of water and marginal land conditions, so it is necessary to use cultivation technology such as hydroponic plant cultivation.
Hydroponic systems can provide a more controlled growth environment without requiring large areas of land or soil.The hydroponic substrate is one type of hydroponics that uses substrate (non-soil media) such as a mixture of charcoal, husks, and bokashi as anchoring places for plant roots.The mixture of husk charcoal and bokashi is able to bind water, store nutrients, and buffer plants well.It does not cause negative effects on plants, has a relatively low price, and is easy to obtain compared to another substrate materials.Hydroponic cultivation also requires fertilizers that suit the needs of plants.The fertilizer used by marigold plants is AB-mix for flower plants (ornamental plants).
Hydroponically growing and producing marigold substrates requires the proper concentration of fertilizers.Fertilizer concentration is related to the nutrient levels in fertilizer that can be absorbed by plants, which are then used for metabolic processes that appear in plant growth and yield.If nutrients are less available, plant growth will be inhibited; otherwise, if the concentration of nutrients is very high, it will cause poisoning in plants [4].
The results of research on AB-mix fertilizer in substrate hydroponic systems in mustard plants show that AB-mix fertilizer increases mustard production in substrate hydroponic systems [5].Research on ABmix concentrations in several varieties of marigolds cultivated hydroponically by DFT states that the best results in flower count and flower diameter were obtained at AB-mix concentrations of 1,200 ppm, and flower weights were achieved at concentrations of 1,500 ppm.[3] This research aims to: 1) Assess the effect of AB-mix nutrient concentration on the yield of marigold plants on hydroponic substrate and 2) Obtain the best concentration of AB-mix nutrients for marigold plant yields on the hydroponic substrate.

Materials and Method
This research was carried out at a screen house owned by the Department of Food Crops and Horticulture, Kupang State Agricultural Polytechnic, from May to July 2022.The tools used are analytical scales, trays, scissors, calipers, brooms, sprayers, buckets, plastic barrels, jerry cans, TDS, pH meters, polybags measuring 15x25 cm, and cameras.The materials used are Yellow Molek Variety marigold seeds, husk charcoal, bokashi, AB-mix fertilizer, Paramudita flowers, water, Virtako, 70% alcohol, and detergent.

Research Study
This study was designed using a single-factor randomized group design (RGD).Seven treatments were tested and repeated three times for 21 experimental units.The treatment tried was the concentration of AB-mix fertilizer, which is 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, and 1,600 ppm.Each experimental unit consists of five plants with three sample plants, so the total population is 105 plants.The experimental data were analyzed using fingerprints, and if the treatments were significantly different, then it was continued with the Tukey Honestly Significant Difference at the 5% trust level.
The cultivation of marigold plants follows the reference of hydroponic substrate cultivation in general, starting with sanitation and sterilization of the tools and screen houses used.The AB-mix fertilizer used is fertilizer for the hydroponic cultivation of flower plants.The preparation of the stock solution follows the instructions on the packaging, and the fertilizer application solution is adjusted to the treatment.Determination of fertilizer concentration using TDS.Watering activities and fertilizer application (fertigation) are carried out five times a day at a dose of 250 ml per plant for each administration, starting at 06.30-07.00and ending at 15.30-16.00local time.Application of AB-mix fertilizer begins at the age of 1 HST to 1 week before the first harvest (32 HST).The observation variable consists of supporting variables, namely the number of branches and flowering age (days), while the main variable consists of the number of flowers (florets), diameter (mm), and flower weight per plant (g).

Number of branches per plant and age of flowering
A branch is part of a plant that grows on the stem or tree of the plant.Branches serve as a place to grow shoots, leaves, flowers, and fruits.The flowering age is the age when the plant has entered the generative phase.The average number of branches of marigold plants and flowering age are shown in Table 1.The application of AB-mix fertilizer to marigold plants cultivated in hydroponics is able to produce a number of branches ranging from 13.78 to 17.89 branches and a flowering age between 14.33 and 16.67 days.AB-mix fertilizer concentration of 1,200 ppm produces marigold plants with the highest number of branches (17.89 branches) and the fastest flowering age (14.33 days) compared to the number of branches and flowering age of other treated marigold plants.
One of the factors that affect plant growth and development is nutrition (water and nutrients).Nutrients as raw materials and energy sources in plant metabolic processes need to be in appropriate quantities, availability, and balance so that they can have a good influence on plant growth and development.This condition is achieved with the application of an AB-mix fertilizer concentration of 1,200 ppm because it is able to produce marigold plants with the highest number of branches and the fastest flowering age compared to other concentrations (Table 1).Nutrient differences in nutrient solutions can affect plant growth, production, and yield [6].
Some macronutrients play a role in plant growth, such as nitrogen (N), which generally stimulates vegetative growth, namely the growth of roots, stems, and leaves, including the formation of branches.Phosphorus (P) plays a role in stimulating root growth, aiding plant assimilation and breathing, accelerating flowering, and ripening seeds and fruits.Nutrient K helps to regulate plant physiological processes such as photosynthesis, accumulation, translocation, carbohydrate transport, opening and closing stomata, and water distribution in tissues and cells.These three nutrients, supported by other nutrients if they are in sufficient conditions in the plant, will support plant growth, including branch formation, and accelerate flowering [7].

Number of flowers
The results of the analysis of variance informed us that AB-mix fertilizer applied at several concentrations has a noticeable effect on the number of flowers on marigold plants.The average number of marigold plant flowers and the honestly significant difference at the 5% trust level are shown in Figure 1.1), which ultimately affected the number of flowers produced.The number of florets on a plant is in harmony with the number of branches on the plant because flowers grow at the ends of the branches [8].

Flower diameter (mm)
The diameter of the flower is the result of the interaction between the genetic properties of the plant and environmental factors in the process of its growth.The results of the analysis of variance inform us that AB-mix fertilizer applied at several concentrations has a significant effect on the diameter of the flowers of marigold plants.The average flower diameter of marigold plants and the honestly significant difference at the 5% trust level are shown in Table 2. Table 2 shows that the average diameter of marigold flowers in the first, second, and third harvests ranges from 65.58 to 79.31 mm.
The diameter of the flowers in Table 2, when compared with the description of marigold plants of the same variety, indicates that the potential size of the flowers is 6.8-8.6 cm.This means that in general, the diameter of marigold flowers produced by this study has been in accordance with the description of the results of the plant, so it can be said that the use of AB-mix fertilizer with a concentration of 1,000-1,600 ppm is able to provide good marigold plant yields.However, to get optimal results, the use of AB-mix fertilizer with a concentration of 1,200 ppm is considered the best concentration because it is able to produce the largest diameter of marigold flowers in harvests 1-3.), in an optimal and balanced amount so as to help plants in the process of forming and enlarging flowers.This is because P nutrients in plants serve as a source and transfer of energy in plants through the formation of ADP and ATP.ADP and ATP are high-energy phosphate compounds that control many reactions within plants, such as photosynthesis, respiration, the synthesis of proteins and amino acids, and the transport of nutrients through plant cells [9].The energy possessed by ADP and ATP will be directed to plant growth and yield processes such as the formation and enlargement of marigold flowers.

Flower Weight (g)
The results of the analysis of variance showed that AB-Mix fertilizer at various concentrations had a significant effect on the weight of marigold flowers in the first and second harvests but had no real effect on the weight of flowers in the third harvest.The average weight of marigold flowers and the honestly significant difference at the 5% trust level are shown in Table 3.The weight of fresh flowers is influenced by their number and diameter.A large number of flowers per plant will result in a high total weight of fresh flowers per plant; besides that, the larger the diameter of the flower, the greater the weight of fresh flowers.[10] Figure 1 and Table 1 inform us that a concentration of 1,200 ppm produces marigold plants with the highest number of flowers (17.67 florets) and the largest flower diameter for all harvests; this has an impact on the fresh weight of heavier flowers.

Conclusion
1. Application of AB-mix fertilizer at various concentrations has a significant effect on the number, diameter, and weight of flowers per marigold plant cultivated hydroponically substrate.2. AB-mix fertilizer at a concentration of 1,200 ppm is the best concentration for marigold plant yields, namely the number of flowers as much as 17.67 florets, a flower diameter of 79.31 mm (harvest 1); 78.12 mm (harvest 2); and 78.16 mm (harvest 3), and the weight of marigold flowers per plant of 15.11 g (harvest 1); 14.33 g (harvest 2); and 12.11 g (harvest 3).

4 Figure 1 .
Figure 1.Effect of AB-mix fertilizer concentration on the number of marigold flowers

Table 1 .
The average number of branches and flowering age of marigold plants due to AB-mix fertilizer with . Average Flower Diameter of Marigold Plants Due to AB Mix Fertilizer Application with Substrate

Table 3 .
Average Flower Weight of Marigold Plants Due to AB Mix Fertilizer Application with Substrate