The response to various concentrations of IBA hormone and transplanting time of potato plantlets cultivar of medians

Potato plants in addition to being able to be propagated through tubers can also be propagated by stem cuttings. The use of the hormone Auxin (IBA-Indole Butyric Acid) is one of the efforts to accelerate the growth of rooting potato stem cuttings. The purpose of the study was to determine the concentration of the IBA (Indole Butyric Acid) hormone and the right transplant age for the growth of plantlet cuttings of the Medians cultivar potato plant. The height of the planting site is ±1,500 m above sea level. The research experimental design to be used is a Complete Randomized Designs with three replications. The result showed that the treatments at the seedling stage have a noticeable effect on the parameters of the number of leaves, the number of saplings, the height of the plant, and the percentage of growth. There is an interaction between the two treatments against all parameters.


Introduction
Potato crops can be propagated in the traditional and modern way.Modern propagation of potato plants can shorten the time of seed propagation and increase the number and quality of seedlings.According to [1], one of the superior potato seed seeding techniques is using stem cuttings which is a treatment for cutting some parts of the plant to increase the number of plant seeds in addition to the use of tubers.The advantage obtained in propagation through cuttings is that new plants are obtained in sufficient quantities with the parent.
Potato plants grow well in highland areas.Potato crops can be propagated by tubers.However, farmers have difficulty reaching potato tubers to be used as seeds because of the relatively high price.[2] mentioned about the business of propagating quality potato seeds is constrained by very slow plant propagation efforts and the presence of diseases attacking seedlings to reduce crop yields.An alternative source of propagation of potato crops can be carried out with a system of plantlet cuttings of potato plants.[3] mentioned that potato plant breeding originated from G0 seeds (vegetative generation to zero) obtained from potato plantlets produced with in vitro techniques either through the growth of micro cutting or micro tuber.The stem cuttings that will be used are given growth hormone to accelerate the growth of new roots, namely auxin which has a function to stimulate root growth in vegetative propagation (grafts and cuttings).Plant propagation through tissue culture is one of the alternatives to obtaining a new source of potato plant material.The plantlets obtained are then carried out through a process of acclimatization IOP Publishing doi:10.1088/1755-1315/1297/1/012063 2 and growth of stem cuttings in the screen house before being transplanted to the planting site.The provision of sufficient water for the growth of cuttings and reducing evaporation from the leaf-like tops is an important factor in the formation of rooting cuttings [4].
Median cultivars are cultivars produced by the Vegetable Crops Research Center.New Superior Variety (VUB) Medians is a technological innovation and is an improvement over the Atlantic variety.The Medians variety is expected to reduce dependence on imported processed potato varieties.Median cultivars can adapt well in highlands with altitudes above 1,200 m above sea level [5].
Medians cultivars is a technological innovation that is expected shortly to reduce processed potato varieties that are still imported from outside.Medians cultivars are the result of improvements from Atlantic cultivars and have been widely ordered and used by several small and medium-sized industries to manage potato chips.Medians cultivars have a potential yield of 24.9 -31.9 tons/ha, with a harvest life of 100-110 days after planting, and shelf life at room temperature of 50-70 days after harvest.The size of the tubers produced is on average, ranging in length from 8.5 -10 cm and width ranging from 5.7 -6.5 cm [5].
According to [6], the hormone auxin is a compound with characteristics that can support cell extension in shoots with the chemical structure of the indole ring, the large amount of auxin content in plants greatly affects plant growth.[7] mentioned that some types of auxin hormones are Indole Acetid Acid (IAA), Indole Butyric Acid (IBA), α-Napthalene Acetid Acid (NAA), Indole AcetoNitrile (IAN), Phexony Acetid Acid (POA), and so on.According to [4] auxin is one of the growth regulators for plants that influence: cell development, phototropism, geotropism, apical dormancy, root growth, parthenocarpy, abscission, callus formation, and respiration.
Plant Growth Regulators (PGR) are used for the propagation of horticultural crops to increase growth and yield.PGR can be used safely for fruit, vegetable, and ornamental crops.Indole 3-Butyric Acid is a growth regulator included in the auxin hormone group which is made from organic or inorganic compounds and can be modified to influence plant physiological processes.IBA regulates growth and influences the process of plant development, including stem elongation, early rooting, callus formation, accelerating flowering, enzyme induction, and aging of leaves and fruits [8].Indole 3-Butyric Acid can increase bud formation and has a positive impact on adventitious root formation on tomato plant stem cuttings [9].
The results of research by [10] showed that giving IBA for root growth on the stem cuttings of the Naga fruit plant (Hylocereus undatus) the higher the IBA concentration, had a positive effect on root growth on the stem cuttings of dragon fruit plants which included the percentage of rooted cuttings, root length, and root biomass.After reaching optimal conditions, it will then decrease due to the addition of IBA concentration.Meanwhile, the results of the study of [11] showed that the provision of IBA for the growth of Pineapple seedlings (Ananas comusus L.) from crown buds had a noticeable effect on the parameters of observing the number of primary roots of pineapple plant seedlings, but did not have a real effect on the parameters of primary root length, wet weight of roots, dry weight of roots, plant height, number of leaves, leaf length, leaf width, and the wet weight of the plant canopy.
The design used for this study was Complete Randomized Design with factorials.The study was conducted with 4 replications.The first factor was the IBA (Indole Butyric Acid) concentrations divided into four levels, namely H0: 0 ppm (control), H1: 1000 ppm, H2: 2000 ppm, H3: 4000 ppm.The second factor was the transplanting time divided into three, namely: U1: 2 WAP (Weeks After Planting), U2: 3 WAP (Weeks After Planting), U3: 4 (Weeks After Planting).The plantlet that was planted for each treatment were ten plantlets.The total number of plantlets was 480 plantlets.
Parameters, namely: Percentage growing, plant height, number of leaves, and number of buds.The treatment of IBA hormone and the transplanting time of potato plantlets had a significant effect on the parameter of the number of saplings.The highest number of saplings at 2 WAP on H0U3 was 1.94, and the lowest in H1U3 was 0.81.The highest number of saplings at 3 WAP on H3U3 was 2.75, and the lowest was at H1U3 at 0.75.The highest number of saplings on 4 WAP was in H3U3 at 3.68, and the lowest was in H1U3 at 1.69.The treatment of IBA hormone and the transplanting time of potato plantlets had a significant effect on the parameter of plant height.The highest plant height at 2 WAP on H3U3 was 6.54 cm, and the lowest in H1U3 was 2.75 cm.The highest plant height at 3 WAP on H0U3 was 7.88 cm, and the lowest was in H1U3 at 4.5 cm.The highest plant height on 4 WAP was in H0U3 by 8.81 cm, and the lowest was in H2U1 by 6.13 cm.The Plant height is influenced by auxin concentrations that stimulate cell division and elongation.

Plant Height
According to [12], auxin concentration at a certain level can increase osmotic pressure, increase cell permeability to water, reduce pressure on cell walls, and improve protein synthesis and cell wall development.The treatment of IBA hormone and the transplanting time of potato plantlets had a significant effect on the parameter of growth percentage.The highest growth percentage at 2 WAP on H0U3 was 100%, and the lowest in H1U3 and H2U1 was 68.75%.The highest growth percentage at 3 WAP was on H3U1, H3U3, and H0U3 was 93.75% cm, and the lowest was in H0U2 at 62.5% cm.The highest growth percentage on 4 WAP was in H0U3 by 100%, and the lowest was in H0U2 at 62.5%.The influence of auxins shows marked differences between treatments.The nurseries created and the treatment given show that the growth percentage is almost the same.The influence of auxin hormone influences early growth because auxin hormone serves to stimulate the roots.At the acclimatization stage, the use of IBA growth hormone has a good influence on the initial growth process of the plantlet.The use of IBA to aid the process of cell division.According to [13] stated that the use of auxin hormones serves to stimulate cell division, cell elongation and differentiation processes.The process of rooting at the beginning of plant growth is influenced by the nature of the impermeability of the bark to water in the process of absorption of nutrient content.[14] mentioned that IBA hormone could break hydrogen bonds and cause stem epidermal cells to expand, causing easy water entry into the stem and stimulating the root growth process.It can be concluded that the application of IBA Hormone does not have any influence on the number of leaves.However, it had a significant effect on the number of saplings and plant height.

Growth Percentage
The longer the age of transplanting potato plantlets, the percentage of growth will decrease.

Acknowledgment:
We would like to thank Lembaga Penelitian (LP) Universitas Sumatera Utara TALENTA 2021 scheme for funding this research.

Figure 2 .
Figure 2. The response of various concentrations of IBA hormone and transplanting time of potato plantlets to a total of saplings for 1WAP, 2WAP, 3WAP and 4WAP.

Figure 3 .
Figure 3.The response of various concentration of IBA hormone and transplanting time of potato plantlets to plant height for 1 WAP, 2 WAP, 3 WAP and 4 WAP.

Figure 4 .
Figure 4.The response of various concentration of IBA hormone and transplanting time of potato plantlets to growth percentage for 1 WAP, 2 WAP, 3 WAP and 4 WAP.

Table 1 .
The response of various concentrations of IBA hormone and transplanting time of potato plantlets to total of leaves for 1 WAP, 2 WAP, 3 WAP and 4 WAP.treatment of IBA hormone and the transplanting time of potato plantlets had a significant effect on the parameter of the number of leaves.The highest number of leaves at 2 WAP on H0U3 was 5.63, and the lowest in H2U1 was 2.38.The highest number of leaves at 3 WAP on H0U3 was 5,63, and the lowest at 2.38 leaves.The highest number of leaves on 4 WAP was in H0U3 by 7.5 leaves, and the lowest was in H0U1 by 1.98 leaves.
Figure 1.The response of various concentrations of IBA hormone and transplanting time of potato plantlets to total of leaves for 1 WAP, 2 WAP, 3 WAP and 4 WAP.The

Table 3 .
The response of various concentration of IBA hormone and transplanting time of potato plantlets to plant height for 1 WAP, 2 WAP, 3 WAP and 4 WAP.

Table 2 .
The response of various concentrations of IBA hormone and transplanting time of potato plantlets to total of saplings for 1 WAP, 2 WAP, 3 WAP and 4 WAP.

Table 4 .
The response of various concentration of IBA hormone and transplanting time of potato plantlets to growth percentage for 1 WAP, 2 WAP, 3 WAP and 4 WAP.