Variability and correlationship of agronomic characteristics of unproducing arabica coffee of Sumatra Island

Indonesia is the main producer of robusta coffee, while the coffee world wants Arabica coffee. The study was conducted in the lowlands at an altitude of 10 meters above sea level using a randomized block design. The treatment was 9 varieties of Sumatran Arabica coffee with three replications. The results showed that the growth of plant height and stem diameter of Arabica coffee in the lowlands was normal. The characteristics of internode length and primary branch length have narrow variability, the characteristics of plant height, stem diameter and length of stem segments have moderate variability, and characteristics of the number of pairs of leaves and canopy area have wide variability. Arabica coffee from Sumatra Island shows a close relationship to coffee from Nangroe Aceh Darusalam and North Sumatra and quite far from coffee from South Sumatra. The growth of Arabica coffee is normal. The number of pairs of leaves and canopy area can be used as selection criteria. The relationship between arabica coffee from Nangroe Aceh Darussalam and North Sumatra is quite close, whereas the coffee from South Sumatra it is quite distant. Germplasm from Sumatra under study needs to be added from other coffee-producing regions.


Introduction
The coffee is an annual plant which is one of the main sources of foreign exchange for Indonesia.The area of coffee plantations in Indonesia reaches 1.30 million hectares, with Robusta coffee covering 1.02 million hectares and Arabica coffee reaching 263,000 hectares.Indonesia's largest coffee plantation area is on the island of Sumatra, namely South Sumatra Province with an area of 249,963 hectares, Lampung Province with an area of 156,836 hectares,Aceh Province with an area of 125,443 hectares, North Sumatra Province with an area of 95,263 hectares, and Bengkulu Province with an area of 86,214 hectares [1,2].
Arabica coffee was the first type to be developed in Indonesia, starting in 1696.The spread of coffee on Sumatra began in 1699 in Pekantan District.It is known as Mandailing Coffee.The coffee grows at an altitude of 1,200 meters above sea level.The taste is unique, which other do not have.The production reaches 10,000 to 15,000 tons per year [3,4].
The Arabica coffee grow well with a temperature of 15 -25 o C and rainfall of 1,500 -2,500 mm per year with 1 -3 drymonths [5,6].Soil requirements are fertile, loose, permeable and a pH between 5.5 -6.5.Land with these requirements is only obtained in the highlands.Coffee development policies in Indonesia are directed at increasing the proportion of Arabica coffee [7,8].The development of Arabica coffee in the highlands is experiencing problems, because most of the highlands are in protected forest areas.Therefore, developing Arabica coffee plantsin the middle and lowlands is an alternative.In the lowlands there are obstacles, namely low growth, productivity, and susceptibility to leaf rust disease.One of the efforts to overcome these obstacles is to choose an arabica coffee genotype that is adaptive and engineered to grow the environment [9][10][11].The selection of genotypes was achieved by planting region-specific genotypes.Therefore, to develop the coffee, it is necessary to study the germplasm from the island of Sumatra.
Coffee producers on the island of Sumatra are in five provinces producing Arabica and Robusta coffee.The provinces of Nangroe Aceh Darussalam and North Sumatra are producers of Arabica coffee and have specialty coffee, namely Gayo Coffee, Mandailing Coffee and Lintong Coffee.The provinces of South Sumatra, Lampung and Bengkulu are known as the coffee triangle area, because they are Indonesia's main robusta coffee producers.Based on this phenomenon, it is necessary to study Arabica coffee genotypes from Sumatra Island based on agronomic, physiological and productivity characteristics.
An important phase in cultivating coffee plants is when the plants enter the young or immature plant phase.The phase requires good maintenance, so that the plants grow optimally.Optimal growth will determine the success of plants entering the productive phase, namely producing plants so as to provide productivity according to their genetic capabilities [12,13].The agronomic properties of unproducing plant will greatly determine the success of Arabica coffee productivity.The agronomic properties of Arabica coffee need to be studied because it can be used as a selection criterion high productivity in the juvenile phase.Selection carried out in the juvenile phase will shorten the selection time for highyielding.Selection can be carried out if the variability in the population from Sumatra is quite wide.
Genetic variability greatly influences the success of the selection process in plant breeding programs.Efforts to obtain genotypes that are suitable for an area, it is necessary plasmanutfah with wide enough genetic variability.Wide enough variability will make the goals to be achieved can be achieved in a short time [14].The study of diversity is very important to determine the amount of genetic diversity in a population [15].The success of a plant breeding business is largely determined by the existence of a wide genetic diversity.This diversity is needed for selection (selection) in order to get the selected genotype.The variability of the agronomic traits of Arabica coffee can be studied by calculating the coefficient of genetic and genetic diversity in the Juvenile phase, i.e. in immature plants.
Germplasm originating from Sumatra, which is spread across the Provinces of Nangroe Aceh Darussalam and North Sumatra, as well as from the coffee triangle area, has no known kinship.Therefore, it is necessary to study the relationship between gentotypes from Sumatra based on cluster analysis.The more similarities in agronomic characters possessed, the closer the kinship was, conversely, the more distant the character similarities, the further the kinship between genotypes in a population [16].

Materials and methods
The research was carried out at the Alnopri Coffee Center Experimental Station in Bengkulu City at a height of 10 meters above sea level.The time of the research starts from May to August 2023, with observations every three weeks for 4 observations.
Data analysis was carried out based on Genetic Diversity Coefficient = genetic variation/average value Penotypic Diversity Coefficient = penotypic variety/average value.Cluster analysis was carried out to produce a similarity matrix to group plant samples based on the agronomic characteristics of Arabica coffee plants using a dendrogram.

Results and discussion
The growth of Arabica coffee plants in the first year immature plant phase is represented by the characteristics of plant height and stem diameter.The growth characteristics of plant height and stem diameter cultivated in the lowlands are presented in Figures 1 and 2.   Figure 2 shows that the growth in stem diameter from the first observation in June 2023 experienced a steady increase without fluctuating.At the end of observations in August 2023, the diameter ranged from 7 cm to 10 cm.These data provide an illustration that the growth in diameter of Arabica coffee stems is good and illustrates the robustness of the plant quite well.Genetic variability and agronomic traits of Arabica coffee from Sumatra Island cultivation in the lowlands are presented in Table 2. Table 2 shows that the characteristics of number of segments and length of primary branches have narrow variability values.The characteristics of plant height, stem diameter, and internode length have moderate variability values.The nature of the number of pairs of leaves and canopy area has wide variability values.The distribution of these variability values indicates that the plasmanutfah population studied is still too small, so it is necessary to add Arabica coffee genotypes from other areas on the island of Sumatra.
Based on this variability value, the agronomic characteristics of the number of pairs of leaves and canopy area can be used as selection criteria to obtain arabica coffee that is adaptableto lowland cultivation.Genetic improvement in the number of pairs of leaves and canopy area can be improved through mass selection in the juvenile phase.Genetic improvements in plant height, stem diameter, number of internodes, internodes length, and primary branch length can be carried out through family selection in the adult generation.This is as done by Suhaendi [17] on Eucayptus urophylla S.T. Blake.Analysis of genetic similarity can be carried out based on agronomic characters, although it has several weaknesses such as the large influence of the environment and the interaction of dominant-recessive genes.Similarities and dissimilarities between the tested Arabica coffee genotypes can be seen using group analysis in the form of a phylogenetic tree or called a dendrogram.The kinship dendrogram is a description of the closeness of 9 Arabica coffee genotypes presented in Figure 3.
Analysis of genetic similarity can be carried out based on agronomic characters, although it has several weaknesses such as the large influence of the environment and the interaction of dominantrecessive genes.Similarities and dissimilarities between the tested Arabica coffee genotypes can be seen using group analysis in the form of a phylogenetic tree or called a dendrogram.The kinship Dendrogram is a description of the closeness of 9 Arabica coffee Genotypes presented in figure 3. The results of the cluster analysis based on the agronomic properties of Arabica coffee on the island of Sumatra showed that 9 genotypes were collected into two clusters.Cluster I consists of genotype number 1. Kopi Karo 2. Sidikalang 3. Lintong 4. Mandailing 5. Sipirok 6. Tarutung 7. Sigararutang and 8. Gayo.Cluster II consists of genotype number 9 (Pasemah coffee) from South Sumatra Province.South Sumatra Province is the number 1 producer of robusta coffee in Indonesia.Local Arabica coffee in South Sumatra is known as "Padang Coffee", because it can grow on the sidelines of Robusta coffee in community coffee plantations ("padang").
Cluster I which consists of 8 genotypes is Arabica coffee from North Sumatra (numbers 1 to 7) and Arabica Coffee from Nangroe Aceh Darussalam (number 8).Geographically, the Nangroe Aceh Darussalam and North Sumatra are directly adjacent, so they have not very different agro-climatic factors.The phenomenon of close correlationships based on the proximity of the Arabica coffee area on the Sumatra is in accordance with the opinion of [18] on durian.Genetic expression of a cultivar can occur optimally when the plant is in a suitable growing environment.Agro-climatic factors in a region greatly determine the diversity of durian genotypes.

Conclusions
The agronomic growth type of unproducing arabica coffee on Sumatra Island cultivated in the lowlands is normal.The genetic variability is narrow and the agronomic characteristics of the Arabica coffee population on Sumatra Island are narrow to broad.Agronomic traits, namely the number of pairs of leaves and canopy area, have wide variability so they can be used as traits for selection.Relationship between Arabica coffee germplasm.The island of Sumatra has 2 groups based on regional proximity, so the germplasm collection must be increased.

Figure 1
Figure1shows that the growth in plant height every three weeks, starting from the first observation on June 3, 2023, has increased steadily, not fluctuating.At the end of the observation on August 5, 2023, the plant height ranged from 40 cm to 60 cm.This growth pattern illustrates that the height growth of Arabica coffee plants is normal.

Table 1 .
Table 1 and estimation of variance was carried out based on the 3 analysis of variance approach at one location and one season.Analysis of variance and middle square expected value.

Table 2 .
Genetic Variability and Typical Characteristics of Sumatran Arabica Coffee.