Lecturer of Doctoral Program of Agricultural Science Department, Postgraduate Program of Uniersitas Medan Area
The campus forest park of Universitas Medan Area is located in Campus I, Jalan Kolam, Medan Estate/Jalan Gedung PBSI, Medan (Figure 1A) . It has a collection of rare plants and annual plants providing the aesthetic of campus environment. Universitas Medan Area is the only one higher education institution in North Sumatra owning a campus forest park that functions not only as a place for plant conservation but also as an educational facility of plant diversity. The campus forest park is one of the assessment parameters that makes UMA become the best private university in North Sumatra and ranked 17th at the national level in UI GreenMetric World University Rankings system that was followed by 72 universities in Indonesia or ranked 230th at the international level out of 780 world universities from 85 countries that participated as green campus based on UI GreenMetric version. UMA is committed to environmental management on campus with various indicators set, such as the ratio and total of green open space in the campus environment, energy efficiency, and utilization of renewable energy, water and waste management, to the availability of zero emission transportation in campus .
Figure 1. Campus Forest Park of Universitas Medan Area. Source : https://ma.uma.ac.id/taman-hutan-kampus/
The campus forest park of UMA plays an important role as the area of education and research for lecturer and student with its main function as a conservation area of biodiversity. One of the biodiversity of plant groups that has high economic value conserved in the campus forest park area is the velvet apple. It is a plant of the Ebenaceae family whose population has been greatly decreased due to the high rate of deforestation. This plant is known as buah mentega atau buah lemak in Malay and called sembolo in Java. Its scientific name is Diospyros discolor with the synonyms of Diospyros blancoi A.DC., Diospyros durionoides Bakh., Diospyros malacapai A.DC., Diospyros merrillii Elmer, Diospyros utilis Hemsl.,dan Cavanillea philippinensis Desr. Based on the scientific classification, it belongs to the kingdom: Plantae. Division: Magnoliophyta. Class: Magnoliopsida. Order: Ericales. Family: Ebenaceae. Genus: Diospyros. Species: Diospyros discolor. It grows well at an altitude of about 0 to 800 masl, and can grow on almost all types of soil  and it is found that it comes into flower in December and ripen in March to May in the campus forest park of UMA .
This type of fruit comes from the Philippines and was introduced to the Bogor Botanical Gardens in 1881 . Velvet apple is a plant that has high economic value due to its high nutritional content, especially fiber, vitamins and antioxidants. Every 100 g of velvet apple contains 2.8 g of protein, 0.2 g of fat, 11.8 g of carbohydrates, 1.8 g of fiber, 46 mg of calcium, 18 mg of phosphorus, 0.6 mg of iron, 35 IU of vitamin A, 18 mg of vitamin C, 0.02 mg of thiamine, 0.03 mg of riboflavin, and 332 kj/100 g of energy. It also contains secondary metabolites including flavonoids which act as antioxidants so that the fruit is used to treat wounds and mouthwash in cases of thrush or aphthous stomatitis . The leaves have antioxidant activity with an IC50 value of 15.06 g/mL , the ethyl acetate fraction of velvet apple juice has a very strong antioxidant power with an IC50 value of 30.0 g/mL . The total flavonoid of a ripe velvet apple is 0.56% and 0.55% for the raw one . The flavonoid content is also found in seeds with a level of about 17.03 to 17.85 %.
The plant height of velvet apple can reach 15-30 meters (Figure 1A,1B). The stem is straight with black bark and the diameter of the base is about 50 cm. The canopy of the tree is similar to a cone with horizontal and terraced branches and dense leaves. The leaves grow alternately and are oval in shape with flat edges, a rounded base and a tapered tip. The upper side of the leaf is shiny dark green while the underside is silver and downy. The flowers appear in the axils of the leaves. The fruit is round or flattened with a size of about 5-12 × 8-10 cm. The rind is downy with a color of reddish brown, bright red and turns slightly dull when it ripes (Figure 1C). The pulp is yellowish white, slightly hard and dense, slightly dry, sweet and a bit sour (Figure 1D). The fruit smells good and is a bit hard like the smell of cheese and durian. It has brown seeds with a hard seed texture, and it has 2-10 seeds in an velvet apple (Figure 1 E).
Figure 1. Velvet Apple (Diospyros blancoi A.DC) in the Campus Forest Park of Universitas Medan Area. Source: Suswati.Doc.2022
For the purpose of velvet apple conservation, the research group of Lecturers and Undergraduate students of Agrotechnology Department of Faculty of Agriculture of Universitas Medan Area has carried out plant propagation by seeds. The seeds obtained from ripe fruit are collected and washed with tap water and dried by placing the seeds on the tissue. The seeds are placed in a plastic box where the bottom of the box is given a damp tissue. The seeds of velvet apple are arranged on a tissue 3-4 cm apart and the top of the seeds is also given a layer of damp tissue. The plastic box containing the velvet apple seeds is placed in a safe location. Every 3 days the tissue is sprayed with sterile water until the 24th day. The seeds will germinate on the 24th day and then the seeds can be transplanted into a polybag with a size of 10 cm x 25 cm containing a mixture of soil and manure (3:1). The application of 10 g of mycorrhizae per sprout is carried out at the time of transplanting. The results showed that mycorrhizae could increase seedling performance and seedling resistance to pests and diseases . The results of velvet apple seed propagation using mycorrhizae can be seen in Figure 2.
Figure 2. The Growth of Velvet Apple (Diospyros blancoi A.DC) seedlings with mycorrhizal application. Source: Suswati.Doc.2022.
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