The sustaining agro-biodiversity through topworking approach: a case of local superior durian conservation on Mount Arjuna

On the slopes of Mount Arjuna there are durian growing areas that are similar to durian forests, and produce a very high diversity of durians. Through the fruit festival, four local durian varieties of good quality have been selected, namely Dupen, Gundul, Tahan and Bawuk. To preserve these varieties, farmers take a top working approach, which replaces unqualified plants with superior varieties. The implementation of topworking in two ways, namely grafting shoot buds and grafting inserts on the trunk of mature plants. The implementation of topworking is carried out by farmers who own the parent tree and non-owners of the parent tree. The results showed that the technique of cutting stems and then grafting shoots was significantly higher than the topworking method of grafting inserts on the trunk of the plant. The success rate of topworking is impacted by the genetic material ownership system. Owners of parent trees consistently perform at a higher level than non-owners, as evidenced by their higher percentage of top working success. The Gundul durian variety, which exhibits a significantly higher percentage of growth than other varieties because the branching arrangement in the tree architecture of the Gundul variety is lower than that of other varieties, demonstrates how the ease of taking enteris also influences the success rate of topworking. This strategy encourages the growth and reproduction of multiple local durian varieties on a single mature plant on the slopes of Mount Arjuna while also enhancing fruit quality by substituting inferior durian varieties with the farmer’s preferred superior durian varieties.


Introduction
Durian (Durio zibethinus Murr) is one of the horticultural plants whose fruit is dubbed the king of tropical fruits, tastes good and has high economic value [1].The predicate as the King of Fruit was first expressed by [2] which contained an article entitled "On the Bamboo and Durian of Borneo" [2] [3].Durian has a natural habitat in the form of forests in tropical climates.As a tree growing in wet rainforests, durian trees typically reach heights of 30-40m [4] and diameters of 2-2.5m, but cultivated varieties in orchards, especially those derived from grafting seedling trees, grow to no more than 12m [5].The distribution of durian stretches from the lowlands to a maximum altitude of 800 meters above sea level, covering Southeast Asia, India, to Pakistan.Environmental conditions that have humidity between 50-80%, with a temperature range of 25 0 -32 0 C are suitable for the growth of durian trees.
The center of ecological diversity for durian is the island of Borneo [6][7] [3], where the fruits of edible Durio species including D. zibethinus, D. dulcis, D. graveolens, D. kutejensis, D.oxleyanus, and D. testudinarium are sold in local markets [8].But the potential agricultural commodity for domestic and international markets is still only D. zibethinus durian, so that this commodity is currently considered a prospective export commodity [9].East Java is the region that produces the most durian in Indonesia in 2021, namely 275,319 tons which is equivalent to 20.35% of the total durian production nationally [10].However, compared to similar commodities from two neighboring countries, namely Thailand and Malaysia, the quality of Indonesian durian is still less competitive (significantly lower) to meet the export market [11].The hills of the eastern slopes of Mount Arjuna, which are included in the Pusuruan Regency, East Java, contain durian growing areas that are similar to durian forests, and produce very high durian diversity [12].This biodiversity is threatened by climate change, habitat destruction, and environmentally unfriendly human activities.This can lead to the extinction of superior local clones, and have a negative impact on the sustainability of human life and the environment.Therefore, it is important to make efforts to conserve local superior durian on Mount Arjuna, because it has high economic value and is one of the most sought-after durian species in Indonesia [13].Meanwhile, durian fruits circulating in the market come from forest plants grown from seeds, and the origin of the variety is unknown, making it difficult to determine the characteristics and quality of the fruit that are right for consumers and market demand.The strategy used in improving the quality of durian in this region requires the selection of plants that meet national durian quality standards, then clonally propagated.The first step is to identify and select promising mother trees through durian fruit festivals.In general, durian fruit festivals in a region are used to preserve the germplasm of local durian plants in the region, including looking for the best potential durian variants to be used as parent trees that are expected in the future to become the flagship superior fruit of the region concerned, using durian festival guidelines contained in the durian fruit assessment standard guidelines [14].The next stage is to characterize and test them over time and in different locations to determine their adaptability.Selection is based on characteristics, including fruit shape, size, odor, color, texture, taste, and tree growth habit [15].As with fruit crops in general, the main challenges are the long juvenile period, long growth cycle, and large tree shape, sterility, allelic incompatibility, polyploidy, and inherent heterozygosity.Incompatibility between durian clones may require the use of complementary clones [16].To shorten that long period, researchers use an approach often called topworking, which involves cutting a durian tree of unknown origin, then the growing shoots are spliced with enteric from a superior variety of durian.The topworking method involves grafting a scion obtained from the desired variety onto the buds that emerge from the transversely cut stem during the rainy season [17].The seasonality of topworking varies slightly from species, as it also depends on the availability of good buds and scions.The scion and rootstock to be joined should be of the same thickness.The advantages of topworking include increasing crop productivity, conversion of old plantations into productive plantations, conversion of nursery plantations or plantations of inferior varieties into new plantations of desired varieties, possibility of grafting several varieties on the same rootstock plant, generating additional income by selling pruned wood during non-fruiting seasons or periods.Disadvantages include the possibility of plant death if not done properly, requiring good management after the pruning period, loss of yield for 2-3 years, and requiring skilled labor for shoot grafting [18].
Research with the aim of obtaining the best working approach in maintaining the diversity and conservation of local superior durian on Mount Arjuna.This research is also expected to provide useful recommendations for local communities, government, and conservation experts in maintaining durian diversity and ensuring the survival of local superior durian in the area.

Methodology
Research to conserve the diversity of durian genetic resources through the topworking approach was conducted from September 2021 to November 2022, taking the locus in the hills of the eastern slope of Mount Arjuna in Pusuruan Regency, East Java Province.Durian diversity in this region is centered in Purwosari sub-district, which is located between Purwodadi sub-district, Sukorejo sub-district, Wonorejo sub-district, a small part bordering Prigen sub-district, lying at 7.30'-8.30'South latitude and 112°30'-113°30'East longitude.The area is a medium to highland with altitudes ranging from 400 m above sea level (asl) to more than 1000 m asl., with land surface conditions sloping to the East and North between 15-65%.The slopes of Mount Arjuna have two types of climate change each year, namely the dry season and the rainy season.October to April is the rainy season, while May to September is the dry season where durian harvest occurs in October-January and depends on the variety.
In the locus area, there are durian planting areas that are similar to durian forests, and produce very high durian diversity.Durian fruit circulating in the market comes from forest plants grown from seeds, and the origin of the variety is unknown.The research was carried out in two stages, namely:

Selection of superior plants
Selection of superior durian plants using the durian contest process by the community, starting with a announcement to the community of durian tree owners, community leaders and durian traders.Then determine the certainty when implementing the contest by paying attention to the opportunity for the availability of fruit as contest material.Prospective participants are asked to register with the Contest Committee coordinated by P4S Karekso, with the requirement to bring a minimum of 3 fruit samples per plant with optimal durian fruit harvest.The jury consisted of five people, namely from elements (1) representing the national durian contest jury appointed by the Directorate General of Horticulture, Ministry of Agriculture as chairman of the jury, (2) representing the National Durian Lovers Group, (3) representing the durian traders association, (4) representing durian breeding expert researchers from the National Research and Innovation Agency (BRIN), ( 5) representing durian farmer community leaders.Before conducting the assessment, the jury conducted a common opinion on the assessment procedures, led by the Chairman of the Contest Committee.The assessment procedure uses the hedonic test procedure, which gives a value to each element that supports the quality of the fruit by tasting the fruit and reasoning through the naked eye of the jury on the appearance that supports the quality of the fruit.The scoring criteria are based on the National Standard Guidelines for Durian Grading [13].In deciding the selected fruit number is superior to the others using durian ideotype criteria as described by [19] presented in table 1.Meanwhile, for varietal characterization using guidelines Descriptors for Durian from Bioversity International [20].Stages of topworking with shoot grafting technique, as follows (1).Select durian trees from seeds that are large enough (φ = 10-15 cm, (2).Cut the selected tree at an angle of about 200, so that water does not stagnate on the former cutting of the trunk or running water to avoid rotting the durian trunk, (3).Let the shoots grow on the trunk until about 3-5 weeks, (4).Select the "yuyu" eyed entres that will be connected, (5).Connect the entres to the buds that have grown to the size of a pencil, using the slit grafting technique, (6).Maintain the stem of the grafting results as the main tree, (7) three or four months after grafting, observe the number of durian trees tukulan from seeds that successfully topworking, (8) calculate the performance of the group in the preservation of durian local superior varieties.

Selection of superior plants
Diversity among durian trees in producing fruit, because of its cross-pollinated nature, so to determine the location-specific parent tree as a durian brand from the slopes of Mount Arjuna, durian fruit competition is needed.Participants of the competition are stakeholders.Stakeholders consist of collecting traders, farmers, farmer groups, self-help extension workers (P4S) Karekso, field agricultural extension officers, village officials, durian lovers groups, Pusuruan District Agriculture Office, and researchers from the Horticulture and Plantation Research Center, BRIN.Prospective participants are asked to register with the Contest Committee coordinated by P4S Karekso, with the requirement to bring a minimum of 3 fruit samples per plant, optimal harvest of ripe durian fruit, and registrants consist of 21 participant numbers with serial numbers 1 to 21.
Based on the quality assessment criteria of durian fruit, it refers to the National Level Durian Assessment Standard Guidelines issued by [14].In deciding the selected fruit number, the criteria for durian ideotypes as described by [19]   Character values that become the selection criteria as an indicator of superior durian determination are presented in table 2, it appears that the durian competition participants in the slopes of Mount Arjuna with participant numbers 3, 5, 8 and 11 as the winner of the competition, respectively with a value of 39, 46, 41, 36 supported by a fairly high hedonic test assessment of 717, 613, 641 and 668 respectively.Henceforth, according to the original names of durians in the region, participant numbers 3, 5, 8 and 11 are called Dupen, Gundul, Tahan and Bawuk durian varieties, respectively.But only the Gundul durian variety really fulfills the pre requisites of national superior durian, because the portion of fruit consumed is more than 30%, the seeds are deflated, and can flower twice a year.Meanwhile, Dupen, Bawukand Tahan durian trees, whose fruit flesh belongs to the thick class, but the portion consumed is lower than 30%, because the seeds are firm, still receive attention in varietal characterization.The fruit characteristics of each variety are presented in figure 1.

Variety characterization
In an effort to facilitate the development of new plants, durian trees whose fruit won the competition were characterized in order to provide information on important plant traits.This information can also help in accelerating a more efficient and effective plant selection process.Characterization such as resistance to pests, diseases, and certain environmental conditions.This information is important for the development of new varieties that are more resistant to adverse environmental conditions or diseases.Characterization can help maintain plant genetic diversity.This is important to maintain the availability of genetic resources for future access and to reduce the risk of losing plant species.Characterization also helps in determining plant identity more accurately.This is important to maintain food safety and to ensure that products delivered to the market are of the desired variety.The characterization results of Dupen, Gundul, Tahan and Bawukdurians are presented in table 3.

Performance of Forest Farmers Group in preserving local superior durian
The performance of Forest Farmer Groups (KTH) in preserving local superior durian can be calculated from the degree of success in implementing topworking.Topworking applied by the three farmer groups, is to replace durian plants of unknown origin that grow in farmers' fields, and often people call it "durian snippet from seeds" replaced with local superior varieties that have been selected, namely durian varieties Dupen, Gundul, Tahan and Bawuk.This topworking practice with a period of about four months after grafting, shows that three KTH consisting of 30 members have multiplied four local superior durian varieties totaling 846 trees or the equivalent of eight hectares of durian germplasm garden if the distance between durian plants is 10 m × 10 m.Observation data on the success of topworking showed that the performance of KTH on the slopes of Mount Arjuna reached 63.4% of the total durian trees snippet from seeds of unknown origin of 1,334 trees successfully repaired with four local superior varieties as show in table 4. Durian variety Gundul showed a higher percentage of topworking growth than other varieties, both the grafted PIT owner in his own garden and the grafted durian trees in other people's gardens than the grafted garden owner for durian trees in his own garden.This description shows that the Gundul durian variety deserves to be developed on a commercial scale, not just for the preservation of genetic resources, because this variety meets the standards of national superior varieties, is easier to breed vegetatively, and is superior to the other three varieties (Figure 2) (Table 3).
PIT owners as grafters have a high role in determining the level of topworking success.This is indicated by the higher percentage of topworking success when he grafted durian trees in his own garden (69.9%) or grafted durian trees in other people's gardens (65.5%) than the percentage of topworking success carried out only by the garden owner (43.8%).Therefore, sociologically, the attitude of ownership of genetic material affects the level of success in varietal improvement and development.This is in line with the practice of biodiversity management and conservation efforts that involve active participation from local communities, including management by farming

Conclusion
Local superior durian on the slopes of Mount Arjuna has an important value as part of Indonesia's biodiversity that needs to be preserved, where the durian contest held in the region has succeeded in inventorying, characterizing, and documenting local superior durian comprehensively and systematically to support community-based land-based conservation activities Forest Farmers Group.

Figure 1 .
Figure 1.The appearance of the contest-winning durian fruit on the slopes of Mount Arjuna.Number 2: photo of Dupen durian fruit; Number 5: photo of Gundul durian fruit; Number 8: photo of Tahan durian fruit; Number 11: photo of Bawuk durian fruit

Table 1 :
[18]nesian durian ideotypes[18]PIT owners carry out grafting in other people's gardens, and (3) garden owners are not PIT owners carry out grafting in their own garden.PIT owners and durian farm owners used for observation of durian germplasm conservation model received intensive training on durian topworking practices.The implementation of topworking by the three farmer groups is to replace durian plants of unknown origin growing in farmers' fields, and often people call it "durian plants from seeds" replaced with local superior durian varieties of competition winners.
members per group, but those who carry out topworking by grafting shoots that grow from transversely cut stems, are sorted into three approaches.This sorting is related to the ability of the single parent tree (PIT) of each variety to provide entries, which is owned by only one farmer who must supply a sufficient amount to fulfill the durian area on the slopes of Mount Arjuna.For topworking must involve the PIT owner, and agreed sorting consists of (1) PIT owners carry out

Table 2 .
are presented in table 2. Assessment of the judges of the durian fruit competition in the Arjuna mountain slope area

Table 3 .
Description of Dupen, Gundul, Tahan and Bawuk varieties [22]own as Community Biodiversity Management (CBM)[21][22].The application of CBM takes into account traditional knowledge and local experiences in managing natural resources, which often prove effective in conserving biodiversity. communities