Grafting Technology Supports Increased Productivity Nutmeg in Indonesia

. The productivity of nutmeg in Indonesia is still low, so it is important to increase it so that farmers' income increases and their cultivation can be sustainable. The purpose of this review is to obtain technology that can increase the productivity of nutmeg. The method used is a literature study on plant characteristics, planting conditions, and the development status of nutmeg in Indonesia. The results show that the nutmeg plant is dioceous so that there are male, female, and hermaphrodite plants and those that bear fruit are female and hermaphrodite plants. One of the main causes of low productivity is the high percentage of male plants. The development of nutmeg still uses seeds and at the seed stage the sex is unknown. So that at the time of planting could not determine the composition of male and female plants. To overcome this by propagating vegetatively and what has been successful is epicotyl grafting technology. This technology is not widely known by farmers and has not been used in the development of nutmeg. If epicotyl grafting technology is used to produce plant materials in extensiﬁcation and rehabilitation activities, the productivity of nutmeg in Indonesia will increase.


Introduction
Nutmeg is a native plant of Indonesia and has become an export commodity with high economic value and a foreign exchange earner as well as absorbing potential workers.Currently in Indonesia there are two types of nutmeg that have economic value, namely Myristica fragrans Hout originating from the Maluku islands and Myristica argentea Warb originating from Papua.Indonesia is the largest producer of Myristica fragrans nutmeg in the world and the only producer of Myristica argentea nutmeg.Fruit, mace, essential oil and nutmeg fat are widely used in the food, beverage, cosmetic industry [1] ; [2], the pharmaceutical industry and have pharmacological effects [3] ; [4].Indonesia is the first nutmeg producer to meet the world's nutmeg needs, the second is India, followed by Guatemala, Nepal, Sri Lanka, Laos, Bhutan, Tanzania, and finally Grenada.In 2019 the total export of Indonesian nutmeg in the form of whole nutmeg seeds, crushed nutmeg seeds, whole mace and crushed mace was 19,957.247kg with a value of US$.138,024,161 [5].
Nutmeg is a dioecious plant, so it is known that there are male, female and hermaphrodite plants.Generally, the ratio between males and females (sex ratio) in the field is 1:1 [6].In nutmeg plantations, only 55% of the 100 nutmeg seeds planted became female trees, while the others were male trees (40%) and hermaphrodites (5%) [7].One male nutmeg plant can pollinate 20-30 female plants [8] ; [9].Therefore, in a nutmeg garden, there are often quite a lot of excess male plants and their position is far from the female plants.The far distance between male and female nutmeg plants will affect the non-optimal pollination so that it does not produce optimally as well.This will be detrimental to farmers because many nutmeg plants do not bear fruit, and is one of the factors causing the low productivity of Indonesian nutmeg.Efforts are needed to increase the productivity of Indonesian nutmeg to support the program Reviving the Glory of Indonesian Spices.Increased productivity of nutmeg will increase farmers' income as well as receive foreign exchange so that their cultivation will be sustainable.Increased productivity is one indicator of sustainable agriculture [10] ; [11] One of the efforts to support increasing the productivity of national nutmeg is by applying grafting technology for the supply of nutmeg plant material using scions (entres) from female plants of varieties that have been released or selected parent trees that have been determined.Currently, there are 8 varieties of nutmeg that have been released by the Ministry of Agriculture, namely Tobelo 1, Tidore 1, Ternate 1, Banda, Makian, Fak-Fak, Nurpakuan Agribun, and Tiangau Agribun which can be used as a source of scions.Through nutmeg grafting technology, the sex of the plant can be known starting from the seed stage.Thus, at the time of planting, the composition of males (5%) and females (95 %) can be determined, so the number of plants that bear fruit is more with high production so that the productivity of Indonesian nutmeg can be increased.

Nutmeg plantation condition in Indonesia
Most of the nutmeg in Indonesia is cultivated in the form of smallholder plantations, which is 95.02% and the rest is in the form of large company plantations [5].In 2019, the total area of Indonesian nutmeg reached 240,620 hectares consisting of smallholder plantations covering an area of 228,640 hectares, large state plantations covering 489 hectares and large private plantations covering an area of 14 hectares.The average increase in the area of nutmeg in 2010-2019 reached 7.47% per year and the average production was 9.47%.However, the increase in area and production was not accompanied by a modest increase in productivity which was only around 3.52% per year.
The national average productivity of nutmeg has always been no more than 0.55 tons/ha, even in the last 6 years the average has only reached 0.51 tons/ha [5], while the potential for nutmeg varieties that have been released has reached 3.68 tons/ha.This shows that the area expansion has not had a significant impact on national nutmeg productivity, so it is not efficient in land use.The low productivity is not only due to the lack of application of nutmeg cultivation technology as recommended, but also because of the large number of plants that do not bear fruit or are not productive because they are propagated from seeds.Nutmeg plantations in 10 nutmeg production centers showed differences in cropping conditions, production and productivity (Table 1).[5] The range of nutmeg productivity in ten production centers showed the lowest of 217 kg/ha to the highest of 1.131 kg/ha.Several factors that cause the wide range of nutmeg productivity due to differences in: 1) land suitability and climate, 2) plant materials used, 3) cultivation techniques applied, and 4) the number of old nutmeg plants.The ten centers of nutmeg production, the rehabilitation activities of nutmeg plants show a high level of rehabilitation, so that the plants that have not yet produced are between 36.15% -90.64 % compared to those that have produced between 22.42% -52.02%.This rehabilitation activity is very important to replace old or damaged nutmeg plants with superior nutmeg plants so that their productivity is expected to increase.Maluku Province has the largest plant area that has produced 17,851 ha with a production of 5,571 tons, while North Sulawesi has a lower mature plant area of 10,031 ha with a higher production of 11.341 tons.This is because Maluku Province has a lower productivity of nutmeg at 312 kg/ha compared to North Sulawesi with a higher productivity of 1.131 kg/ha.Therefore the level of productivity is very important to improve the efficiency of land use.

Strategy to increase productivity of nutmeg
Research has been carried out with the aim of increasing the productivity of nutmeg to produce superior varieties, good rootstock and scion preparation, and grafting technology using the epicotyl grafting technique.

Superior varieties of nutmeg
The results of the selection of mother trees in high yielding blocks in several nutmeg production centers have successfully released 8 high-yielding varieties of nutmeg, namely Banda, Ternate 1, Tidore 1, Tobelo 1, Makian, Fak-Fak, Nurpakuan Agribun, and Tiangau Agribun ( Table 2).The essential oil content in mace ranges from 3.27% -20%, and the largest is the Banda variety.While the essential oil content in the seeds ranged from 3.95% -13.13% and the highest was the Tiangau Agribun variety.The number of nutmeg seeds/kg dry peeled is between 100-200 grains and the most is the Tidore 1 variety.The fruit productivity of these 8 superior varieties of nutmeg is between 2,500-11,064 grains/tree/year.If the average weight of peeled dry seeds is 5.35 g/grain and the average productivity of nutmeg is 6.880 fruit/tree/year and the population per hectare is 100 trees, then the potential production of high-yielding varieties of nutmeg is 3.68 tons/ha.The enormous production potential of this superior nutmeg variety must be accompanied by the application of good cultivation technology so that its genetic potential can emerge.

Grafting propagation
Plant propagation by grafting requires the preparation of rootstock and scion and the grafting technique used.

Preparation of rootstock
Nutmeg seeds to be used for rootstock should come from selected parent trees with mature seeds and an average weight of > 9 g.Nutmeg seeds from Amasing and Papaloang have heavier nutmeg seeds than seeds from Babang.Seeds that are heavier in size indicate that they have more food reserves so that they germinate and germinate faster.The seeds from Amasing and Papaloang began to germinate on the 25 th day, while the seeds from Babang began to germinate on the 38 th day [12].Seed weight greatly affects the quality of rootstock growth and the success of grafting.This is because in the epicotyl grafting method of nutmeg grafting, the energy required for the connection between the scion and the rootstock relies heavily on energy sourced from the epicotyl.Seed growing media and seed treatment before sowing also affect the germination and speed of germination of nutmeg seeds.Two-hole physical scarification treatment could increase nutmeg seed germination with earlier root and shoot emergence.Sand media is a significantly better medium with increasing germination and shoot height.Scarification of two-hole nutmeg seeds planted in sand media resulted in significantly higher number of lateral roots and better growth of nutmeg seeds in sand media [13].In addition to the sand medium, there are other media that have a good effect on the germination and speed of germination of nutmeg seeds, namely a mixture of soil: fine coir: sand: vermicompost (1:1:1:1) [15].

Preparation of scion (entres)
To support the production and development of grafted nutmeg seeds, it is necessary to have a scions garden of varieties that have been released or selected mother trees that have been established.However, until now there is no nutmeg mother garden available for vegetative propagation (grafting).Entres mother garden developed from vegetative propagation is an attempt to duplicate parent trees of varieties that have been released or selected parent trees that have been determined which are limited in number and far from the grafting site.If the scion source is far from the grafting location, it is necessary to treat the shoots to keep them fresh from the scion location to the grafting location.Entres put in a plastic bag and then covered with a moist soft fiber will maintain the freshness of the nutmeg scions for up to 10 days and the success of the grafting 62.2% to 63.7% for each [15].The scion used can be derived from plagiotropic shoots (fruit branches) or orthotropic shoots (water shoots).Nutmeg plants that were grafting using scions from orthotropic shoots had better morphological characters than those from plagiotropic shoots [16] (Table 3).The crown shape of orthotropic shoots grew more completely upwards, while nutmeg plants which were grafted with plagiotropic shoots grew wider (Figure 1).Therefore, nutmeg plants grafted with orthotropic shoots can be planted with wider spacings such as 10 m x 10 m, while nutmeg plants grafted with plagiotropic shoots can be planted with narrower distances such as 5 m x 5 m.

Nutmeg grafting technology
Research on the propagation of nutmeg by shoot grafting has been carried out in India since 1979.Grafting using the cleft graft method and the Myristica beddomei wild nutmeg rootstock resulted in 12% success in grafting, then increased to 48% using dormant scion shoots.The success of grafting nutmeg increased again with the treatment of grafting time in August (80%) and September (74%) [15].The treatment of growth regulators IBA and NAA at a dose of 500 ppm resulted in the success of grafting nutmeg at 37.33% and 43.03%, respectively [17].The results of several studies that vegetative propagation of nutmeg can be done by using epicotyl grafting, soft grafting, budding, and approach grafting methods [18] ; [19] ; [20].

Epicotyl grafting technique
The study of grafting nutmeg in the nursery resulted in a successful grafting of > 80 using the epicotyl grafting technique.The epicotyl grafting is a grafting technique when the rootstock still has an epicotyl.Grafting technology is also applied to jackfruit [21], walnut [22], cashew [23], mango plants [24], and clove [25].The stages of nutmeg grafting to produce a successful grafting > 80 are as follows (Figure 2): In the epicotyl grafting technology on nutmeg, what needs to be tried is the bonding of the rootstock with the scion.Until now, they are still using plastic straps.The material that has the potential to be used is silicone hose and has been applied to clove grafting [25].Grafting results are of better quality and require less time.

The potential for grafting in the field (top working) to increase the productivity of nutmeg
Top working has been successfully carried out on citrus [26], apple [27], mango [28], walnut [29], and cashew nuts [30].Meanwhile, top working on nutmeg plants is still at the trying stage, so further research is still needs to be done to get high success.Top working is carried out on existing nutmeg plantations with the aim of: 1) to replace female nutmeg plants with low production by grafting high-yielding varieties of nutmeg, or 2) to replace male nutmeg plants by grafting high-yielding female nutmeg scion.Replacement of male nutmeg plants is divided into 2 stages of age, namely 1) grafting on new flowering nutmeg plants aged 5-7 years and the sex is known.The grafting is done directly on the dominant apical.In male nutmeg plants that are > 10 years old, pruning is done to a height of ± 1.5 m above the soil surface so that later new shoots will grow for grafting with female entres of high-yielding varieties of nutmeg (Figure 3).

Extensification and rehabilitation of nutmeg plantations
One of the efforts to increase the productivity of Indonesian nutmeg is by applying grafting technology that uses scions from superior varieties in the procurement of plant material for extensification and rehabilitation activities.These activities must be accompanied by the application of correct nutmeg cultivation technology (Good agriculture practices), because the genetic potential of superior varieties will not appear if they are not maintained properly.

Extensification
Extensification activities that began in 2020 covering an area of 100 ha then increased sharply in 2021 to 8,000 ha, in 2021 an area of 7,450 ha, in 2022 an area of 6,650, and in 2024 an area of 6,750 ha, so the total area for 5 years is 28,950 ha.The need for plant material for the extensification activity is 3,474,000 plants (Figure 4).The need for plants per hectare is 120 plants so that the spacing used is 9 m x 9 m.The results of observations in the Cicurug Research Instalation-RISMC, nutmeg plants which are planted rarely 8 x 8 m, the crowns between plants have overlapped at the age of 24 years [31].In the overlapping canopy conditions, the humidity in the nutmeg plant canopy is high enough to trigger disease attacks, especially nutmeg rot.Therefore, the determination of a spacing of 9 m x 9 m is good enough but it would be better if the distance is widened to 10 m x 10 m, so that sunlight can enter the canopy and between the nutmeg plants.Thus the humidity in the canopy will be low so it will avoid disease attacks.

Rehabilitation
Rehabilitation can be interpreted as an activity to increase productivity by replacing old or damaged nutmeg plants with nutmeg plants that are grafted to superior varieties.The rehabilitation program implemented by the Directorate General of Estate Crops, starting in 2020 with an area of 1,500 ha, increased sharply in 2021 to 10,550 ha, in 2022 an area of 10,200, in 2023 an area of 9,800 ha and in 2024 an area of 8,850 ha, bringing the total area of rehabilitation for 5 years to 40,900 ha.For the rehabilitation activities, a total of 2,454,000 plants of nutmeg seeds are required.Plant seeds for rehabilitation needs are expected to be seeds of nutmeg plants that are grafted with high-yielding varieties and have taken into account the needs of male and female plants.
Rehabilitation in nutmeg plantations can also be interpreted as an activity to increase the productivity of existing plantations (existing nutmeg plantations) by replacing low-producing female nutmeg plants or replacing male nutmeg plants with superior varieties of female nutmeg through direct grafting in the field (top working).Thus it will change the proportion of sex ratio that was previously not ideal (number of male nutmeg plants > 40% or 4 : 10) to be ideal (number of male nutmeg plants < 10% or 1 : 10), so that production increases from 60% to 90%.

Conclusions
One of the efforts to increase the productivity of nutmeg in Indonesia is by providing plant material from vegetative propagation.The technology for propagating nutmeg in nurseries that has been successful is the epicotyl grafting technique with a success rate of >80%.Another grafting technology that has the potential to be developed is grafting in the field (top working) using the top grafting technique.Top working is very appropriate for existing nutmeg plantations in plant rehabilitation activities.At present the top working on nutmeg is still in the try stage, so further research is needed to obtain a high success rate.

Fig. 2 .
Fig. 2. The stages of grafting nutmeg with the epicotyl grafting method

Fig. 3 .
Fig.3.Replacement of male nutmeg by grafting high-yielding varieties of female nutmeg shoots

Fig. 4 .
Fig. 4. Extensification and rehabilitation developments target and the number of seeds needed in 2020 -2024.

Table 1 .
Nutmeg plantation conditions in 10 production centers

Table 2 .
Description of eight high yielding varieties of nutmeg

Table 3 .
Effect of orthotrope and plagiotrope shoots on the growth of nutmeg grafting at 20 months of age.Numbers followed by the same letter in the same column are not significantly different at the 5% level.