Preliminary communication THE POSSIBILITY OF CROP CULTIVATION AND UTILIZATION OF EDIBLE GUM FROM HERB ( DOREMA AMMONIACUM D . DON ) IN DRYLAND FARMING

Gum ammoniacum (Dorema ammoniacum D. Don) is one of the most important food, industrial and medicinal plants of Iran which is mainly distributed in semi-arid and desert areas. It is endangered due to superfluous and unsustainable harvesting methods. The objective of this study was to evaluate the possibility of crop cultivation in terms of dryland farming and the best operation method for collecting gum resin. For this purpose, the effects of different scarification methods (traditional, concave and staircase) and cut-off frequencies (5, 10 and 13 times) on gum yield of the five-year-old plants were studied at Toroq farm in Mashhad. The treatments were studied under a split plot structure in time experiment which was arranged in a completely randomized design with three replications. The rate of the root gum production and the rate of plant survival in the years after the withdrawal were measured, and finally the data were analyzed. Results showed no significant differences among cutting methods at p<0.05. The yield of gum was affected by times of harvesting and the highest yield was observed (p<0.01) in 13 cut-off times with 31.67 g/plant. The lowest gum yields were seen in 5 cut-off times with 5.84 g/plant. The traditional cutting method destroyed crown buds and caused the death of the plant (p<0.01). Reasonable gum yields and plant regeneration rates were obtained with the use of stairs method which is an easy method to be applied by the farmers or beneficiaries.


Introduction
Gums and resins, forming an important group of non-wood products of forest and medicinal plant products, are considered as the byproducts or end products of certain metabolic pathways.Gum is produced by a large number of plants of Apiaceae family such as asafetida, galbanum and ammonicum (Iranshahi, 2007).
The genus Dorema (Apiaceae) is represented in the flora of Iran with seven species among which Dorema glabrum Fisch.C.A. Mey, D. aucheri Boiss and D. ammonicum D. Don are endemic (Rajani et al., 2002;Mozaffarian, 2003).D. ammonicum D. Don is a perennial species growing up to 2.5 m in some locations in semi-arid and desert areas of Iran.It is distributed in the provinces Kerman, Isfahan, Tehran, Sistan Baluchestan, Khorasan and Semnan (Mozaffarian, 2012).Mohamadabad Ghaen is one of the main and most important natural habitats of Dorema ammoniacum for resin production in South Khorasan in Iran (Figure 1).Gum ammoniacum with hermaphrodite and self-fertile flowers prefers loamy, acid neutral or alkaline soils.Furthermore, it can grow in semi-shade conditions.Twenty-nine compounds were identified and quantified in ripe fruits of D. ammoniacum, representing 95.1% of the total oil.(Z)-Ocimenone (22.3%) and (E)ocimenone (18.1%) were the main components of the oil.The extract of ammoniacum gum shows antimicrobial activities.It is known as an aromatic gum resin (Iranshahi et al., 2007;Rajani et al., 2002), produced when the plant is stung by a beetle.They are present either in the intercellular space (ducts or cavities) of the root and crown parts or as exudates produced due to injury.The cavities formed due to injury are called traumatic ducts/cavities.The amount of volatile oil Ammoniacum (0.1-0.3%) is less than the amount either asafoetida (6-17%) or galbanum (10.6-32.8%)contains (Ghannadi and Amree, 2002;Khajeh et al., 2005).Its gum resin, being bitter, nauseous, and acrid, is used in the traditional medicine and is widely used in food, cosmetic and detergent industries (Pereira, 1854;Flannery, 1969).
The use of chemical tapping methods like ethephon (2 chloroelhyl phosphonic acid), a plant growth regulator, increases exudation of gum/gum resin in certain plants such as Acacia nilotica.Such methods have been suggested for the sustainable yield, regeneration and survival of the tapped trees (Raj, 2014).
The optimum temperature for this plant was observed at 30 o C, and an increase in the temperature decreased the germination percentages of the seed.Besides, the lowest germination percentage (0%) was recorded at 15 o C (Ghasemi Arian et al., 2009).
Millions of people worldwide, especially in the developing countries, depend on the collection of gums, resins and latex as a means for their livelihood.Overtapping leads to the death of the tapped plants and erratic supply of these products in the market (Nair, 2000).In Iran, commercial tapping of gum and resin is done by blazing or making deep cuts on the crown and root of some plants such as Ferula assa-foetidam, Dorema amoniacum and Ferula gummosa (Askarzadeh, 2000;Behpour et al., 2011).
A study of the effect of different methods of cutting on gum yield and Ferula assa-foetida survival showed that sap rate was changed from 19.6 to 62.9 g per plant by different cutting methods and times of cutting (Omidbeygi and Pirmoradei, 2006).Shad (1995) reported that four cuts at harvesting period and a 6day interval between cutting and collection is the best collection method with 5.28 g/plant gum yield.Salar et al. (2006) mentioned that the best harvesting age for this plant is when the plant is 5 years old or older.Regarding gum yield, Askarzadeh (2000) observed a non-significant difference between different cutting methods in gum yield.Habitats of this species are seriously disturbed by conversion of natural ecosystems to rain-fed farms.Domestication and recovery of natural habitats by seed planting can be a suitable strategy to conserve and regenerate the valuable endangered medicinal plant where the wild source plant is not enough to provide the gum for consumers and additional incomes for local farmers (Cronk et al., 2001).The aim of this study was to evaluate the possibility of crop cultivation in terms of dry land farming and the best operation method for collecting gum resin.

Material and Methods
The main habitats of Gum ammoniacum were identified in August according to the latest researches and field work in South Khorasan province.The sample plants were selected in Mohmadabad area in Ghaen for the field studies.
A field experiment was conducted under dry farming conditions with the factor of scarification methods (traditional, staircase and concave) based on a completely randomized design with three replications (Figure 2).Times of cutting (5, 10 and 13 times) were applied for resin harvesting on each selected plant.A split in time experiment was performed to analyze the effect of scarification methods at three different times during the growing season.
Seeds were planted at soil depth of 1-2 cm in the plot with an area of 4 x 2 m 2 with row-spacing of 50 cm, plant spacing of 40 cm in mid-December after determining the germination test in the laboratory.Plants were thinned at two-leaf stage in mid-April.In the fifth year after planting, there was the possibility of harvesting the gum.In order to study the effects of treatments, plants were selected randomly and marked in the plots.Some growth characteristics such as number of leaves, plant canopy and collar diameters were measured before applying the harvest treatments.A wooden cover was laid above the hole after carving out around the crown or root of the plant to avoid evaporation from cut parts.Then, the scarification treatments were applied on the five-year-old plants (Figure 3).
The gum resin was harvested 3-4 days after cutting.The harvest gum and its cumulative amount of product were measured every time in each plant.The regeneration of the plants was checked and recorded in the following years.
Figure 3.A wooden cover was laid above the hole after carving out around the crown to avoid evaporation from cut parts.

Results and Discussion
The results of the analysis of variance (ANOVA) showed a significant (p≤0.01)effect between the times of cutting (p≤0.01) on gum yield and a nonsignificant (p<.05) effect between different scarification methods (traditional, staircase and concave).
Based on the Duncan's new multiple range test (MRT), no differences for the yield of gum between traditional scarification (12.95 g/plant) methods, concave (10.89 g/plant) and staircase (10.78 g/plant) methods were observed.
The traditional methods, causing more damage to the layers of plant root in the time of cutting, affect the opening of the urethra and the increased secretion of gum up from the root after each cutting (Figure 4).However, the cumulative gum yield was not significantly different (p<0.01)from other harvesting methods.The following pictures show the situation of the gum under the status of the different scarification methods (Figures 5-7).There is lack of damage to the growing bud and crown when using the concave scarification method for gum harvesting.

Times of scarification
Times of cutting and cut-off frequency influence the amount of damage to plant roots, secretion of gum, gum harvesting and finally plant survival (Gholami and Faravani, 2014).The results of this study showed a significant difference (p<0.05) between various cut-off frequencies (5, 10 and 13 times) on the gum yield.With an increase in the frequency of the cut-offs, the harvested cumulative gum was raised from 5.84 g/plant in 5 cut-off times to 16.67 g/plant in 13 cut-off times (Figure 8).Duncan's new multiple range test (MRT) has been done on the data to get more details.Results revealed that the highest gum production could be increased by times of cut-off frequencies up to 4-6.However, the secretion of gum gradually decreased in the plant root system in 12-13 cut-off times (Figure 9).
The highest plant survival and regeneration percentages of plant after the fifth year were observed in the control concave, and staircase cutting methods, respectively (Figure 10).The lowest regeneration (0-8.3%) was observed in the traditional cutting method with 13 times of cutting.Based on the obtained results, the traditional method was mostly applied by local people to provide high gum yield.In addition, this method not only destroys the crown buds of the plant but also hinders the plant survival in the next year.The best harvesting method which provides a considerable yield and also gives a chance to plants for regeneration and surviving is concave or staircase harvesting method with 5-6 cutting times.Gum production is influenced by tapping intensity, rainfall, and minimum and maximum temperatures at tapping time (Ballal et al., 2005;Raj, 2014).The results confirm the findings of Shad's study (1995), who reported that four cut-offs at harvesting period with a 6-day interval between cutting and harvesting were the best collection method.He indicated that the new method of cutting increased the gum yield per plant from 2.150 g/plant by the conventional method to 3.546 g/plant.Nonetheless, Askarzadeh (2000) observed no significant differences in gum yield between different cutting methods.

Figure 1 .
Figure 1.One of the main habitats of Dorema ammoniacum D. Don in Mohamadabad Ghaen, South Khorasan.

Figure 2 .
Figure 2. Field of Gum ammoniacum in dry farming system.

Figure 4 .
Figure 4. Gum resin yield of Gum ammoniacum using different cutting methods compared by the Duncan's new multiple range test (MRT).

Figure 5 .Figure 6 .
Figure 5.The situation of secretion of gum from the root in June-July by the traditional method.

Figure 7 .
Figure 7.The situation of secretion of gum from the root in June-July by the concave method.There is lack of damage to the growing bud and crown when using the concave scarification method for gum harvesting.

Figure 8 .
Figure 8.Effect of different cut-off frequencies (5, 10 and 13 times) on gum yield of plant during an annual harvesting period.

Figure 9 .
Figure 9.The best cut-off frequencies for gum production (g/plant).

Figure 10 .
Figure 10.Effect of different cutting methods on plant survival (%).