Quality of Untraded Rattan Stem from Central Sulawesi (Indonesia) Based on the Morphology

3.1 Rattan morphology character

Based on the identification and determination of the non-traded rattan in Central Sulawesi, 10 speciess were found as shown in Table 2. Meanwhile, the observations and measurements of internode length, diameter, cylindricity, groove, color, and rod surface appearance are presented in Table 3.

Based on the description in Table 3, the six morphological characters are unable to comprehensively explain the characteristics of rattan. However, they play a role in the quality determination based on SNI 01-7254-2006 [4] regarding rattan. According to Dranfield [5], complete data are needed to fully describe rattan with root organs, rods, leaves, flowers, fruits, as well as the auxiliary tools such as cirrus and flagella. The internode length, diameter, cylindricity, groove depth, color, and surface appearance of rods are unable to accurately determine the specific species, therefore, other characteristics are still needed. In a plant classification system, to determine the species accurately, it is necessary to have a complete variety of characters from morphological aspects such as roots, stems, leaves, flowers, fruits, and seeds. Currently, species determination is no longer limited to morphological aspects, but anatomical and chemical aspects have been used, even genetic aspects such as DNA. The characters of xylem and fiber can be used as a determinant of plant species such as only rattan. However, in determining plant species, the anatomical aspect has not been widely applied, except if the morphological aspect cannot provide accurate instructions, then the anatomical aspect is used as a comparison. To determine the quality of the species in the rattan trade, a reference based on the morphological characters with SNI 01-7254-2006 is recommended.

The characters described above are only the characters used in determining the quality level of each rattan species which could be used for industrial raw materials, as explained from the six characteristics (Table 2 and Table 3), while the other characters are not used as the determining character for the quality level of each rattan species.

To explain the character of rattan comprehensively, other characters are needed, such as root character, leaf character, flower and fruit character, growth and development character, ecological character, anatomical character, chemical content, and other physical and mechanical characteristics.

3.2 The average difference test of rattan rod morphological characters

This study describes six morphological characters of rattan which include internode length, diameter, cylindricity, texture, color, and surface appearance of the rods. However, based on the standard rules, they are not enough to obtain adequate information on the various species of rattan. Nevertheless, for trade purposes that rely on experience and visuals, these characters are used as a basic reference in determining the species and quality.

The analysis results showed that there are three of the six characters studied including internode length, rod diameter, and cylindricity have potential to provide explicit differences, meanwhile the other three are homogeneous, hence, the level of differentiation is very low. These characters are not analyzed using a statistical approach because the data is qualitative. However, the analysis was carried out visually and only applies to non-traded rattan.

Even though these characters are homogeneous and not significant in determining the quality level of rattan, in the world of rattan trading, these characters are still used as characters to determine the quality of rattan, because if these characteristics are not fulfilled then the rattan species has a potential to be rejected by the buyers, or at least it has lower price than the quality rattan.

The analyzed morphological characters include internode length, diameter, and cylindricity, while the texture, color, and surface appearance were not analyzed because the data were more homogeneous and qualitative. The homogeneity analysis showed a significant difference at α 0.01, therefore, it was continued with the analysis of variance test. Furthermore, the results showed a significant F value at α 0.01, indicating that the characters of internode length, rod diameter, and cylindricity are significantly different from one species to another.

The length of each rattan internode was significantly different from one another at α 0.05. The 10 speciess of rattan studied were divided into nine different groups, eight are not clustered, while the other two form one group. Moreover, each species in a group showed no significant difference but was significantly different from other species and groups. Additionally, the rattan with the longest internode was Daemonorops macroptera while the shortest was found in C. insignis.

The internode length varies based on the species of rattan, species with a longer internode have a better appearance than the shorter one. This is because, during processing, rattan with longer internodes produces a higher quality compared to others with shorter species which are usually coarser and difficult to bend. Therefore, the quality of rattan is determined based on the length of the internode, but this depends on its designation.

The rod diameter was significantly different for each rattan species at α 0.05. Each species in a group showed no significant difference but were significantly different from other species and groups. Based on the results, the species of rattan with the largest rod diameter was K. celebica while the smallest was found in C. minahasae.

Furthermore, the rattan rod diameter varies depending on the species namely small (≤ 18 mm) and large diameter (> 18 mm - 40 mm). However, certain rattan has a diameter greater than 4 cm, but is rarely sold in the market and even has no price. Seven of the 10 speciess of rattan studied are classified as small in diameter, including C. insignis, C. minahasae, C. Orthostachyus, Calamus leptostachyus, Calamus boniensis, D. lamprolepsis, and K. Celebica. Meanwhile, there are three species with a large diameter, namely C. koordersianus, D. robusta, and D. Macroptera.

The rod cylindricity was significantly different from one another with α 0.05. The 10 speciess of rattan studied were divided into seven different groups, six species were not clustered, while the other four formed two groups. Each species in a group showed no significant difference but significantly different from other species and groups. The rattan species with the highest cylindricity namely a value close to one includes C. inops, while the lowest was found in C. ornatus var. celebicus.

The cylindricity of rattan rods greatly determines the quality and varies depending on the species. This is because it determines the processing outcomes, specifically in polys and core. When the cylindricity is less than 9, a high level of skin tends to be removed to obtain a uniform result. Therefore, it is not good enough to make polys and core. In contrast, rattan is classified as good when the cylindricity is greater or equal to 9. In this study, the rattan in the good category based on the cylindricity include C. insignis, C. minahasae, C. orthostachyus, and C. leptostachyus.

The rods' texture is generally flat, except for certain speciess, based on the results, six speciess of rattan were found with flat texture or not grooved, namely C. insignis, C. leptostachyus, C. boniensis, D. lamprolepsis, D. robusta, and K. celebica. Meanwhile, four textured or grooved speciess were found, including C. koordersinus, C. minahasae, C. orthostachyus, and D. macroptera. Grooved rattan processing tends to be very difficult, hence, its quality is lower compared to the flat-textured species.

The color and appearance of the rod also play a role in determining the rattan quality. A good color turns to white after processing as found in C. minahasae, C. leptostachyus, C. boniensis, and D. lamprolepsis. Meanwhile, greenish colors including green, and turquoise produce poor results after processing as they usually remain greenish as found in C. koodersianus, C. insignis, C. orthostachyus, D. robusta, D. macroptera, and K. celebica. The appearance of the rod surface either glossy or dull, also determines the rattan quality. Dull rattan does not have a good appearance after processing, hence, it is only suitable for making core and pitrite, for example C. koordersianus. Although the texture, color, and surface appearance of the rods do not show significant differences, these three characters are very important in determining the species and quality of rattan.

3.3 Quality standard approach

The quality determination of rattan is only based on the morphological characteristics and the hardness of the rod. Meanwhile, the internode length, diameter, texture, color, and appearance of the rods vary by species. These variations indicate the quality level as previously reported by Stiegel et al. [25] and Jasni and Krisdianto [26]. Moreover, based on the interviews with rattan communities and furniture entrepreneurs in Central Sulawesi, the quality of rattan is largely determined by the morphological character of the rods.

The analysis of internode length, diameter, cylindricity, groove depth, color, and surface appearance of the rod, indicates that the rattan quality standards are also arranged based on the rod morphological characters. The internode length differs based on the specific species, rattan with a longer internode tends to have a better appearance compared to a shorter one, specifically for whole round rattan. During processing, the results of a longer internode are often better than others with a shorter internode which usually appears to be more coarse and difficult to bend. Therefore, the quality of rattan is determined based on the internode length, depending on its designation [3, 15, 23].

The diameter of the rattan rod varies depending on the species and is divided into two categories, namely small with < 18 mm and large diameter with 18 mm or more. This parameter significantly influences its use, for example, large-diameter rattan is widely used for the manufacture of furniture frames, while the small species is used for woven and binding raw materials. In this study, five among the 10 speciess of rattan studied were classified as small in diameter, including C. insignis, C. Minahasae, C. Orthostachyus, Calamus leptostachyus, and K. celebica, while five were large-diameter speciess, namely C. koordersianus, C. boniensi, D. lamprolepsis, D. robusta, and D. macroptera. Furthermore, the diameter of the rod greatly determines the process and designation, hence, it is used as a character to categorize rattan based on its quality. Large diameter rattan is generally used as a frame material, while others with a small diameter are utilized in making accessories or as core and pitrit [3, 15, 23, 27].

The cylindricity of rattan varies depending on the species and greatly determines its quality. This is because cylindricity determines the processing outcomes, specifically polish and core. When the value is less than 90%, a high level of skin is removed, thereby producing a uniform result with a low yield. Moreover, the processing requires more time and is capital intensive, hence, rattan with less than 90% cylindricity is not good for polish and core. However, when the value is equal to or higher than 90% rattan is categorized as good. In this study, C. insignis, C. minahasae, C. orthostachyus, and C. leptostachyus were categorized as good based on the cylindricity. An absolutely cylindrical rod is rare, based on the existing diameter range, rattan quality is divided into three categories, namely: 1) cylindricity ≥ 90% of A quality, 2) 85-99 % of B quality, and 3) < 85 % of C/D quality [3, 15, 23].

Near-perfect cylindrical rods are more useful for large-diameter speciess due to the wide application for making furniture frames. Usually, rattan with almost perfect cylindrical properties is made by book scraping or mechanical sanding. However, this method requires additional costs and energy, hence, it is not uneconomical.

The rattan rods studied were generally not grooved, except for four speciess namely C. koordersinaus, C. minahasae, C. orthostachyus, and Daemonorops macroptera which have shallow grooves. Meanwhile, rattan with extremely deep grooves requires more time and costs with inefficient as well as low yields. Moreover, it decreases uniformity, hence, rattan with grooves has lower quality than others without. Based on this parameter, the quality is divided into three categories, including: 1) rattan without grooves of A quality, 2) shallow grooves of B quality, and 3) deep grooves of C/D quality [3, 15, 23].

The rod color varies not only in different speciess but also among the same species, the better the color, the more expensive the price, and vice versa. Furthermore, the color of the young rattan rods is different from the old, while the color at the rod base is different from the middle and extremities. Both color and appearance play a role in determining the quality of the rattan. A good color changes to white after undergoing processing. However, when the color varies, the quality of the rattan product tends to decrease. This is in line with Januminro [28] and Rachman and Jasni [29], which stated that green rattan rods at old age change to white after the silica membrane are peeled off and becomes white again after the bleaching process.

The rod surface appearance namely glossy or dull also determines the quality of rattan after processing. Glossy rattan rods reflect light, give a special characteristic, and add to the beauty [30]. The surface appearance in the form of gloss varies depending on the anatomical structure, content of extractives, and the angle of light incidence. Moreover, the rattan luster is also influenced by the water content, the higher the value, the lower the gloss. Similarly, the presence of fatty and oily substances reduces the luster of rattan [31]. Dull rattan does not appear good after processing, hence, it is only suitable for manufacturing core, for example, C. orntatus var celebicus. Furthermore, color and surface appearance are applicable as quality determinants when the rattan to be processed is not peeled. This is because rattan to be peeled into core and pitrite does not require standard color and surface appearance.

Presently, the quality level of rattan is mostly determined based on the morphological properties and rod hardness. Meanwhile, internode length, diameter, texture, color, and appearance of the rods vary by species, these variations indicate differences in the quality levels. However, a definite determination is difficult, as it is only based on a visual assessment. This is in line with Rachman and Jasni [29], as well as the results of interviews with communities and entrepreneurs in the semi-finished processing rattan industry and furniture in Central Sulawesi.

The 10 rattan varieties based on the morphological characters have visual similarities and were classified as the favorite speciess according to the general standard [2, 13-15]. Therefore, they have almost the same quality with varying levels. Moreover, the quality of each species is still considered to fulfill maturity standards and free from defects. Maturity and the percentage of defects are the factors that determine the price. Although the rattan in this study has a good quality, it is still young and has several defects, hence, the price might be adjusted to the prevailing standard [3, 15, 23, 29].

Quality determination of rattan based on the morphological characters of the rods is carried out quantitatively by assigning weights according to the level of differences in the analysis results of each observed feature. The rattan values of Tellu [2] were used because they are the favorite speciess and are widely traded in the market for both domestic and export needs. Furthermore, the higher the total weight, the higher the quality of the rattan, as shown in Table 4. The data in Table 4 describes the total weight of each rattan species as a sum of the morphological characters. Based on the total weight, a quality rating was assigned from 1 to 10 for each species of rattan studied and then grouped into three quality categories. Quality A includes Calamus boniensis, D. lamprolepsis, and K. Celebica, while C. insignis, Calamus leptostachyus, and D. robusta were in the B category. Furthermore, quality C includes C. koordersianus, C. minahasae, and C. daemonorops macroptera, while C. orthostachyus was in D.

Table 4. Quality of rattan based on the weight of each rod morphology character