Calamus tetradactylus (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Calamus tetradactylus Hance

Protologue: Journ. Bot. 13: 289 (1875).

Family: Palmae

Chromosome number: 2n= unknown

Vernacular names

• China: baiteng (generally known as white rattan throughout southern China).

Origin and geographic distribution

C. tetradactylus occurs on Hainan Island, in the southern parts of Guangdong, Guangxi and Fujian Provinces to the south of latitude 2330'N, and Hong Kong. It has also been introduced to West Guangxi, South Yunnan and the middle of Fujian Provinces, and a few plants have been introduced to the arboretum at Kepong, Peninsular Malaysia. In China it is commonly planted on a small scale.

Uses

C. tetradactylus in China is a first class cane of small diameter and one of the most important sources of cane for making rattan handicrafts, basketware and furniture. On Hainan Island, where it is abundant, it is also used as cordage, to bind thatch and to make implements.

Production and international trade

Production of C. tetradactylus occurs mainly in Hainan Island and to a small extent in southern Guangdong and Guangxi. Hainan Island produces 7080% of the total supply of canes in China, but it is difficult to indicate what percentage of this is actually C. tetradactylus . In comparison with SouthEast Asian countries, China has a well developed rattan manufacturing industry but poor indigenous cane resources. To supply the rattanbased cottage and furniture making industries with rattan, China needs to import about 30000 t of canes annually. Traditionally, canes collected from the wild are sold to buying stations where a certain amount of processing is carried out before the canes are shipped to manufacturers in Haikou, Guangzhou and other places for making furniture and handicrafts for the local market and export.

Properties

C. tetradactylus has a resilient and durable cane and its uniform texture makes it suitable for being split into fine strips for weaving handicrafts and making furniture. The cane has a lightyellowish colour and a glossy surface. Internodes vary from 1030 cm in length. The specific gravity is 0.432. Tensile strength is 38.0 N/mm². Lignin content is 18.7%. Quality of the cane depends on age, moisture content and growing conditions (e.g. light, water and soil, etc.), which affect the internodal length and diameter, and the degree of resilience of the canes. Quality is also adversely affected by poor processing. Being a smallsized cane, the ratio of bark of the cane to tissue is rather high in comparison with other species.

Description

Clustering, slender, dioecious rattan, climbing to 30 m or more. Stem without leafsheaths varying from 58 mm in diameter, with sheaths to about 12 mm in diameter; internodes to 20 cm or more in length. Whole leaf to 80 cm including leafsheath; leafsheath dullgreen, armed with scattered spines c. 0.5 mm×0.2 mm; petiole up to 15 cm long in juveniles, very short in adult climbing stems, armed with scattered, triangular short spines; flagellum borne on leafsheath, armed with short spines; leafrachis to 50 cm long, no cirrus; leaflets generally arranged in groups of 2, sometimes singly near the base, 711 on each side of the rachis, the uppermost, 46 in a group and always with terminal flabellum formed by two apical leaflets joined along at least 2/3 length, lanceolate, up to 15 cm×3 cm, with 35 distinct veins, dark green, armed with bristles along margins and grouped at the tip. Inflorescences borne on the leafsheath, up to 1 m long, the male and female superficially similar, the number of branches varying from 47, and each branch bearing 923 rachillae, female rachilla to 3.5 cm long, with 313 flowers. Ripe fruit 1seeded, generally rounded, 710 mm in diameter, rather conspicuously beaked, covered in 2123 vertical rows of neat reflexed whitishyellow scales, 1012 scales in each row. Seed globose, to 7 mm in diameter, weighing c. 0.1 g, pitted, endosperm deeply ruminate, embryo basal. Seedlingleaf forked, with 6 leaflets, dark green.

Cane anatomy The epidermis is built up of one layer of rectangular silicified cells and the subepidermal layer is composed of 34 layers of lignified parenchyma cells. The density of vascular bundles is 914/mm². The average length of fibre is 1.28 mm.

Growth and development

Usually seed starts to germinate 1525 days from sowing; a few seeds germinate after 6090 days. The development of the seedling is slow; the first leaf appears after 23 months; after 1830 months, the primary stem may exceed 50 cm in length, and the first flagellum and 23 sucker shoots may have developed. Suckers at the stem base develop as short horizontal rhizomes, never longer than 10 cm. Due to competition between aerial stems, most suckers may remain dormant. Two to three years after establishment, the aerial stem may grow at rates exceeding 2.0 m/year. At 7 years old, a clump growing under suitable conditions may already consist of over 30 aerial stems, with individual stems growing to a maximum length of 15 m, and the total stem length of such a clump may reach 78 m. Flowering begins 34 years after planting. Clumps consisting of over 100 aerial stems with a total stem length of over 350 m have been found in the wild. The phenological cycle is as follows: inflorescence appears in March; flower buds form from May to June; the earliest flowering starts in the middle of June, reaches its peak in August and ends in September when fruiting begins, but the fruit does not mature until April or May of following year. There are a few variations in the phenological cycle from place to place.

Other botanical information

Rather little is known of the basic biology of C. tetradactylus . It is very similar to C. bonianus Becc. but differs in inflorescence, size of leaf, stem and seed; C. bonianus has denser partial inflorescences, longer leaflets, but smaller seed.

Ecology

C. tetradactylus occurs in the lowlands to hillslopes under 600 m altitude in primary or secondary tropical forests and in subtropical broadleaved forest to the south of latitude 2330'N. The most favourable niche for this rattan is wet hollows and mountain valleys, but young seedlings may not be able to withstand severe flooding. In general, ecophysiological requirements of C. tetradactylus for normal growth are as follows: air temperature of 2030C (2C and lower may kill seedlings), more than 1300 mm annual rainfall with relative humidity of over 78%, 50% sunlight, fertile and damp soil with medium to high amount of humus and pH value of 4.56.5.

Propagation and planting

Like other clustering rattans, C. tetradactylus can be propagated by sucker shoots, but propagation by seeds is a more common method. Seeds should be extracted and cleaned immediately after the mature fruits are collected, in order to obtain high germination percentage. The outer scaly pericarp of the fruits and the sarcotesta can be removed completely by rubbing the seeds in water with some sand, then the extracted seeds have to be cleaned and kept at a moisture content of 2535%. Seed moisture content of less than 25% will decrease viability and below 20%, the seeds may dry out, causing the embryo to die. Germination percentage of fresh mature seeds can reach 98%. Normal nursery practice in China is first to soak seeds in clear water for 13 days, then to sow seeds in clean sand beds under shade. After 5070 days, young seedlings, with the primary leaf unexpanded, can be transplanted into potting bags containing soil with mixed nutrients (the ratio of forest topsoil to pond mud to composted manure is 50:50:1); the potted seedlings have to be placed in the nursery under semishade which is the optimum light regime for C. tetradactylus seedlings. Maintenance has to be carried out to ensure fast and healthy growth. It includes providing plenty of moisture without waterlogging, and weeding, loosening soil, applying fertilizer and controlling diseases and pests. Seedlings 15 to 18 months old and with 79 leaves are ready for planting out in the field. Because seeds are readily available, C. tetradactylus is the most commonly planted species in China.

Smallholders plant C. tetradactylus in agroforestry systems, e.g. under fruit trees or around gardens; on a commercial scale, it has been intercropped in lowland forests, loggedover forests, scrub, plantation forest, and also in rubber plantations. Site preparation involves thinning the forest canopy to permit 4050% light penetration, cutting and cleaning planting lines and preparing planting holes. Seedlings need organic manure for optimum growth. Planting should be carried out in the rainy season. At present, it is uncertain as to what the optimum spacing is for this species. In southern China, planting is at a spacing of 1 m×3 m, 2 m×3 m, and 1 m×4 m. Seedlings are planted singly or in groups of 2. Cultivators prefer close spacing rather than sparse planting, so as to increase the yield per unit area; this may pose problems in that profuse development of sucker shoots and growth of aerial stems result in damage to other immature stems at the time of harvest. Although it is recognized that C. tetradactylus, like D. margaritae (Hance) Becc., has the capacity to grow well in open areas, young leaves may be scorched by full sunlight. C. tetradactylus gives the highest yield when planted as a sole crop.

Husbandry

To encourage growth of C. tetradactylus , the following measures have to be taken once or twice a year in the first 3 years after planting: cleaning the planting lines and thinning the forest canopy to allow more light to reach the seedlings; loosening the soil and mulching around the clumps; and adding adequate fertilizers. After 3 years, the plant requires little attention apart from protection from animals that eat its cabbage.

Diseases and pests

Few diseases and pests have been reported. Leafspot, leaf blight, and ringspot diseases usually occur in nurseries but are the result of poor management; the pathogens responsible are Pestalotia sp ., Pyrenochaeta sp., and Conithyrium sp. . The most important pests of C. tetradactylus and other rattan species are locusts, moths, scale insects and Dynastes gideon . It is reported that rats can seriously damage not only young plants but also adult plants.

Harvesting

Harvesting of C. tetradactylus varies slightly from that of moderatesized rattans, but essentially consists of cutting the mature stem at the bottom, removing the dried leafsheaths, dragging the stem out of the canopy, cutting away the green leaves, and discarding the uppermost metre which is immature and hence useless, and then divesting the canes of leafsheaths and debris. The cane is then cut into lengths of about 45 m or more and bent, tied in bundles and carried to the village. Smallholders may cut stems but leave them until the leaves and sheaths are dry, and then collect the canes so as to make harvesting operations easier. In such cases, harvesting is carried out in the dry season.

Yield

In the experimental plantations in Guangdong Province of China, C. tetradactylus established on hillsides is ready for harvest at 7 years after planting, with a yield of about 1.2 t/ha; the second harvest at the 11th year after planting yields about 1.1 t/ha; and further harvesting is possible 4 times in a rotation of 3 years. The projected yield may reach a total of 6 t/ha within a management period of 25 years. These yields are rather low in comparison with D. margaritae and C. simplicifolius Wei because C. tetradactylus is a smallsized cane. However, under good conditions, it has the potential to develop more aerial stems and yields could exceed 15 t/ha in a management period of 25 years.

Handling after harvest

Postharvest treatments are usually applied by middlemen at purchase stations, where canes are recleaned of the remains of leafsheaths, sundried, and sorted. Canes are then transported to manufacturers, where additional treatments to remove silica and nodal scars are carried out to further improve the quality of the canes.

Genetic resources

Although no specific collection has been established to represent the considerable variation of C. tetradactylus in the wild, it is represented in several botanic gardens and arboreta in southern China.

Breeding

There has been no breeding of C. tetradactylus in China. Selection of superior phenotypes through provenance trials has to be done for this and other rattan species.

Prospects

C. tetradactylus is an endemic species of southern China. Owing to the exploitation of natural forest for timber and conversion for agriculture, its habitat has largely been destroyed, and this has been compounded by severe overexploitation of the species. Although cultivation of rattan in China is in its early stages, initial results show that C. tetradactylus and D. margaritae as cultivated crops have a great potential as a source of income for rural people. However, prospects for C. tetradactylus as a largescale plantation crop have yet to be proven. The yields in plantation are lower when compared with those of D. margaritae and C. simplicifolius . C. tetradactylus has been widely planted in southern China because it is an adaptable species and there is a rich source of seeds. It is currently under trial in Malaysia. Further studies on this species are needed and should be focused on provenance trials, genetic improvement, plantation and harvesting technology, socioeconomic aspects, and utilization.

Literature

• Cai, Z.M., 1989. Distribution of vascular tissue in four rattan canes. Acta Botanica Sinica 31(8): 569575.
• Dransfield, J., 1979. A manual of the rattans of the Malay Peninsula. Malayan Forest Records No 29. Forest Department, Kuala Lumpur. pp. 723.
• Pei, S.J. & Chen, S.Y., 1991. Flora reipublicae popularis sinicae 13(1). Science Press, Beijing, China. pp. 8788.
• Rao, A. N. & Vongkaluang, I. (Editors), 1989. Recent research on rattans. Proceedings of the International Rattan Seminar, Chiangmai, 1214 November 1987. Faculty of Forestry, Kasetsart University, Thailand and International Development Research Centre, Canada. pp. 98104.
• Xu, H.C., 1984. Research on biological and ecological characteristics of Calamus tetradactylus and its planting techniques. Tropical Forestry (Science & Technology) 1984(2): 927.
• Xu, H.C., Zhou, Z.Z. & Yin, G.T., 1991. Nutrition evaluation of shoots of two rattan species. Rattan Information Centre Bulletin 19(4): 1720.
• Yin, G.T. & Xu, H.C., 1988. A preliminary study on the effect of different levels of light intensity on the growth of rattan seedlings. Forest Research 1(5): 548551.
• Zhou, Z.Z., Xu, H.C. & Yin, G.T., 1991. A financial appraisal of three commercial rattan plantations. Forest Research 5(1): 4755.

Authors

H.C. Xu & G.T. Yin