Plantation of Agar in denuded hilly areas
In Bangladesh
Abstract:
Experimental planting with Aquilaria malaccensis Lamk. Was undertaken to assess its suitability on denuded hilly areas of cittagong, Bangladesh. Germination of the species was 70 percent, and the seedlings attained a height of 40-60 cm in the nursery at the age of one year. Average survival of the out-planted seedlings in four locations was 34.7 percent with 1.85m mean eight and 1.92 cm mean diameter after three years. Survival and seedling increment decreased with increasing height of hill slope, apparently because of gradual low soil moister content. Strong and direct sunshine seem to have adverse effect on seedling survival. The prospect of Aquilaria malaccensis appeared to be uncertain for the denuded areas. However, further investigation needs to be undertaken.
Introduction:
Aquilaria Aquilaria agallocha Roxb (Family Thymelaeaceae), locally known as agar, is a moderately tall and erect evergreen tree. It may grow to a height of 20 m. The species is distributed naturally in India, Bhutan, Bengal and Myanmar. It is particularly found in Assam on hill forest of Khasia, Garo, Naga, Cachar and Sylhet (Anon 1948). The wood is soft and light. The main value of the species is the formation of dark color, resinous and aromatic substance in word called agar (Troup 1921). In Bangladesh, A. malaccensis occurred naturally at Adampur of Sylhet forests but has become rare due to indiscriminate felling of trees for agar wood. Forest department has plantations of agar at Lawachara of Sylhet (Das and Alam 2001).
Agar is highly priced materials and used for cosmetics, perfume and medicinal purposes (Anon 2001). Previously it was believed that agar formation was the result of fungal attack. However, Gibson suggested that agar formation was not related to fungal activity. Rahman and Basak (1980) and Rahman and Khisa (1984) conducted studies on the relationship between fungal activities and agar production but with no conclusion and suggested further studies in this direction. In Bangladesh agar plantation was never raised commercially. However forest department personnel casually planted agar in some localities of Sylhet and Chittagong and found the growth rate of this species to be satisfactory. At present about 25-30 families in Sylhet and Moulavibazar are engaged in agar processing using the raw materials mostly collected from abroad. Because of the value of the agar, Bangladesh forest department undertook a pilot project for agar plantation in 1998-99 in the denuded hilly areas. In order to support the plantation programme, and observed the feasibility of the species in denuded hilly areas. Bangladesh forest research institute conducted studies on nursery and plantation techniques of agar. This paper is based on data collected from the experiments initiated in 1999 by the BFRI and experience gained during nursery raising and planting.
Methodology:
This seminar paper is prepared by analyzing the secondary data. Secondary data have been collected from various books, journals and Internet.
Material and methods:
An agar plant was found to profuse and viable seeds from the age of ten years. Seeds of agar were collected in June by climbing trees at Bilaschara (Srimangal) and Moulavibazar of Sylhet Division. These were cleaned manually and 1100g of seeds were sown in each bed (1.2m×3m) at BFRI nursery in Cittagong. There were three beds the seed bed was prepared by mixing cow dung and sandy soil in the proportion of 1:6. After seed sowing, the beds were protected from direct sunlight by shading. Watering of seed beds when necessary was made till pricking of seedlings. Initiation and completion of germination and its success were recorded .The seedlings were transferred from the bed to polybegs (15cm×25cm) 25 days after germination. Seedling mortality & seedling height were recorded over time in the nursery. Shade was provided to the polybag seedlings for two months after pricking from the beds. The seedlings were maintained in the nursery for one year. Regular watering, weeding and rearrangement of bags were made during this period.
One-year-old seedlings were out-planted at four sites viz. Hinguli, Kororhat, BFRI campus and Padua under Chittagong Division. The original tree vegetation of this denuded areas included Dipterocurpus alatus, D. turbinatus, Anisoptera scaphula, Hopea odorata, Syzygium grande, Artocarpus lakoocha, Artocarpus chaplasha, Albizia spp, Gmelina arborea etc (Das, 1990). Vegetation of the denuded areas included grass and climber like Ipomoea fistulosa, Hyptis suavoters, Smilax roxburghiana, Imperata cylindrical, Eupatorium odoratum, Clerodendrum viscosum etc. The plantation sites were in the low hills with gentle to medium slope gradient. However, at Podua, the slope was medium to steep and thus allowed observing the effect of increasing height of site on the performance of planted seedlings. The annual rainfall of these areas is in the range of 2500-3500mm with an average temperature of 20°-30°C. The elevation of the sites from the mean sea level is within 10-40m. The soil is generally deep being the effective soil depth 0.5-1.0m. Soil moisture is Udic. Soil texture varies from sandy clay loam to silty clay loam. Soil is acidic, pH range from 4.5-6.0. Organic matter content is low to medium and up to 30cm depth it varies from 1.2-1.8%. The available nutrient (NPK) is low.
After weeding, climber cutting and jungle clearing a total of 2500 seedlings were planted in four locations covering an area of about four hectares. The planting spacing was 2.5m×2.5m. At Padua, the experiment was laid out in a Completely Randomized Design (CRD) along of the slope of the hill. Prior to planting in July during the monsoon each planting pit was provided with 50g (1:1 TSP and Potash) of fertilizer. Weeding was made thrice a year. Gap filling was undertaken ten months after initial planting with two-year-old seedlings. Last data on survival, seedling height and diameter (at breast height) were collected three years after out planting.
Result and discussion
Fruit and Germination
The fruit is capsule, 3.5-5cm long, ovoid and brown when mature. The pericarp is coreacious, hard, woody and thinly velvety. A fruit contains 3-4 seeds. One kilogram contains 650-680 fruits, which provide approximately 1050-1100 seeds. The germination is epigeal. It started from seven days after sowing and continued up to 30 days. Average germination in three beds was 70±1.5 percent as obtained from sowing 1kg seeds.
Pricking and Seedling Growth
The seedling attained a height of 6-8cm with 3-5 leaves in 15 days when they were suitable for pricking and transfer to the polybags. Pricking could safely be undertaken between 15 and 30 days following germination. Seedling mortality after pricking out was almost 15% usually due to fungal attack. According to the suggestion of the Forest Protection Division of BFRI the fungicide Cupravit (Copper oxychloride) was sprayed. Afterwards the seedlings were not found to die in the nursery. The seedlings grew to height of 40-60cm at the time of out planting, i.e., at the age of one year.
Survival and Growth after outplanting:
It was possible to raise healthy seedlings of agar in the nursery. But initial mortality of seedlings was high during first year after out planting in all the four locations. Average survivals at site 1, 2, 3 and 4 were 40.7, 37.3, 29.5 and 31.4 percent respectively after 3 years (Table1). Draught seemed to be one of the main causes of high mortality. At site-2 greater proportion of planted seedlings on the southern aspect of the hill died, possibility due to direct sunshine. Survival and vigour of seedlings on northern aspect were satisfactory indicating preference of the species for certain level of shade at the initial growing stage. Again survival appeared to be related to soil moisture content. Thus mean survival after three years for top, middle and base of the hill slope on significantly different (F=43.1; P<0.01) f="145.0;">
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