influence of growth rate, elevation and sunlight on the...

Philippine Journal of Science138 (1): 55-66, June 2009ISSN 0031 - 7683

Key Words: Cell wall thickness, elevation, fiber length, fiber percentage, growth rate, modulus of elasticity, modulus of rupture, specific gravity, sunlight exposure

*Corresponding author: [email protected]

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Influence of Growth Rate, Elevation and Sunlight on the Anatomical and Physico-Mechanical Properties of

Plantation-Grown Palasan (Calamus merrillii Becc.) Canes

Willie P. Abasolo* and Olga C. Lomboy1

Forest Products and Paper Science DepartmentCollege of Forestry and Natural Resources

University of the Philippines, Los Baños, College Laguna1Office of the Chancellor, University of the Philippines Los Baños, College, Laguna

INTRODUCTIONRattan are climbing palms that belong to the Arecaceae family and utilized for their flexible stems (Sunderland & Dransfield 2002). There are about 64 species of rattan from four genera, namely Calamus, Daemonorps, Korthalsia, and Plectocomia (PCARRD 1991) that are distributed all over the Philippine Archipelago. The continued increase in the demand for finished rattan products, coupled with the unabated destruction of its natural habitat, had placed the country’s rattan resources into a condition in which it could no longer sustain the

The influence of growth rate, elevation and sunlight exposure on the properties of plantation-grown palasan canes was verified in order to promote the utilization of cultivated canes to encourage the establishment of more palasan plantations. Properties evaluated were fiber length, wall thickness, fiber distribution, ovendried specific gravity, Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) using standard procedures. Growth rate ranged from 0.36 to 3.79 m/yr, elevation was from 10 to 980 masl and sunlight exposure from 20 to 90.28%, showing that palasan plants can thrive in varying site conditions. Among the properties evaluated, only fiber percentage was moderately affected by both growth rate (r = 0.53) and amount of sunlight exposure (r = 0.51). Elevation, on the other hand, moderately influenced wall thickness (r = 0.45). Mechanical properties of the cane were unaffected by the three parameters. Therefore, the study proved that palasan plant is an ideal plantation species because it thrives in any kind of site and its properties are minimally affected by the major site characteristics such as elevation and sunlight exposure. Thus, it is recommended that more palasan plantations be established to provide a sustainable supply of raw canes to the rattan furniture industry.

burgeoning handicraft industry. If nothing is done to improve the supply of raw canes, soon this multimillion dollar enterprise would be lost.

One good alternative source of raw materials is rattan plantations. Properly managed plantation could provide unlimited supply of raw canes but it has yet to get the acceptance of the industry. This is partly due to the fact that the properties of its cane are still unknown. The utility and acceptability of any plant material for a specific end-use depends largely on the quality, e.g., density, stiffness, and flexibility, of its stem. However, stem production is the result of a series of growth processes that the

Abasolo & Lomboy: Influence of Growth Rate, Elevation and Sunlight on Plantation-Grown Palasan Canes

Philippine Journal of ScienceVol. 138 No. 1, June 2009

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plant undergoes and as such its quality is affected by anything that influences its growth rate (Larson 1972), e.g., site elevation, amount of sunlight, and seasonal fluctuations of moisture, among others. Stem quality is determined by its flexibility (Modulus of Elasticity) and maximum stress before breakage (Modulus of Rupture). These parameters are dependent on the amount of cell wall substance per unit area (specific gravity) that varies from species to species based on its fiber wall thickness, fiber lumen diameter, and fiber ratio within the tissue.

The growth rate of the plant would determine the total harvestable volume. Faster growing trees would produce longer and larger diameter stems than slower growing trees. Nonetheless, accelerated growth would also lead to the development of low quality stems (Haslett et al. 1991), one of the drawbacks of utilizing plantation-grown trees. For example, fast growing trees normally develop shorter tracheids and fibers (Hildebrandt 1960) due to the tendency of their fusiform initials (meristematic cells responsible for longitudinally oriented cells) to divide even before reaching their potential length (Bannan 1967). Furthermore, cell wall thickness is determined by the availability of carbohydrates and hormonal activity within the cell (Richardson 1964). Rapid growth stimulates cell division in the vascular cambium (Taylor 1982) which in turn consumes the food reserves of the plant, leading to the development of thinner cell wall. Consequently, this would result in a decrease in specific gravity and a reduction in stem stiffness (Downes et al. 2002). Lower strength would limit the possible end-uses of the material leading to the reduction of its value.

The relationships between growth rate and stem characteristics have been extensively evaluated in trees grown in plantations (Bamber et al. 1982; Ohbayashi & Shiokura 1989; Wahyudi et al. 2000) but for rattan canes, this information is limited only to the growth rate of some species (Dransfield & Manokaran 1993). Now that the utilization of plantation-grown rattan canes is being promoted it is essential that this association be elucidated. Likewise, due to the significant influence of site elevation and the amount of sunlight exposure on the growth rate of rattan plants (Abasolo 2006), their influence on cane properties should also be verified.

The current report aims to clarify the impact of growth rate, elevation, and amount of sunlight exposure on the basic properties of palasan canes. This is aimed at promoting the utilization of plantation-grown palasan canes to further encourage the establishment of more palasan plantations.

MATERIALS AND METHODS

Plant MaterialSample canes were obtained from 12 Palasan (Calamus merrillii Becc.) plantations situated in different parts of the Philippines (Figure 1). These plantations differ in their ages and sizes and were established either by the Department of Natural Resources (DENR) or by the Philippine National Oil Company- Energy Development Corporation (PNOC-EDC) (Table 1). They were established in secondary forest or logged-over areas where Dipterocarps and Almaciga trees used to thrive. Seeds used to propagate the planting stocks were taken from a natural stand in Ormoc, Leyte. After approximately three months of conditioning in nurseries, seedlings were out planted with a spacing of 2m x 2m. Besides weeding for the first three (3) years of establishment, no other silvicultural treatments, e.g., fertilizer application, canopy modification, were performed on all the sites.

Elevation and sunlight exposure determinationThe elevation of the individual sites was measured using a standard altimeter in meters above sea level (masl). Average measurement of two readings was used in the evaluation.

Before cane extraction, digital images of the forest canopy exactly where the cane was growing were taken using a Fujifilm FinePix 4500. These images were subjected to image analysis software (Image J) to estimate the open spaces in the canopy. Through these spaces, sunlight could penetrate the forest canopy and could be utilized by the plant for growth and development. From this, the amount of utilizable sunlight was estimated (Abasolo 2006). The mean value of two measurements was used in the analysis.

Growth rate Palasan plants undergo a rosette/grass stage (Figure 2). This is a peculiar primary growth behavior of most palms wherein the stem first completes its diameter/ thickening growth before internodal elongation occurs (Tomlinson 1961). At this time, cane production is dormant and this would normally take 3-5 years (Tomlinson 1990). In some cases, it may take even longer depending on the characteristics, e.g., physical, environmental, of the site (Abasolo 2006). Without knowing exactly when cane production has started, it would be very difficult to determine the actual growth rate of the cane. For this reason, the rosette/grass stage was disregarded in the analysis and it was assumed that cane development started right after a year of establishment. This would simplify



Figure 1. Location map of the individual palasan plantations.

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Figure 2. Palasan plant in its rosette/grass stage.

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the evaluation and standardize the results. This would also serve as one of the limitations of the study, though based on a previous paper (Abasolo 2007), disregarding the rosette stage would not significantly affect the outcome of the work. Therefore, growth rate per year was obtained by dividing the total length of the cane by its age.

Sample preparationAfter determining the total length, two meter long samples coming from the base, middle, and top most portions of the stem were obtained. Sample disks were cut off from the three portions. The peripheral and core regions were delineated out and from these regions, 1 cm3 sample blocks were processed. Parallel to the blocks, match-stick samples were prepared. The former were used for fiber area percentage determination while the latter were used for fiber length and cell wall thickness measurements.

Fiber CharacteristicsThe sample cubes were boiled in water for several hours to soften the tissues. After boiling, 35 – 45 μm thick cross sectional slices were cut off with a sliding microtome. Slices were stained with safranin and fast green then mounted on clean permanent slides. With a microscope equipped with a digital camera, at least five digital images were taken for every region. Fiber area percentage was

Table 1. Growth rate, elevation and amount of sunlight exposure of the individual samples coming from different sites.

Sample Age LocationTotal

Length(m)

Growth rate

(m/yr)

Elevation(masl)

Sunlight Exposure

(%)

QP2-84 20 Pagbilao, Quezon 16 0.80 500 21.00

LP2-86 18 Daraga, Legaspi 41 2.28 10 72.91

TP-89 15 Ormoc, Leyte 33 2.20 220 83.34

LP1-90 14 Daraga, Legaspi 53 3.79 10 83.90

NP-93 11 Southern Negros 4 0.36 660 63.74

MPL-93 11 Ormoc, Leyte 11 1.00 980 42.43

QP1-94 10 Pagbilao, Quezon 6 0.60 480 20.00

AKP-94 10 Ormoc, Leyte 10 1.00 520 53.75

MP-94 10 Southern Negros 8 0.80 460 22.79

MP-96 8 Southern Negros 17 2.13 460 90.28

PNOC-97 7 Sorsogon 5 0.71 480 50.58

NP-97 7 Southern Negros 11 1.57 800 32.67



Figure 3. Palasan plantation in Ormoc, Leyte

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determined using the procedures illustrated in a previous article (Abasolo et al 2005). The digital images were subjected to image analysis software (Image J). The area occupied by the fibers was delineated out. Area percentage was then obtained by dividing the total fiber area with the total image area multiplied by 100. The data from the two regions (peripheral and core) for the three portions (base, middle, and top) were consolidated and average values were calculated.

The match stick-sized samples were macerated in 50:50 solutions of glacial acetic acid and 20% hydrogen peroxide. Upon defibrillation, at least 30 whole fibers were randomly selected. Fiber length, fiber diameter, and lumen diameter were measured using a standard light microscope with a built-in vernier scale. Cell wall thickness was obtained by getting the difference between fiber diameter and lumen diameter then the answer divided by two. Average values coming from every portion were used in the evaluation.

Physico-mechanical characteristicsA universal testing machine (UTM) was utilized to determine the mechanical attributes of the individual cane. Static bending tests were performed following the American Society for Testing Materials standard for small clear specimens of timber (ASTM 1975). Modulus of rupture (MOR) and modulus of elasticity (MOE) were derived. Two measurements were performed for the base, middle, and top most portion of the cane. The average of

these six measurements was obtained in order to get a general perspective of the mechanical characteristics of the individual rattan stems.

After static bending tests, sample disks were again prepared. Similar to the previous preparation (fiber analysis), the peripheral and core regions were delineated out. From these regions, 0.5 x 0.5 x 1 cm sample blocks were prepared. A total of ten blocks per region were made. Following the gravimetric method, ovendry specific gravity was derived. Average values coming from all regions and from all portions were obtained and were used in the analysis.

Statistical analysisStandard analysis of variance (ANOVA) at α = 5% was performed on all the data set. Likewise, standard deviation from the mean was computed. Finally, relationships between parameters were analyzed with a simple linear regression.

RESULTS AND DISCUSSION

Growth RateFigure 3 shows a palasan plantation in Ormoc, Leyte. The different palasan plantations yielded varying growth rates ranging from 0.36 to 3.79 m/yr (Table 2) which is comparable with the recorded growth rate of 0.70 m/yr reported by



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Cadiz in an annual reportt (1987). The individual sites differ in elevation (10 masl–980 masl) and sunlight exposure (20%–90.28%) representing a wide range of geographical conditions. It appears that palasan canes grow in a wide variety of environments corresponding to the observations of Siebert (2005) in Indonesia. This is very promising to rattan plantation developers because it would mean that palasan plantations could be established anywhere in the country.

Fiber CharacteristicsFiber characteristics and distribution are important structural traits because they influence cane density (Bhat & Verghese 1991) and stiffness (Bhat & Thulasidas 1992). The samples gave varying fiber characteristics and distribution (Table 2). Fiber length was shortest in NP-93 (Southern Negros) at 1.3649 mm while it was longest in QP1-94 (Pagbilao, Quezon) at 1.9124 mm. The cell wall was thickest in MLP-93 (Ormoc, Leyte) with 0.0109 mm whereas it was thinnest in QP1-94 (Pagbilao, Quezon) with 0.0054 mm. Fiber amount, on the other hand, was minimal in QP2-84 (Pagbilao, Quezon) with 21.14% and was abundant in LP2-86 (Daraga, Legaspi) with 38.42%. Analysis of variance (ANOVA) revealed that the individual sites were significantly different from one another in both fiber characteristics and distribution.

Physico-Mechanical Specific gravity and cane stiffness determine the acceptability of rattan canes for a particular end use because these factors dictate the dimensional stability of

the material as well as its flexibility. Table 3 provides the physico-mechanical attributes of the different samples. Specific gravity was lowest in MP-96 (Southern Negros) and PNOC-97 (Sorsogon) with 0.38 while it was highest in QP2-84 (Pagbilao, Quezon) with 0.51. The data was comparable with the specific gravity of Calamus manan in Peninsular Malaysia (Sulaiman & Lim 1991). MOR was smallest in QP1-94 (Pagbilao, Quezon) with 14.35 MPa and was largest in NP-93 (Southern Negros) with 32.45 MPa. MOE was minimum in PNOC-97 (Sorsogon) with 3.23 GPa and was again maximum in NP-93 (Southern Negros) with 6.37 GPa. Among the three characteristics evaluated, only specific gravity varied significantly between samples based on the ANOVA. MOR and MOE of the samples were virtually the same for all the sites.

Table 2. Fiber characteristics of the individual rattan samples.

Sample Fiber length(mm)a

Cell wall thickness(mm)a

Fiber Percentage(%)b

QP2-84 1.5140 (0.3437) 0.0076 (0.0036) 21.14 (8.40)

LP2-86 1.5363 (0.4446) 0.0079 (0.0027) 38.42 (23.42)

TP-89 1.5805 (0.2800) 0.0079 (0.0066) 31.25 (15.32)

LP1-90 1.7044 (0.4849) 0.0057 (0.0011) 36.15 (16.57)

NP-93 1.3649 (0.1886) 0.0065 (0.0008) 30.42 (15.77)

MLP-93 1.6559 (0.3078) 0.0109 (0.0330) 33.38 (13.91)

QP1-94 1.9124 (0.4137) 0.0054 (0.0014) 30.70 (16.41)

AKP-94 1.5339 (0.1836) 0.0071 (0.0013) 31.58 (15.75)

MP-94 1.4240 (0.1732) 0.0058 (0.0006) 25.63 (10.84)

MP-96 1.4183 (0.2864) 0.0059 (0.0038) 27.37 (7.54)

PNOC-97 1.7630 (0.5716) 0.0062 (0.0014) 29.53 (12.29)

NP-97 1.3778 (0.1155) 0.0077 (0.0045) 30.21 (13.00)

ANOVA**Fcom = 6.593 Fcom = 4.388 Fcom = 1.917

F tab = 1.802 F tab = 1.802 F tab = 1.831 Italized values inside parenthesis = standard deviation** Significant at α = 0.05; Fcom = F computed; F tab = F tabulated

Table 3. Physico-mechanical properties of the individual rattan samples.

Sample Specific Gravitya Modulus of Rupture(MPa)b

Modulus of Elasticity(GPa)b

QP2-84 0.51 (0.15) 27.55 (3.62) 4.99 (1.08)

LP2-86 0.42 (0.21) 26.75 (12.30) 5.35 (2.78)

TP-89 0.47 (0.19) 27.62 (15.67) 4.46 (2.90)

LP1-90 0.46 (0.17) 25.13 (7.79) 4.76 (1.38)

NP-93 0.48 (0.15) 32.45 (11.58) 6.37 (2.11)

MPL-93 0.39 (0.13) 30.97 (16.82) 5.79 (3.45)

QP1-94 0.50 (0.12) 14.35 (3.31) 6.11 (2.39)

AKP-94 0.46 (0.15) 25.2 (11.43) 4.64 (2.77)

MP-94 0.47 (0.19) 28.38 (14.33) 4.56 (2.06)

MP-96 0.38 (0.14) 18.52 (7.06) 3.46 (1.69)

PNOC-97 0.38 (0.15) 18.85 (10.91) 3.23 (1.73)

NP-97 0.50 (0.16) 27.38 (14.31) 4.47 (2.16)

ANOVA**Fcom = 3.572 Fcom = 1.291 Fcom = 1.034

F tab = 1.809 F tab = 1.952 F tab = 1.952Note: a n = 60; b n = 6Italized values in parenthesis = standard deviation** Significant at α = 0.05; Fcom = F computed; F tab = F tabulated

Influence of Growth Rate on Stem Qualities The influence of growth rate on the different cane properties is depicted in Figure 4. Regression showed that growth rate and fiber characteristics e.g., length and cell wall thickness; were not correlated with r = 0.04 and r = -0.07, respectively. Although these parameters differ between sites, the findings showed that the rate at which the plant grows has nothing to do with such discrepancy. Only fiber distribution gave a moderate correlation with growth rate (r = 0.53). As the growth rate was enhanced a corresponding increased in fiber quantity was noticed.

Modulus of rupture, modulus of elasticity, and specific gravity were unaltered by growth rate. Irrespective of how



1

1.2

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1.6

1.8

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Growth rate (m/year)

Fib

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(m

m)

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Ce

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are

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du

lus o

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Mo

du

lus

of

Ela

sti

cit

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f.

Figure 4. Influence of growth on fiber length (a), cell wall thickness (b), fiber percentage (c), ovendried specific gravity (d), Modulus of Rupture (e), Modulus of Elasticity (f). ns = not significant, ** = significant at α = 5%.

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fast or how slow the growth of the palasan plants was, the physico-mechanical attributes of the cane were not significantly different. Fiber characteristics are directly related to both physical and mechanical characteristics of the cane (Bhat et al. 1990). It follows that when fiber characteristics are unaffected, specific gravity and material stiffness would also be unaltered by growth rate.

Influence of elevation and sunlight exposure on cane propertiesFigure 5 provides the impact of elevation on cane properties. The elevation of the site did not show any significant effect on the basic properties of the cane. Normally, trees grown at higher altitudes or higher elevations produce wood of lower specific gravity and



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1.2

1.4

1.6

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0 200 400 600 800 1000

Elevation (masl)

Fib

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len

gth

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m)

y = 1.62 - .0001 xr = - 0.20 ns

a.

0.002

0.004

0.006

0.008

0.01

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0 200 400 600 800 1000

Elevation (masl)

Cell w

all t

hic

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ess (

mm

)

y = 0.006 + 2.37E-6 xr = 0.45 **

b.

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Elevation (masl)

Fib

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perc

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%)

y = 33.20 - 0.006 xr = - 0.37**

c.

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0.45

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Elevation (masl)

Ov

en

dri

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ific

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vit

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y = 0.45 - 2.1E-6 xr = - 0.01 ns

d.

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Elevation (masl)

Mo

du

lus o

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ture

(M

Pa)

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e.

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0 200 400 600 800 1000

Elevation (masl)

Mo

du

lus o

f E

lasti

cit

y (

GP

a)

y = 4.56 + 0.001 xr = 0.19 ns

f.

Figure 5. Influence of elevation on fiber length (a), cell wall thickness (b), fiber percentage (c), ovendried specific gravity (d), Modulus of Rupture (e), Modulus of Elasticity (f). ns = not significant, ** = significant at α = 5%.

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shorter cells (Zobel & van Buijtenen 1989). However for palasan canes such conditions were not detected. Except for the moderate relationship of elevation to cell wall thickness (r = 0.45) and fiber distribution (r = 0.37), the rest of the properties were minimally affected.

Likewise, the amount of sunlight did not significantly affect cane properties (Figure 6). Though sunlight exposure enhances seedling growth as reported by Dela Cruz (unpublished project report 1987) and stem development (Manokaran 1985), it only has minor



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1.2

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m)

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Oven

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Amount of sunlight (%)

Mo

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lus o

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Amount of sunlight (%)

Mo

du

lus o

f E

lasti

cit

y (

GP

a)

y = 5.4 - 0.01 xr = -0.28 ns

f.

Figure 6. Influence of amount of sunlight exposure on fiber length (a), cell wall thickness (b), fiber percentage (c), ovendried specific gravity (d), Modulus of Rupture (e), Modulus of Elasticity (f). ns = not significant, ** = significant at α = 5%.

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influence on the kind of cane produced by the plant. This means that it would only have a significant impact on the rattan plant during the establishment stage because of its direct influence on the rosette/grass stage of the plant. Thus based on the results, palasan plants that were partially exposed to the sun produced the same type of cane as a fully exposed individual.

Impact of growth patterns on the quality of the stemThis was not the first study in which rattan canes were

shown to behave differently from trees. In 1999, Abasolo et al. noted a contradicting growth stress pattern between wood and rattan stems. Therefore, it was not surprising if the influence of growth rate, elevation, and sunlight exposure on the properties of rattan canes was again different to that of wood.

Generally, stem growth is achieved by the plant through primary growth (growth in length) and secondary growth (growth in diameter). The former is accomplished by means of the apical meristems located at the tip of



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shoots (Ridge 2002) while the latter is attained via the lateral meristems situated at the peripheral region of the stem (Panshin & de Zeeuw 1978). Rattan stems lack the necessary lateral meristems to undergo secondary growth, thus, its stem is generated solely through primary growth. Limited diameter growth could only occur through ground parenchyma cell enlargement (Tomlinson 1961). Trees, on the other hand, produce their stem by means of both primary growth and secondary growth.

Growth rate would only influence the primary growth of the rattan stems particularly internodal elongation through intercalary growth (Sinnott & Wilson 1963). While for trees, both primary and secondary growth would be simultaneously affected. The way in which growth rate would influence these two types of stem development would have a big impact on the overall quality of the stem produced by these individual plants. For one, the two meristems differ in the way they divide and the frequency of division during growth (Zimmermann & Brown 1971). This could bring forth variation in their interaction to growth rate. However, this topic is beyond the scope of the current report.

CONCLUSIONSGrowth rate did not significantly influence the structural, physical and mechanical attributes of palasan canes grown in plantations. Likewise, elevation and amount of sunlight exposure have little influence on cane properties. This means that site characteristics would only have minimal effect on the kind of stem produced by the palasan plant. It would only have a big influence during the establishment period of the plantation because of the direct impact on the rosette/grass stage of the plant. However, after the internodal elongation, it would only have minor impact on cane quality. As pointed out by Tomlinson (1990), rattan stems are incapable of undergoing secondary growth, thus, the plant has no alternative but to produce an overbuilt stem capable of withstanding future load requirement. For this reason, growth rate, elevation and amount of sunlight exposure would only have minimal effect on stem quality.

Implication of the resultsThe present report was able to discover the relationships between growth rates and stem quality of palasan plants. It was able to show that growth rate did not significantly influence the quality of the palasan stem except for the fiber percentage. Similarly, it showed

that elevation and sunlight exposure did not give any significant interaction with most of the cane properties. This means that it was highly possible that activities aimed at hastening the growth rate of the plant, e.g., silvicultural treatments, would also have minimal effect on the quality of its stem. Rattan plantation developers could perform fertilization, thinning activities, etc. to improve cane growth without worrying about any negative impacts these treatments would have on the quality of the cane produced by the plants. If the quality of the cane was unaltered, its utilization would not be affected.

RECOMMENDATIONThe report was able to prove that palasan plants are ideal plantation species because they grow in any kind of site and their stems are minimally affected by varying site conditions, e.g., elevation and sunlight exposure. This means that the establishment of palasan plantation is a good investment because it would not entail so much risk in the part of the investors. As proven by a previous article (Abasolo 2007), the qualities of plantation-grown palasan canes are comparable with rattan canes growing wild in the forest. Being such, rattan industries would have no problem utilizing them, thus, palasan growers would have a sure market for their products. Therefore, palasan plantation establishment would not only be profitable, it would also contribute to the conservation/preservation of the remaining rattan stocks found in natural forests. Thus, it is recommended that more palasan plantations be established.

ACKNOWLEDGMENTThis study was funded by the International Foundation for Science under research grant no. D/3499-1. The authors also acknowledges the assistance of C. Dapla and W. Palaypayon of the Deparment of Environment and Natural Resources; and A. de Jesus, E. del Rosario and M. Paje of the Philippine National Oil Company-Energy Development Corporation.

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