Differences in Growth and Starch Yield of Sago Palms (Metroxylon Sagu Rottb.) Among Soil Types in Sarawak, Malaysia

Jpn. J. Trop. Agr. 47(4) : 250 -259, 2003

Differences in Growth and Starch Yield of Sago Palms (Metroxylon sagu Rottb.) among Soil Types in Sarawak, Malaysia

Yoshinori YAMAMOTO,Tetsushi YOSHIDA,Yuusuke GOTO1,Youji NITTA2, Ken-ichi KAKUDA3,Foh Shoon JONG4,5,Laiberi Biut HILARY4and Abdul Halim HASSAN6

Faculty of Agriculture, Kochi University, Nankoku-shi, Kochi 783-8502, Japan 1 Guraduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan 2 Faculty of Agriculture , Ibaraki University, Ami-machi, Ibaraki 300-0393, Japan 3 Faculty of Agriculture , Yamagata University, Tsuruoka-shi, Yamagata 997-8555, Japan 4 Department of Agriculture , Sarawak, Malaysia 5 Present address; PT. National Timber and Forest Products, Tebing-Tinggi, Riau, Indonesia 6 Land Custody and Development Authority (LCDA), CRAUN,Sarawak, Malaysia

Abstract The growth and starch accumulation process of sago palms cultivated on deep (DPS) or shallow peat soil (SPS) and mineral soil (MS) at Mukah and Dalat in Sarawak, Malaysia, were analyzed to examine the effects of the soil types on the growth and starch production. For the sago palms cultivated on DPS, longer years were required to reach the harvesting stage, while values for growth parameters including leaf emergence, trunk elongation and increase in trunk weight and volume were lower and resulted in lower trunk weight and volume at the harvesting stage compared with the sago palms cultivated on SPS and MS. On the other hand, the starch accumulation in the pith of trunk was monitored in the same way and a substantial starch accumulation started in the 3rd and 4th years after trunk formation in the sago palms cultivated on MS or SPS and DPS, respectively, while the trunk length and weight at that time were about 3m and 250- 300kg, irrespective of the soil types. The soil types did not affect the average starch yield at the harvesting stage, i.e., 160- 180kg per palm (dry weight basis). However, these results might be due to the higher starch percentage in the pith of the sago palms cultivated on DPS associated with the favorable light conditions in the garden because of the short duration of the period after the opening of the garden compared with the sago palms cultivated on MS and SPS. Key Words: Growth rate, Growth stage, Metroxylon sagu, Starch accumulation, Years after trunk formation

マレーシア,サラワク州におけるサゴヤシの生育・デンプン収量― 土壌の種類による差異― 山本由徳・吉田徹志・後藤雄佐1・新田洋司2・角田3―3・Foh Shoon JONG4,5・Laiberi Biut HILARY 4 and Abdul Halim HASSAN6高知大学農学部〒783-8502南国市物部乙2001東北大学大学院農学研究科〒981-8555仙台市青葉区堤通雨宮町1-12茨城大学農学部〒300-0393茨城県阿見町中央3-21-13山形大学農学部〒997-8555鶴岡市若葉町1-234サラワク州農業局マレーシア,サラワク5現在;PT.National Timber and Forest Products 6LCDA(CRAUN)マレーシア,サラワク

要約サラワク州のムカとダラトにおいて,生育土壌の種類(深い泥炭質土壌;DPS,浅い泥炭質土壌;SPS,鉱質土壌;MS)を異にするサゴヤシの幹立ち後から収穫期に至る生育経過とデンプン蓄積経過を明らかにして,土壌の種類によるデンプン生産性の差異について検討した.DPSに生育するサゴヤシは,MSやSPSに生育するサゴヤシに比べて,収穫まで年数が長かったが,出葉速度,樹幹伸長速度,樹幹重および容積の増加速度などの生長速度は遅く,収穫適期における樹幹重と容積はMSやSPSに生育するサゴヤシに比べて劣った.一方,髄部のデンプン蓄積経過には土壌の種類による差は認めらなかった.髄部の澱粉蓄積は,幹立ち後 MSとSPSでは3年目以降,DPSでは4年目以降に急増を開始したが,その時の樹幹長,樹幹重は土壌の種類に関わりなく,それぞれ3mと250～300kgであった.収穫適期における樹幹当たりのデンプン収量は,土壌の種類による差は小さく,平均で160～180kg (乾燥デンプン)であったが,これにはDPSのサゴヤシ園の開園後年数が若く,そこに生育するサゴヤシの髄部デンプン含有率が MSやSPSに生育するものに比べてやや高かったことが密接に関係していると考えられた. キーワード生育時期,生長速度,デンプン蓄積,Metyoxylon sagu,幹立ち後年数

elevation of 700m (FLACH,1977). The underground Introduction environment varies in terms of soil types, level Sago palm (Metroxylon sagu Rottb.) is mainly of water table, frequency of sea water invasion, distributed in swamp area with a high temperature degree of flooding in the rainy season, etc. and abundant sunshine located at latitude between (YAMAMOTO,1998). It was reported that sago 10•‹ North and South, and it can grow up to an palm is the only crop that can grow well on deep Received May 26, 2003 peat soil which is characterized by low pH Accepted Aug. 30, 2003 values, a high water table all the year round, a Yamamoto et al.: Starch yield of Sago Palms among soil types 251 deficiency in mineral elements, etc. without any improvement of these characteristics (SATO et Surveyed Areas and Experimental Methods al., 1979; TIE et al., 1977, 1991). Surveyed areas and methods In Sarawak, Malaysia, where commercial The surveys were carried out in farmers' production of sago starch is the most popular in gardens in the Mukah and Dalat Districts of the world, sago palms are planted over an area Sarawak State, Malaysia in 1996-1998 (Table 1). covering about 19,720ha with soil types consisting In the Mukah area, the farmers' gardens were of peat soil (62%) and mineral soil (33%), located in the Jebungan and Tellian villages east respectively. Moreover, in 38% of the peat soil and south of Mukah town, respectively (YAMAMOTO area, peat soil is more than 150cm deep, while et al., 2003). In the Jebungan village, soil types the remaining 24% area consists of shallow peat of the surveyed gardens consisted of shallow soil (TIE et al., 1991). The growth and starch peat soil (SPS) 20-60cm and 70-120cm thick or yield of the sago palms cultivated on different mineral soil (MS). The soil type of the gardens soil types in Sarawak, Malaysia were reported surveyed in the Tellian village consisted of MS. by SIM and AHMED (1978), TiE et al. (1991), In the Dalat area that is located about 20km YAMAGUcHIet al. (1994 and 1997), JONG and southwest of Mukah town, the surveys were F1.Acu (1995) and KANEKOet al. (1996). According conducted in the farmer's sago palm garden of to these reports, for the sago palms cultivated Balan village which is close to the Sungai Talau on deep peat soil, longer years from sucker Peat Research Station (STPRS) (YAMAGUCHI et planting or emergence to trunk formation and al., 1994) and the soil type of this garden harvesting stage were required and the values consisted of deep peat soil (DPS) 300-450cm of growth parameters including leaf expansion and thick. All the sago palms surveyed belonged to trunk elongation were lower. Starch productivity the non-spiny type. Although the planting space of sago palms cultivated on different soil types, of each surveyed sago palm garden was about however, is poorly documented and very few the same (9-lOm •~ 9-10m), the duration of the reports are available on the starch accumulation period after the opening of the garden in Dalat process in relation to the growth stages after was about less than 20 years and the garden was trunk formation (long, 1995; YAMAMOTOet al., younger than those in Mukah. 2003). One to three sago palms with different ages, This study was conducted to analyze the i.e., different years after trunk formation which differences in the growth and starch productivity were selected by the owner of the garden in one of sago palms cultivated on different soil types, to three area in each garden was felled using a i.e., deep and shallow peat soils and mineral soil chainsaw. The number of sampled sago palms in relation to the growth stages after trunk and their age are shown in Table 1. After felling, formation at Mukah and Dalat in Sarawak, growth parameters including palm height, trunk Malaysia. length, number of leaf scars and living leaves

Table 1. Outline of the surveyed sago palm gardens at Muka and Dalat, Sarawak, Malaysia and number of sampled sago palms.

1)J , T and B in the parenthesis indicate the Jebungan, Tellian and Balan village. 2) Categorized after Tie et al . (1991). 3) Depth from soil surface in dry season . 4) Yeas after trunk formation esimated by the owner of the garden . 252 Jpn. J. Trop. Agr. 47 (4) 2003 were measured. Trunks were cut into sections duration of the former period was usually 4-6 about 0.9m long (hereafter referred to as •glog•h), years in the case of MS and 6-8 years in the case i.e., the standard length of a log for selling in of DPS, while that of the latter period was about these areas and the weight of each log section 2 years, irrespective of the soil types (JUNG and was measured. The average diameter of the HiuLu y, personal communication). In sago palms, trunk was calculated based on the diameter of since starch accumulated in the trunk is utilized, all the logs and that of the bottom, top and the growth and starch accumulation process of middle log when the number of logs was less sago palms cultivated on different soil types and more than three, respectively. Samples of after trunk formation should be compared. pith tissues weighing 50-100grams (unit of 0.1g) Therefore, the palm age in this study was using an electronic balance (HL-200 type, expressed by the years after trunk formation

Kagakukyoei Co., Ltd.) were taken radially from (YATF) estimated by the owner of the garden. the center of a disk with 2-3cm thick in the The ages of the sampled palms in this study middle of each log for which the diameter was ranged from 1.5-8 in MS, 1.5-9 in SPS and 2-10 measured. YATF in DPS, and those in the 7th and 8th years Experimental materials and methods in MS, 9th year in SPS and 10th year in DPS The pith samples were dried in a ventilation- attained at the flower formation or bolting stage oven at 80 •Ž for about 2 days, and brought to (Table 1). The number of mature sago palms Japan, and again dried in a ventilation-oven at 65•Ž that had reached the harvesting stage beyond for 2 days to measure the dry weight. The the full trunk length stage (TONG, 1995) were 5 contents of total sugar and starch were analyzed in MS (6-8 YATF, 4 in SPS (6-9 YATF) and 4 in by the same methods as those described in the DPS (8.5-10 YATF). previous report (YAMAMOTO, et al., 2003). Total Growth after trunk formation sugar and starch percentages were expressed as Relations between YATF and the growth glucose and multiplied 0.9 to obtain glucose parameters of sago palms cultivated on different percentage per dry weight, respectively. The soil types were analyzed to compare the differences average values of pith dry matter, total sugar in the pattern of growth progress after trunk and starch percentages were calculated from formation associated with the soil types as follows. the values of all the logs when the number of Plant length of the sago palms cultivated on logs was three or less and according to the formula: different soil types was not appreciably different [LL+UL+ML •~ (number of logs-2) /number of immediately just after trunk formation, ranging logs], where LL, ML and LL denote the values from 10-12m and reached values of 15-18m at of bottom, middle and top logs when the the harvesting stage. Number of living leaves number of logs more than three. The starch ranged from 15 to 20, irrespective of the soil content (the amount of starch yield) of a trunk types and growth stages, although the number was calculated by the following formula; trunk in the 10th year palms in DPS was much higher. fresh weight •~ 0.8 •~ average dry matter percentage Annual rate of increase of expanded leaves on a of pith /100 •~ average starch percentage of pith palm calculated by adding the number of leaf /100. Since the weight of the bark accounted for scars and living leaves after trunk formation was about 20% of the trunk weight (YATSUGI, 1977), higher in the order of sago palms cultivated on the value was multiplied by 0.8 in the formula. SPS (10.6 leaves) > MS (9.2 leaves) > DPS (8.1 leaves) (Fig. 1). This rate is considered to indicate Result the average leaf emergence rate after trunk Determination of age of sago palms formation. It is necessary to estimate the palm age Changes in the trunk length and average exactly for a comparison of the effects of soil trunk diameter of the sago palms cultivated on types on the growth and starch yield in sago the different soil types after trunk formation was palms. As for the growth stages of sago palm, it shown in Fig. 2. The trunk length increased at a was suggested that the growth period from sucker rate of 90-130cm per year on the average in the planting or emergence to trunk formation was order of sago palms cultivated on SPS•†MS more affected by the soil types than that from >DPS, and the length of the trunks cultivated on flower bud formation to flowering, i.e., the DPS was shorter than cultivated on SPS and MS Yamamoto et al.: Starch yield of Sago Palms among soil types 253

compared at the same YATE Trunk length at the harvesting stage, however, did not show appreciable differences among the sago palms cultivated on different soil types, ranging from 6- 8m, except for the 9th year palms cultivated on SPS. The average trunk diameter of sago palms ranged from 35 to 55cm, with a maximum value immediately after trunk formation and tended to decrease with YATF in the order of sago palms cultivated on MS followed by SPS and DPS. Changes in the trunk weight and volume of the sago palms cultivated on different soil types after trunk formation are shown in Fig. 3. Yearly

Fig. 1. Relation between years after trunk formation growth rates of the trunk weight and volume were higher in the order of sago palms cultivated and number of leaf scars and leaves in sago on MS (152kg) > SPS (121kg) > DPS (74kg) and palms cultivated on different soil types. *Estimated by the owner of the garden MS (0.166m3) •† SPS (0.142m3) > DPS (0.09m3), .•› respectively, and the rates of sago palms cultivated , mineral soil; • , shallow peat soil; •œ, deep peat

soil. on MS were about two times higher than those of the palms cultivated on DPS. The trunk

Fig. 2. Relation between years after trunk formation Fig. 3. Relation between years after trunk formation

and trunk length (A) or trunk diameter (B) and trunk weight (A) or trunk volume (B) in

in sago palms cultivated on different soil sago palms cultivated on different soil types. *Estimated by the owner of the garden types. *Estimated by the owner of the garden.•› .•›

, mineral soil; • , shallow peat soil; •œ, deep peat , mineral soil; • , shallow peat soil; •œ, deep peat soil. soil. 254 Jpn. J. Trop. Agr. 47 (4) 2003

Fig. 4. Correlation between trunk length and trunk

weight.•›

, mineral soil; • , shallow peat soil; •œ, deep peat soil. weight and volume at the harvesting stage ranged from 600 to 1100kg and from 0.7m3 to 1.3m3, respectively, and the values of the sago palms cultivated on DPS tended to be considerably lower than those of the palms cultivated on MS and SPS. Regardless of the soil types, a highly significant and positive correlation was observed between the trunk weight and volume (MS; Fig. 5. Relation between years after trunk formation r=0.983***, SPS; r=0.980***, DPS; r=0.957***) and dry matter (A) or starch percentage of pith and the trunk weight per m3 volume was higher (B) in sago palms cultivated on different soil in the order of sago palms cultivated on MS types. *Estimated by the owner of the garden.•› (887kg) > SPS (822kg) > DPS (767kg). A highly , mineral soil; • , shallow peat soil; •œ, deep peat significant and positive correlation was observed soil. between the trunk length and trunk weight as well and the trunk weight per m calculated from rapidly increased to the 6th and 8th years after the regression line was heavier in the order of trunk formation in the palms cultivated on MS the sago palms cultivated on MS (125kg) or SPS and DPS, respectively. Irrespective of the followed by SPS (91kg) and DPS (84kg) (Fig. 4). soil types, the percentages of dry matter and Based on the results obtained, the growth starch were mostly distributed within the range rates of sago palms in terms of leaf number and of 40-50%and 60-70%,respectively, at the harvesting trunk elongation, weight and volume after trunk stage, although these percentages tended to be formation that were cultivated on different soil slightly higher in the sago palms cultivated on types are listed in Table 2, which shows that DPS than those in the palms cultivated on MS these growth rates were lower in the sago palms and SPS. A closer relation was observed between cultivated on DPS than in those cultivated in the percentages of dry matter and starch and SPS and MS. their relation was regressed by a logarithmic Starch accumulation process and starch yield equation, however, the starch percentage tended Changes in the percentages of dry matter to be higher in the order of sago palms cultivated and starch in the pith of trunk after trunk on DPS followed by SPS and MS at more than formation are shown in Fig. 5. Only a slight 30% of dry matter (Fig. 6). increase in these percentages was observed Total sugar percentage in the pith of trunk until the 3rd and 4th years after trunk formation showed an extremely high value, 40-50%, in the in the sago palms cultivated on MS or SPS and 1st and 2nd years after trunk formation, but DPS, respectively, but thereafter the values thereafter the values exponentially decreased Yamamoto et al.: Starch yield of Sago Palms among soil types 255

Fig. 6. Correlation between dry matter percentage Fig. 7. Relation between years after trunk formation

and starch percentage of pith.•› and total sugar percentage of pith in sago

, mineral soil; • , shallow peat soil; •œ, deep peat palms cultivated on different soil types. soil. *Estimated by the owner of the garden .•›

, mineral soil; • , shallow peat soil; •œ, deep peat and finally reached 2-5% at the harvesting stage, soil. irrespective of the soil types (Fig. 7). A closer negative correlation was observed between the total sugar and starch percentages (r=0.969***). Changes in the amount of starch accumulated in the pith (starch content) of trunk are shown in Fig. 8. The starch content did not increase appreciably until the 3rd and 4th years after trunk formation in the sago palms cultivated on MS or SPS and DPS, respectively, but thereafter the content linearly increased, irrespective of the soil types. The coefficients of regression lines showed that the starch accumulation rate per year was higher in the order of sago palms cultivated on MS (48kg) followed by SPS (39kg) and DPS (32kg) (Table 2). Fig. 8. Relation between years after trunk formation Correlations between the trunk length or and starch yield in sago palms cultivated on weight and starch content in the pith of trunk different soil types. *Estimated by the owner are shown in Fig. 9 to analyze the relation of the of the garden. growth parameters to starch accumulation. Before Regression lines in the figure were calculated the trunk length reached value of 3m or the trunk for the palms after 3 years of trunk formation weight reached values of 250 (DPS) -300kg (MS on the mineral and shallow peat soils and for and SPS), only a small amount of starch those after 4 years on the deep peat soil.•› accumulated in the pith. However, thereafter, , mineral soil; • , shallow peat soil; •œ, deep peat soil. starch accumulated in parallel with the trunk elongation or trunk weight, irrespective of the soil types (Fig. 9A, B). Based on the coefficients weight) were higher in the order of sago palms of regression lines shown in Fig. 9A, the starch cultivated on DPS (36%) followed by MS (31%) accumulation rate per 1m trunk elongation was and SPS (29%). higher in the order of sago palms cultivated on Starch yield and related growth parameters MS (40kg) followed by DPS (35kg) and SPS of sago palms at the harvesting stage are shown (31kg). The coefficients of the regression lines in Table 3. Although for the sago palms cultivated in Fig. 9B which lists the ratios of the starch on DPS, it took 2-3 years longer from trunk amount (dry weight) to the trunk weight (fresh formation to harvest and the palms showed a 256 Jpn. J. Trop. Agr. 47 (4) 2003

Table 2. Differences in growth and starch accumulation rates of sago palms cultivated on the different soil types.

1) Dry starch . 2) Years after trunk formation at the beginning of rapid starch accumulation . The starch accumulation rates were calculated after that year.

Discussion It was reported that the sago palms cultivated on MS reached harvesting stage after 10-12 (JOHNSONand RAYMOND,1956) or 8-12 years after planting (TONGand FLACH,1995), while for those cultivated on DPS, it took 12-15 GONGand FIACH,1995; YAMAGUCHIet al., 1997) or 15-17 years (JOHNSONand RAYMOND,1959). These reports clearly revealed that the growth duration from planting to harvest varied depending on the soil types and was longer in the sago palms cultivated on DPS than in those cultivated on MS. Moreover, the growth duration from planting to trunk formation in the former took about 6-8 years GONG and HILARY,personal communication) and this duration was 2-4 years longer compared with 4-6 years in the latter. In this study, we tried to compare the growth and starch accumulation process of the sago palms cultivated on MS, SPS (thickness of peat soil layer; 150cm>) and DPS (ibid.; 150cm<) to analyze the effects of the soil types on the sago growth and starch productivity (Table 1). The growth duration from trunk formation

Fig. 9. Correlation between trunk length (A) or to harvesting (over full trunk length stage, weight (B) and starch yeeld in sago palms JoNG, 1995) was longer in the order of sago cultivated on the different soil types. palms cultivated on DPS (8-10 years) followed Regression lines in the figure were calculated by SPS (6-9years) and MS (6-8 years) and the for the palms more than 3m long (A) and growth duration including years to trunk with a trunk weight more than 300kg on the formation was 10-14 years for MS and 14-18 mineral and shalllow peat soils, and 250kg years for DPS. These results were in agreement on the deep peat soil (B). with those of the above-mentioned reports. It 0, mineral soil; 0, shallow peat soil; •, deep also took 6-8, 9 and 10 years to the flower-bud peat soil. formation stage after trunk formation for the sago palms cultivated on MS, SPS and DPS, lower trunk growth than those cultivated on MS respectively. and SPS, no difference was observed in the The results of the correlation analysis starch yield among the soil types due to the between YATF and growth parameters which higher starch percentage of palms grown on DPS. revealed the presence of a highly significant and Yamamoto et al.: Starch yield of Sago Palms among soil types 257

Table 3. Differences in some growth parameters and starch yield per trunk of sago palms cultivated on the different soil types at harvesting stage.

1) Years after trunk formation at harvesting stage . 2) Dry starch . Values are mean •} standard deviation.

positive correlation in the number of leaf scars of the period after the opening were considered and living leaves, trunk length, weight and to have inhibited the trunk elongation. Moreover, volume, etc., irrespective of the soil types were the trunk weight and volume at the harvesting linearly regressed on these growth parameters stage were also lower in the sago palms

(Fig. 1•`3). The growth rates expressed by the cultivated on DPS in spite of their longer growth coefficients of regression lines were remarkably duration compared with those cultivated on MS lower in the sago palms cultivated on DPS than and SPS (Table 3). in those cultivated on MS and SPS (Table 2). In No differences were observed in the starch

particular, the trunk elongation rate of the accumulation process of the sago palms cultivated former was 87cm per year and this value was 35 on MS, SPS and DPS (Fig. 5B). Total sugar and 27% lower compared with the values for MS percentage in the pith immediately after trunk (134cm / yr) and SPS (118cm / yr), respectively. formation which was remarkably high, ranging Moreover, the growth rate of the trunk weight from 40 to 50%, tended to increase from the base

per year was higher in the order of the sago to the top of the trunk (Fig. 7). The total sugar palms cultivated on MS (152kg) > SPS (121kg) > percentage, however, decreased with YATF as DPS (74kg), and the rates of palms cultivated on starch accumulation proceeded from the base to DPS were 51 and 39% lower than those of the the top (YAMAMOTOet al., 2003). Finally at the palms cultivated on MS and SPS, respectively. harvesting stage, the total sugar and starch This was also true for the average trunk percentages in the pith did not show appreciable diameter after the 4th year of trunk formation differences among the positions on the trunk (Fig. 2B). These results were consistent with (SIM and AHMED, 1978; JONG, 1995; YAMAMOTO the findings reported by KANEKO et al. (1996) et al., 2003). These results suggested that the and YAMAGUCHI et al. (1997) who compared the starch syntase activity in the pith of sago palms trunk growth rate of the sago palms cultivated of the early stage of trunk formation was low, on DPS with the rate of the palms cultivated on but that the enzyme was rapidly activated in some MS at Dalat in Sarawak. KAKUDA et al. (2000) YATF and led to the promotion of transformation suggested that one of the factors responsible for from sugar to starch (SATOet al., 1979; YAMAMOTO

poor growth of the sago palms cultivated on et al., 2003). The higher starch percentage in DPS was the lower mineralization of nitrogen the pith of the sago palms cultivated on DPS at per unit volume of DPS. On the other hand, the harvesting stage compared with that of the although TIE et al. (1991) and KUEH et al. (1991) sago palms cultivated on MS and SPS (Fig. 5B) reported that the trunk length at the harvesting might be due to the favorable light conditions in stage was longer in the sago palms cultivated on the garden associated with the short duration of DPS than in those cultivated on MS, in our the period after the opening, as mentioned study, no significant differences were observed above. TIE et al. (1991) and KUEH et al. (1991) among the soil types. Trunk elongation may be reported that the starch percentage in the pith affected by the light conditions, such as mutual of the palms cultivated on DPS was lower than shading in the sago palm garden (FLACH and that of the palms cultivated on MS at the SCHUILING, 1989). Therefore, better light conditions harvesting stage. in the garden of DPS due to the short duration Starch yield per trunk is determined by the 258 Jpn. J. Trop. Agr. 47 (4) 2003

pith (dry) weight and its starch percentage. The yield. This discrepancy may be due to the increase in the starch yield was limited until the difference in the light conditions and nutrient 3rd year for MS and SPS or the 4th year after status of the soil and underground water in the trunk formation for DPS, but thereafter the sago gardens of DPS where the sago palms yield increased linearly with YATF (Fig. 8). This were sampled (FUNAKAWAet al., 1996; KAKUDAet starch accumulation process of sago palm was al., 2000). On the other hand, KUEH et al. (1991) proposed by SATOet al. (1979) and experimentally reported that the starch yield of the sago palms confirmed by YAMAMOTOet al. (2003). Yearly cultivated on DPS (277kg) was higher than that starch production rate could be estimated from of the palms cultivated on MS (219kg) at Mukah the regression lines after the 3rd or the 4th year in Sarawak. after trunk formation and the values were It could be concluded that for the sago higher in the order of sago palms cultivated on palms cultivated on DPS longer years were MS (48kg) followed by SPS (39kg) and DPS required for reaching the harvesting stage, but (32kg) (Fig. 8). These results revealed that the that their trunk weight and volume were starch production rate of the sago palms considerably lower than those of the palms cultivated on DPS was 33 and 18% lower than cultivated on MS and SPS due to the lower that of the palms cultivated on MS and SPS, growth rate and the start of remarkable starch respectively. Remarkable starch accumulation in accumulation in the pith of trunk was about one relation to the trunk growth parameters started year late, although the starch accumulation when the trunk was about 3m long and weighted process was similar, irrespective of the soil 250-300kg, irrespective of the soil types (Fig. 9). types. Although no differences in starch yield According to the report of JONG (1995), the were observed in the sago palms cultivated on suitable stage for harvesting in sago palm is different soil types, these findings might be from full trunk to the flowering stage, and closely related to the higher starch percentage within these stages starch yield does not differ in the pith of the sago palms cultivated on DPS appreciably. Average starch yield of the sago due to the favorable light conditions in the palms within these stages that were cultivated garden because of the short duration of the on each soil type in this study was 164-180kg per period after the opening of the garden. It was palm (dry weight basis) and differences among eventually suggested that starch productivity of the soil types were not conspicuous (Table 3). sago palms cultivated on DPS was slightly lower These results agreed well with those reported than that of the palms cultivated on MS and SPS by TIE et al. (1991) and YAMAMOTOet al. (2003) for about the same starch percentage under who failed to observe significant differences in about the same light conditions in the sago starch yield between the sago palms cultivated garden. on MS and DPS or on MS and SPS at Mukah Acknowledgement and Dalat in Sarawak, respectively. The starch yield level obtained in this study was close to We thank the staff of the Land Custody and the values of 189kg for MS and 179kg for DPS Development Authority (LCDA), CRAUN, Sarawak, reported by SIM and AHMED (1978), 155-214kg Malaysia, for their kind assistance in the field for MS (average; 192kg) and 166-244kg for SPS research. The research was financially supported (average; 199kg) by YAMAMOTOet al. (2003) at by the Japan Society for the Promotion of Mukah in Sarawak and 203-219kg for DPS at Science in 1996 and the Toyota Foundation in Dalat in Sarawak by JONG (1995). However, in 1997 and 1998. the current study, the higher percentage of References starch and reduced trunk growth of sago palms cultivated on DPS compared with the values of FLACH,M. 1977 Yield potential of the sago palm and its the palms cultivated on MS and SPS did not realization. In: Sago -'76: Papers of the 1st international result in any difference in the starch yield among sago symposium. (TANKOOLIN,M. A. ed.) (Kuala soil types, while TIE et al. (1991) reported that Lumpur) 157-177. the lower starch percentage but the increased FLACH,M. and D. L. SCHUILING1989 Revival of an ancient starch crop: a review of the agronomy of the sago. trunk growth of sago palms cultivated on DPS Agroforestry System 7: 259-281. did not bring about any differences in starch FUNAKAWA,S., K. YONEBAYASHI,F S. JONGand E. C. O. Yamamoto et al.: Starch yield of Sago Palms among soil types 259

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