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Articles by Amartalingam Rajan
Total Records ( 5 ) for Amartalingam Rajan
  Muyang Tawie Sulok Kevin , Osumanu Haruna Ahmed , Wan Yahaya Wan Asrina , Amartalingam Rajan and Mohamad Ahzam
  A pot study was carried with the following objectives: (i) To investigate N and K uptake of Bario rice on Bekenu series (Tipik Tualemkuts), and (ii) To investigate N and K use efficiency of Bario rice on Bekenu series. Treatments evaluated were: (i) Bario rice under fertilized condition (T1), and (ii) Bario rice under unfertilized condition (T0). The experiment was conducted in a glasshouse at Universiti Putra Malaysia Bintulu Campus, Sarawak, Malaysia. Altogether 18 pots were used. The experimental design was completely randomized design (CRD) with 9 replications. Nitrogen and K were applied in the forms of urea (46 % N) and muriate of potash (60 % K2O) at the rates of 0.52 g N g and 0.60 g K2O per pot respectively at specific times. The fertilizers applications were done 20 and 45 days after seeding (for T1 only). However, P was applied to T1 pots only in the form of Christmas Island Rock Phosphate (36 % P2O5) at a rate of 0.54 g P2O5 per pot. At 65 days after planting, the Bario rice plants were sampled and partitioned into roots and stem. Their dry weight, N, and K concentrations determined using standard procedures. Soil sampling was done before and after fertilization stages. Soil total N was determined using the Kjeldahl method while exchangeable K, Ca, Na, and Mg were extracted using the double acid method and their concentrations determined using atomic absorption spectrophotometry. Dry ashing method was used for the determination of K, Ca, Na, and Mg concentrations in plant tissues while the Kjeldahl method was used to determine total N in plant tissues. The concentrations multiplied by the oven dried weight of roots and stem provided N, K, Ca, Na, and Mg uptake in these plant parts. The N and K use efficiency were then calculated using the subtraction method. With the exception of Ca, urea and KCl (MOP) application significantly increased soil N, K, Mg, and Na concentrations. Total dry weight for both stem and roots showed no significant difference under T1 and T0. Except for Mg concentration in stem and roots, K concentration in stem and that of N in roots were significantly higher under T1 than under T0. The other comparisons showed no significant difference. Due to N and K fertilization, there was significant increase in plant height and number of panicles under T1 compared to T0. Nitrogen, K, Na, and Mg uptake in stem were significantly higher for T1 than T0. However, those of roots were not significantly different. The overall N and K use-efficiency of the Bario rice were 9.90 % and 4.23 % respectively, and were considered low, indicating that rice grown within the time frame of this study did not efficiently utilize these nutrients. This was partly attributed to low N and K recovery during reduced condition and low organic matter status of Bekenu series as Bario rice is noted for being cultivated organically. Additionally, slow adaptation to inorganic fertilizers and sudden climatic change involved in this study cannot be ruled out as one of the reasons for the low efficiency because the rice is traditionally cultivated in the highlands of Sarawak, Malaysia. However, with appropriate fertilization and soil maintenance (through further research), Bekenu series could be used for Bario rice production. Probably supplementing inorganic fertilizers with organic ones may help to improve growth and development of this rice on Bekenu series. Future studies may consider mimicking or modifying the environment to suit Bario rice growth and development at lower elevations. Certainly, the quality of Bario rice at lower elevations should also be considered in future fertilization programmes or trials.
  Choon-Fah J. Bong , Chin-Chin Er , Pang-Hung Yiu and Amartalingam Rajan
  Biology and growth performance of Red Stripe Weevil, Rhynchophorus schach Oliv. were studied using meridic diets. The diets consisted of sugarcane (Saccharum officinarum L.) bagasse, copra (Cocos nucifera L.) cake and sago (Metroxylon sagus Rottb.) flour as main ingredients. Larvae or locally known as sagoworm, in copra cake diet exhibited the fastest growth with maximum weight gain of 1609 mg in week 5, while those of sugarcane bagasse diet had slowest growth with peak weight gain of 1024 mg in week 9. Sago flour diet gave the longest larval period at 96.3 days with the highest final larval weight of 8132.1 mg. The R. schach larvae had 8 instars. Head capsule width within each instar was constant irrespective of diets given. Instar period was dependent on diets given and varied from 6.3-12 days. Pupal duration ranged from 38.5-41 days. Adult emergence was 90%. Sago flour diet had the heaviest pupae and adults. Male weevils emerged earlier than the females, but females lived 10-13 days longer. Fecundity was low at 67 eggs per female but the hatchability was 92%. Life cycle for the insect ranged from 130.2-138.8 days, with a lifespan of 178.2-183.8 days. Larvae raised on sago flour diet had the highest fat content at 57.8% but with the lowest fiber at 4.7%. Larvae were generally rich in Mg, Ca, Zn and Fe, but low in Cu. This study showed that sago flour constituted the most suitable diet. The results also suggested that growth and development of the weevil could be further improved by incorporating copra cake and sugarcane bagasse into the sago flour diet. Larvae could be readily mass produced as a source of nutritious food, besides its potential use as a laboratory test organism.
  Pang-Hung Yiu , Jian See , Amartalingam Rajan and Choon-Fah J. Bong
  Boric acid (H3BO3) is detrimental to human health if consumed in excess. However, it continues to be used in the production of food especially noodles and some processed seafood such as fish ball. Five kinds of noodles and a type of fish ball were collected over a period of four weeks from a random sample of manufacturers in Bintulu, Sarawak, Malaysia. The boric acid in these food samples were analyzed by the curcumin-acetic acid method using 2-ethyl-1, 3-hexanediol (EHD) extraction. Results showed that yellow noodles contained highest concentration of boric acid throughout the four weeks with a mean of 2.034 μg g-1. In general, the mean concentrations in most food types were inconsistent throughout the sampling period and were relatively low compared to studies reported in Peninsular Malaysia. Although it is not a permitted food preservative or additive, this study showed that local food manufacturers were still using boric acid.
  Pik-Kheng Hoe , Choon-Fah J. Bong , Kadir Jugah and Amartalingam Rajan
  Problem statement: Coptotermes curvignathus (Isoptera: Rhinotermitidae) is a common termite pest found in oil palm plantation planted on peat. Currently, the control methods focus on using insecticides that lead to high cost and adverse effect to the environment. Approach: Biological control like the use of entomopathogens provides an alternative control method for termite infestation problem. However, several factors need to be investigated in order to obtain a virulent strain with potential to be developed into a biopesticide. Results: Three local isolates (MG, LR2 and TA) of Metarhizium anisopliae were obtained and identified as M. anisopliae var. anisopliae using molecular techniques. Growth performance of isolates on four basal media namely, Potato Dextrose Agar (PDA), Potato Dextrose Agar with 1% yeast extract (PDAY), Sabaroud Dextrose Agar (SDA) and Sabaroud Dextrose Agar with 1% yeast extract (SDAY) was assessed. The pathogenicity of each isolate was tested against subterranean termite Coptotermes curvignathus at three concentrations of 1x106, 1x107 and 1x108 conidia mL-1. Infections of the isolates were examined using electron microscopy technique. The growth performance of each isolate differed significantly. Among all basal media, only SDAY was able to produce high growth performance and thick conidia mats with all isolates. The most pathogenic isolate was LR2, which caused 100% mortality at 1x107 conidia mL-1 within 3 days post-inoculation. Conclusion/Recommendations: All three isolates were pathogenic against C. curvignathus as they were able to germinate and penetrate into the termite cuticle within 15 hours post-inoculation. The three local isolates of M. anisopliae var. anisopliae have potential to be developed as biopesticides to control termites, C. curvignathus in oil palm plantations.
  Sie-Cheong Kiing , Pang-Hung Yiu , Amartalingam Rajan and Sie-Chuong Wong
  Problem statement: Rice is rich in complex carbohydrates and beneficial bioactive compounds such as γ-Aminobutyric Acid (GABA), γ-oryzanol and vitamin. Several bioactive components are known to accumulate in rice during germination process. This study was to investigate the effect of germination process on γ-oryzanol levels in selected Sarawak local rice cultivars. Approach: Rice seeds were germinated for 4, 8, 12, 16, 18, 20 or 24 h at 25°C and samples were processed and analyzed for γ-oryzanol content. A partial extraction method was used for quantitative γ-oryzanol analysis. Results: Result showed γ-oryzanol concentrations in the rice cultivars varied from 0.099-0.340 mg g-1 on dry weight basis. Cultivars Udang Halus and Silah showed the highest concentration of γ-oryzanol after 16 h germination. Conclusion: The germination process exhibited diverse effects on the γ-oryzanol accumulation in rice and it was cultivar dependent.
 
 
 
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