Universiti Putra Malaysia
Download Latest Complete Journal - JTAS Vol. 38 (4) Nov. 2015
Foreword by the Chief Executive Editor
No.ArticlesDownloads
1
Full Article
(Downloads: 49)
Abstract (Viewed: 34)As the world's population continues to grow, human water needs are growing accordingly, thus reducing the water available for sustaining our freshwater biodiversity. This is likely to be further exacerbated in areas where rainfall will decrease as a result of global climate change. Molecular ecologists have contributed substantially in recent years to our understanding of first, the levels and patterns of current biodiversity and second, to understanding patterns of connectivity among populations of aquatic species and their significance for their conservation and management. Both are critical for prioritisation of areas for protection and for designing rehabilitation programmes. In this paper, I attempt to synthesise our understandings to date. I argue that a multi-disciplinary approach that incorporates new technological approaches in acquisition of molecular data is the best way forward for our aquatic biodiversity. Molecular ecologists can contribute by collaborating with other ecologists, especially in the fields of species distribution modelling and conservation planning. This approach will help to prioritise conservation actions for the best possible outcomes.Freshwater, Aquatic biodiversity, Climate change, Aquatic species, Molecular ecologists, Biological connectivity
2
Full Article
(Downloads: 44)
Abstract (Viewed: 5)Through evolutionary time, the ever changing environmental conditions have been faced by plants among which water stress is the most common. Nevertheless, a great deal of variations in responses of plants to water deficit and their sensitivity to water scarcity has been noticed. For perception, signalling and response to water stress, plants are supposed to have programmed capability. Under the conditions of water scarcity, improved resistance to drought has been provided by AM fungi by enhancing efficiency of water absorption, uptake of mineral nutrients, especially phosphorus, accumulation of osmoprotectants like proline and sugars, activity of antioxidant enzymes like SOD, CAT and POD, production of isoprenoids, stomatal conductance, chlorophyll contents, photosynthesis and decline in ABA content. Expression of drought related plant genes like p5cs genes, aquaporin genes, as well as nced genes, brings about the physiological response of mycorrhizal plants to drought stress. Moreover, the efficacy of AM in reducing the use of phosphorus fertilisers and enhancement of soil stability increase the value of mycorrhizae for sustainability and ecosystem services. Their appropriate management has prospective to ameliorate the effectiveness and sustainability of drought tolerance.Arbuscular mycorrhizal fungi, water stress, osmoprotectants, aquaporin genes, stomatal conductance
3
Full Article
(Downloads: 40)
Abstract (Viewed: 2)The meat characteristics of Red jungle fowl (Gallus gallus Spadiceus) and Malaysian Domestic chicken (Gallus gallus Domesticus), which are known as slow growing birds, were studied. Results were compared with those of the commercial broilers (ROSS) which are fast growing birds. The objective of the study is to determine the meat characteristics (pH, muscle fibre diameter and collagen content) of the breeds and the correlation to their meat quality. For this purpose, a total of 90 chickens (30 chickens for each breed) were used in this study. The chickens in each group were sacrificed at 20, 56 and 120 days posthatching. Findings indicated that collagen content, pH, cooking loss and shear force values in Red jungle fowl and Malaysian Domestic Chicken were significantly higher (P<0.05) than the commercial broilers. The smaller muscle Fibre diameters and lower glycogen reserved contributed to higher pH. Meanwhile, the collagen content showed significantly (P<0.05) Positive correlation to shear force and more prominent factors than the size of Muscle fibre that determines tenderness of the meat. The commercial broilers' meat is much tender than that of the Malaysia Domestic chicken and Red jungle fowl.Red jungle fowl, Malaysian Domestic chicken,Commercial broilers, meat characteristic, correlation, meat quality.
4
Full Article
(Downloads: 35)
Abstract (Viewed: 3)The influence of seed nut size, storage period and hydro priming duration on seedling emergence and early seedling vigour in Brazilian cashew biotype was investigated. Seed nuts were hand graded into three sizes - large, medium and small - and dried under ambient conditions (29 C, RH70%) for 30 days before storing them under ambient conditions for 210 days. Stored nuts were evaluated at 0, 30, 90, 120, 150 and 210 days under three different pre-sowing hydro priming hours (0, 12 and 24 hrs) for seedling emergence and vigour characters. Data collected were statistically analysed. Significant differences were found to have occurred among storage periods, hydro priming durations and nut sizes for the four seed quality characters examined. In particular, large seed nuts had the highest seedling emergence of 79% above the medium and small nuts with a marginal increase of 5 to 6%, respectively. Meanwhile, small nuts emerged earlier than the other seed nut fractions but large nuts had the longest days to emergence. Seed nuts hydro primed for 24 hrs had the best seedling emergence (79 %), reduced days to emergence (15 days) and 0 greater seedling vigour and shoot growth. Highest seedling emergence of 80 to 81% was observed at early storage (30-90 days) and which thereafter declined to 72% at the end of 210 days, with 10% reduction. Hydro primed small nuts had significant reduction in days to emergence (12-16 days) at each storage time investigated. The beneficial effect of priming was observed in large nuts hydro primed for 24 hrs with the highest storage performance. Thus, in order to obtain good seed nut quality parameters, storage period of large nuts can be extended up to 210 days or thereafter, while medium nuts can be stored for 150-210 days but the storage duration of small nuts should not exceed 150 days under ambient conditions. In conclusion, hydro priming of cashew nuts before sowing is a possible way of enhancing seedling emergence and early vigour characters.Germination, seed deterioration, seed enhancement, seed grading, water treatment, seedling growth.
5
Full Article
(Downloads: 25)
Abstract (Viewed: 2)Effects of post-urea treatment and extended heating time after Compregnation on the formaldehyde emission and properties of rubberwood were investigated in this work. Rubberwood strips having nominal dimensions of 150 mm x 50 mm x 5 mm were Compregnated with medium molecular weight phenol formaldehyde (MmwPF, mw 2,000) and low molecular weight phenol formaldehyde (LmwPF, mw 600), respectively. Compregnated rubberwood were then soaked in urea solutions in different concentrations of 10%, 20% and 40%, respectively, for 1 minute. Extended heating times of 0, 12, and 24 hours under 100 ± 2°C were applied to another set of rubberwood Compregnated with LmwPF. Properties such as formaldehyde emission, mechanical and physical properties were also tested. Results showed that the post-urea treatment and extended heating time reduced the formaldehyde emission of the Compregnated rubberwood. However, mechanical strength of Compregnated rubberwood was not significantly affected by both the treatments. Improvements in water absorption (WA) and thickness swelling (TS) of Compregnated rubberwood were observed when the heating time was lengthened. Nevertheless, the formaldehyde emission obtained is still far beyond the standard threshold limit of 0.16 - 2.0 mg/l. Thus, further study has to be conducted by lengthening the heating time and increasing the concentration of urea solution.Compreg, extended heating time, formaldehyde emission, phenol formaldehyde resin, post-urea treatment, rubberwood
6
Full Article
(Downloads: 22)
Abstract (Viewed: 2)Ocimum tingid, Cochlochila bullita Stål (Hemiptera: Tingidae) is a pest of Lamiaceae plants such as basil, tulsi and coleus. It is now being recorded in Malaysia as a pest of the cat's whiskers plant, Orthosiphon aristatus (Blume) Miq. Nevertheless, apart from its brief biological description, no other information is available. The life table of this pest was studied in laboratory conditions. Development time for C. bullita feeding on O. aristatus was 23.3 ± 0.9 days, which was found to be similar to those feeding on Ocimum basilicum (22.8 ± 0.3 days). Although C. bullita posts a higher mortality rate on O. aristatus than on O.basilicum (52% vs. 37%), the adult longevity of the bugs that feed on O. aristatus (♀: 33.9; ♂: 38.2 days) was found to be significantly higher than those bugs that feed on O.basilicum (♀: 27.2; ♂: 26.0 days). The pre-ovipostion, ovispostion and fecundity of C. bullita were also different between the host plants. The net reproductive rates (R), finite rate of increase (λ) and intrinsic rate of increase (r) were also higher on O. aristatus (10.7504, 1.0690 and 0.0667), although there was an increased in immature survival on O. basilicum (6.0287, 1.0556 and 0.0541). Therefore, it is concluded that O. aristatus is as good as O. basilicum, or the population growth of C. bullita is more favoured as compared to O. basilicum.Basil, cat's whiskers plant, lace bug, life table parameter, Malaysia, Ocimum tingid
7
Full Article
(Downloads: 27)
Abstract (Viewed: 5)A non-protein thiol, glutathione (GSH), presents abundantly in plant and affects the growth and development of the plants. In this study, the effects of N-acetyl cysteine (NAC), a precursor of GSH, on manganese (Mn)-induced corn production was evaluated. Different Mn concentrations (0.2, 1.5 and 3.0 ppm of Mn), with or without 100 µM of NAC, were arranged as completely randomised design with 5 replicates. Results show that both NAC and Mn affected plant height and leaf numbers. Treatment of NAC increased Mn-induced relative water content (RWC), photosynthesis (Pn) and photosynthetically active radiation (PAR) in leaves of corn plants. In the Mn-treated plants, chlorophyll (Chl) content, Chl fluorescence (Fm) and quantum yield (Fv/FM) were found significantly higher than the Mn-untreated plants. In addition, corn plants showed improved yield and cob length in NAC-treated plants in the presence of Mn. Thus, this study suggests that NAC might improve some physiological functions of plants to enhance Mn-induced corn production, with 1.5 ppm of Mn showed the best results.Manganese, relative water content, photosynthesis, chlorophyll content and chlorophyll fluorescence
8
Full Article
(Downloads: 24)
Abstract (Viewed: 5)The diversity of dung beetles (Coleoptera: Scarabaeidae) was measured at the Bangi Forest Reserve in Selangor, Malaysia (Hutan Simpan Bangi, HSB), as a model sampling site for the secondary forest ecosystem. The diversity analysis gave a value of 2.17 for the Shannon diversity index (H'), 1.42 for the richness index (R') and 0.87 for the evenness index (E). A total of 575 individuals belonging to 10 species of dung beetles were collected. They comprised of Catharsius renaudpauliani, Catharsius sp. 1, Microcopris aff. hidakai, Onthophagus "obscurior group", Onthophagus crassicollis, O. recticornutus, O. rutilans, O. trituber, Paragymnopleurus maurus and Sisyphus thoracicus. The small dung beetle Onthophagus crassicollis had the highest number of individuals (137/575, 23.83%) with a body size range of 4.5 ± 2.5 mm in length. A total of 9/10 species collected in HSB were classified as small-bodied species (8% large body, 92% small body) and the statistical analysis showed a significant body size difference compared with the large-bodied species, C. renaudpauliani. O. crassicollis showed the highest abundance in the secondary forest, a model site for studying forest disturbance. The abundance of dung beetles could potentially be used as a good bioindicator of habitat disruption in the tropical forest ecosystem. Our study also highlighted that the abundance of species based on body size was affected by the availability of the food sources also from different sizes of mammal dung.Scarab beetles, biodiversity, bioindicator, Shannon diversity index
9
Full Article
(Downloads: 26)
Abstract (Viewed: 4)Compression moulding is generally applied to thermoset-based polymer material composites (PMCs), which consist of a reinforcement phase embedded in a polymer matrix to strengthen the polymer. Thermoset compression-moulded composites have advantageous thermal and mechanical properties. Natural fibres are typically used in composites as a reinforcing material either as continuous (very long) or discontinuous (chopped) fibres. Interest in using natural fibres to make high-performance engineering products is increasing because their mechanical properties are better than those of synthetic fibres. The types of matrix, types of fibre, chemical treatment of fibre, orientation of fibre and processing parameters that reveal converging problems, which can be studied in future research, are still being investigated. This work intends to review current studies on material processing and characterisations in terms of the thermal and mechanical properties of thermoset composites reinforced with natural fibres by compression moulding.Kenaf, thermoset, material processing, mechanical and physical properties
10
Full Article
(Downloads: 21)
Abstract (Viewed: 2)This study focused on the development of an efficient cutting system for kenaf harvesters. Laboratory experiments were conducted on cutting kenaf stems of variety V36 using a rotary serrated cutting system. The Torque Trak 10k data acquisition system was used for the experiment. The effect of cutting speed on cutting torque and cutting power of varying kenaf-stem diameters and at different moisture contents was investigated. Four different cutting speeds of 400 rpm, 500 rpm, 600 rpm and 700 rpm were used. The experiments showed that cutting speed had significant effect on cutting torque and cutting power requirements. The cutting speed was directly proportional to the specific cutting power, while the cutting torque was inversely proportional to the moisture content. Increasing the rotational speed from 400 rpm to 700 rpm reduced the cutting torque from 1.91 Nm to 1.49 Nm. The cutting torque was observed to be higher at lower moisture levels of less than 35%. As the moisture content was increased to values greater than 35%, the torque decreased considerably. This invariably indicated that an increase in moisture content reduced cutting torque as shown by the model coefficient of moisture content. Thus, more energy saving and hence, high efficiency, were achieved at high cutting speeds as compared to impact cutting system at similar speeds. Regression equations capable of predicting cutting torque and cutting power at varying stem diameters and cutting speeds, in relation to kenaf stem moisture contents, are presented.Cutting power, cutting speed, cutting torque, harvester, kenaf stem, moisture content
11
Full Article
(Downloads: 27)
Abstract (Viewed: 3)The effects of filling poly (lactic acid) (PLA) composites with cellulose thermally-grafted with hydrolysed 3-aminopropyltriethoxysilane (APS) were investigated. Composites containing 30 wt% of kenaf-derived cellulose (C) and silane-grafted cellulose (SGC) were melt-blended into a PLA matrix before being hot-pressed into 0.3 mm sheets. The tensile strength of neat PLA was 47 MPa. With addition of C and SGC, the tensile strength was improved by 13% and 23%, respectively. The tensile modulus was approximately doubled for both of the composites. PLA/C and PLA/SGC composites remained brittle with marginally lowered elongation at break. The addition of C and SGC significantly increased the oxygen barrier of PLA with the reduction of oxygen transmission rate (OTR) of PLA at 76.6 cc/m2/day to 42.2 cc/m2/day and 40.3 cc/m /day, respectively. This was due to the tortuous path created and crystallites induced by the fillers. The water vapour transmission rate (WVTR) for PLA, PLA/C and PLA/SGC was in the range of 21-23 g/m2/ day. From the water absorption test, PLA/SGC reported slightly better water resistance as compared to PLA/C. The reinforcing results from these bio-based materials may suggest contribution towards packaging oxygen and moisture sensitive food.Cellulose, kenaf, mechanical barrier, poly(lactic acid), silane coupling agent, water absorption
12
Full Article
(Downloads: 29)
Abstract (Viewed: 3)The conversion of natural fibre into biocomposites is rapidly being exploited globally. Locally, there are some viable natural fibres that can be utilised for this. In this research project, several types of composites were produced, all of which were made from natural fibres. Four different natural cellulosic fibres were chosen, namely, kenaf, pineapple (pina), banana and coir. Hybrids of kenaf blended with each of these fibres were also woven. The samples were woven manually as weft yarn while the warp yarn used plied polyester thread. The samples were fabricated into composites using four types of matrices which were epoxy, polyester, polypropylene and polyethylene. The composites were fabricated using the manual compression method. These composites were then tested for their tensile strength in weft direction. All results were also analysed using Analysis of Variance (ANOVA) and ranked accordingly. It was found that woven samples made of 100% kenaf fibre exhibited the best tensile strength for all types of resin while coir was found to be the poorest. All kenaf hybrid composites mostly exhibited better results than the non-hybrid composites.Banana fibres, biocomposites, coir, kenaf, pina, pineapple fibres, tensile strength
13
Full Article
(Downloads: 30)
Abstract (Viewed: 7)Natural fibre composites can have varying combinations of physical and mechanical properties, such as low density, low cost, high stiffness and strength. Kenaf (Hibiscus cannabinus) was used in this study as a natural fibre to reinforce polypropylene (PP) in the fabrication of polymer composite materials. The injection moulding method, with an injection temperature of 170°C, was used in this study. This study aimed to investigate the effect of sodium hydroxide (NaOH) on the mechanical properties of kenaf/PP using the injection moulding method. PP was mixed with different compositions (5, 10, and 15 wt%) of kenaf particles with increasing concentrations of NaOH as a treatment agent to enhance the adhesion between kenaf and PP. Morphological and structural changes of the sample fracture were observed under a scanning electron microscope (SEM). The results showed that the mechanical properties of the composite were increased when the percentage of kenaf composition was increased, and decreased when NaOH concentration was increased. The highest tensile value of the sample was 21.93 MPa at 15 wt% composition of kenaf particles, while the lowest value of 16.42 MPa was observed when NaOH was present. The improvement of flexural strength was highlighted, in 5 wt% composition of kenafreinforced PP with NaOH that was 32.07 MPa, but when the NaOH concentration was increased to over 10%, the Flexural value decreased to 26.97 Mpa. Based on the results, the researchers concluded that NaOH treatment may increase the bond strength of kenaf composite; however, increasing the NaOH concentration can lead to a decrease in mechanical properties.Injection molding, natural fibre polymer composite, kenaf, mechanical properties, physical properties

BACK
Online Submission| Call for Papers| Special Issues| Subscribe Journals| Resources| Site Map| 724083