Download Latest Complete Journal - JTAS Vol. 43 (4) Nov. 2020
Foreword by the Chief Executive Editor
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1https://doi.org/10.47836/pjtas.43.4.01
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(Downloads: 220)
Abstract (Viewed: 14)This review briefly highlights previous studies on the effects of Spirulina platensis and Chlorella vulgaris on the health and reproduction of fish. These microalgae have diverse potentials. This study can be used as a stepping stone in advancing the aquafeed industry by formulating microalgae-based feeds. It can be made to specifically enhanced the health status of fish and its reproductive system through the supplementation and/or replacement of fishmeal or other plant proteins such as soybean meal. Hence, it could be more sustainable than depending on natural fish stocks. The usage of antibiotics and vaccines to solve the issue of disease outbreak in aquaculture, as well as the usage of hormones for the growth and reproduction of fish, can also be replaced by the usage of S. platensis and C. vulgaris. The inclusion of these microalgae in fish feed has affected hemathological parameters and survival in fish as it boosts the numbers of white and red blood cells and thus affecting the immunity-stimulating capacity in fish. Besides, these microalgae also affect the fecundity and survival of fish eggs and thus directly affecting the reproduction performance of fish. Spirulina platensis affects eggs production and survival in fish whereas C. vulgaris enhances oxidative stress that affects the reproduction of White rabbits. This review aimed to deliver the results on the research of S. platensis and C. vulgaris on the immunity and reproduction of various fish species.Chlorella vulgaris, immunity, microalgae, reproduction, Spirulina platensis
2https://doi.org/10.47836/pjtas.43.4.02
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(Downloads: 76)
Abstract (Viewed: 11)This study aimed to determine the lethal concentration (LC50) of Terminalia catappa leaves extract on three cyprinid species; carp (Cyprinus carpio), goldfish (Carassius auratus) and tiger barb (Puntigrus tetrazona) through the acute toxicity test. The leaves of T. catappa were extracted with methanol and prepared in various immersion concentrations (40, 80, 100, 150, 200, 250, 300, and 350 mg/L). These extracts were immersed in the aquarium and left for 24 h before performing the acute toxicity test. The water quality was also analyzed before and after adding the extract immersions into the aquarium. The acute toxicity test conducted for 96 h with 10 fishes of each cyprinid species (4.0-6.0 cm length) in 30 L water capacity aquarium. The mortality of each cyprinid species was recorded at 24 h time interval and LC50 of the extracts throughout 96 hours was determined through the probit analysis application. Specifically, the LC50 of T. catappa leaves extract were 349.89, 338.65 and 318.48 mg/L exhibited for carp, goldfish and tiger barb, respectively. A high concentration range of any plant-based extract has the potential to become toxic to particular fishes. Thus, it is an effort from this study to identify the safety margin of T. catappa leaves extract before its therapeutic values can be further manipulated and elucidated in aquaculture research.Leaves extract, lethal concentration, mortality, ornamental fish
3https://doi.org/10.47836/pjtas.43.4.03
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(Downloads: 41)
Abstract (Viewed: 8)Diseases such as blast, brown spot and sheath blight considerably affect the health and productivity of rice worldwide. Chemical fungicides have been routinely used in combating these diseases; however, a safe and environmental-friendly approach using bio-fungicides is desirable in disease management of food crop such as rice. Identification of botanical extracts with antifungal potentials would be instrumental in the development of bio-fungicides. In this study, the antifungal potentials of Andrographis paniculata, Backhousia citriodora, and Phaleria macrocarpa against selected rice fungal pathogens were analysed. Crude extracts obtained from leaves of these plants were diluted to 5, 10, 15, and 20% and tested against Pyricularia oryzae, Exserohilum rostratum, and Rhizoctonia solani in vitro using poisoned agar method. Percentage inhibition of diameter growth (PIDG) of each crude leaf extract against test pathogens was calculated. The aqueous extract of A. paniculata showed a significant mycelial inhibitory effect against P. oryzae at 20% concentration (PIDG 81.9%) as compared to other test concentrations and pathogens. On the contrary, the aqueous extract of B. citriodora at 15 and 20% concentrations had little influence on the mycelial growth inhibition on P. oryzae and E. rostratum with PIDG values less than 50%. In addition, P. macrocarpa methanol extracts at concentration of 10% and above significantly inhibited the mycelial growth of P. oryzae, E. rostratum, and R. solani (PIDG 100%). Phaleria macrocarpa leaf extract had been identified to give the highest efficacy against all three rice pathogens in vitro and therefore, has the potential to be developed into a bio-fungicide as a safe alternative to synthetic fungicides for disease management of rice.Biopesticide, botanical extract, green technology, percentage inhibition of diameter growth (PIDG), poisoned agar method
4https://doi.org/10.47836/pjtas.43.4.04
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(Downloads: 52)
Abstract (Viewed: 6)Pepper (Piper nigrum L.) is one of the most important cash crops in Sarawak. The productivity of pepper is consistently low due to the low yield of berry production. One of the major problems of pepper production is inconsistent flowering time. This is due to the morphology and inheritance of functional male, female and hermaphrodite (bisexual) flower in P. nigrum which affect the productivity of pepper. For the exploitation of pepper for its maximum production, the detailed of flower development and flower composition are important factors to be considered. A field survey was conducted to determine the status of farming practices and problems encountered by the farmers. The study was also done to determine the composition of flower which influenced the consistency of berry production in P. nigrum in Sarawak. Surveys were conducted at 18 pepper farms in Sarawak to determine the composition of flowers in different types of Sarawak pepper varieties which are Kuching, Semenggok Aman and Semenggok Emas. Nine spikes were harvested in each pepper vine. Three pepper vines were selected randomly for each variety. The spikes were then observed under 3D Keyence microscope to determine the number of flowers of each type of flower. The survey on the farming practices were also conducted. The composition of flower was found to be varied between varieties. ‘Kuching’ variety had less hermaphrodite flower when compared to ‘Semenggok Aman’ and ‘Semenggok Emas’ varieties. In addition, a proportion of 29% farmers had encountered root rot disease problem in their farm, while 21% stated that unsynchronisation of berries production in each harvesting time as a major problem.Flower composition, Sarawak pepper and berries production
5https://doi.org/10.47836/pjtas.43.4.05
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(Downloads: 28)
Abstract (Viewed: 2)Liberica coffee is a minor species that is planted all around the world. Therefore, there is little study conducted on this coffee species as only one percent is cultivated all around the world. In Malaysia, there is still no research focusing on coffee pulp from Sarawak liberica sp. and thus leading to this study. The wastes and by-product such as coffee pulps will become the residues as they were not needed in processing the coffee. This will create environmental pollution. Thus, this research aimed to evaluate the feasibility study on the physicochemical properties of coffee pulp from Sarawak liberica sp. including determination by colorimetric assays for phenolic and flavonoid content, antioxidant activity, and reducing sugar analysis. The antibacterial activities of coffee pulp were evaluated against Gram-positive, Staphylococcus aureus, and Gram-negative Salmonella typhimurium using a disc diffusion method. As a result, Sarawak liberica sp. coffee pulp extract contained total phenolic content of 24.24 mg GAE/g of coffee pulp, a total flavonoid content of 39.39 mg QE/g of coffee pulp, DPPH scavenging activity of 92.24 ± 0.03%, reducing sugar analysis of 13.13 mg GE/g of coffee pulp, and there was no significant effect of antibacterial activities. Therefore, the physicochemical study determination in this study would add values toward Sarawak liberica sp. coffee pulp by-product and thus reducing the disposal of Liberica coffee wastes in the future.Antibacterial activity, antioxidant properties, coffee pulp, flavonoid compound, phenolic compound, reducing sugar analysis
6https://doi.org/10.47836/pjtas.43.4.06
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(Downloads: 24)
Abstract (Viewed: 3)The yellow rice stem borer, Scirpophaga incertulas (Walker) is a prevalent pest in paddy fields worldwide. In Sarawak, a survey on pest of paddy carried out from 2009 to 2011 covering 166 paddy fields revealed that rice stem borers caused 11.4% of total paddy damage. In order to reduce the damage, identifying resistance paddy variety is crucial. The objective of this study was to screen Sarawak paddy landraces with resistance to S. incertulas. Twelve Sarawak paddy landraces were selected randomly for this study. Antixenosis resistance screening was performed in aquariums (60 x 28 x 33 cm). Three replications of one-month-old seedlings were randomly arranged in aquarium and exposed to adult S. incertulas. The number and position of egg mass on each plant were recorded. Egg mass abnormalities were also observed. For antibiosis, rice culms of two-month old seedlings from each landrace were infested with larvae. The length of surviving larvae from five rice culms was measured. The experiment revealed variations in landrace of preference for ovipositing. Among the twelve Sarawak paddy landraces, Kanowit was more preferred by S. incertulas for ovipositing in comparison to other paddy landraces suggesting susceptibility towards the pest. Abaxial leaf surface was the preferred oviposition site. There was no clear antibiosis response of the paddy landraces towards S. incertulas larvae in this study.Antibiosis, antixenosis, rice insect pest
7https://doi.org/10.47836/pjtas.43.4.07
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(Downloads: 28)
Abstract (Viewed: 4)Ants play a vital role in removing dead arthropods from the environment. Complex foraging patterns are used by ants to locate food items and overwhelm even larger insects such as cockroach. Consequently, the biotic interaction between the ants and the American cockroach, Periplaneta americana, another home infesting and a vector of major food-borne diseases, may lead to microbial handover and ease the spread of mechanically transmitted human pathogenic microbes. This study was done to determine the diversity and abundance of cockroach-foraging ants in Nasarawa State, Nigeria. Ten households were randomly selected from 14 locations: 5 residential communities from three most urbanized areas (Lafia, Akwanga, and Keffi) and 5 rural communities. Four remaining locations were nonresidential from Lafia and Akwanga, respectively. A total of 1,364 ants belonging to three subfamilies (Myrmicinae, Formicinae, and Ponerinae) were collected from 140 households. Pheidole rugaticeps Emery recorded the highest relative abundance (52%) followed by Pheidole decarinata Santschi (16%), Pheidole sp. (17%), Camponotus maculatus (7%), Paratrechina longicornis (7%), while both Crematogaster sp. and Brachyponera sennaarensis recorded the lowest relative abundance (1%). There is a significant difference in the species diversity between the urban and the rural communities. Pheidole rugaticeps, P. decarinata, Pheidole sp., and P. longicornis were more organized in foraging and operating in group by recruiting nest-mate for collecting fragments of dead cockroach. Studies on the epidemiology, conservation implications, and biocontrol potentials of these Pheidole species are recommended.Abundance, diversity, Periplaneta americana, Pheidole, scavenging ants, rural, urban
8https://doi.org/10.47836/pjtas.43.4.08
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(Downloads: 20)
Abstract (Viewed: 3)Leaf folder and stem borer are pest moths (Lepidoptera) of paddy crop and caused serious damage and significant rice yield loss. The richness, abundance, and diversity of the pest moths were calculated in one paddy planting season and sampled from a model conventional paddy field, located on the west coast of Peninsular Malaysia (Sabak Bernam, Selangor). The adult and immature stages of moths associated with paddy plants have been sampled using active sampling namely sweep net and stem cross-cutting. A total of 189 individuals belonging to five species under two families (Crambidae and Noctuidae) were recorded. Overall, the richness (R’), diversity (H’), and evenness (E’) index of lepidopteran species were 0.76, 1.51, and 0.90, respectively. The richness and species abundance throughout the paddy stages were discussed. The DNA barcode of five collected species using cytochrome oxidase subunit 1 (CO1) viz. Cnaphalocrocis medinalis (Guenée) (leaf folder), Scirpophaga incertulas (Walker), Chilo auricilius Dudgeon, Sesamia inferens (Walker), and Parapoynx stagnalis (Zeller) (stem borers) were presented. This study’s outcomes are very important as the initial stage for conservation purposes, especially in managing the strategy in handling the pest species populations in the paddy field.Agricultural ecosystem, CO1, genetic, grain insect pests, infestation, Lepidoptera, Malaysia
9https://doi.org/10.47836/pjtas.43.4.09
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(Downloads: 29)
Abstract (Viewed: 5)The constraints on the effectiveness of nuclear polyhedrosis virus (NPV) as biocontrol are usually due to environmental factors such as temperature and ultraviolet (UV) exposure. Zeolite has been commonly used as a carrier or delivery system for nuclear polyhedrosis viruses. In this study, zeolite powder was reduced into nanosized particles by beads milling method and was investigated for the effect of its concentration in the delivery system of Helicoverpa armigera nuclear polyhedrosis virus (HaNPV1) on the lethal time against the larvae Crocidolomia pavonana. The formulation used three concentrations of nanozeolite suspension, 0.5, 1, 1.5, and 2 wt.% applied for each 4 × 107 of HaNPV1. A randomized block design (RBD) method was applied with 3 replications. The results showed that the scanning electron microscope (SEM) from nanozeolite was seen coating the entire surface of the HaNPV1 polyhedra and an increase of zeolite concentration caused acceleration of   the lethal time of C. pavonana instar III. Thus, the fastest lethal time was 1.2 days receiving a concentration of 2 wt.%, which was significantly higher compared to without delivery (2.9 days). The increase of the zeolite concentration up to 2 wt.% in the delivery system for HaNPV1 improved their performance on lethal time and mortality against C. pavonana. It was concluded that nanozeolite as a delivery system enhanced and created a synergy in infecting C. pavonana.Crocidolomia pavonanaHaNPV1, nanoparticle, nanozeolite, pest control
10https://doi.org/10.47836/pjtas.43.4.10
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(Downloads: 16)
Abstract (Viewed: 3)Hibiscus sabdariffa L. is no stranger to the field of pharmacology, as its calyx extract is highly rich in beneficial compounds and has been demonstrated to possess antihyperglycemic, antihypertension, anticancer and antioxidant properties. Thus, it is labelled as a functional food with great health benefits and therapeutic potentials. The medicinal and nutritional components of the calyx are well reported. On the contrary, not much is known about the molecular machineries governing the biosynthesis of beneficial compounds in this plant. Obtaining good yields of high-quality RNA is crucial for the success of downstream research pertaining to molecular biology. However, the presence of high quantities of phenolic compounds, polysaccharides, mucilage and pectin in the fibrous calyx tissue poses major challenges for RNA extraction in H. sabdariffa. Here, we modified a CTAB-based method for efficient extraction of high-quality RNA from the calyx tissue. High quality RNA samples having RNA integrity number of more than eight were successfully extracted. The purities of RNA samples were also confirmed by the A260/280 and A260/230 values. Subsequent successful preparation of a sequencing library using one of the RNA samples extracted via the modified CTAB method further emphasized the efficiency of this extraction protocol and quality of the RNA samples. The results showed that the modified CTAB method was effective in extracting good quality RNA from the challenging calyx tissue of Hibiscus sabdariffa L. suitable for sensitive downstream application.CTAB, high viscosity, mucilage, polysaccharide, RNA integrity, roselle, transcriptome profiling
11https://doi.org/10.47836/pjtas.43.4.11
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(Downloads: 25)
Abstract (Viewed: 4)Musa troglodytarum L. (‘Pisang Tongkat Langit’), a banana cultivar which originated from Eastern Indonesia, has an economic potential due to the high β-carotene content on its pulp. Being a climacteric fruit, M. troglodytarum has a short shelf-life that can reduce fruit quality. In this study, the effect of 1.25% (w/v) chitosan coating on M. troglodytarum fruit shelf-life and ACS1 and ACO1 gene expression analysis using quantitative PCR were evaluated. Results showed that the application of chitosan coating delayed the fruit ripening process for two days by delaying several fruit physical and chemical changes. ACS1 and ACO1 gene expression analysis showed a different expression pattern, the expression level was lower on chitosan-coated fruits on the first day compared to control. In conclusion, chitosan-based edible coating delayed M. troglodytarum fruit ripening and changed the ACS1 and ACO1 gene expression pattern, compared with the chitosan coating effect on Cavendish banana which also prolonged fruit ripening and suppressed ACS1 and ACO1 expression in a previous research.ACO1, ACS1, chitosan, fruit ripening, Musa troglodytarum L., real time PCR
12https://doi.org/10.47836/pjtas.43.4.12
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(Downloads: 21)
Abstract (Viewed: 2)Banana is one of the most essential commodities in Bali island. It is not only for nutrition sources but also for cultural and religious aspects. However, Bali banana genetic diversity has not been explored; therefore, in this study, we focused on its genetic relationship using a molecular approach. This research aimed to determine the genetic relationship of Bali banana cultivars using the internal transcribed spacer 2 (ITS-2) region as a molecular marker. A total of 39 banana samples (Musa spp. L.) were collected from Bali island. The ITS-2 DNA regions were then amplified and sequenced from both ends. ITS-2 sequences were predicted using the ITS2 Database (http://its2.bioapps.biozentrum.uni-wuerzburg.de/). The multiple sequences alignment was performed using ClustalX for nucleotide-based tree and LocARNA to provide the secondary structure information. Phylogenetic trees were constructed using neighbor-joining (Kimura-2-parameter model, 1,000 bootstrap). The result showed that two clades were formed, one clade was abundant in A genome (AA and AAA), and the other rich in the B genome (BB and ABB). This result suggested that cultivars that had similar genomic compositions tended to be grouped within the same clade and separated with different genomic compositions. This study gives perspectives that ITS-2 sequences in bananas are quite similar and differ much compared to other families. Secondary structure has been described to provide more robust resolving power in phylogenetic analysis.Genetic diversity, ITS-2, phylogenetic tree, secondary structure
13https://doi.org/10.47836/pjtas.43.4.13
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Abstract (Viewed: 2)Brassinosteroid (BR) is a class of polyhydroxysteroids plant hormones known to regulate shoot and root growth. Genetic and molecular analyses demonstrate that receptor kinase BRI1 protein acts as a perceiver for BR. One of the characteristics of bri1 mutant’s phenotypes is the complete BR insensitivity in the root. Biochemical evidences of the BRI1 protein complex indicates that somatic embryogenesis receptor kinase 1 (SERK1) and SERK3 participate in the BR pathway in Arabidopsis root. While only serk3 mutants show partial reduction to BR sensitivity, serk1 presents a normal BR penetration phenotype compared to the wild type. Interestingly, the double mutant serk1serk3 displays more, but not full resistance to BR in root length assay. In this study, we aimed to enhance the BR insensitivity of the double mutant serk1serk3 by crossing serk1 mutant allele with a strong serk3 and bri1 mutant alleles. In our study, by generating serk1-3serk3-2 double mutants, a complete insensitivity to BR that phenocopied bri1-301 mutant was recorded. However, we were unable to increase BR resistance in the root of serk1-3serk3-2 double mutant by crossing with bri1 mutant allele in the triple mutant serk1-3serk3-2bri1. As a result, all the BRI1 signaling in the root was mediated through the SERK1 and SERK3 co-receptors. Additionally, we established that based on conventional BR assays, the At1g27190 protein was also involved in BR signaling. Preliminary data indicated that the triple mutant serk1serk3-2At1g27190 showed a dwarfed phenotype. Whether or not this dwarfed phenotype is linked to BRI1 signaling impairment needs to be further investigated.At1g27190, brassinosteroid , brassinosteroid insensitive, somatic embryogenesis receptor kinase
14https://doi.org/10.47836/pjtas.43.4.14
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(Downloads: 16)
Abstract (Viewed: 1)The beneficial effects of feeding rabbits with forages have been recommended. However, limited study has been made on feeding values of locally available forages in rabbits. Therefore, an experiment was conducted to evaluate the effect of Asyastasia gangetica and Brachiaria decunbens on intake, digestibility, and growth performance of rabbits. Twelve rabbits were distributed into three diets: (i) 100% commercial pellet as control (T1), (ii) 50% pellet plus Asyastasia gangetica ad libitum (T2), and (iii) 50% pellet plus Brachiaria decumbens ad libitum (T3). Daily feed intake, nutrient digestibility, weekly body weight, and feed conversion ratio (FCR) were measured. Intakes of total dry matter (DM) (121.2-134.3 g/d) and organic matter (OM) (115.1-132.5 g/d) were similar (p>0.05) for all the groups. The crude protein (CP) intake of rabbits fed with T1 (10.1 g/d) and T3 (9.6 g/d) diets was similar (p>0.05), but lower (p<0.05) than T2 (14.1 g/d) diet. Ether extract intake of rabbits fed with T2 (2.9 g/d) and T3 (3.9 g/d) diets was similar (p>0.05), but lower (p<0.05) than T1 (5.1 g/d) diet. Neutral detergent fibre (NDF) intake was higher (p<0.05) for rabbits fed with T3 (55.8 g/d) diet followed by T2 (41.7 g/d) and T1 (31.7 g/d) diets. There were no differences (p>0.05) on the digestibilities of DM, OM, and CP among treatments. Total weight gain and daily weight gain were higher (p<0.05) for rabbits fed with T1 (568 and 11.0 g) and T2 (468 and 9.0 g) diets than T3 (155 and 3.3 g) diet, respectively. The lowest FCR was obtained with T1 (12.3) and T2 (13.9) diets, whereas the highest was obtained with T3 (30.3) diet. In conclusion, diet containing Asyastasia gangetica showed more benefits in terms of CP and NDF intakes, weight gain and FCR than the diet containing Brachiaria decumbens. A combination of concentrate and Asyastasia gangetica is recommended as a partial replacement for concentrate in rabbit production.Asyastasia gangetica, Brachiaria decumbens, digestibility, growth performance, intake, rabbit
15https://doi.org/10.47836/pjtas.43.4.15
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Abstract (Viewed: 3)‘Cempedak’ fruit, an aromatic fruit that has a short shelf life can be converted into powder through spray-drying process. However, the spray-dried powder that was obtained had a high tendency to cake. Hence, three different anti-caking agents (calcium silicate, silicon dioxide, and calcium phosphate) were added separately at a concentration of 1.5% (w/w). It was found that calcium phosphate (1.5% w/w) yielded ‘cempedak’ fruit powder with lowest moisture content, water activity, hygroscopicity, and caking (change in cake height ratio), with minimal color changes in its reconstituted form and low viscosity. Different calcium phosphate concentration (0-2.00% w/w) was then applied in the production of ‘spray-dried’ powder. With increase of calcium phosphate addition from 0 to 0.66%, the moisture content, water activity, hygroscopicity, cake height ratio of ‘cempedak’ powder decreased, with no significant decrease with further addition. Calcium phosphate (0.66 % w/w) yielded powder with the best properties: lowest moisture content (4.65%), water activity (0.18), hygroscopicity (22.0), and change in cake height ratio (0.17). In addition, there was a minimal change in color of its reconstituted powder, with a slight change in viscosity.Anti-caking agent, caking properties, ‘cempedak’ fruit, spray-drying
16https://doi.org/10.47836/pjtas.43.4.16
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(Downloads: 21)
Abstract (Viewed: 2)Passiflora quadrangularis L., also known as giant granadilla, belongs to the family Passifloraceae together with the well-known species Passiflora edulis Sims. This species has received attention from growers in recent years due to its aromatic flowers, unique and excellent fruit flavor and phytotherapeutic properties. Despite the numerous health benefits of this Passiflora species, information on their agronomical features and production is scarce. Therefore, the objective of this study was to examine the reproductive biology and fruit setting of P. quadrangularis cultivated in Sarawak, Malaysia. The findings revealed that the giant granadilla was a steady-state species that produced flowers lasting for only one day. Passiflora quadrangularis started to produce flowers 3 months after transplantation, followed by fruiting two months after anthesis. In East Malaysia, the flowers started blooming at dawn (0625±0.17 hours) followed by anthesis at 0806±0.23 hours and remained open until sunset. In contrast to P. edulis which flowered all year round, this species only exhibited two peaks, with a minor peak recorded from January-March and a major peak from September-December, coinciding with warm temperatures and moderate rainy season. Good fruit yields were recorded which was attributed to the ability for self-pollination due to autogamy and geitonogamy, in addition to the presence of effective pollinators. The yearly production of P. quadrangularis, produced relatively larger fruit with weights ranging from 884.4-2892.7 g, was 20,151.36 kg ha-1 (8993 fruits). Detailed information on the reproductive behavior of P. quadrangularis growing in local climates can be used for commercial cultivation and future breeding studies.Floral, giant granadilla, Passiflora quadrangularis, passion fruit, phenology, self-pollination
17https://doi.org/10.47836/pjtas.43.4.17
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(Downloads: 43)
Abstract (Viewed: 13)Rice (Oryza sativa L.) ‘KDML105’ is the most popular aromatic rice originating in Thailand. This cultivar is highly susceptible to abiotic stresses, especially drought and salt stress during the seedling stage. The objective of this study was to investigate the photosynthetic performance in response to drought and salt stress of four improved breeding lines, specifically CSSL94 and CSSL103 (containing drought-tolerant quantitative trait loci: DT-QTLs) and RGD1 and RGD4 (containing a salt-tolerance gene, SKC1), with ‘KDML105’ (susceptible) and DH103 (tolerant to drought and salt stress) as the controls. Rice seedlings were grown for 21 days in hydroponic solutions and then exposed to salt stress (150 mM NaCl) or drought stress (20% PEG6000) for 10 days. The results indicated that when subjected to drought and salt stress, all rice lines/cultivar exhibited significant reductions in net photosynthesis rate (PN), stomatal conductance (gs), transpiration rate (E), the maximal quantum yield of PSII photochemistry (Fv/Fm), the effective quantum yield of PSII photochemistry (Fv’/Fm’), photosynthetic pigments, and SPAD readings, whereas water use efficiency (WUE) and non-photochemical quenching (NPQ) increased. Compared with ‘KDML105’, CSSL94, and CSSL103 were more tolerant to both drought and salinity, showing less reduction in all photosynthetic parameters. For RGD1 and RGD4, it was confirmed that these lines had a higher level of salt tolerance than ‘KDML105’ based on better photosynthetic performance under salt stress, demonstrating that these lines were also more tolerant to drought stress.Chlorophyll fluorescence, drought stress, photosynthetic performance, rice, salt stress
18https://doi.org/10.47836/pjtas.43.4.18
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Abstract (Viewed: 9)Microorganisms in the rhizosphere possess numerous metabolic activities. The addition of inorganic substance such as fertilizer could affect the microbial functional diversity. This study was conducted to evaluate the effect of different rate of NPK fertilizer on microbial functional diversity in the rhizosphere of local aerobic rice variety. Aerobic rice variety MRIA 1 was used in this study. Peat was taken from a non-agricultural area in Klang, Malaysia. The effect of fertilizer rate was determined with 4 different rates (C = non-fertilized; T1 = 100 kg/ha NPK; T2 = 200 kg/ha NPK; T3 = 400 kg/ha NPK). Microbial functional diversity was performed using Biolog™ Ecoplate System and measured by microbial activities, such as average well color development (AWCD), species richness (R), Shannon-Weaver index (H index) and species evenness (E). As a result, microbial activity increased to 5.7% when fertilizer applied at T2, while fertilizer rate at T3 increased species richness by 3.2%. However, addition of fertilizer did not affect the H index while species evenness slightly decreased by 1.1% when applied at T3. Bacteria population was reduced when fertilizer added at T1. Fertilizer addition to the peat soil decreased the culturable population of nitrogen-fixing microbes while no effect was found on culturable fungal, actinomycetes and phosphate-solubilizing microbe population. Microbes in T2 utilized many carbon sources. Variation in carbon sources used by microbes was found when fertilizer was applied at different rates. D-cellobiose, pyruvic acid methyl ester, and L-serine were the carbon sources that influenced the microbial function in soil. It is concluded that fertilizer has an effect on microbial functional diversity in the peat rhizosphere of local aerobic variety. The recommended fertilizer rate (T2) increased the microbial activity while high fertilizer rate (T3) increased species richness and decreased species evenness.Carbon source, fertilizer, microbial functional diversity, rhizosphere
19https://doi.org/10.47836/pjtas.43.4.19
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Abstract (Viewed: 8)Invasive introduced fish species are well known for their deleterious impacts on aquatic biodiversity and environment. This study provides the first report on the occurrence of introduced Amazon sailfin catfish, Pterygoplichthys pardalis from the Gombak basin, Selangor, Malaysia, where the suckermouth catfish, Hypostomus plecostomus and vermiculated sailfin catfish, Pterygoplichthys disjunctivus had been previously reported. Besides, selected morphometric and meristic measurements between P. pardalis and P. disjunctivus from the Pusu River, Gombak basin were compared. Moreover, we also described two body patterns of the P. pardalis collected from the river. The body pattern which does not fit entirely with the known characteristics of P. pardalis or P. disjunctivus is suspected to be a result of hybridization between both species, but deeper study should be conducted to confirm this claim.Biological invasion, conservation, Gombak basin, invasive fish, Klang Valley