Category Archives: Volume 39 No. 1 (2017)

Supporting Struggling Grade 8 Science Students’ Motivation, Participation and Performance through Peer-Tutoring Approach

Authors: Joy A. Bellen1 and Amalia B. Jomoc2


Research shows that cognitive and affective abilities among science students can be enhanced using peer tutoring approach. However, peer tutoring approach remains an underutilized peer support (Bond & Castagnera 2006). This study determined the effects of peer tutoring approach in motivation, participation and academic performance of grade 8 students. Using regression discontinuity design, the respondents were non-struggling, struggling who accepted peer tutoring and struggling students who declined peer tutoring. Results showed that struggling students who accepted peer tutoring showed better participation, expertlike perceptions of junior high school science, and exam performance relative to their peers who were not attending the peer tutoring sessions. The results of this study provide evidence to teachers who want to plan targeted peer support for students who are struggling in junior high school science.

Keywords: motivation, participation, performance, peer tutoring approach, struggling students

Annals of Tropical Research 39(1):147-157(2017)
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A Cross-sectional Study on the Self-Efficacy of Pre-service Science and Mathematics Teachers in a Philippine State University

Authors: Ma. Rachel Kim L. Aure and Richard R. Jugar


This study investigated the self-efficacy levels of pre-service science and mathematics teachers in a Philippine state university. A total of 172 pre-service science and mathematics teachers served as respondents of the study. Data collection was done through the use of the Science and Mathematics Teaching Efficacy Belief Instrument for Pre-service Teachers. The ANOVA indicated significant difference self-efficacy according to year level such that fourth year pre-service teachers indicated a statistically significant decrease. No significant difference was observed for gender and specialization. As regards to the type of courses as predictors of self-efficacy level, general education courses showed low positive predictive power (β = 0.180) whereas specialization courses and professional education courses showed a negative predictive power of β = -0.198 and β = -0.702 respectively. General education and professional education courses displayed significant predictive power at p < 0.05 whereas specialization courses did not (p=0.151). The overall explanatory power of the regression model was 61.1% (R2 = 0.611, F(3,171) = 90.419, p < 0.001). The 2 implications on the teacher education preparation as well as for future directions are likewise discussed.

Keywords: pre-service, science and mathematics education, self-efficacy, teacher preparation

Annals of Tropical Research 39(1):135-146(2017)
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Assessing the Microlevel Impacts of Sin Tax Law on Cigarette Consumption: A Case Study for Mahaplag, Leyte, Philippines

Authors: Lemuel S. Preciados1* and Jayson E. Carcajente1


Examined in this study were the effects of Sin Tax Law at the microlevel. Using the before-and-after method of analyzing impacts, we applied a multiple regression analysis incorporating difference-in-difference approach of econometric estimation. It appeared that youths had significantly lower cigarette consumption after the implementation of this law. This suggests that Sin Tax Law (STL) discouraged the youth from smoking. In contrast, consumption of cigarettes among adults did not change significantly implying that the tax induced price-increase was relatively less effective. Therefore, it is recommended that there should be specific policies targeting adult smokers to inhibit them from consuming more cigarettes. Results also provide important lessons for future research in monitoring and evaluating public policies.

Keywords: smokers, adults, youth, difference-in-difference

Annals of Tropical Research 39(1):120-134(2017)
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Determination of limiting nutrient to Sweetpotato (L.) growth on Samoa Oxisol using a Ipomoea batatas Nutrient Omission Technique

Authors: Taniela Kepa Siose1, Mohammed Abdul Kader1,3,4 and Anabella B. Tulin1,2


This study was conducted to investigate the influence of various macro- and micronutrients on the growth and root yield of sweetpotato (variety IB/PH/03) grown in a Samoan Oxisol under semi-controlled screenhouse conditions. The following nutrient elements were considered: N, P, K, Mg, S, B, Cu, Fe, Mo, Mn, Ni, and Zn. The set-up involved pot nutrient omission trials wherein the twelve nutrient elements were combined to form an ALL treatment with subsequent 12 treatments made by excluding one nutrient consecutively from the ALL combinations. Treatments were arranged in a randomized complete block design with four replications for all treatments while six for the ALL treatment. Results showed that P was the most limiting factor to sweetpotato vegetative growth and root yield. Reduced storage root yield in relation to ALL were also observed when N, P, K, S, B, Fe, Mn, Mo and Ni were not supplied, although the difference was insignificant. Thus unless P deficiency is addressed, the deficiency effects of these nutrients on storage root yield remain insignificant.

Keywords: sweetpotato, Samoan Oxisol, limiting nutrients, nutrient omission technique

Annals of Tropical Research 39(1):105-119(2017)
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Soil-Landscape Relationship in the Northern Volcanic Mountain of Leyte, Philippines

Authors: Roland V. Rallos1,2, Victor B. Asio1 and Faustino P. Villamayor1


Studies on soil-landscape relationships are necessary to improve our understanding of the spatial distribution and variation of soils for their sustainable management. This study evaluated the relationship between soil properties and landscape position in the northern volcanic mountain of Leyte, Philippines. Five soil profiles located on summit, shoulder, backslope and footslope positions were evaluated. Findings revealed that the degree of soil development as well as the soil morphophysical and chemical properties varied with landscape position. The soil in the most stable position (summit) had thicker solum and slightly more developed soil profile than the soils in other landscape positions. On the other hand, soils in the unstable position (backslope) generally had thinner solum. All the five soils also revealed the influence of the andesitic volcanic parent material on their properties. They all showed some properties typical of Andisols such as low bulk density and high pH in NaF although they were classified as Andic Dystrudept. The soils all possessed physical and chemical constraints for crop production.

Keywords: landscape positions, fertility characteristics, volcanic soils, pedogenesis, topography, Inceptisols, Cambisols

Annals of Tropical Research 39(1):87-104(2017)
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Growth and Yield Performance of Inbred and Hybrid Rice Varieties as Influenced by Combined Application of Organic and Inorganic Fertilizers

Authors: Raynilda R. Baoy1 and Dionesio M. Bañoc2


The study evaluated the effects of organic and inorganic fertilizers on the growth and yield of two lowland rice varieties; determined the proper fertilizer combination; and evaluated the profitability of rice production as influenced by the combined application of organic and inorganic fertilizers. This was laid out in split plot arranged in a RCBD design with variety and fertilizer treatments as the main plot and subplot, respectively.
Results revealed that the period from sowing to heading, shoot dry weight, number of filled grains per panicle and weight of 1,000 grains were significantly influenced by the variety. The yield, yield components and harvest index (HI) were significantly influenced by fertilizer application. A significant interaction effect was noted on the period from sowing to heading as observed that inbred rice (NSIC Rc212) headed late than hybrid (TH82). Plants applied with 120-60-60 kg ha-1 N, P2O5 and K2O produced taller height, larger LAI, longer panicles, more productive tillers and filled grains, and consequently highest grain yield and HI. These plants also produced the heaviest root and shoot dry weights resulting to higher root shoot ratio compared to unfertilized plants. Highest net income was obtained in plants applied with inorganic fertilizer at the rate of 120-60-60 kg ha-1 N, P2O5 K2O due to high grain yield. Irrespective of fertilizer treatments, inbred rice was more profitable than hybrid. Highest production cost was incurred in plants applied with pure organic fertilizer due to the high cost of the material.

Keywords: Hybrid rice, Inbred rice, Inorganic Fertilizer, Organic fertilizer

Annals of Tropical Research 39(1):70-86(2017)
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Biomineralization of Calcium Oxalate Crystals in Leaves of (L.) Schott (Araceae) in Colocasia esculenta Response to Herbivory and Water Regime

Authors: Kenneth C. Eco and Beatriz S. Belonias


Calcium oxalate crystals are common constituents of plant tissues and are believed to play a role in protection against herbivory, calcium regulation and even heavy metal sequestration. In this study, calcium oxalate crystals in leaves of Colocasia esculenta were studied in order to elucidate the biomineralization process of these inorganic components in response to herbivory and different water regimes. Different crystal types occurring in the leaves of C. esculenta were identified, described and quantified in terms of density and distribution. Two general types of calcium oxalate crystals were found, namely: the raphides and druses. The raphides were of two types, the defensive and non- defensive, and both occurred as bundles of elongated crystals enclosed in specialized cells called idioblasts. Druses were spherical conglomerate crystals extensively distributed throughout the leaf. Although degree of herbivory did not significantly affect overall density of calcium oxalate crystals, there was a highly significant interaction effect between herbivory and crystal type. With increasing degree of herbivory from 10% to 30%, the density of druses and non-defensive raphides decreased significantly but that of the defensive type increased. Water availability had a highly significant effect on overall crystal density. Interaction effect between water regime and crystal type was also highly significant. Density of druses significantly increased under waterlogged than non-waterlogged conditions while those of the defensive and non-defensive raphides were unaffected.

Keywords: defensive raphides, non-defensive raphides druses, crystal density, idioblasts

Annals of Tropical Research 39(1):54-69(2017)
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Extracellular Enzymes and Antimicrobial Activities of Celluloytic Bacteria from the Gut of Black Surgeonfish (Acanthurus gahhm)

Authors: Francis S. Legario1 and Agile J. Pesina2


The diverse microflora of the gastrointestinal tracts of fish is a promising frontier for the discovery of beneficial bacteria and further microbiological investigations. Isolation, characterization, and determination of the enzymatic and antibacterial activities of the culturable cellulolytic bacteria from the gut of Acanthurus gahhm(black surgeonfish) were investigated. The bacterial strains were isolated from the three gut regions (anterior, mid and hind) using minimum medium. The isolates were characterized morphologically, biochemically and physiologically using standard methods. The isolates were qualitatively tested for activities of extracellular enzymes such as in amylase, protease and lipase. Results showed that the cellulolytic bacteria were Grampositive bacilli, coccobacilli and cocci exhibiting varied biochemical activities most notably fermentative abilities. Physiological tests revealed that the bacteria were able to tolerate high salt concentration.The strains exhibited varying levels of activities for protease and lipase but not on amylase. The isolates were further tested for their antibacterial activity and only one isolate, AG 5H showed signs of efficacy through a zone of inhibition against S. aureus but not for E. coli. The isolate AG5H is interesting because of its high level of enzymatic activities and antibacterial action, which can be exploited for further study for fish health and nutrition and other industrial applications.

Keywords: cellulolytic, gut, surgeonfish, enzymes, antibacterial

Annals of Tropical Research 39(1):39-53(2017)
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Occurrence of Secondary Metabolites and Free Radical Scavenging Ability towards Better Adaptability of Some Mangrove Species in Elevated Salinity of Indian Sundarbans

Authors: Nirjhar Dasgupta1, Paramita Nandy2, Chandan Sengupta3 and Sauren Das1*


Mangrove, a specialized group of plant communities, provide immense ecological and protective benefits to the coastal areas of the tropical and subtropical world where they thrive. Demographic obligation and climatic hostilities have massively altered their vegetation pattern and, even ruined some key species to large extent. The present study aims to consider Reactive Oxygen Species (ROS) scavenging skills in some degrading mangrove taxa of Indian Sundarbans (Xylocarpus granatum and Heritiera fomes) compared with some opulently growing ones (Excoecaria agallocha, Bruguiera gymnorrhiza and Phoenix paludosa) in increasing salinity gradient, in relation to their sustainability. Non-enzymatic antioxidants (secondary metabolites) Proanthocyanidin and Tannin were estimated and Free radical scavenging ability was evaluated by Singlet Oxygen Scavenging Activity Assay, Reducing power assay, effects on Peroxynitrite, Nitric Oxide Radical Scavenging, Hydrogen Peroxide Scavenging Activity Assay, Reaction with Hypochlorous Acid, Superoxide Radical Scavenging Activity Assay and Hydroxyl Radical Scavenging Activity. Relatively higher occurrence of secondary metabolites and improved antioxidant ability were recorded in E. agallocha, B. gymnorrhiza and P. paludosa; than the other two plants X. granatum and H. fomes; where the trend showed a decline in the ROS scavenging after a certain increase in salinity. Strong positive correlation of both secondary metabolites and radical scavenging ability with salinity pose the three stable taxa more viable in the higher salty environment of the Indian Sundarbans. But relatively less ROS scavenging ability in more saline zones, may be the potential reason for the unfavorable existence of the two red listed plants, which would ultimately lead to gradual natural extinction of them from the Indian Sundarbans.

Keywords: Antioxidant, free radical scavenging, mangroves, Sundarbans, Sustainability

Annals of Tropical Research 39(1):13-38(2017)
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Coping up with the Risks and Increasing Sustainability: Strategies for Small-scale Shrimp Farming in Indonesia

Authors: Riski A. Lestariadi1 and Masahiro Yamao2


Small-scale shrimp farmers have contributed significantly in increasing shrimp production in Indonesia. However, they face various risks that resulted to high fluctuation in their income. Risk management strategies in shrimp farming are needed to cope with inherent risks in order to enhance sustainability of shrimp farming. This study analyzed the sources of risks, ex-ante risk management and ex-post risk coping strategies in small-scale shrimp farms in Indonesia. A field survey of 166 shrimp farmers was conducted in the North and South coastal zones of East Java. Results revealed that the top three sources of risks that influenced in shrimp farming were shrimp price volatility, high mortality due to diseases, and increasing formulated feed price. Requesting for government technical assistance was the common formal onfarm risk management strategy used by the shrimp farmers. Sharecropping was the main ex-ante strategy to mitigate risk. Small-scale shrimp farmers tended to avail of informal loans that resulted to loss of savings. They also used family labor as informal ex-post strategy to reduce expenses. They used social assistance from the government as formal ex-post risk coping strategies.

Keywords: Aquaculture risk, shrimp farming, sustainability of shrimp farming, risk management strategies, Indonesia

Annals of Tropical Research 39(1):1-12(2017)
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