Category Archives: Volume 39 No. 2 (2017)

Vulnerability of Farm Households to Impacts of the Abaca Bunchy Top Disease: A Case in Leyte, Philippines

Author(s): Jedess Miladel N. Salomon*


The abaca bunchy top disease (ABTD) has destroyed thousands of hectares of abaca farms, leading to the decline in agriculture and economic production of farmers and their households. This paper frames the widespread disease incidence as a disaster and analyzes the factors that made farm households in Barangay Pinamonoan, an abaca-growing community, vulnerable to the disease and its impacts. It grounds its analysis on the pressure and release (PAR) and access models by Blaikie et al (1994) and the sustainable livelihoods framework by Scoones (1998, 2009). From these, an analytical framework was developed to illustrate the complexity of the relationships of the different factors contributing to farm households’ vulnerability to a widespread crop disease.
The reliance of farm households on abaca production was influenced by the high global demand of abaca fiber. This global demand made abaca an important export commodity; hence, government policies and programs were focused on increasing its production and less on ensuring that the livelihoods of farm households were secure. While abaca production is profitable, sole reliance on this could prove disastrous in the event of a hazard. Access to resources determined how farm households absorbed the shock and recovered from it. Households who had significant assets were able to shift to other crops or enterprises. Households with access to people with resources and who could provide assistance were also more likely to cope. The most affected in the village were the households who, even before the disease, had limited resources, both in terms of material assets and social support networks.

Keywords : sustainable livelihoods, assets, crop disease, disaster

Annals of Tropical Research 39(2):107-123(2017)

Physico-chemical and Functional Properties of Two Jackfruit (Artocarpus heterophyllus Lam.) Varieties in Eastern Visayas, Philippines

Author(s): Lorina A. Galvez1* and Erlinda I. Dizon2


Quality is a wide-ranging concept determined by many factors. It is a composite of those physical and chemical properties of the material which govern its acceptability and processing suitability. This study aimed to determine the physico-chemical and functional properties of the two jackfruit varieties (EVIARC Sweet and AES-2) grown in Eastern Visayas, Philippines. Fresh ripe jackfruit varieties were subjected to physico-chemical properties and functional component analyses following standard protocols. The two jackfruit varieties were found to have the following properties: the pH were 4.80 and 5.50; total soluble solids (TSS), 24.00 and 22.60oB; total titratable acidity (TTA), 0.33% and 0.12% citric acid; moisture content (MC), 77.30% and 75.96% (wb); total phenolics (TP), 127.73 and 125.91mg CE/100g; tannin content (TC),127.73 and 208.72 mg VE/100g; total reducing sugar (TRS), 15.43% and14.38%; total sulfur (TS), 0.36 and 0.57ppm; and antioxidant activity (AOA), 39.55 and 52.35% LP (lipid peroxidation) for EVIARC sweet and AES-2, respectively. Variety significantly affects the pH, TSS, TTA, %MC, TC, TRS, TS and AOA. Non-significance was noted on their TP contents.

Keywords : Total phenolics, tannins, antioxidant activity, lipid peroxidation, sensory evaluation, EVIARC Sweet and AES-2

Annals of Tropical Research 39(2):100-106(2017)

Effect of Drying Methods on the Physico-chemical Characteristics and Antioxidant Capacity of Taro, Sweetpotato, Stevia and Malunggay Leaves

Author(s): Inish Chris P. Mesias*, Julie D. Tan, Daniel Leslie S. Tan and Benjamin L. Cinto, Jr.


Fresh leaves are sensitive to high temperature so that appropriate drying method should be selected to dry leaves. This study aimed to determine the effect of drying methods on the physico-chemical characteristics and antioxidant capacity of taro (Colocasia esculenta), sweetpotato (Ipomea batatas), stevia (Stevia rebaudiana), and malunggay (Moringa oleifera) leaves. Fresh, healthy and mature leaves of taro, sweetpotato, stevia, and malunggay were subjected to solar drying, mechanical drying, and sun drying. The parameters evaluated in this study included moisture content, rehydration ratio, bulk density, water activity, total chlorophyll, antioxidant capacity, and non-enzymatic browning. Results showed that solar drying obtained the highest moisture removal capacity, rehydration ratio and water activity reduction while sun drying had the least. However, it was also with solar drying that the degree of non-enzymatic browning was the highest. Minimum bulk density was attained using solar and mechanical drying. In terms of chlorophyll content, mechanical drying had the highest. No apparent difference at p<0.05 between solar and sun drying methods was observed in terms of their effects on chlorophyll retention and antioxidant capacity. Variable effects of the different drying methods include little or no change, significant declines or enhancement of the leaves’ physico-chemical and antioxidant attributes.

Keywords : drying methods, antioxidant capacity, taro, sweet potato, stevia, malunggay

Annals of Tropical Research 39(2):88-99(2017)

Acetylcholinesterase Activity in Nile Tilapia (Oreochromis niloticus Linn.) Following Exposure to Carbamate Insecticide

Author(s): Ris Menoel R. Modina*


Acetylcholinesterase (AChE) activities were determined as affected by exposure to sublethal doses of fenobucarb (BPMC) on Nile tilapia. Fish were exposed for different periods, namely: 0, 7, 14, 21, and 28 days. AChE activities of brain and muscle tissues were measured spectrophotometrically. The sublethal doses of the insecticide did not induce treatment-related poisoning but were enough to significantly induce effects on the hepatosomatic index. The concentration used was also enough to significantly induce AChE inhibition on brain and muscle. AChE inhibitions were significantly different between unexposed and exposed fish in both brain (KW=14.02, P<0.05) and muscle (KW=6.87, P<0.05) tissues. The inhibition on brain AChE was highest on the 14 day-exposed fish. The inhibition on muscle AChE was highest on the 21-day-exposed fish which could be due to the direct exposure of muscle tissues to toxicants. The sensitivity of the relative liver weights and AChE activity of Nile tilapia could therefore be used as potential bioindicator of carbamate insecticide contaminated waters.

Keywords : fenobucarb (BPMC), acetylcholinesterase (AChE) inhibition, bioindicator, Nile tilapia, Oreochromis niloticus Linn.

Annals of Tropical Research 39(2):78-87(2017)

Dried Poultry Manure as Non-Protein Nitrogen Additive of Napier Grass (Pennisetum purpureum Schumach) Silage Fed to Sheep

Author(s): Clarita Ecleo Morbos1, Sulpecio C. Bantugan2 and Lolito C. Bestil2*


The study was conducted to describe the physical characteristics of napier grass silage added with dried poultry manure (DPM) as non-protein N source, and to assess its acceptability and digestibility in sheep. Three types of silages were evaluated: T1 – napier grass alone, T2 – napier grass + DPM (at a ratio containing 10% crude protein), and T3 – napier grass + DPM (at a ratio containing 12% crude protein). These were stored in airtight plastic drum silos for 45 days at room temperature. After evaluation, the silages were tested with 9 male growing sheep for intake and digestibility measurements arranged in completely random fashion.
Physical evaluation in terms of color, smell, and texture of the 3 silages showed no significant differences, and all showed good quality silage characteristics. However, significantly higher pH level (p<0.05) approaching normal rumen pH was observed in silages containing DPM (T2 and T3) compared to that without (T1). Chemical analysis showed significantly higher dry matter (DM) and crude protein (CP) contents in T2 and T3 silages than in T1. The OM content, however, was significantly reduced with the addition of DPM (T2 and T3) than without (T1) while acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents showed no significant differences. Nutrient intakes significantly increased with silages containing DPM (T2 and T3) while increases in nutrient digestibility by sheep for the 3 silages showed no significant differences in all parameters measured. The addition of DPM to napier grass silage to contain 10 to 12% CP is recommended to increase CP and DM contents and improve nutrient intakes without affecting nutrient digestibility.

Keywords : Napier grass silage, dried poultry manure additive, intake and digestibility

Annals of Tropical Research 39(2):67-77(2017)

Microbial Respiration as Indicator of Soil Quality of Different Land Uses in Cienda, Gabas, Baybay City, Leyte

Author(s): Jessa May T. Malanguis1, Cheryl C. Batistel1* and Marlito Jose M. Bande2


Land use conversion affects soil ecosystem quality and balance, which can be reflected by microbial activities. This study was conducted to assess the effectiveness of microbial respiration as indicator of soil quality of different land uses, reforestation site, agricultural land and grassland, in Cienda, Gabas, Baybay City, Leyte. The amount of CO2 evolved after one, three and seven days of incubation was used to determine microbial respiration rate of different land uses and across relief. Relationship between microbial respiration on pH, organic matter, total nitrogen, and moisture content at field capacity were also examined.
Results revealed that microbial respiration varies significantly among land uses with the highest rate observed in grassland while the lowest was in the reforestation site. Across relief, amount of CO2 released was significantly higher in the lower slope compared to the upper and the middle. The process tends to be significantly influenced by soil organic matter and moisture content. Results suggest that there is an inverse relationship between microbial respiration and organic matter, and a direct relationship with moisture content. High soil respiration in the grassland and in the lower topographic relief implies that the soil organic matter is converted into inorganic forms which are available for uptake by plants. A significant interaction between land use types and relief was also observed in both organic matter and moisture content leading enhanced microbial respiration. Land use and relief showed no significant effect on total nitrogen and soil pH.

Keywords : microbial respiration, soil quality, land uses, organic matter, decomposition

Annals of Tropical Research 39(2):55-66(2017)

Evaluation of Sugarcane-Based Land Utilization Types in Negros Occidental, Philippines

Author(s): Clea Anne V. Corsiga1*, Rodrigo B. Badayos2, Pearl B. Sanchez2, Erlinda S. Paterno2 and Pompe C. Sta. Cruz2


Five major soil series (Guimbalaon, Isabela, Luisiana, San Manuel, and Silay) in Negros Occidental were studied to identify the different sugarcane-based land utilization types (LUTs) in the province; determine the physical and chemical characteristics of different land utilization types cultivated to sugarcane; evaluate the existing management practices of different sugarcane-based land utilization types; and draw soil management recommendations for sugarcane production based on soil constraints of major soil series.
LUT 5 received the highest pH value and was also rated very high in exchangeable Ca and available P. Organic carbon content was rated very low in all LUTs and low in percent total N. Exchangeable Mg was rated medium in LUTs 1, 3, 5, and 6 while LUTs 5 and 6 were also rated medium in cation exchange capacity. Exchangeable K, on the other hand, was rated high in LUT 4 and low in LUTs 1, 2, 3, and 5 while exchangeable Na was rated low (LUT 1) to very low (LUTs 2–6). Soil management recommendations for constraints on topography in Guimbalaon and Luisiana series (LUTs 1, 2, and 4), were the implementation of a good soil conservation cropping and tillage practices such as contour terracing or farming while problems on wetness in Isabela, San Manuel, and Silay series (LUTs 1–6) could be managed by raising the height of the soil surface and elevate the site by adding 25-30cm of well-drained topsoil, compost or other organic matter to raise the planting zone and build drainage canals to direct water away from plants or other spots that collect water.

Keywords : sugarcane-based, land utilization types, soil management recommendations

Annals of Tropical Research 39(2):34-54(2017)

Organic Acid Profile of “Batuan” (Garcinia binucao [Blco] Choisy) Fruit

Author(s): Elizabeth S. Quevedo1*, Erlinda I. Dizon2 and Florinia E. Merca3


“Batuan” fruit (Garcinia binucao [Blco.] Choisy), an indigenous acidulant grown in the Visayas State University, Baybay City, Leyte was analyzed for its organic acid profile at different stages of maturity for the development of potential food and non-food products. The analysis of organic acid content was done using Reverse Phase-High Performance Liquid Chromatography. Organic acids in the dried, powdered “batuan” fruit samples were extracted with the mobile phase (50mM KH2PO4/ H3PO4, pH2.8). The sample extracts and organic acid standards (oxalic acid, tartaric acid, malic acid, citric acid, fumaric acid, lactic acid, acetic acid, and succinic acid) were injected to RP-HPLC under isocratic elution with the mobile phase at a flow rate of 1.0mL min-1 and using UV-vis detection at 210nm. “Batuan” fruit samples contain oxalic acid, tartaric acid, malic acid, citric acid, fumaric acid, succinic acid, acetic acid, lactic acid, and a few unidentified organic acids. Among the organic acids present, citric acid accumulated the highest in the ripe “batuan” fruit; fumaric acid, the least.
Results of this study show that “batuan” fruit could be a good natural source of acidulant for food and non-food applications.

Keywords : “batuan”, citric acid, fumaric acid, organic acids, RP-HPLC

Annals of Tropical Research 39(2):25-33(2017)

A New Phenol Glycoside from Root Exudates of Peperomia pellucida L. HBK. and its Role in Plant Invasion

Author(s): Suparna Mandal Biswas1*, Nabanita Chakraborty1, Soma Rani Patra2 and Prasanta C. Bhowmik3


Peperomia pellucida is an annual, shallow-rooted, succulent, delicate, glabrous herb. It is a native weed species of tropical North and South America, and it is now pantropic in distribution and abundant in India as an invasive aggressive colonizer. Medicinal properties of the plant have been well documented but no work has been done to find out the reason behind its invasive aggressive nature. The objective of our present work was to study the allelopathic activity of allelochemicals released by root exudates of P. pellucida which may play an important role in invasive and aggressive properties of the plant. Root exudates of P. pellucida were collected in root exudates trapping system. Main compound was isolated from methanol fraction of root exudates of P. pellucida, purified by thin layer and column chromatography and finally subjected to mass spectra, infrared, and nuclear magnetic resonance (both 1H and 13C) for complete structural elucidation. In vitro allelopathic activities of the compound were studied by rice, wheat and mustard seed bioassays. A new phenol glycocide [(6-(4-hydroxyphenoxy)-tetrahydro-2H-pyran-2, 3, 4, 5-tetraol); C11H14O7; Mol. Wt. 258] has been isolated and purified from root exudates of P. pellucida. This pure compound exhibited significant allelopathic activities on rice, wheat and mustard seeds in vitro bioassay experiment. This compound showed maximum inhibitory activity on rice, than in wheat and mustard bioassays. Peperomia pellucida released a phenol glycoside through root exudates into rhizophere which may act as a major allelopathic agent and may be responsible for its invasive and aggressive nature.

Keywords : Phenol glycoside, Peperomia pellucida L. HBK., root exudates, invasive, allelopathic effect.

Annals of Tropical Research 39(2):13-24(2017)

Occurrence and Damage of Broad Mites (Polyphagotarsonemus latus Banks) in Sweet Pepper (Capsium annuum L.) in Samoa

Author(s): Leikitah K. Naituku1, Manuel K. Palomar1* and Elio Jovicich2


Broad mites regularly infest sweet pepper crops in the tropics. A survey was carried out to assess the incidence broad mite infestation in sweet pepper crops in Upolu, Samoa. The population density of broad mites was related to plant development stages with the highest number of broad mites per leaf recorded at the early fruiting stage; no broad mites were recovered from plants at the seedling and vegetative stages. In a separate experiment, 3 sweet pepper varieties were artificially infested with 2 gravid female mites per seedling. At 7 days after infestation, a significant difference was observed in the 3 varieties with Yellow having the highest number of broad mites per plant followed by Giant Bell and Yolo Wonder at 62.0, 37.0 and 19.7, respectively. At 10 days, there was a significant difference in the mean population of broad mites on the varieties namely, Yellow (59.1 mites/plant), Giant Bell (32.4/plant) and Yolo Wonder (24.3/plant). The highest population of broad mites was observed on plants that had damage index level of 3 which corresponds to slight curling in the top leaves. This damage index was more common in Giant Bell and Yolo Wonder while leaf necrosis and defoliation were common on Yellow. Typical damage injuries observed on seedlings included distorted cupped leaves with zigzag veins, elongated petioles, and bronzed leaves and stem that later became necrotic and died. Farmers can use a severity index scale to help them recognize the presence of broad mites in their farms so that timely management can be done.

Keywords : Broad mites, Occurrence, Sweet pepper varieties, Damage Index

Annals of Tropical Research 39(2):1-12(2017)