Category Archives: Volume 37 No. 1 (2015)

Characteristics and Nutrient Status of Two Degraded Upland Soils in Samar, Philippines

Author(s): Victor B. Asio, Kier Lambert B. Demain, Dernie T. Olguera and Leo Jude D. Villasica


The study evaluated the morpho-physical, chemical, and biological characteristics as well as the nutrient status of two degraded upland soils located in Sta. Rita, Western Samar and in Salcedo, Eastern Samar. Soil profiles were examined and soil erosion was determined. Composite soil and plant tissue samples were collected from different vegetation cover or crops planted by the farmers. All laboratory analyses were done following standard procedures. Results indicate that: 1) the Sta. Rita soil which is relatively younger than the Salcedo soil shows less severe degree of degradation than the Salcedo soil; 2) the nutrient status of the degraded upland soils in Sta. Rita and Salcedo are low; 3) the low nutrient status is more severe in the Salcedo than in the Sta. Rita ;4) both sites have strongly acidic soils which are low in OM, total N, and available P contents; 5) considerable variations in the soil nutrient status were observed under different vegetation covers or crops; 6) soil erosion the appears to be major soil degradation process in both degraded uplands; 7) the low nutrient concentrations in the tissues of the plants growing at the sites reflect the low nutrient status of the soils; and 8) bulk density, porosity, aggregate stability, soil pH, organic matter, and carbon dioxide evolution appear to be good indicators of soil degradation.

Keywords : soil degradation, soil formation, shale, ultramafic rock, soil erosion

Annals of Tropical Research 37(1):142-166(2015)

Biological Sinks for Carbon Dioxide – An Option for Agroforestry Systems in the Tropics

Author(s): Friedhelm Göltenboth1 and Paciencia P. Milan2


One of the core questions, that need to be answered in the present discussion about climate change, is how the increase of carbon dioxide content in the atmosphere can be minimized if not stopped.
This Greenhouse Gas (GHG) is the main reason for the increase of average temperature. Under business as usual (BAU) conditions an increase in temperature between 1.7-4.5֯C is expected during the next 100 years.
One option to counter this trend is through reforestation and the conservation of forests functioning as carbon sinks. Estimates are giving an amount of 60 Petagram (Pg) or 60 Gigatons (Gt) as exchange of carbon between the terrestrial ecosystems and the atmosphere annually.
Tropical forests and agroforestry systems show promising options in the process of binding atmospheric carbon dioxide. The use of agroforestry methods, like the Rainforestation Farming strategy, open very interesting options due to ecological and economical advantages, while contributing to the reduction of carbon dioxide concentrations.

Keywords : Climate change, agroforestry, Rainforestation Farming, carbon sequestration

Annals of Tropical Research 37(1):129-141(2015)

Design, Fabrication, and Evaluation of a Village-Scale Yarning Machine

Author: Feliciano G. Sinon


A multi-stranded yarning machine was designed to produce a material comparable with the “tinagak” yarn. The prototype was fabricated using locally available materials at NARC, VSU, Baybay City, Leyte. Modification activities were done to improve some perceived problems in the mechanical timing device, locking mechanism, and clutching assembly. Mechanism of the spooling assembly was also improved to allow easy joining of the synthetic yarn in case it breaks during the operation.
The improved prototype can produce 2 continuous abaca yarns simultaneously with lengths of 1.2 kilometer by wrapping around the abaca fiber with fine synthetic yarn. The yarn produced is also automatically arranged in the spool while a timing device automatically releases the locking rod when the yarn reaches 1.2 kilometer long.
Evaluation showed that an unskilled operator produces yarn at the rate of 380 – 430 m/h at an efficiency of 80-95%. A neatly woven product comparable to “sinamay” was produced from the multi-stranded yarn at the Matalom Abaca-Based Integrated Project (MABIP), Matalom, Southern Leyte.

Keywords : multi-stranded yarn, untwisted yarn, abaca yarn, tinagak yarn

Annals of Tropical Research 37(1):110-128(2015)

Development and Promotion of the Reversible Airflow Flatbed Dryer in the Philippines

Author(s): Caesar Joventino M. Tado1, Dexter P. Ona1, John Eric O. Abon1, Eden C. Gagelonia1, Nguyen Thanh Nghi2 and
Le Quang Vinh2


A flatbed dryer with a reversible airflow was introduced in the Philippines through a collaborative project between Nong Lam University of Vietnam and the Philippine Rice Research Institute (PhilRice). In this design, airflow is reversed at some point during the drying period to achieve uniform drying without mixing the grain.
An 8-ton capacity dryer was constructed at PhilRice Central Experiment Station in Nueva Ecija to evaluate its performance and adaptability under Philippine conditions. Appropriate and locally available materials were used in the construction of the pilot unit. Nine (9) additional dryers were then constructed at PhilRice stations (Nueva Ecija, Isabela, Negros, Agusan, Central Mindanao University, and Midsayap) that served as pilot units for technology promotion in their respective areas of coverage. Performance of the dryer was evaluated in terms of the following parameters: (1) drying; (2) quality of dried grains; and (3) economic analysis of using the dryer. The performance evaluation was conducted in three drying batches of newly harvested rice seeds.
Paddy dried with the reversible airflow flatbed dryer at full load capacity has a uniform moisture content with one percent (1%) moisture gradient at different layers of the grain mass along the depth and across the drying bin. The drying rate was 1% moisture reduction per hour.
The drying cost of using the reversible dryer is PhP0.74 per kg which is lower than the prevailing mechanical drying cost of PhP1.13 per kg. It has a payback period of 2.5 years and break-even point of 53.0 batches/year. To date, eight (8) privately-owned units have already been constructed and fully operational in the provinces of Nueva Ecija, Quirino, and Bukidnon, with PhilRice receiving inquiries from interested individuals here and abroad regarding the technology.

Keywords : reversible airflow flatbed dryer, drying rate, moisture gradient

Annals of Tropical Research 37(1):97-109(2015)

Effects of Meloidogyne incognita on the Yield and Quality of Sweet Potato in the Humid Lowlands of Papua New Guinea

Author(s): Macquin K. Main and Shamsul Akanda


Field experiments were conducted in 2012 and 2013 to study the effects of inoculum densities of Meloidogyne incognita applied at 10, 100, 1000, 5000, and 10000 juveniles/eggs per 500 cm3 along with un-inoculated control treatments, on a susceptible sweetpotato variety, K9. At the highest initial inoculum (Pi), an average marketable tuber yield of 991 kg ha-1 was recorded compared to 3495.5 kg ha-1 from un-inoculated control, accounting for 72% relative yield reduction. Significant (p≤0.05) yield reduction of 37% was also recorded from the lowest Pi of 10 juveniles/500 cm3. Probit analysis projected that 50% loss to marketable tubers are likely to occur at populations as low as 40 nematodes/500 cm3.There was a high positive correlation (r = 0.87**) between percentage relative yield loss and initial inoculum densities.
There was significant (p≤0.01) impairment in marketable tuber quality with 4% cracking at 10 M. incognita per 500cm3, increasing to 37% at the highest Pi of 10,000. Highly significant positive correlations were also observed for cracked tubers (r = 0.93**) and non-marketable tubers (r = 0.96**), when tested against the Pi densities of M. incognita. Nematode population was monitored during the cropping season revealed an overall significant increase (p≤0.05) in juvenile populations at mid-season (60 days after inoculation) from the initial inoculum populations. A reverse in trend of juvenile numbers was observed at harvest (120DAI).

Keywords : Meloidogyne incognita, yield and quality, sweet potato, Papua New Guinea.

Annals of Tropical Research 37(1):84-96(2015)

Zea mays (L.) Pollen as Nutriment to Aedes aegypti (Diptera: Culicidae) Larvae under Laboratory Conditions

Author(s): Kristine Mae Y. Bentoy1, Stephanie L. Sayson1, Dan Anthony U. Bataan2 and Frances E. Edillo1


This study investigated if maize (Zea mays Linnaeus) pollen can serve as a nutrient source to Aedes aegypti Linnaeus larvae, the primary dengue mosquito vector in the Philippines. First instar larvae of Ae. aegypti were subjected to different treatments of maize pollen reared in mineral water or in rain water to determine their effects on the larval development into adult emergence. Results showed that the overall development time, survivorship, and mean duration of sub adult stages differed (P <0.05; univariate ANOVA) but not on wing length among the treatments of Ae. aegypti. Larvae fed with maize pollen and reared in rain water took 7.36 d to emerge into adults and had 65% survivorship, whereas those reared in mineral water took 7.88 d to become adults and had 62% survivorship. Larvae in positive control took 6.05 d to become adults and had 79% survivorship. Mean duration from first to third instar larval stages differed (P<0.05) among treatments. Post hoc analysis using Scheffe’s pairwise comparison test showed that larvae fed with maize pollen and reared in rain water did not significantly differ (P>0.05) from the positive control (fishfood) on their development time, survivorship, and mean duration of subadult stages. These suggest that maize pollen provides nutrients for Ae. aegypti larvae similar to the positive control. Carbohydrates and proteins were detected in Molisch, Iodine, and Biuret tests. Results are relevant for future work in establishing the link between dengue mosquitoes and maize plantations in the Philippines.

Keywords : Aedes aegypti, dengue, maize pollen, larval development

Annals of Tropical Research 37(1):69-83(2015)

Evaluation of Bioactive Traits of Eclipta alba (L.) Hassk. Root Exudates

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


Eclipta alba (L.) Hassk (Asteraceae) is a branched herbaceous plant known for its curative properties against various tropical and sub-tropical diseases. In India, it is commonly known as Bhringaraj and Karisilakanni and in Bengali it is called keshut. The extensive growth of the plant in moist areas of diverse topology indicates its invasiveness and signifies its intense allelopathic activity. Morphologically the plant bears soft and sessile stem. In view of this allelopathic potential, the roots of the plants are considered as a vital biochemical mediator to the environment. Hence, the present study attempts to evaluate the allelopathic activity of the root exudates of E. alba. Amongst the major solvent extracts from the roots, the methanol fraction was found to possess significant antimicrobial activity against microbes with multiple hosts and environment. Bioassay on crop germination establishes it as a natural agricultural resource for fertilizer. The experimental finding inferred statistical significance at 0.001 level and validates practical implication.

Keywords : Allelochemical, Antimicrobial activity, Bioassay, Eclipta alba, Rootexudates.

Annals of Tropical Research 37(1):54-68(2015)

Aerobic Rice Production System(ARPS): Improving Productivity and Profitability in Water-Scarce Areas of Bulacan

Author(s): Dinah Marie C. Dayag1, Junel B. Soriano2, Josie A. Valdez1, and Gregory Moses Villacorta1


On-farm study on rice-based cropping system following recent water-saving technologies for rice production such as ARPS-ARPS, ARPS-alternate wetting and drying (AWD) and existing or Farmers’ Practice (FP) was conducted in a rainfed lowland area in Brgy. Mataas na Parang, San Ildefonso, Bulacan. Field experiments were conducted from June to November 2011 for the wet season and December 2011 to March 2012 for the dry season. Variety used for the ARPS and AWD was NSIc Rc192 and PSB Rc18 for FP. Yield and yield components of the three treatments showed no significant difference during WS. Significant higher number of tillers hill was observed for ARPS-ARPS and -1 ARPS-AWD compared to FP. No significant difference was observed for the yield and yield components during the dry season (DS) for ARPS-ARPS and ARPS-AWD. FP was not established during the DS because of the unavailability of water during the time. During WS, ARPS was the most appropriate cropping system since this intervention obtained higher water productivity and ROI when compared with the FP. During the dry season, AWD and ARPS were suitable to the rainfed lowland areas of Bulacan. Results of this study showed that aerobic rice production system for the rainfed lowland areas improved water and land productivity as well as increased annual rice production and farmers’ income most particularly in ARPS-AWD which consistently gave the highest net income of PhP36,896.20, PhP14,417.50 and PhP51,313.70 during the Wet Season, Dry Season and for the total two cropping seasons, respectively

Keywords : Aerobic rice production system, alternate wetting and drying, farmer’s practice, water productivity, cropping system, rice ecosystems

Annals of Tropical Research 37(1):44-53(2015)

Effects of Soil Chemistry on the Physico-Chemical Characteristics of the Grains of Adlay (Coix lacryma-jobi Linn) Grown in Bukidnon, Philippines

Author(s): Felvin E. Coludo1, and Gerardo C. Janairo2


The amounts of P, K, Ca, Mg, Na, Fe, Zn, Mn, Cu, B, Pb, and Cd in both grits and hull/testa of Adlay (Coix lacryma-jobi L., Gulian variety) in Bukidnon, Philippines, were quantified relative to the pH, electrical conductivity (EC), cation-exchange capacity (CEC), and amounts of organic matter (OM), N, P, K, Ca, Mg, Na, Fe, Zn, Mn, Cu, B, Pb, and Cd of the soils where these plants were grown. The P, K, Ca, Fe, and Cu contents in grits were differentiated by P, CEC, Ca, Fe, and Zn of the soil, respectively. The accumulations of both Mg and Zn in grits were influenced only by the pH of the soil while the Mn contents in grits were influenced by both pH and Mn content of the soil. The Fe, Zn, and B contents of hull/testa were significantly differentiated by the Zn, Fe and OM of the soil, respectively. The mean amounts of macr-oelements in both grits and hull/testa were in the order of K>P>Mg>Ca. The mean micro-element contents in grits were in the order of Fe>Na>Mn>Zn>Cu>B, while for hull/testa, Fe>Na>Mn>Zn>B>Cu. The Pb contents in grits and hull/testa were below the detection limit of the method while the amounts of Cd in both grits and hull/testa were below the permitted maximum level of the Joint FAO/WHO Food Standards Programme-Codex Committee on Contaminants in Food. From the amounts of these elements in Adlay, this indigenous crop may well be a good alternative food crop for human and animal consumption.

Keywords : Coix lacryma-jobi L., Adlay, Micro-elements, Macro-elements, Lead, Cadmium

Annals of Tropical Research 37(1):26-43(2015)

Improving Mulberry (Morus alba L.) Leaf Yield and Quality to Increase Silkworm Productivity in Northern Luzon, Philippines

Author(s): Mabel M. Caccam1 and Teodoro C. Mendoza2


Cocoon silk, a high priced fabric, should be produced in large quantities to meet local and international demands using sustainable farming practices. To determine the effects of planting systems and agroecosystems manipulations on the mulberry growth, leaf yield, and quality for silk worm rearing, six agroecosystems manipulations using pit planting, organic manuring, inorganic fertilization, green and green leaf manuring were evaluated and the best alternative to increase production was selected.
Pit planting method and fertilized with any of the following: (1) 100-5050 kg NPK/ha + 10 tons manure + green manure + mulch (LEISAI); (2) 5050-50 kg NPK/ha + 10 tons manures + green + green leaf manure + mulch (LEISA II); and (3) 10 tons manure + green manure + green leaf manure + mulch (Organic Farming I) gave higher mulberry leaf yields (taller mulberry plants, longer shoots, heavier single leaf weights), higher protein contents, and acceptable range of moisture (high moisture contents for young-age worms and low moisture contents for late-age silkworms). The use of sustainable and organic farming techniques can be a good alternative to conventional farming to improve the productivity of sericulture farms.

Keywords : sericulture, agroecosystems, organic farming, low external input sustainable agriculture (LEISA), conventional agriculture, mulberry, pit planting method

Annals of Tropical Research 37(1):1-25(2015)