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June 2020, Vol. 103 No. 2

The mangrove forest along the Sabang River in Puerto Princesa, Palawan, Philippines is composed of 47.55 ha of century-old mangrove trees that have served as a habitat to its diverse flora and fauna. It has been a breeding site to different species of plants, fish, mammals, reptiles, birds, and other endangered wildlife. The mangroves are part of the Puerto Princesa Subterranean River National Park (PPSRNP) which has been declared as a Protected Area (PA) by the International Union for the Conservation of Nature (IUCN). It is considered one of the most important biodiversity conservation areas in the Philippines. As part of the local efforts to preserve the pristine condition of this ecosystem, mangrove seedlings have been grown approximately 150 meters from the beach, which will later on be transplanted into the deeper mangrove forest.

{Photograph courtesy of Ms. Armi R. Creencia, Philippine National Collection of Microorganisms (PNCM), National Institute of Molecular Biology and Biotechnology (BIOTECH), University of the Philippines Los Baños, College, Laguna 4031, Philippines}




Cryopreservation of ‛Laguna Tall’ Coconut (Cocos nucifera Linn.) Mature Zygotic Embryos
J. Kumaunang, O. P. Damasco and C. M. Protacio

Received: 11 November 2014/ Revised: 03 June 2019/ Accepted: 24 October 2019

‘Laguna Tall’ coconut (Cocos nucifera L.) zygotic embryos were successfully cryopreserved through cryoprotection using pretreatment-desiccation or vitrification, rapid freezing in liquid nitrogen, rapid thawing at 40°C for 2 min, and recovery and growth of frozen embryos in coconut germination medium. Pretreatment in 0.5 M sucrose for 1 d followed by 24 h desiccation in silica gel gave the highest recovery and complete germination (47%) of cryopreserved embryos. This was followed by 24 h desiccation alone (43%), 3 d sucrose pretreatment + 24 h desiccation (33%), and the least recovery from vitrification using PVS4 solution (13%). Embryo reinvigoration as a post thawing treatment and addition of 0.5 mg L-1 benzyl amino purine + 1.0 mg L-1 naphthalene acetic acid onto Y3 germination medium hastened recovery and significantly improved complete germination of cryopreserved embryos. The study demonstrated the feasibility of cryopreservation for long-term conservation of coconut genetic resources and for the first time reported on the success in cryopreservation of ‛Laguna Tall’, an endemic coconut variety grown in the Philippines.

Vegetative Growth and Nutrient Use Efficiency of Tissue-Cultured ‛Saba’ Banana (Musa) Plantlets in Response to Fertigroe® N, P, and K Nanofertilizers
Domingo E. Angeles, Job Jonas C. Ruzgal, Graciela L. Caballero and Alvin P. Crodua

Received: 10 April 2019/ Revised: 07 August 2019 and 06 May 2020/ Accepted: 15 May 2020

The study determined the effect of using FertiGroe® Nano N (18-0-0), Nano P (0-18-0), and Nano K (0-0-38) nanofertilizers on the growth and nutrient use efficiency of tissue-cultured ‛Saba’ banana (Musa ABB) plantlets. For 7 wk, conventional fertilizers (CF) and FertiGroe® nanofertilizers (NF) were applied to the plantlets at graduated level of the recommended rate (RR). Vegetative growth was monitored weekly. At the end of the experiment, samples were collected for dry matter partitioning and leaf tissue analysis. Fertilizer treatment significantly improved pseudostem growth and dry matter production of ‛Saba’ banana plantlets. Plantlets applied with neither conventional fertilizer (CF) nor nanofertilizer NF (control) produced significantly shorter and thinner pseudostem, and less dry matter compared to plantlets that were applied with NF or CF, regardless of the recommended rate (RR) used. Despite having significantly shorter and thinner pseudostem, plantlets applied with NF at 50% RR and 75% RR produced dry matter comparable to plantlets applied with CF at 75% RR and 100% RR by allocating more dry matter to the leaves. Foliar P concentration was not limiting to the plants and its nutrient concentration in the leaves did not vary significantly across the treatments. N uptake was highest in plantlets applied with NF at 75% RR (0.187 g) and CF at 75% RR (0.158 g), 100% RR (0.167 g) and 125% RR (0.173 g). K uptake was highest in plantlets that received NF at 50% RR (0.355 g) and 75% RR (0.358 g) and CF at 75% RR (0.353 g). Nutrient use efficiency of the plantlets was measured using apparent nutrient recovery. Apparent potassium recovery of the plantlets applied with NF was higher compared to that of plantlets applied with CF. The computed optimum RR for FertiGroe® N nanofertilizer was 23.5% lower than the computed optimum RR for CF. FertiGroe® N nanofertilizer can also increase apparent nitrogen recovery by 36.87% compared to CF.

Phenotypic Characterization of Selected Traits in ‛Saba’ Banana (Musa balbisiana), Chico (Manilkara zapota) and Pummelo (Citrus maxima) for Crop Improvement
Pablito M. Magdalita and Alangelico O. San Pascual

Received: 05 July 2019/ Revised: 08 May 2020/ Accepted: 15 May 2020

Phenotypic characteristics of ‛Saba’ banana, chico and pummelo were assessed for variability, clustering patterns and character association of 67 saba clones, 71 chico and 73 pummelo genotypes collected mainly from Luzon. Characters were analyzed for agglomerative clustering and correlation analyses. Five clusters for saba, chico and pummelo genotypes were arbitrarily formed a highly branched dendrogram for each species was generated. In ‛Saba’, 22 grouped in Clusters 1, 24, 18, 1 and 2 in Clusters II, III, IV and V, respectively. In chico, 67 genotypes clustered in Cluster I, while 1 each belongs to Clusters II, III, IV and V. In pummelo, 37, 4, 29, 2 and 1 genotypes grouped, respectively, in Clusters I, II, III, IV and V. High degree of association between characters indicated dependency of certain characters on others, suggesting that evaluation of traits can be reduced to save time, effort and resources during peak of evaluation periods. Eighteen saba clones of Cluster III, while in Chico, CH7-IPB in Cluster II and 41 accessions from Clusters I and II of pummelo could be used in varietal improvement due to high total soluble solids (TSS) and edible portion, heavy fruit weight and size, and few number of seeds for chico and pummelo.

Total Flavonoid, Total Phenolic Content and Antioxidant Activity of Erechtites valerianifolia Herb Extracts
A. R. Puspaningtyas, E. N. Sholikhah, P. Astuti and S. Riyanto

Received: 11 January 2019/ Revised: 02 September 2019/ Accepted: 13 September 2019

Erechtites valerianifolia (Link ex Wolf.) Less. ex DC. or “Jonggolan” (Indonesian name), a member of the family Asteraceae, was collected from Meru Betiri Forest, Indonesia. This study investigated the antioxidant activity of E. valerianifolia and its total phenolic and total flavonoid content. Methanol, ethyl acetate, dichloromethane, and hexane extracts of E. valerianifolia herbs were tested using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals scavenging assay. Antioxidant activity was expressed in IC50 values of the n-hexane, dichlormethane, ethyl acetate and methanol extracts (367.8000 ppm, 139.5200 ppm, 911.0540 ppm, and 401.9530 ppm, respectively) with the best antioxidant activity observed in dichloromethane (DCM) extract. Total phenolic content (TPC) of the n-hexane, dichloromethane, ethyl acetate and methanol extracts were 10.6400 ± 0.0338 mg GAE/g; 6.4500 ± 0.0000 mg GAE/g; 6.6900 ± 0.0323 mg GAE/g; and 3.2300 ± 0.0000 mg GAE/g, respectively (with gallic acid as reference). Total flavonoid content (TFC) of the n-hexane, dichlormethane, ethyl acetate and methanol extracts were 1.4000 ± 0.0784 mg QE/g; −2.3900 ± 0.0000 mg QE/g; 0.4400 ± 0.0000 mg QE/g, and 0.1100 ± 0.0000 mg QE/g, respectively (with quercetine as reference). Total flavonoid content of the n-hexane, dichloromethane, ethyl acetate and methanol extracts were 2.3700 ± 0.1180 mg RE/g; −2.7900 ± 0.0000 mg RE/g; 0.9100 ± 0.0000 mg RE/g; and 0.2400 ± 0.0000 mg RE/g, respectively (with rutin as reference). The correlation between total phenolic/total flavonoid content and antioxidant test was less than 50%, indicating no direct/negative correlation between polyphenolic content of the extracts and antioxidant activity.

Consumer Purchasing Behavior for Fresh Soursop (Annona muricata L.): Evidence from Metro Manila and CALABARZON, Philippines
Dormita R. Del Carmen, Elda B. Esguerra and Arjay A. Gerance

Received: 20 June 2019/ Revised: 15 November 2019/ Accepted: 26 May 2020

A survey of urban and peri-urban consumers in major market centers and residential estates in Metro Manila and CALABARZON in the Philippines was conducted to determine their purchasing behavior for fresh soursop as influenced by demographic characteristics and preferences. Household income, education and household size were strongly correlated with consumer preference on soursop attributes. As household income increased, consumers tended to look for more desirable attributes which can be classified into search (size, color, peel thickness) and experience (taste, juiciness and pulp texture). Education had a similar influence but to a lesser extent. Consumer household size and fruit size also showed marked correlations, indicating that larger households (those with more members) bought larger fruits. Using cluster analysis, two consumer segments, the size/shape conscious and the taste-discriminating groups were identified. Majority of the consumers were not satisfied with the soursop purchased due to quality defects such as pulp hardening, sour or off-taste, and fruits that did not ripen and fruits with insect/disease damage, which had an adverse impact on their repeat purchase. Moreover, the resulting losses from fruits with defects also impacted on income of stakeholders, particularly the farmers and traders. Quality improvements in the soursop supply chain can, therefore, be undertaken to provide the quality of fruits that will satisfy the different types of consumers, and to reduce losses to increase income of farmers and traders.

Effect of Entomopathogenic Fungi Metarhizium (Nomuraea) rileyi (Farl.) Samson on the Third Instar Larvae of the Onion Armyworm, Spodoptera exigua Hübner (Lepidoptera: Noctuidae), under Laboratory Conditions
Melissa P. Montecalvo and Marcela M. Navasero

Received: 19 July 2019/ Revised: 08 May 2020/ Accepted: 15 May 2020

The armyworm, Spodoptera exigua Hübner (Lepidoptera: Noctuidae), caused severe destruction in the production of onion and other crops in the Philippines. This study examined the virulence of an entomopathogenic fungus against this insect pest. Metarhizium (Nomuraea) rileyi was successfully isolated from mummified larvae of S. exigua. In a laboratory bioassay, third larval instars were exposed to conidial concentrations of M. rileyi by mist spraying. The fungus was highly pathogenic to S. exigua, which caused infection starting 2 d after treatment. More than 50% of the larvae succumbed to infection 6 d after treatment. M. rileyi at 1 x 107 and 1 x 108 conidia mL-1 caused 100% mortality 7 d after treatment. Conidial concentrations caused 73–100% mortality 10 d after treatment with mean lethal time of 4.17–7.83 d. Calculated median lethal dose (LD50) from 7–10 d after treatment was 1.49 x 106 to 9.57 x 104 conidia mL-1. High epizootics due to M. rileyi resulted in low pupation rate (<20%) and adult emergence (3%). Larval duration, pupal size, and weight did not vary significantly. Our findings suggest the virulence of M. rileyi against S. exigua, which must be further evaluated to determine its potential as biocontrol agent and as an alternative management option to chemical pesticides.

Genotypic Diversity of Escherichia coli Isolates in Philippine Native Swine from Quezon Province, Philippines as Revealed by Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR
Czarina May E. Vigo-Prutscher, Justin Benedict L. Balcera and Rina B. Opulencia

Received: 29 August 2018/ Revised: 02 March 2020/ Accepted: 06 May 2020

The Philippine native swine (PNS) is an economically important livestock in Quezon Province and recognized as more disease-resistant than the white crossbreeds or hybrids. This study was conducted to determine the genotypic diversity of the Escherichia coli population in the intestine of PNS and to identify factors that might have influenced E. coli dissemination in PNS. E. coli were isolated from the intestinal tract of 76 PNS and from 38 soil and water samples from 20 farms in seven municipalities in Quezon Province and analyzed by enterobacterial repetitive intergenic consensus (ERIC)–PCR. Results revealed extensive genotypic diversity in 114 E. coli isolates from PNS from various farms. However, genotypic diversity was not strictly correlated with municipality or geographical origin of the isolate or PNS, phenotypic traits of swine, and swine farm management practices. These results suggest that the population of E. coli in gut of PNS is dynamic and members of the population might have been derived from various sources. The diversity might have been influenced by multiple factors, including swine and farm management practices.

Seasonal Variability in the Prokaryotic Community Structure of the Sabang Mangrove Soil in Puerto Princesa, Palawan, Philippines Assessed by Next-Generation Sequencing of the 16S rRNA Gene
Armi R. Creencia, Rina B. Opulencia, Maria Genaleen Q. Diaz, Edwin P. Alcantara and Rosario G. Monsalud

Received: 05 March 2019/ Revised: 02 February 2020/ Accepted 10 May 2020

The influence of seasonal variation on the bacterial and archaeal diversity of the mangrove soil in Sitio Sabang, Barangay Cabayugan, Puerto Princesa, Palawan, Philippines was investigated. Sample collections were done in three selected sampling sites along the Sabang River during the dry and wet seasons of 2017. The prokaryotic community structures were determined by Next-Generation Sequencing (NGS) targeting the V3–V4 regions of the 16S rRNA gene, using Illumina Hiseq 2500. Results showed that the soil microbial community in the Sabang mangroves was predominantly inhabited by members of the Phyla Proteobacteria, followed by those of Phyla Chloroflexi and Bacteroidetes. Members of Phyla Firmicutes, Bathyarchaeota, Actinobacteria, Acidobacteria, Euryarchaeota, Cyanobacteria and the DHVEG-6 cluster were also present in varying relative abundance. There was no significant difference in the prokaryotic community structures between the dry and wet seasons, which implies that mangrove health and its microbial resources have been conserved. Significant differences were observed only for the relative abundance of Proteobacteria and Firmicutes (more abundant in wet season), and Acidobacteria, Chloroflexi and DHVEG-6 cluster (more abundant in dry season). The steep species diversity curves indicate that several other microbial species are yet to be discovered. Additional sampling and further molecular surveys of the Sabang mangrove prokaryotic community structure for at least 2 yr are thus recommended.

Research Note

Identity of the Giant Fig Thrips (Thysanoptera) Infesting Ficus nota (Blanco) Merr. in Leyte, Philippines
Cecilia P. Reyes, Ruben M. Gapasin and Cynthia B. Mintu

Received: 01 April 2019/ Revised: 25 February 2020/ Accepted: 25 May 2020

Ficus nota (Blanco) Merr. (Moraceae), locally known as “tibig” or “tabog,” is endemic to the Philippines. This species of fig is well known for its medicinal importance and is one of the high value trees planted and managed by rural households in the province of Leyte. The study aimed to establish the identity of thrips or “kulisipsip” associated with F. nota in the campus of the Visayas State University in Baybay, Leyte. Thrips samples were collected from 20 leaves selected randomly from “Tibig” once a month from December 2018 to March 2019. Specimens were sorted under a stereomicroscope, cleared, mounted on slides using Canada balsam, and examined under a light microscope. The giant fig thrips, Gigantothrips elegans Zimmermann, was the only species found. Thrips feeding damage on the leaves was severe. Larvae, female and male thrips fed on the underside of the leaves and were found aggregated. This result implies that the G. elegans population reproduced sexually and the aggregation suggests that pheromones were involved. Since this species of thrips is colonial or gregarious, aggregation pheromone-baited traps could be developed by future researchers to manage this insect pest.

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