Category Archives: Volume 28 No. 2 (2006)

Distribution and abundance of avifauna on the foothills of Mt. Pangasugan, Baybay, Leyte, Philippines


Author(s): Maritess B. Labrador and Teofanes A. Patindol

Abstract

This study determined the distribution and abundance of avifauna on the foothills of Mount Pangasugan using the standard transect method. A total of 46 avifaunal species belonging to 12 orders and 27 families with 24% endemism were found in the three selected sites based on habitat types, degree of disturbance and elevation range. Most represented order is Passeriformes while the most represented family is Columbidae.
Patterns of distribution and abundance of avifauna tend to be associated with habitat type and degree of disturbance. The most abundant and most frequently encountered species are the generalists, which can tolerate various degree of disturbance in a wide range of habitats; the least frequently occurring and least abundant species are mostly endemic interior species which prefer relatively intact forest at higher elevations where disturbance is very minimal. These specialist groups of avifaunal species, which are mostly internationally recognized as threatened, show unique association with particular habitat type, thus considered to be highly sensitive to habitat change. Protection of the remaining forests in Mount Pangasugan is deemed necessary for the survival of these interior species.

Keywords : avifauna, distribution and abundance, Mt. Pangasugan

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Screening of blue crab (Portunus pelagicus L.) eyestalk extracts for growth inhibition of Pectobacterium carotovorum subsp. carotovorum (Hauber et at. 1998) (Erwinia carotovora) Jones (Holland) and Raistonia solanacearum (Yabuuchi et al. 1995) (Pseudomonas solanacearum) E. F. Smith


Author(s): Julissah C. Evangelio and Bernardita P. Germano

Abstract

Crustacean eyestalks are known to contain neurosecretory hormones that inhibit molting, growth and gonadal development. Along this framework, this study was conducted to: screen crude eyestalk extracts from the blue crab Portunus pelagicus for possible growth inhibition on two bacterial pathogens Ralstonia solanacearum and Pectobacterium carotovorum subsp. carotovorum. and determine effective concentrations of the crude extract against the pathogens. The screening was done through bioassay using the top agar inoculation technique with 70% ethanol as the extracting solvent and streptomycin as the positive control. Different concentrations of blue crab extract and streptomycin were obtained using serial dilution.

Keywords : Portunus pelagicus eyestalks, growth inhibiting hormone, Pseudomo carotovorum subsp. carotovorum, Ralstonia solanacearum

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Is Heritiera fomes Buch. Ham. less adapted to the present conditions of the Indian Sundarbans compared to other mangrove species?


Author(s): P. Nandy (Datta)1, M. Ghose1, R. Spooner-Hart2 and S. Das1

Abstract

The Sundarbans forest forms one of the largest mangrove vegetation in the Bengal Basin. The name indicates dominance of the tree species Heritiera fomes Buch. Ham., locally known as ‘Sundari’ because of its elegance. Explosive demographic pressure and indiscriminate exploitation of natural resources caused imbalance in this ecosystem. Moreover, reduced fresh water influx and increased sedimentation appeared to be an increasing problem for navigation that in turn, led to elevated soil salinity. In the Indian part of this forest, scarcity of Heritiera fomes can be attributed to these manual and environmental adversities. In comparison to the other predominating species in Sundarbans, H. fomes is less equipped in its leaf anatomical adaptations and water-use management. Considerably thin cuticle and high stomatal frequency encourage water efflux; whereas, poorly developed water storage tissue and low frequency of terminal tracheioids weaken the water retention mechanism. This inefficiency is reflected well by the transpiration rate and stomatal conductance that continuously increase even beyond 1600 μmol m-2s-1. In H. fomes, assimilation potential declines beyond 1250 μmol m-2s-1 PAR, which unlike the other taxa, can be attributed to the poorly developed palisade tissue and low nitrogen content in leaf. The optimum leaf temperature for photosynthesis

Keywords : Heritiera fomes, mangroves, metabolites, micromorphology, photosynthesis, Sundarbans, water use.

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Abundance status of flora in Mananga-Kotkot-Lusaran Watersheds, Cebu, Philippines


Author(s): Justino M. Ouimio

Abstract

The paper describes the abundance status of forests and their species composition in the Mananga-Kotkot-Lusaran Watershed of Metro Cebu, Philippines. Data collection and analysis were undertaken according to the Braun-Blanquet (1964) methodology.
Six vegetation types, such as grassland, brushland, pioneer vegetation, young plantation, 60-year old tanguile (Shorea polysperina) plantation and old-growth forest finest were sampled in 69 plots. The range of occurrence of species in sampled vegetation types is discussed. The study had recorded 414 species, in 249 genera and 103 families. They included 47 species of large trees, 71 medium trees, 118 small trees, 2 straggler figs, 7 shrubs, 2 palms, 74 erect herbaceous plants, 21 woody lianas, 32 grasses, 22 ferns and 1 moss. Aerial plants were not included in the inventory.
Seven patches of natural growth remained extant in the watersheds but only one, the 40-hectare Tabunan forest patch, was big enough to have interior type forest. The other patches were only about 8 hectares or much less degraded in structure, poor in species, covered by climbing plants and pioneer trees and located either in rocky sleep slope or in cliff.

Keywords : flora, diversity, Cebu watershed, Braun-Blanquet

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Effects of a video-mediated student-centered learning environment on students’ understanding of plant pathology principles


Author(s): Erik-Ray Matthew S. Palomar1,2 and Rotacio S. Gravoso2

Abstract

Working with the faculty of Plant Protection, a video-mediated learner-centered learning environment was designed, implemented, and evaluated in a PPrt 21 (Principles of Plant Protection) class. Students’ learning outcomes, measured in terms of conceptual understanding and knowledge transfer, were compared with students in the control group who studied the same topics in a traditional learning environment.
Post-test results showed highly significant differences between the experimental and the control groups in terms of conceptual understanding and knowledge transfer, with the experimental group scoring higher than the control group.
Based on feedback, the learning environment did not only enrich students’ understanding of plant diseases. It also promoted development of skills in teamwork, communicating, researching, and problem-solving. The students and the teacher suggested the use of this type of learning in other subjects.

Keywords : learning outcomes, student-centered learning, constructivist learning, video-mediated learning, plant pathology

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Time of incorporation of field legume herbage and its influence on the growth and yield of upland rice


Author(s): Berta C. Ratilla1 and Rodolfo G. Escalada2

Abstract

Three species of legumes such as mungbean, cowpea, amd bushbean were incorporated into the soil at flowering to later stages of growth namely; after 1st, 2nd, and 3rd priming operations. These were followed by two croppings of upland rice.
Significantly lower soil bulk densities were obtained after the first crop of rice when mungbean and bushbean herbage were used as green manure. The pH, O.M., P and K contents of the soil planted to rice were not markedly affected by the species and timing of field legume incorporation. Interaction effects between the two variables on O. M. and pH were noted after the harvest of the first and second crops of rice, respectively.
Most of the growth and yield parameters of both crops of rice were not significantly influenced by the treatments involved. [his indicates the feasibility of modifying the usual practice of green manuring at flowering stage to later stages of growth using grain legumes without necessarily sacrificing their expected yields. Cowpea was the most suitable green manure crops for upland rice. Its use resulted in the highest combined net income for two croppings of rice, generating PhP 48,698.98 ha-1 or PhP 2.12 income per peso invested.
Regardless of field legumes used, herbage incorporation after the first priming generated an income of PhP 1.56 per peso invested while green manuring at flowering stage gave only PhP 0.69.

Keywords : green manuring, time of incorporation, field legume herbage, upland rice

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Effect of in vitro and in vivo induction of polyethelene glycol-mediated osmotic stress on hybrid taro (Colocasia esculenta (L.) Schott)


Author(s): Manas Ranjan Sahoo, Madhumita DasGupta and Archana Mukherjee

Abstract

Taro hybrid TSL (Topi X Satasankha), along with its parental lines, was evaluated for stress tolerance under in vitro and in vivo polyethelene glycol (PEG) -mediated osmotic stress conditions. Aseptic cultures were raised in vitro under control and PEG-mediated stress conditions. Stress index for survival and growth parameters like rooting ability in cultures and number of leaves produced per plantlet revealed the better response of hybrid lineTSL than its parental lines. The plantlets were hardened and transferred to pots for evaluation of morpho-physico-biochemical parameters under PEG-mediated osmotic stress conditions. Significant variations were observed in stress index for plant height. number of leaves, leaf area, % relative water content (RWC), chlorophyll stability mdex (CSI), % injury by dessication and yield. Decline in biochemical traits like protein content but increase in catalase and peroxidase activities was observed under the osmotic stress conditions. Less variation in morpho-physico-biochemical characters were recorded in TSL under stress conditions as compared to its parents. The hybrid line-TSL showed tolerance to osmotic stress with a minimum yield reduction. TSL can be used for the future breeding program for the development of drought tolerant lines and can become the source of favorable genes for drought tolerance in taro.

Keywords : hybrid taro, in vitro, in vivo, PEG-6000, osmotic stress, stress index

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