Papers by Constancio De Guzman
Annals of Tropical Research
This study aimed to determine the influence of potassium (K) fertilization on the physico-chemica... more This study aimed to determine the influence of potassium (K) fertilization on the physico-chemical and sensory qualities of ‘Magallanes’ pummelo [Citrus maxima (Burm. Ex Rumph.) Merr.] fruit. The field experiment was conducted for 12 months at South Davao Corporation (SODACO) farm in Davao City. Five treatments with increasing K levels were applied per tree: control, no K, 150g K basal, 225g K basal, and 225g K basal + foliar application. The fruit physico-chemical qualities and sensory attributes were analyzed the following harvest. Data were analyzed using analysis of variance and honest significance difference tests. Application of 225g K rates positively influenced the fruit quality but not the sensory attributes of pummelo. Fruit pulp diameter increased by 36% while peel thickness decreased by 29-75%. An increase of 39% juice weight per fruit was obtained in 150g K. The yield of juice per tree increased up to 11 times with 225g K level. The 225g K rates also increased juice pH ...
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Annals of Tropical Research
This study aimed to determine the influence of potassium (K) fertilization on the functional comp... more This study aimed to determine the influence of potassium (K) fertilization on the functional components and antioxidant activity of 13-year-old 'Magallanes' pummelo [Citrus maxima (Burm. Ex Rumph.) Merr.]. The field experiment was conducted at South Davao Corporation (SODACO) farm, Davao City for 12-month duration. Five treatments with increasing K levels were applied per tree: control, no K, 150g K basal, 225g K basal, and 225g K basal + foliar application. The functional components and antioxidant activity were analyzed following harvest at the University of the Philippines, Los Baños. Application of 225g K rates positively influenced functional components of pummelo. The yield of total phenol, flavonoid, vitamin C and oil per tree increased by 3-10 times with 225g K application. The effects of basal alone and foliar + basal application of K were only significantly different from each other in terms of flavonoid yield per tree. On the other hand, the application of 225g K ...
Science for Sustainable Societies, 2017
In Chapter 19 titled "Biowaste Reuse Through Composting: The Response of Barangay Holy Spirit in ... more In Chapter 19 titled "Biowaste Reuse Through Composting: The Response of Barangay Holy Spirit in Quezon City, Philippines, to Solid-Waste Management", the name of the author is incorrect. The name should be Makoto Yokohari on the online and print version. The author name is also updated in the Table of Contents of the Frontmatter.
The Philippine Entomologist, 2015
SummaryWell-irrigated aerobic rice (Oryza sativa L.) plants are often shorter with smaller leaves... more SummaryWell-irrigated aerobic rice (Oryza sativa L.) plants are often shorter with smaller leaves, and the leaf appearance rate is slower in well-irrigated than in flooded environments. This observation questions the functional relationship between the leaf appearance rate, which is correlated with the apical cell production rate, and leaf length that is in turn correlated with the leaf division zone length.Meristem size, blade size, and appearance were monitored for all leaves from leaf 6 on the main stem of rice plants in field experiments using two varieties, two watering systems, and three sowing dates.Leaf blade and division zone lengths were correlated in all leaves of the main stem of rice plants. New stable linear relationships were found between the leaf division zone growth duration and internal cell production rate, which changed after leaf 11. These stable relationships imply a stable link between the rates of cell production in the stem apex and leaf meristem, explainin...
Manila, Philippines: key actors, activities, benefits and constraints
International Journal of Sciences: Basic and Applied Research, 2016
Bacteria-derived crude auxin, cytokinin and gibberellin were isolated from plant gowth-promoting ... more Bacteria-derived crude auxin, cytokinin and gibberellin were isolated from plant gowth-promoting bacteria containing 826.43 ± 3.3mg/g IAA equivalence, 489.66 ± 1.0mg/g Kinetin equivalence and 588.90 ± 6.3mg/g Gibberellic acid equivalence respectively. The isolated plant growth regulators (PGRs) were also successfully encapsulated, using phospholipid and β-sitosterol with encapsulation efficiency of 82.6 ± 0.50%, 84.6% ± 0.01% and 66.75 ± 0.62% for indole-3-acetic acid (IAA)-loaded, cytokinin (Ck)-loaded and gibberellin (GA)loaded liposomes respectively. -----------------------------------------------------------------------* Corresponding author. International Journal of Sciences: Basic and Applied Research (IJSBAR)(2016) Volume 27, No 1, pp 37-56 38 Improved solubility of the PGR-loaded liposomes in aqueous solution was also observed. The PGR-loaded liposomes showed controlled-released behavior of the active component at pH 5.0 and 7.0. Higher stability of the encapsulated PGRs was...
Journal of Soil Science and Plant Nutrition, 2020
Amaranth (Amaranthus tricolor L.) is a plant that is rich in vitamins, minerals, and phytochemica... more Amaranth (Amaranthus tricolor L.) is a plant that is rich in vitamins, minerals, and phytochemicals. It is grown as a leafy vegetable in marginal environments, but high salinity levels in the soil can have a detrimental effect on its growth. These deleterious effects of salinity can be alleviated by exogenously applying signaling compounds such as salicylic acid (SA) and calcium (Ca), which can improve plant adaptation to stressful conditions. The present study evaluated the physiological and phytochemical responses of red amaranth (Amaranthus tricolor L.) to foliar-applied salicylic acid (SA; 0.005 mM) and calcium (CaSO 4 •2H 2 O; Ca, 2.5 mM) either alone or in combination (SA + Ca) under conditions of 100 mM NaCl salinity. The setup was placed under greenhouse condition from May to October 2017. Treatments without salinity and applied with SA or Ca were used as controls for comparison. Salinity stress reduced the growth and biomass, total chlorophyll contents, and increased electrolyte leakage with Na + and Cl − accumulation in shoot and roots. Nonetheless, exogenous applied SA and/or Ca 2+ reduced the adverse effects of salinity by modulating growth, Na + exclusion from roots, and increased total phenolics, flavonoids, and antioxidant activity in red amaranth. The combined application of salicylic acid and calcium can be a better strategy for improving the salinity tolerance of amaranth under salt-stressed conditions.
KIMIKA, 2019
Numerous cases of arsenic (As) poisoning from contaminated groundwater have been reported worldwi... more Numerous cases of arsenic (As) poisoning from contaminated groundwater have been reported worldwide including the Philippines. The maximum contamination limit has been set by World Health Organization (WHO) for arsenic in drinking water at 10 ppb. This study determined the As(III) and total As content of groundwater samples in selected sites of Bulacan, Batangas, and Laguna by differential pulse anodic stripping voltammetry (DPASV). The pH, temperature, conductivity, total solids, turbidity, and salinity of the groundwater samples were also determined during sample collection. Groundwater samples from Laguna were naturally warm, with collection temperatures exceeding 30 oC, compared to water samples from Batangas and Bulacan ((T = 27 to 29.5 ˚C). The pH and turbidity of all samples were found to comply with the limits based on acceptability set by the WHO and the Philippine National Standards for Drinking Water (PNSDW). However, some samples had total dissolved solids and salinity b...
Acta Scientific Agriculture, 2019
Benguet lily (Lilium philippinense) is an endemic lily found in the mountains of the Cordilleras ... more Benguet lily (Lilium philippinense) is an endemic lily found in the mountains of the Cordilleras with a high potential of being utilized as cut flower and as potted plant since it has a high resemblance to commercially produced liliums. During the past decade, however, its population continuously declined these prodded the conduct of studies aimed to conserve, domesticate and propagate the plant through tissue culture Unfortunately, the growth and development of Benguet Lily collected from the wild and those that were invitro propagated maintained under greenhouse condition has not been adequately described. The aim of the present study is to evaluate and compare the performance of the wild and the in-vitro propagated Lilium philippinense when both are grown in the greenhouse. The wild and in-vitro propagated Benguet lily plants exhibited similar growth phases in the greenhouse. The major growth phases include shoot emergence, flower bud emergence, flower opening, capsule emergence, capsule maturation, dehiscence of seeds and plant senescence. The duration of the growth phases and corresponding climatic condition were different for the two types of plants. Shoot emergence in both plant type coincides with a relatively cooler temperature and humid condition. More humid and warmer temperature favors flower bud emergence in wild plants while cooler and humid condition favors it in-vitro propagated plants. Flower opening of both plant type was favored by cold and more humid condition. Capsule emergence and maturation in wild plants is favored by comparably cold and humid condition while warmer and drier condition favors capsule emergence and maturation in in-vitro propagated plants. The differences observed in the transition and duration of each growth phase between appeared to be highly attributable to the difference in maturity of the planting material used. The high adaptability of L. philippinense to both field and greenhouse conditions points to a high potential for commercialization.
Asian Journal of Research in Agriculture and Forestry, 2019
This study aimed to determine the influence of potassium (K) fertilization on the vegetative grow... more This study aimed to determine the influence of potassium (K) fertilization on the vegetative growth, flowering and fruit development of 13-year old ‘Magallanes’ pummelo [Citrus maxima (Burm. Ex Rumph.) Merr.] trees. The experiment was conducted at South Davao Corporation (SODACO) farm, Davao city for 12-months duration. Five treatments were observed with increasing K levels were applied per tree: control (no fertilization), without K, 150 g K basal (recommended rate based on soil analysis), 225 g K basal, and 225 g K basal + foliar application. The critical stage of tree growth coincided with the months of May and August. Peak leaf flushing occurred in June and peak flowering with fruit set in April. The crucial stage of fruit development was noted two months after fruit set. Thus, optimum fertilization must be applied during these stages for maximum growth and production in ‘Magallanes’ pummelo. The vegetative growth of pummelo was not affected by increasing K rates. The recommende...
Science for Sustainable Societies, 2017
Biowaste is the large volume of solid waste generated daily by households, and it presents enviro... more Biowaste is the large volume of solid waste generated daily by households, and it presents environmental and health hazards if not reused. Composting is one of the best options for such reuse. This study documents biowaste generation and collection from households and reuse through composting in Barangay Holy Spirit, Quezon City, Philippines. This barangay (the smallest administrative unit) has made pioneering efforts in composting, having developed it from a simple process to a mechanized process. The barangay’s composting has been integrated with its vegetable and flower urban garden, which serves as a demonstration and training center on how to provide livelihood opportunities and environmental benefits. However, to enhance the compost’s marketability, issues relating to quality, such as the high organic carbon, high carbon-to-nitrogen ratio, and low levels of nitrogen, phosphorus, and potassium, need to be addressed. The barangay intends to boost compost production and sales, thereby increasing income, which can further improve the solid-waste management and increase staff salaries. Barangay Holy Spirit is one of the most developed barangays in terms of solid-waste management, and it can serve as a model for other barangays.
Science for Sustainable Societies, 2017
This chapter provides an overview of urban agriculture (UA) in the Philippines. Several academic ... more This chapter provides an overview of urban agriculture (UA) in the Philippines. Several academic and government initiatives are described that relate to UA and have led to an awareness and recognition of UA. The practice of UA is illustrated through studies conducted on commercial vegetable production within Metro Manila and also on a peri-urban livelihood system based on the jasmine species known as sampaguita (Jasminum sambac Ait), which is used to make garlands in San Pedro, Laguna, a municipality adjacent to Metro Manila. These studies reveal the positive impact of urban and peri-urban agricultural activities on employment and income generation as well as the promotion of positive social values. Most crop production in Metro Manila has been discontinued owing to the inability to compete with land use prioritization. The lack of clear government policy with respect to UA has contributed to the decline of the practice. Recommendations are made for the promotion of urban and peri-urban agriculture.
环境科学与工程 a, 2013
This study aimed to determine the influence of different rates of K (potassium) and K foliar appl... more This study aimed to determine the influence of different rates of K (potassium) and K foliar application on the quality and plant nutrition condition of 13-year old 'Magallanes' pummelo trees [Citrus maxima (Burm. ex Rumph.) Merr.]. The experiment was conducted at SODACO (South Davao Corporation) farm, Davao City, Philippines from March to October 2010. Five treatments with increasing K levels were applied per tree: control, no K, 150 g K basal, 225 g K basal and 225 g K basal + foliar application. Application of 225 g K rates positively influenced fruit quality of pummelo. Fruit pulp diameter and juice weight increased while peel thickness decreased. The 225 g K rates also increased juice pH, TA (titrable acidity) and TSS (total soluble solids) per tree. The yield of total phenol, flavonoid, vitamin C and oil per tree increased with 225 g K application. Results of the soil analysis before and after the conduct of the study showed an evidence of fertilizer absorption by the trees. It was also observed that foliar fertilization reduced soil acidity. This indicates the important role of K in improving the nutrient utilization and quality of 'Magallanes' pummelo.
The Philippine Agricultural Scientist, Jan 29, 2014
Bitter gourd (Momordica charantia L. cv. Makiling) was grown in soil amended with organic fertili... more Bitter gourd (Momordica charantia L. cv. Makiling) was grown in soil amended with organic fertilizers, namely, Bio-N, commercial compost and vermicompost, at the rate of 0.075 g seed -1 , 150 g plant -1 and 231 g plant -1 , respectively. As a positive control, the plants were fertilized with inorganic fertilizer by adding 32.4 g plant -1 of complete fertilizer (14-14-14) applied basally and 6.52 g plant -1 of urea sidedressed at flowering based on the recommended application rate of 100 N – 60 P2O5 – 60 K2O kg ha -1 . Vegetative growth and herbage yield of bitter gourd were significantly enhanced by the application of different organic fertilizers. Relative to the control, the total herbage yield was improved by 30%– 40% when vermicompost, Bio-N and commercial compost were applied to the plants. The promotion of vine growth of bitter gourd, brought about by organic fertilizers, was comparable to that as a result of applying inorganic fertilizer. Flowering occurred 45–52 d after seedling emergence in organically grown plants, 1–2 wk earlier than flowering in the control plants. The least number and the smallest fruits were harvested from unfertilized bitter gourd plants while the highest number of fruits was gathered from plants fertilized inorganically. The latter treatment, however, yielded the highest number of both marketable and non-marketable fruits. Fruit yield and yield components of bitter gourd treated with organic fertilizers were similar to those of plants treated with inorganic fertilizer, except for the total number and the weight of fruits. Among the three organic fertilizers used, the application of commercial compost resulted in the greatest improvement in both vegetative and reproductive growth as well as in the total herbage and fruit yield of bitter gourd. Organically grown bitter gourd also produced higher amounts of antioxidants in the leaves compared with the chemically fertilized plants. The leaves of Bio-N-treated plants collected from the middle section of the stem (between 60 and 120 cm from the shoot tip) generally contained the highest total phenolics, total flavonoids and total tannins. Vitamin C concentration in the leaves of both fertilized and control plants were similar. In the fruits, the total phenolics of all fertilized plants was higher compared with that of the unfertilized bitter gourd. The latter treatment also resulted in the highest vitamin C concentration in the fruits. Regardless of fertilizer treatment, bitter gourd fruits were best harvested 36 d after transplanting as they contained the greatest amount of total phenolics, total tannins and % lipid peroxidation. Key Words: ampalaya, antioxidants, Bio-N, bitter gourd, commercial compost, Momordica charantia L., vermicompost
The Philippine Agricultural Scientist, Feb 10, 2013
In vitro plantlet regeneration and production of roots in the shoot base explants of vetiver [Vet... more In vitro plantlet regeneration and production of roots in the shoot base explants of vetiver [Vetiveria zizanioides (L.) Nash] was investigated using Murashige and Skoog's (MS) medium supplemented with different types and concentrations of plant growth regulators. Extensive shoot proliferation was maintained at 5 mg L-1 6-benzylaminopurine (BAP). Increasing the concentration of BAP to 20 mg L-1 significantly inhibited the growth of shoots. Root production was greatly enhanced by the addition of either 0.25 mg L-1 naphthaleneacetic acid (NAA) or 20 mg L-1 indole-3-butyric acid (IBA). Roots induced by NAA were short and thick, whereas those induced by IBA were long, thin and fibrous. Supplementation of 0.5 mg L-1 NAA to MS basal medium and further enrichment with 0.5 mg L-1 kinetin (Ki) significantly enhanced the proliferation of roots. However, addition of 0.2 mg L-1 paclobutrazol (PBZ) into the NAA-supplemented MS medium suppressed both shoot and root growth of vetiver. Key Words: in vitro culture, plant regeneration, root production, shoot induction, Vetiveria zizanioides (L.) Nash Abbreviations: BAP - 6-benzylaminopurine, Ca(OCl)2 - calcium hypochlorite, IBA - indole-3-butyric acid, Ki - kinetin, MS medium - Murashige and Skoog's medium, NAA - naphthaleneacetic acid, PBZ - paclobutrazol
Water Sci Technol, 2005
Presently, Metropolitan Manila (MM) generates about 6,000 tons of municipal solid wastes per day ... more Presently, Metropolitan Manila (MM) generates about 6,000 tons of municipal solid wastes per day of which 2,800 tons is estimated to be biodegradable. Despite a legal framework and policy that aims at recycling 25% of the biodegradable wastes, presently (only) 160 tons/d of these biowastes (ca 6%) is source-separated and processed in 22 small-scale composting plants. Evaluation of the performance of 3 of these plants revealed flaws in obtaining compost with the officially required quality standards. A survey among 50 horticultural farmers showed that only 34% of them use organic fertiliser. The main impediments for increased compost application are low expectations about the yields of compost versus inorganic fertilizers, the relatively high price and cumbersome handling of the bulky product. At 25% recycling in MM an agricultural area in the order of 20,000 ha would have to apply municipal biowaste-based compost in quantities of ca 10 tons/ha/yr, which is far more than the agricultural area within the city's boundaries. Enhancement of the municipal biowaste reuse chain in MM would require synchronous expansion of the markets, the composting and the collection of segregated wastes. In order to develop a vision on chain enhancement a research programme covering Manila and several other South East Asian megacities is proposed. A determined collaboration of the stakeholders involved in the chain, farmers, compost producers, waste generators, waste collectors and waste managers, is seen as a prime prerequisite in the development of this vision.
The Philippine Agricultural Scientist, Feb 10, 2013
The use of compost generated from municipal biowastes was investigated for the production of Aste... more The use of compost generated from municipal biowastes was investigated for the production of Aster ericoides L. Different levels of biowaste compost (2.5, 5.0 and 7.5 kg m-2) alone or in combination with the prevailing farmers' practice of inorganic fertilization [60 g m-2 urea (46-0-0) and 20 g m-2 complete fertilizer (14-14-14)] were employed. Addition of 2.5 kg m-2 biowaste compost with or without inorganic fertilizer gave optimum results in terms of increase in height, length and weight of flower stalk and number of secondary and tertiary panicle branches of aster. Plants also exhibited 100% survival, bolting and flowering under these conditions. On the other hand, application of higher dose of compost, 7.5 kg m-2 in particular, had detrimental effects on the growth of aster as manifested by the low survival rate, yellowing and narrowing of leaves, and the dwarfing of plants.The end of the decorative or functional life of aster was observed on the 8th day after harvest for plants treated with inorganic fertilizer and with 2.5 kg m-2 compost alone or in combination with inorganic fertilizer; those for the other treatments were noted a day earlier. Total moisture loss of the flower stalk was higher in plants under inorganic fertilizer and lower in plants provided with 2.5 kg m-2 compost alone. Overall, municipal biowaste compost applied at the rate of 2.5 kg m-2 resulted in the maximum growth, yield and postharvest life of Aster ericoides L., indicating its potential as a substitute for fertilizer requirement or as soil conditioner in the production of this crop. Key Words: aesthetic value, Aster ericoides L., bolting, flowering, municipal biowaste compost, panicle branches, postharvest quality Abbreviations: C - compost, IF - inorganic fertilizer, MSWC - municipal solid waste compost
The Philippine …, 2009
In vitro culture of ilang-ilang [Cananga odorata (Lamk) Hook. f. & Thomson] was done to determine... more In vitro culture of ilang-ilang [Cananga odorata (Lamk) Hook. f. & Thomson] was done to determine the responses of the different explants (shoot tip, node, young leaf, ovary and petal) to Woody Plant Medium (WPM) and Murashige and Skoog’ s (MS) culture ...
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Papers by Constancio De Guzman