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December 2022 – Vol. 105 No. 4


Huanglongbing (HLB) caused by Candidatus Liberibacter asiaticus and tristeza caused by Citrus tristeza virus (CTV) are the major diseases affecting citrus species including calamansi (Citrofortunella microcarpa Bunge) in the country. Oriental Mindoro, aptly called the “Calamansi King” of the Philippines, produces more than 97%, contributing to 33% of the country’s total calamansi production (PSA 2017). Disease surveillance found that HLB and tristeza are prevalent in the province, and they occur mostly in mixed infection with symptoms of blotchy mottle and interveinal chlorosis on the leaves.

Synthesis and Characterization of Nanozeolite from Sugarcane Bagasse Ash and Its Nutrient Loading Potential
Quincy E. Ybañez, Pearl B. Sanchez, Marcial S. Buladaco II, and Joy Eloiza M. Rosales
Received: September 21, 2021/ Revised: August 12, 2022/ Accepted: August 17, 2022

Sugarcane bagasse, a known agricultural waste product in the Philippines with 88% silica (SiO2) content based on elemental analysis, is a viable starting material for zeolite synthesis. In this study, silica derived from sugarcane bagasse ash (SBA) collected from La Carlota, Negros Occidental, Philippines, was extracted via an alkaline extraction method using 2M NaOH and precipitation with 5 N H2SO4 under constant stirring at elevated temperature. Sodium aluminate was added as aluminum source then subjected to ageing at 80°C for 72 h to form the clinoptilolite-type zeolite crystals. Characterization using Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy and X-Ray Diffractometry confirmed the successful synthesis of the SBA silica and clinoptilolite, with an Si/Al ratio of 1.59 and average pore diameter of 85.77 nm. Surface modification was done by adding CTAB, a cationic surfactant. Nutrient loading was performed using synthesized nanozeolite (SNZ) for N and K loading and surface modified synthesized nanozeolite (SMSNZ) for PK loading which was compared with nutrient loading performance of commercial natural zeolite. The nanozeolite was added to 1 M urea for N loading, 1 M potassium chloride (KCl) for K loading, and 1 M potassium dihydrogen phosphate (KH2PO4) for PK loading at 1:10 (solid: liquid) solution ratio for 8 h under constant stirring followed by filtration and air drying. Chemical characterization of the synthesized nanozeolite revealed that it has a total CEC of 199.30 meq 100 g-1, ICEC of 182.51 meq 100 g-1, and ECEC of 16.79 meq 100 g-1. Nutrient loading resulted in a 9.62% N and 17.01% K2O content using SNZ and a 13.35% P2O5 and 16.26% K2O content using SMSNZ, which were relatively higher compared to using a commercial natural zeolite. These can be attributed to the high internal CEC due to the high quantity of nanopores in the zeolite, which can capture and store the K+ and NH4+ ions via geometric fit, then release them to the soil ondemand via ion-exchange or occlusion. The surface modification with a surfactant drastically alters the surface chemistry of zeolite allowing simultaneous adsorption of anions (PO4) externally and cations (K+) internally. The chemical characterization confirmed successful loading of N, K, and PK to synthesize nanozeolite from SBA-derived silica, and its potential as a controlled release fertilizer can be tested in further studies.

Rheological Properties and Postharvest Behavior of Onion (Allium cepa L. ‘Superex’) Subjected to Different Preharvest Treatments to Control Armyworm [Spodoptera exigua (Hubner) Lepidoptera: Noctuidae]
Daphne Cassandra H. Gonzales, Ryan Anthony O. Lualhati, Kim John R. Nate, Cielo Azul P. Dumlao, Emmanuel Q. Amatorio, Elda B. Esguerra, and Bonifacio T. Cayabyab
Received: June 06, 2022/ Revised: September 07, 2022/ Accepted: September 16, 2022

Heavy reliance on synthetic pesticides has led to insecticide resistance of pests such as the onion armyworm, leading to the use of alternative strategies such as biopesticides. While studies on the efficacy of these biopesticides on pest control and yield exist, their subsequent effects on the quality and postharvest behavior of bulb onions during cold storage need to be determined. Allium cepa L. ‘Superex’ yellow type onion plants were subjected to preharvest treatments of microbial (NPV crude), botanical (neem oil), synthetic insecticide (chlorfenapyr), and Farmer’s Practice (control) for the control of onion armyworm (Spodoptera exigua (Hubner)). Bulbs were then harvested at commercial maturity, cured at ambient condition (33.6°C, 48.5% RH) for 11 days, then stored at 4.7 ± 0.6°C, 91.7 ± 1.6% RH for 5 months. Rheological properties of the bulbs after curing and prior to storage did not vary significantly across treatments. Stiffness, however, decreased by 50 − 70% during storage, with bulbs from NPV crude having higher values. Weight loss during the five-month storage ranged from 10 − 12%. Pungency of the bulb increased with increasing duration of cold storage concomitant with the onset of internal sprouting on the fifth month. Bulbs preharvest-treated with NPV crude had the highest pungency of 4.85 μmol g-1FW on the third month and increased to 6.72 μmol g-1FW on the fourth month. The preharvest treatments nor the storage duration did not affect the total soluble solids content of the bulbs which ranged from 6.9 − 7.1°Brix. Internal sprouting occurred on the fifth month at 75 − 100% but external sprouting was very low at 0 − 1.0%. At ambient condition post-storage, it took 45 − 63 days for bulbs to exhibit external sprouting after being taken out of cold storage on the fourth month. After five months of cold storage, bulbs sprouted after 6 − 19 days at ambient condition. New root growth occurred on the fourth month in all stored bulbs regardless of the preharvest treatment. Disease incidence during the five-month storage was 0 − 1.1%. The recommended storage is four months for the yellow type ‘Superex’ onions with bulbs having a shelf life of almost two months at ambient retail condition (33.6°C, 48.5% RH).

Flowering Habit and Photoperiodic Flowering Response of Stevia (Stevia rebaudiana Bertoni) in the Philippines
Kennilyn May Balbin-De Luna and Bong M. Salazar
Received: June 01, 2020/ Revised: September 21, 2022/ Accepted: October 02, 2022

Stevia is a perennial shrub commercially cultivated for the sweet-tasting compounds known as steviol glycosides (SVglys). SVglys are extracted from the green leaves, thus maintenance of vegetative growth is critical in stevia production. This study described the flowering habit and response of potted stevia plants to different photoperiods under Philippine conditions. Photoperiodic treatments (10, 11, 12, 13, and 14 h) were provided using light chambers. Stevia has both terminal and axillary flowering habits. It has five white florets enclosed in a capitulum and exhibits an opposite branching pattern. Results showed that stevia is a facultative short-day plant with a critical daylength of about 12 h. Earlier and more profuse flowering was observed in plants exposed to photoperiods less than 12 h. Earliest flowering response was in 10 h photoperiod which occurred 10 d after light treatment, while flowering time was extended to 23 d in the 14 h photoperiod. Plants subjected to the 10 h photoperiod had the largest number of flowers (34 flower clusters or capitula), while the most number of leaves (37 leaves) was recorded in the longest photoperiod treatment. The study also established that stevia under a 10 h photoperiod requires 10 inductive cycles to induce flowering. Photoperiod was found to have significant positive correlations with the number of nodes and flowering time.

Determination of Some Seed Characteristics of False Flax (Camelina sativa L. Crantz) Genotypes Grown Under Semi-Temperate Conditions
İlhan Subaşı, Yusuf Arslan, Tamer Eryiğit, Vahdettin Çiftçi, and Mahmut Çamlıca
Received: March 08, 2021/ Revised: June 20, 2022/ Accepted: August 30, 2022

Camelina is an alternative low-input oil plant grown in marginal areas in Turkey. This study aimed to determine some quality characteristics of 39 camellia genotypes in ecological conditions in Bolu, Turkey. The field experiments were carried out in an augmented design with randomized blocks. In this work, some important properties such as thousand seed weight, oil content, fatty acid composition, and protein ratio were investigated. Results showed that mean data for thousand seed weight, oil ratio, and protein ratio were 0.63 – 1.5 g, 26.69 – 39.17%, and 21.81 – 29.81%, respectively. Considering the oil content of the genotypes used in the study, the PI 650158 genotype had the highest oil ratio, while the PI 650164 genotype had the highest seed protein ratio. In conclusion, the PI 311735 and PI 650158 genotypes were found to be within acceptable limits in terms of both oil and protein ratios in places with semi-temperate conditions.

Sub-acute Oral Toxicity Evaluation of Philippine Bignay (Antidesma bunius (L.) Spreng cv. ‘Kalabaw’) Fruit in ICR Mice
Jonina Marie J. Tengco, Liezl M. Atienza, Maria Amelita C. Estacio, Mark Joseph M. Desamero, Roxanne P. Gapasin, Jonna Rose C. Maniwang, Katherine Ann T. Castillo-Israel, Rohani C. Navarro, Dianne Jane A. Sunico, James Ryan D. Aranzado, Ann C. Cayetano, Joan I. Delomen, and Loraine B. Ancheta
Received: July 12, 2022/ Revised: September 22, 2022/ Accepted: October 05, 2022

This study evaluated the safety of Bignay (Antidesma bunius (L.) Spreng cv. ‘Kalabaw’) fruits through a subacute oral toxicity test in male and female ICR mice. The evaluation was done through oral gavage of the aqueous fruit sample at 2,000 mg kg-1 body weight dose for 28 d. Results showed that there were no significant changes in feed and water intake of male and female ICR mice as compared to the control groups that received distilled water (p < 0.05). Blood chemistry and hematology values for all mice groups were comparable to the controls and published values. All mice groups also had appreciable body weight gain (10.89% – 21.69%) with zero morbidity and mortality. Lastly, the gross and microscopic examination of the brain, heart, lungs, GI tract, liver, spleen, and kidneys showed normal architecture and histology, suggesting that the fruits did not induce any morphological abnormalities. Results of this study showed that Bignay (cv. ‘Kalabaw’) fruits are safe for consumption with an LD50 of greater than 2,000 mg kg-1 body weight.

Micropropagation of Grammatophyllum multiflorum var. ‘tigrinum‘ Lindley and Evaluation of its Antimicrobial Activities
Eufrocinio C. Marfori
Received: April 08, 2022/ Revised: September 13, 2022/ Accepted: October 02, 2022

Grammatophyllum multiflorum var. ‘tigrinum’ Lindley is an endangered orchid species endemic to the Philippines. To ensure its sustainable utilization as a source of phytochemicals, the types and concentrations of cytokinin, and auxin for shoot and root induction using nodal explants from in vitro germinated seedlings for its mass propagation were established. Seeds were germinated in vitro using MS medium without growth regulator. The nodal explants from the in vitro germinated seedlings were placed in MS medium containing different cytokinins and auxins to optimize multiple shoots and root formation, respectively. Thidiazuron (TDZ) at 2.5 μM was found to be the best cytokinin for multiple shoot formation, while naphthaleneacetic acid (NAA) at 5 μM was found to be the best auxin for root formation. Rooted plantlets were potted out using coir as medium and hardened in the nursery under partial shade condition. No abnormality was observed in terms of growth and morphology between the mother plant and the tissue culture-derived plants. Antimicrobial bioassays of the extracts from different parts of the tissue culture-derived G. multiflorum showed remarkable antimicrobial activities suggesting the potential of this orchid as a source of important antimicrobial compounds.

Evaluation of Triticale Lines Compared to Wheat Cultivars in Terms of Agronomic Traits Using Supervised Learning Methods and Multivariate Statistics
Sara Farokhzadeh, Hossein Shahsavand Hassani, Zahra Zinati, and Mahdiyeh Rajaei
Received: March 20, 2021/ Revised: September 01, 2022/ Accepted: October 02, 2022

The first man-made cereal grain triticale merges the yield and quality potential of wheat with tolerance of rye against environmental stresses. To find the traits with the greatest impact on the superiority of triticale over wheat, four promising triticale lines and six bread wheat varieties were evaluated in a randomized complete block design (RCBD) with three replications in the field of the Agricultural Research Station of Shiraz University, Iran. Attribute weighting algorithms revealed main leaf width (MLW), grain number per spike (GN/S), spikelet number per spike (SN/S), 1000-grain weight (TGW), plant height (PHT), main leaf length (MLL), and grain yield (GYLD) as the most discriminative traits between triticale lines and wheat cultivars. According to the principal component analysis, the first two components explained 33.46% and 24.79% of the total variation in traits, respectively, while the first component was more positively correlated to GYLD, TGW, GN/S, SN/S, leaf number (LN), and MLW. Stepwise regression study showed that grain yield as a dependent variable has been modeled as a function of the independent variables GN/S, days to heading (DHE), and SN/S. Triticale and wheat clusters, respectively, were created using cluster analysis for genotypes. Integrating results of supervised learning methods and multivariate statistics indicated that GN/S and SN/S traits can be used to create a selection index for high yield. Furthermore, the M45 triticale line with the highest value of harvest index, GYLD, and GN/S can be introduced as a promising line for high-yield production. This study specify the key grain yield-related traits being subsequently used to increase the yield of bread wheat cultivars and triticale lines.

Potential of Mechanical Grain Dryers in Addressing Exposure of Rice Farmers to Weather Risks
Hernaiz G. Malanon and Zenaida M. Sumalde
Received: January 09, 2022/ Revised: August 30, 2022/ Accepted: September 20, 2022

Weather risks brought by prolonged rainfall and cloudy days hamper grain drying operations in the Philippines as majority still employ the sun drying method, which limits the opportunity of rice farmers to earn a higher income. While mechanical dryers are considered an important adaptation mechanism to address weather risks, more research needs to be done on their benefits and their disadvantages. This study adapted the Inter-governmental Panel on Climate Change (IPCC) concept which equates hazard, exposure, and vulnerability to quantify risk. Hazard was assessed in terms of the probability of four straight rainy- or cloudy-day occurrences based on a 30-year daily rainfall and cloudiness data. Exposure of famers and traders to this event was described in terms of a cropping calendar followed by the farmers, while vulnerability was quantified in terms of the effects of exposure to continuous rains, particularly as price discounts for quality-degraded grains. About 74% of the total rice harvest in Isabela, Philippines is being dried using the sun drying method. Based on the probability of exposure to extended rainy/cloudy days and the qualitative losses as indicated by price penalty for quality-degraded grains, total qualitative losses amounting to 117 metric tons valued at PhP 407.17 million (USD 8.14 million) is incurred in the province every year. With artificial or mechanical grain dryers, exposure of rice farmers to prolonged rainfall or cloudy days that constrain sun drying operations can be minimized or eliminated.


Mixed Infections of Ca. Liberibacter asiaticus and Citrus Tristeza Virus Affecting Calamansi (Citrofortunella microcarpa Bunge) in Oriental Mindoro, Philippines
Alliah Czarielle N. Mañugo, Julie Ann Mae G. Bolo, Julianne G. Camacho, Jamil de Guzman, Edna A. Aguilar, and Filomena C. Sta. Cruz
Received: March 16, 2022/ Revised: May 24, 2022/ Accepted: June 01, 2022

Huanglongbing (HLB) and tristeza are the most destructive diseases affecting citrus crops worldwide, including calamansi (Citrofortunella microcarpa Bunge Wijnands) in the Philippines. Oriental Mindoro is the largest calamansi-producing province contributing to about 33% of the country’s production. This study was conducted to determine the current status of the occurrence of HLB and tristeza diseases affecting calamansi in the province through visual observation of symptoms in field surveys and detection of the causal pathogen. Both HLB and tristeza were found in all the nine villages surveyed located in the municipalities of Naujan, Pola, Roxas, and Victoria. Plants were showing the HLB symptom of blotchy mottle accompanied by interveinal chlorosis similar to zinc deficiency, defoliation, and twig die-back. Leaves were small, narrow, thick, and corky with enlarged veins and erect in appearance. Among the total of 155 plants tested from the surveyed farms, 150 were positive for HLB disease. Polymerase chain reaction using the LAS606F and LSSR primer pair that amplifies a 500 bp fragment of the Candidatus Liberibacter asiaticus 16S rDNA has detected the HLB causal pathogen in symptomatic samples with blotchy mottle. Likewise, 154 out of 155 plants were also positive for tristeza by enzyme-linked immunosorbent assay. HLB and tristeza occurred mostly in mixed infections in seven farms while 83% and 90% in the other sites. HLB symptoms appeared to be dominantly expressed.

Germination and Early Seedling Growth Attributes of Rice (Oryza sativa L.) Cultivars under Different Salinity (NaCl) Stresses
Shahid Hussain, Shuli Liu, Rui Zhang, Yinglong Chen, Altaf Adil, and Qigen Dai
Received: June 18, 2022/ Revised: July 30, 2022/ Accepted: August 18, 2022

The impact of different salinity stresses [0, 6.4, 12.8, 19.2, and 25.6 dS/m (NaCl)] on the final germination percentage, speed of germination, germination capacity, shoot and root length, seedling vigor index, and total plant dry weight of ten rice cultivars at germination and early seedling stages was investigated in this study. Salinity stress significantly decreased the final germination percentage, speed of germination, germination capacity, shoot and root length, and seedling dry weight in all cultivars, with the most severe effects from the levels 19.2 and 25.6 dS/m NaCl. Rice cultivars were classified as tolerant, moderately tolerant, moderately susceptible, and susceptible based on reduction of dry matter, which is considered the most limiting factor at high NaCl concentrations. The cultivars NJ9108, 3Y9H, 6Y9H, XD22, 5W01, and HLYH3 showed greater efficiency in salt tolerance during germination at 19.4 dS/m salinity. While 20H025, 6Y9H, and XD22 at the seedling stage performed better based on their dry weight reduction. The study found that NJ9108 and XD22 may be used to investigate the effects of salinity on the development processes and physiological consequences at the advanced stage of growth, as salt tolerance during germination and the early seedling stage may be varied from the developed stages. Furthermore, the results suggest that tolerant rice cultivars can be used to study the effects of salinity on the development and other physiological impacts at vegetative and reproductive stages. These findings will support salt-tolerant rice cultivars that may be developed for better production in terms of coping with salinity stresses in the germination and early growth stages.

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