Thai Agricultural Research Journal

Development of a Diagnostic Technique using Species-Specific Primers for the Guava Fruit Fly, Bactrocera correcta (Bezzi) (Diptera: Tephritidae)

2022-04-12T06:07:02+07:00

The guava fruit fly, Bactrocera correcta(Bezzi) causes major economic losses in fruit and vegetable crops in Thailand and many countries. It is also aquarantine pest of countries currently importing the fly’s host commodities from Thailand or are potential new markets. The morphological similarity between immature guava fruit fly and other fruit fly species makes visual identification difficult. Thus, methods for the rapid and accurate identification of immature fruit flies are needed to support quarantine officials at the border stations to make correct decisions when inspecting both importing or exporting commodities. In this study, we used molecular diagnostic methods based on cytochrome c oxidase subunit I (cox1) and species-specific markers to identify B. correcta. DNA barcode sequences obtained from 113 individuals of 11 fruit fly species were used. Based on these 650 bp barcode sequences, we successfully designed species-specific primers for identification of B. correcta in all life stages (egg, larva, pupa and adult).The size of the B. correcta specific fragment was 141 base pairs. The diagnostic protocol based on these primers elicited no cross-reactions with the other 10 tephritid species tested. A PCR product confirmed the specificity of the primers. The species-specific primers have greatly assisted plant quarantine of imported/exported fresh agricultural produce. The diagnostic protocol from this study can be used by pest diagnostic agencies and research organizations worldwide to develop tools for the rapid, accurate identification of invasive alien fruit fly species.

Development of Aflatoxin B1 Determination Method by Competitive Lateral Flow Immunoassay

2023-05-24T15:55:21+07:00

The objective of this study was to develop a prototype test kit using competitive lateral flow immunoassay technique for the visual qualitative assessment of aflatoxin B1 (AFB1) contamination in agricultural produces. We found that the prototype test kit had the limit of detection (LOD) and cut off values for buffer solution of 0.5 and 5.0 ng/ml, respectively. Whilst for peanut extract, the kit had the LOD and cut off values at 1.0 and 8.0 ng/ml, respectively. The accuracy and precision of the test results of prototype assays in peanut extract were within the acceptable range. Result of AFB1 contamination assessment using the prototype test kit was consistent with the HPLC analysis. The percentage accuracy of the test kit was 93.33%. Overall, the test results showed that the prototype test kit was rapid, accurate and reliable. The kit could be used in the initial assessment or monitoring of AFB1 contamination. After demonstrating the prototype test kit to the Plant Quarantine officials, we received the feedback opinion that the kit was convenient to use, the extraction method was simple, gave quick results which were easy to assess and the cost was economical.

Evaluation of Thai Rice Varieties for Resistance to Bipolaris oryzae, the Causal Agent of Brown Spot Disease

2023-03-27T17:42:10+07:00

Brown spot disease of rice is caused by the fungus Bipolaris oryzae. This fungal pathogen could infect leaves, leaf sheaths, panicles, and seeds. The use of resistant varieties is an effective and safe way for farmers. However, the resistance will change when the new fungal strains invades the area. This study aimed to determine the resistance of rice varieties to three isolates of B. oryzae. The combined analysis of ITS rDNA, 28S rDNA, and GAPDH revealed that these isolates had clustered sequences similar to those of the type species of B. oryzae. The resistant screening of 72 rice varieties to the three isolates of B. oryzae and cluster analysis UPGMA showed consistent results. Results revealed that Homsuphan displayed resistance (R) and moderate resistance (MR) while RD29 and Niao Dam displayed high susceptibility (HS) to all three isolates. The information was useful for future rice breeding programs for brown spot disease resistance.

Study on Quality, Morphology of Thai Seed and Seedling of Cannabis Landrace and Imported Commercial Cultivars

2023-01-13T17:48:37+07:00

Cannabis may be come an economic crop. In the past, study on cannabis seed aspects were limited due to legal prohibition. The objective of this study was to investigate the quality and morphology of seeds and seedlings of 10 landrace/collected cannabis cultivars in Thailand and 5 imported commercial cannabis cultivars. The experiment was conducted at cannabis planting greenhouse of Biotechnology Research and Development Office and laboratory of Seed Research and Development Division and Plant Varieties Protection Office, Department of Agriculture, during March 2021 – January 2022. Results showed that the ground color and pattern color of landrace/collected cannabis cultivar seeds in Thailand were gray brown and black while those of the imported commercial cannabis cultivar seeds were gray and brown. The 100-seed weight of the landrace/collected cannabis cultivar seeds showed more variation than that of the imported commercial cannabis cultivar seeds,1.1–3.1 and 2.4–4.7 g, respectively. Moreover, the imported commercial cannabis cultivar seeds gave the germination up to 100 %, speed of germination was 1.4 – 2.1 plants/day and height of cannabis seeding at 7 DAP was 7.0 – 9.2 cm., which were more than those of the landrace/collected cannabis cultivar seeds in all aspects. However, the seedling growth had the same digitate leaf shape pattern in leaf no. 1 – 5. The number of lobes increased according to number of leaf, 3 – 5 lobes on leaf no. 2 and 7 – 9 lobes on leaf no. 5. The data obtained from this study can be used in seed management, planning of planting or selection/breeding of cannabis variety in Thailand in order to enhance the use of cannabis for medical purpose in the future.

Application of Antagonistic Microorganisms for the Biocontrol of Yellow Leaf Blotch on Vandaceous Orchid Caused by Pseudocercospora dendrobii

2023-06-28T20:38:27+07:00

The efficacy of cell suspensions and culture filtrate of Bacillus amyloliquefaciens, B. cereus and spore suspensions of Trichoderma asperellum strain CB-Pin-01 were tested in inhibiting spore germination of Pseudocercospora dendrobii, the causal agent of yellow leaf blotch on Vanda orchids at 24 hrs. The result showed that the antagonistic microorganisms were able to inhibit the germination of P. dendrobii spores by 85.38 - 99.74% and shorten the germ tube growth compared to the control treatment. Spore suspension of T. asperellum strain CB-Pin-01 and cell suspension of B. amyloliquefaciens were the most effective in inhibiting germ tube germination at 99.74% and 99.30% while germination inhibition percentages of culture filtrate of B. cereus, T. asperellum strain CB-Pin-01, B. amyloliquefaciens and B. cereus cell were 95.13, 89.83, 86.61 and 85.38%, respectively. Spraying of the 3 antagonistic microorganisms on diseased orchid leaves during the rainy season resulted in significant reduction of disease incidence 7 days after the application compared to the control treatment. B. cereus contributed to the smallest lesion size of 0.01 mm, followed by B. amyloliquefaciens of which lesion size was 1.34 mm, while the size of the lesion in the control treatment was 8 mm. Treatments of folpet and T. asperellum strain CB-Pin-01 showed the lesion sizes of 5.34 and 3.34 mm, respectively.

Comparing the Andrographis paniculata (Burm. f.) Wall. Varieties for High Yield and Andrographolide Content

2023-06-19T15:11:47+07:00

Andrographis paniculata is a medicinal plant which contains an important andrographolide substance that inhibits the multiplication of COVID-19 virus. The National List of Essential Medicines prescribes andrographolide treatments for respiratory symptoms and the digestive system disorder. The current problem of A. paniculate production is the inconsistency of yield and andrographolide content that varies with genetics and environmental conditions. This research was to compare and select A. paniculata varieties that possess high productivity and andrographolide content. The experiment was conducted in 3 locations: Phichit Agricultural Research and Development Center, Uttaradit Agricultural Research and Development Center and a farmer’s farm in Bang Krathum, Phitsanulok in the rainy season of 2021. Two selected A. paniculata lines Phitsanulok 5-4 and Phichit 4-4 were compared with cultivars Nakhon Pathom and Prachinburi using randomized complete block design with five replications. Results showed that at Phichit Agricultural Research and Development Center, Phitsanulok 5-4 line gave the highest fresh and dry yield of 3,013 and 1,006 kg/rai, followed by Phichit 4-4 line which gave the fresh and dry yield of 2,732 and 810 kg/rai. While at the Uttaradit Agricultural Research and Development Center and farmers field in Bang Krathum, Phitsanulok, Phichit 4-4 gave the highest fresh and dry yields. Planting at Phichit Agricultural Research and Development Center and Uttaradit Agricultural Research and Development Center, Phichit 4-4 line gave the highest andrographolide contents of 5.87 and 3.56 g/100 g dry weight, respectively.

Morphology and Antioxidant Properties in Pseudostem, Leaf, Petiole and Inflorescences of Diploid and Triploid Banana

2023-05-23T20:59:57+07:00

The objective of this research was to compare psuedostem, leaf, petiole and inflorescence morphological characteristics of five banana varieties against their total phenolic contents and antioxidant activities. These varieties included two diploids, ‘Nam Thai’ (AA) and ‘Ta Nee’ (BB), and three triploid varieties, ‘Hom Khieo Khom’ (AAA), ‘Sam Doen’ (AAB), and ‘Kluai Hak Muk Som’ (ABB). The average pseudostem heights in this selection of bananas ranged between 2.0 to 3.7 m., except for the Dwarf Cavendish ‘Hom Khieo Khom’, which was 1.25 m. Leaf lengths ranged from 107.8–201.7 cm and leaf widths from 45.5–68.3 cm. The leaf of the diploid BB ‘Ta Nee’ was the largest at 201.7cm in length and 68.6 cm in width. Banana inflorescence weights ranged from 291.7-600.8 g. The average moisture contents of the pseudostems and inflorescences were similar, ranging between 90.2–93.7%, followed by the petiole at 82.7–86.9% and the leaf at 72.0–78.6%. The diploid bananas had total phenolic contents and antioxidant activities higher than the triploid bananas. The ‘Ta Nee’ leaf had the highest total phenolic content of 198.2 mg GAE/g, followed by ‘Nam Thai’, ‘Hom Khieo Khom’, ‘Hak Muk Som’ and ‘Sam Doen’ at 141.4,108.7,100.4 and 90.1 mgGAE/g with significant difference (p < 0.05). Inflorescences had the highest antioxidant activities, followed by leaves, petioles and pseudostems. The ‘Ta Nee’ had the highest antioxidant activities in the FRAP and DPPH assays at 36.5 and 10.5 mg TEAC/g, respectively, followed by ‘Nam Thai’ (21.8 and 5.1 mg TEAC/g), ‘Hom Khieo Khom’ (6.2 and 2.5 mg TEAC/g), ‘Hak Muk Som’ (3.6 and 1.3 mg TEAC/g) and ‘Sam Doen’ (1.9 and 1.2 mg TEAC/g) with significant difference (p < 0.05). Morphological characteristics of the different banana varieties had no effect on total phenolic compound content and antioxidant activity.

Comparison of Yield Components between Young Mature and Mature Phases of Five Tenera Oil Palm Varieties

2023-07-10T14:22:17+07:00

This study aimed to evaluate the yield performance of five Tenera varieties during the young mature and mature phases with the objective of identifying high-yield planting materials. The assessment was conducted at Golden Tenera Limited in Krabi, Thailand, using a randomized complete block design with three replicates. The oil palm trees were spaced 9.0 meters in a triangular pattern. This study spanned from 2009 to 2023, allowing for acomprehensive analysis of yield performance over a significant time period. The findings revealed that the mature phase, spanning from 6 to 11 years after planting, exhibited higher values for fresh fruit bunch (FFB) at 260.18 kg/palm/year and average bunch weight (ABW) at 16.62 kg/bunch/ year. Conversely, the young mature phase, ranging from three to five years after planting, displayed a higher bunch number (BNO) of 25.20 bunches/palm/year. Among the 5 evaluated Tenera varieties, V4 demonstrated the highest values for FFB at 244.12 kg/palm/year and BNO at 22.90 bunches/palm/year. Furthermore, V4 consistently exhibited the highest FFB and BNO values in both young mature and mature phases. The findings of this study will improve the selection and cultivation of productive Tenera varieties, boosting their efficiency and productivity in palm oil plantations.

Performance of Oil Palm Hybrids in Early Mature Phase in Upper Southern Region of Thailand

2023-07-19T18:11:36+07:00

Eight hybrids of commercial oil palm seedlings, 4 from Thai and 4 from oversea sources, were transplanted into the experimental field in AoLuek district, Krabi province,Thailand in 2013. Randomized complete block design (RCBD) was applied with 3 replications. Sixteen palms per plot were random sampling for the agronomic traits data. Growth characteristics were collected every 6 months from 12 to 60 months after transplant (MAT) while the yield data were collected from 31 to 66 MAT, covering a span of 3 years for yield harvesting. The Thai hybrid oil palm tends to have higher production of fresh fruit bunch (FFB) compared to hybrid oil palm from other countries. Hybrids of Deli× Yangambi-T and Deli×Tanzania-T exhibited statistically significant higher vegetative traits such as petiole cross-section, rachis length, and leaflet length when compared to other varieties, The two hybrids also demonstrated significantly higher yields, with maximum FFB valuesof 194.9 and 192.9 kg/palm, respectively in the 3^rd year of harvesting.The hybrid with the highest kernel content was Deli × Tanzania-T with kernel to fruit ratio (KTF) and kernel to bunch ratio (KTB) values of 11.94% and 9.40% respectively. On the other hand, Deli× Yangambi-T showed the highest significant oil yield of 8.78 tons/ha/year at the age of 5 years after transplanting. This experiment demonstrates that certain improved hybrid oil palm varieties in Thailand have the potential for better growth, productivity, and superior components compared to imported hybrid varieties from oversea countries.