Thai Agricultural Research Journal

Biotechnology Research Progress in Plant Breeding for Disease Resistance of Department of Agriculture

Tue, 26 Aug 2025 00:00:00 +0700

The infestation and outbreak of plant diseases, such as viruses, bacteria, and fungi, is one of many causes that reduces the quantity and quality of agricultural products and poses a threat to food security. Plant breeding for disease resistance is one of the essential methods to minimize crop losses and sustain high productivity. This review gives a brief overview of the biotechnology used to develop plant disease-resistant crop varieties, including marker-assisted selection, genomic selection, genetic modification, and genome editing. These modern biotechnologies offer more precise, efficient, and faster procedures in producing disease-resistant varieties. However, each technology has its own advantage and limitation. Thus, the selection of biotechnology for use in the experiment must be based on various aspects, including plant types, regulations, laboratory readiness, and knowledge. Furthermore, this review also discusses research conducted by the Department of Agriculture on improving disease-resistant plant varieties using biotechnology to facilitate selection and development of resistant varieties in economic crops of Thailand.

Design and Development of Sugarcane Leaf Pruning Machine and Trash Incorporator

Tue, 26 Aug 2025 00:00:00 +0700

The pruning of sugarcane leaves is usually done before harvesting to facilitate human labor in harvesting and to increase the stalk weight. Besides, sugarcane residue incorporation is important for increasing soil fertility. There is no equipment that could operate both processes of leaf pruning and trash incorporation. The objective of this research was to design the equipment for operating both processes by applying the hydrostatic power transmission to the sugarcane leaf pruning machine and the mechanical power transmission to the spiral notched disc. A diameter of the sugarcane leaf pruning roller was 248 mm, which revealed that filling the grass trimmer line could increase diameters up to 1,054 mm, and a diameter of the spiral notched disc was 18 inches. It was tested with the DOAKhonKaen3 sugarcane cultivar at the age of 9 months in Sikhio district, Nakhon Ratchasima province. The average soil cone index was 3.4 MPa. The soil moisture content and bulk density were 14.20% (db) and 1.64 g cm^-3, respectively. The experiments were conducted at a forward speed of 1.95 km h^-1, gang angles of 36°, disk revolution speeds of 150 rpm, and roller revolution speeds of 800 rpm. The experimental results showed that the trash covering efficiency was 92.4%, the pruning of sugarcane leave efficiency was 82.2%, the effective field capacity or performance was 1.75 rai h^-1, and the fuel consumption was 1.65 L rai^-1. The cost of this sugarcane leaf pruning machine and trash Incorporator was 164,000 Baht. The break-even point was 116.21 rais. The use of this machine can facilitate workers in harvesting without burning sugarcane field.

Infection, Seed Transmission and Sequence Variation of Pepper chat fruit viroid in Pepper and Eggplant

Kanyarat Aubonrat, Samabhorn Sinhabandhu — Tue, 26 Aug 2025 00:00:00 +0700

Pepper chat fruit viroid (PCFVd) is a significant quarantine pest impacting the production of pepper and tomato crops for exportation. This study aimed to evaluate the pathogenicity, disease symptoms, seed transmission rate, and nucleotide sequence variation of PCFVd. Mechanical inoculation was conducted on 13 pepper accessions and 16 eggplant accessions. Reverse transcription-polymerase chain reaction was used to detect viroid infection. The results showed 100% infection in all pepper samples, which led to reduced fruit size, though seeds were still produced. Among the eggplant samples, 12 showed infection rates of 10-100%, while 4 accessions were not infected. Infected leaves and flowers of eggplant exhibited reduced sizes but still produced viable seeds. Seedlings from infected plants exhibited transmission rates of 48.9 and 2% in pepper accessions CA1181 and CA1220, respectively, and 1.2% in eggplant accessions SM021B. The RNA from the infected seeds and seedlings was also pathogenic when reinoculated into a susceptible tomato variety, Seedatip4. The nucleotide sequence comparison of the DNA products obtained in this study with the database of GenBank confirmed the species as PCFVd. Nucleotide sequence variation was identified in the terminal right domain, exhibiting 96–99% sequence identity to the LPng20-11c1 isolate (accession no. JF446893). This study demonstrated that PCFVd can induce disease and be transmitted through seeds of both pepper and eggplant plants.

Cost Analysis of Import and Bring in Transit Permit under the Plant Quarantine Act B.E. 2507 and Amended

Angkana Suwannakoot, Sreenual Bungsongsree, Watanyoo Klinneam — Tue, 26 Aug 2025 00:00:00 +0700

This study aimed to analyze the service cost of import and bring in-transit permit under the Plant Quarantine Act B.E. 2507 and amended and to find guidelines for controlling costs of Technical Groups, Office of Agricultural Regulation, Department of Agriculture. The study followed a structured approach in the fiscal year 2022, encompassing four main steps: 1) investigation of general information on import and bring in-transit permit services, 2) analysis of organizational structure to determine cost units, 3) calculation of unit costs for permit services, and 4) analysis of approaches to control service unit cost. The results of the study revealed that the unit cost of import- and bring in-transit permit services for prohibited articles was 248.44 Baht per issue. This cost was further broken down into direct costs (228.50 Baht) including labor (218.50 Baht) and material costs (10.01 Baht), and indirect costs (19.94 Baht) including indirect labor (14.16 Baht) and indirect material costs (5.48 Baht). No investment cost was incurred, as depreciation was calculated to be 0 Baht. The analysis of cost distribution indicated that total labor costs constituted the highest proportion, accounting for 93.65% for permits. In contrast, total material costs made up only 6.35% for the permit. This discrepancy was attributed to the electronic permit system, which streamlines the process from application submission to receiving the permit. The findings of this study emphasized the significance of implementing guidelines for controlling labor costs in service provision. Besides, the fees should be revised to reflect a more reasonable cost.

Effects of Growth Regulators on Yield and Quality of Vegetable Soybean cv. DOA Chiang Mai84-2

Tue, 26 Aug 2025 00:00:00 +0700

The demand for vegetable soybean cv. DOA Chiang Mai84-2 has been increasing in the market. Increasing the yield of this soybean by extending the planting area was not practical due to the limitation of appropriate planting areas. To increase yield, the effects of spraying growth regulators at the flowering stage on the yield and quality of vegetable soybean cv. DOA Chiang Mai84-2 were investigated. The experiment was conducted at the Chiang Mai Field Crops Research Center in two dry seasons during the years 2022-2023. A randomized complete block design of six treatments with 4 replications was applied. The treatments were comprised of spraying soybean at the flowering stage (R1) with different growth regulators: 1) brassinolide 0.01 ppm, 2) gibberellic acids (GA₃) 1 ppm, 3) abscisic acid (ABA) 1 ppm, 4) kinetin 5 ppm, 5) naphthalene acetic acid 10 ppm and 6) spraying water (control). The results showed that spraying all growth regulators gave a total yield of 1,397-1,511 kg/rai, a marketable yield of 1,335-1,464 kg/rai, and a standard pod yield (grade A) of 530-623 kg/rai, which were slightly different. The ABA spraying gave the highest grade A pod yield of 623 kg/rai, which was not different from other growth regulators but significantly higher than that of GA₃ spraying. All growth regulator spraying treatments gave higher yields than that of water spraying, causing marketable yield increases of 19.5-31.1%. Nevertheless, all growth regulator treatments did not affect other yield components. The benefit-cost ratio of all spraying treatments was greater than 1, indicating that the investment was worthwhile. Therefore, spraying these growth regulators was recommended as an alternative method to increase the yield of vegetable soybean cv. DOA Chiang Mai84-2.

Wing Morphometrics for Species Diagnosis of Leafminer Flies (Genus Liriomyza) in Thailand

Tue, 26 Aug 2025 00:00:00 +0700

Leafminer flies of the genus Liriomyza are serious pests that damage a wide range of vegetable crops. These flies are also significant quarantine pests that exported vegetables must be inspected to prevent the infestation of these pests in plant materials. Accurate species identification of the genus Liriomyza using conventional external characters is difficult due to morphological similarities among Liriomyza species. This study aimed to evaluate the wing morphometrics in distinguishing among five Liriomyza species: L. brassicae, L. chinensis, L. huidobrensis, L. sativae and L. trifolii. Sixteen homologous landmarks were digitized on the wings for geometric morphometric analysis. The results revealed significant differences in centroid size among species (P<0.05) with L. brassicae exhibiting the smallest wing size (1.58 ± 0.03 mm) and L. huidobrensis the largest (2.34 ± 0.05 mm). Canonical variate analysis demonstrated that L. chinensis and L. huidobrensis could be clearly separated from the remaining three species based on wing shape, while L. brassicae, L. sativae and L. trifolii exhibited highly similar wing morphologies, making them more difficult to distinguish. In conclusion, wing morphometrics is an effective tool for identifying L. chinensis and L. huidobrensis from the remaining three species and can be applied for plant quarantine inspection for vegetable exports in Thailand. However, due to overlapping wing shapes among L. brassicae, L. sativae and L. trifolii, further dentification using male genitalia or nucleotides is recommended to improve the accuracy of species discrimination.

SNPs Marker Development for Lycopene Beta-Cyclase (lcyB) Gene Related to Beta-Carotene Biosynthesis in Cassava

Tanavadee Kumchoo, Adcharapun Chaicharoen, Suwaluk Sansanee, Krittaya Petchpoung — Tue, 26 Aug 2025 00:00:00 +0700

Single nucleotide polymorphisms (SNPs) molecular markers can be effectively applied to select various traits in plant breeding. The objectives of this study were to develop SNPs markers for the lycopene beta-cyclase (lcyB) gene, which is related to beta-carotene biosynthesis in cassava, to examine the genetic variation of SNPs by using the polymerase chain reaction-restriction fragment length polymorphism technique, and to analyze beta-carotene content in the fresh root. Twenty cassava cultivars/lines (10 cultivars/lines of yellow fresh root and 10 cultivars/lines of white fresh root) were used in the experiments. The results showed that the yellow fresh root group had beta-carotene content ranging from <40.00-172.93 µg/100g, with the MPER297 variety exhibiting the highest beta-carotene content. In contrast, the white fresh root group contained beta-carotene levels below 40.00 µg/100g. A total of 44 SNPs in the lcyB gene were identified, along with 12 restriction enzymes capable of cutting nucleotides at the SNPs positions. Among these 12 SNPs markers of lcyB, 8 SNPs showed polymorphism while 4 SNPs were monomorphism. The polymorphic information contents for these SNPs ranged from 0-0.50, with SNP lcyB g.1673969 having the highest. The accuracy of these markers varied from 0-75%, with SNP lcyB g.1674619 demonstrating an accuracy of 75%. This marker can be used for selecting cassava varieties with high beta-carotene content.

Distribution Survey, Plant Growth and Seed Germination of Sumatran Fleabane (Conyza sumatrensis (Retz.) E. Walker)

Jarunya Pinsupa, Mallika Srichanklad, Choosak Kunuthai, Pairoh Khwanngam — Tue, 26 Aug 2025 00:00:00 +0700

Conyza sumatrensis is an invasive weed species found in Thailand and has been increasing in agricultural areas. Effective Integrated weed management requires an understanding of weed biology. Therefore, this study aimed to investigate the distribution of C. sumatrensis in agricultural areas across the country. Surveys were conducted in field crops, vegetable crops, industrial crops, and fruit orchards in all regions of Thailand during 2022–2023. Plant growth and seed germination were studied during 2023–2024. The result showed that the spread of C. sumatrensis was found in all agricultural areas, both open spaces and shaded areas. Approximately two weeks after germination (WAG), the seedlings developed true leaves, which were simple. Vegetative growth rate was low from 3–8 WAG, followed by rapid growth during 9–10 WAG. Flowering and seed maturation began at 13 and 15 WAG, respectively. Maximum seed production was observed around 18 WAG. By 29 WAG, plant growth had declined, and no additional flowering or seed set occurred. The seed germination study showed that mature seeds sown on the soil surface had an average germination rate of 44%, whereas seeds sown at depths of 5, 10, 15, 20 and 25 cm did not emerge above the soil surface. Therefore, to prevent the spread of C. sumatrensis, deep soil tillage to a depth of more than 5 cm to completely cover the seeds on the soil surface and removal of C. sumatrensis before flowering are recommended, as a single C. sumatrensis can produce more than 20,000 seeds.

Estimation of Plant Nutrient in Fingerroot Grown on Sandy Clay Loam Soil at Nakhon Pathom Province

Chattanaporn Kueanoon; Pinyaluck Ratanavirakul, Somrutai Tuncharoen — Tue, 26 Aug 2025 00:00:00 +0700

General fertilizer application was recommended for fingerroot, which did not align with the crop’s actual nutrient requirements. This experiment aimed to study crop nutrient requirements in fingerroot grown on sandy clay loam soil in Nakhon Pathom province. Treatments were laid out in a randomized complete block design with four replicates. The result revealed that the plant height and dry weight were not statistically different among treatments. The concentration of each plant nutrient varied across different parts of the plant. Potassium in leaf sheaths, nitrogen and calcium in leaves, and magnesium in leaves, leaf sheaths, roots, and shoots showed the highest concentrations. However, the phosphorus levels in all parts of plants did not differ. Nitrogen concentration decreased with increasing plant age in all parts except the rhizomes. Potassium in the leaves and leaf sheaths tended to decrease as the plant age increased, while no changes of potassium in other parts were observed. Phosphorus, calcium and magnesium in all plant ages were not different. Fingerroot grown in sandy clay loam soil, in which organic matter and exchangeable potassium were low but available phosphorus was very high, required fertilizer applications 2, 3, 4, 5, 6 and 7 months after planting at the rate of 15-6-49, 29-26-256, 289-136-1,159, 332-187-1,521, 1,239-717-4,709 and 774-674-3,564 mg N-P₂O₅-K₂O/clump, respectively. Precise nutrient management according to the requirements of fingerroot in each growth stage can enhance fertilizer use efficiency. These findings can serve as a guideline for developing site-specific fertilizer recommendations based on local soil conditions.