Thai Agricultural Research Journal

Evaluation of Total Soluble Solid in Sonya Watermelon Fruits Using Near Infrared Spectroscopy Hyperspectral Imaging Technique

Pachara Subsueng — 2025-12-16

Near-infrared hyperspectral imaging (NIR-HSI) is a rapid accurate, and non-destructive technique for analyzing the composition and internal quality of agricultural products. This study aimed to develop a method for assessing the internal quality of the 'Sonya' watermelon cultivar using NIR-HSI by constructing a predictive model for total soluble solids (TSS) content based on 100 watermelon samples. The reflectance spectra were measured in the wavelength range of 900–1700 nm. The obtained data were in the form of hypercube spectral data, and an equation was created to predict the total soluble solids content using the partial least squares regression technique. The best prediction equation had a correlation coefficient of 0.977, a root mean square error of 0.231°Bx and a bias of 0.047, indicating that it was effective for quality assessment. Additionally, the absorbance values from each pixel of the hypercube data were used to create a map showing the distribution of TSS in the watermelon samples. The findings of this study demonstrate that NIR-HSI can effectively predict TSS content and visualize its spatial distribution within whole watermelons, highlighting its potential application in future automated systems for watermelon quality grading.

Design and Development of a Tractor-Attached Non-Chemical Weeder

Pongphun Panmayura — 2025-12-16

Sugarcane is an important economic crop in Thailand. Farmers face challenges in weed control due to the limitations of chemical herbicides, which pose health and environmental risks, as well as mechanical methods that are constrained by field conditions and timing. This research aimed to design and develop a tractor-mounted weed control machine utilizing flame and hot water, and to evaluate its performance in sugarcane fields. Two factors were tested: three levels of forward speed and three nozzle heights (10, 20, and 30 cm). Results indicated that the flame-based system, with a nozzle height of 10 cm and a forward speed of 8.89 km/h, achieved the highest weed control efficiency at 100% within 7 days after treatment. The maximum temperature at the sugarcane base reached 48.75°C, while soil moisture decreased by 0.14%. The field capacity was 0.40 rai/h, and the field efficiency was 66.77%. LPG consumption was 10.29 kg/rai, with a break-even point of 12.19 rai/year and a payback point of 67.19 rai. Meanwhile, the hot water system, with a nozzle height of 10 cm and a speed of 8.41 km/h, achieved a maximum weed control efficiency of 93.40% within 7 days. The maximum temperature at the sugarcane base was 33.5°C, while soil moisture increased by 0.35%. The field capacity was 0.40 rai/h, and the field efficiency was 71.27%. LPG consumption was 15.14 kg/rai, with a break-even point of 30.48 rai/year and a payback point of 167.95 rai. These findings suggest that the flame-based weed control machine provides greater efficiency and economic feasibility, making it more suitable for weed management in sugarcane fields.

Sensitivity of Exserohilum tucicum to Carbendazim and the Fungicide’s Efficacy in Controlling Northern Corn Leaf Blight in Thailand

Thanada Nakngoen — 2025-12-16

Northern corn leaf blight is caused by Exserohilum turcicum. The use of carbendazim in combination with demethylation inhibitor fungicides is included in the recommendations for controlling this disease in Thailand. However, the efficacy of carbendazim against E. turcicum remains unclear. This research assessed the sensitivity of E. turcicum isolates (n = 36), collected during 2021–2022, to carbendazim along with sequence analysis of the ß2-tubulin (Tub2) gene at codons 167, 198, and 200 of the E. turcicum isolates with the highest and lowest sensitivity to carbendazim (n = 2/group). Field efficacy of carbendazim and other fungicides for controlling E. turcicum in sweet corn was also determined. The results revealed that approximately half of the E. turcicum isolates exhibited EC₅₀ values exceeding the established baseline sensitivity (1.23–8.70 µg/mL). The frequency distribution of EC₅₀ values showed a unimodal distribution with positive skewness, indicating a shift towards reduced sensitivity in the population. Sequence analysis of the Tub2 gene revealed no differences between the isolates with the highest and lowest sensitivity to carbendazim. Field trials with natural infection revealed that carbendazim (50% SC) was less effective at disease suppression compared to tebuconazole+trifloxystrobin (50+25% WG) and azoxystrobin+difenoconazole (20+12.5% SC), applied at recommended rates. These findings suggest a decline in sensitivity to carbendazim within the E. turcicum population in Thailand. The control efficacy of carbendazim on E. turcicum was relatively low compared to the other recommended chemical mixtures.

Diversity and Morphology of Portulaca L. (Portulacaceae)

Kanchana Pruesapan — 2025-12-16

Many species of Portulaca L. (Portulacaceae) pose a significant risk of spreading in agroecosystems as weeds. Contamination of agricultural products by these plants may significantly impact international trade. Effective prevention should be based on the knowledge of their botanical names. This research aimed to study the diversity and morphology of the genus Portulaca by surveying plants in agroecosystems and related distribution areas, collecting samples, recording morphological data, and identifying the collected specimens. A total of
25 plant samples were collected, and 7 species were identified based on morphological characteristics: P. amilis Speg., P. grandiflora Hook., P. oleracea L., P. pilosa L., P. quadrifida L., P. umbraticola Kunth, and Portulaca sp. The study found that P. amilis and P. umbraticola have never been previously reported in Thailand. The distribution of P. oleracea, P. pilosa, P. quadrifida and Portulaca sp. showed their status as weeds in agricultural areas that should be monitored. Meanwhile, P. amilis, P. grandiflora and P. umbraticola were mostly found as ornamental plants in community areas. All plants found can serve as a reference database for plant protection and development in the future.

Multi-Environment Evaluation of Potential and Stability for Promising Cassava Breeding Lines Series 2018 using GGE Biplot

Rungravee Boontung — 2025-12-16

An ideal cassava variety should exhibit high potential and stability in key agronomic traits under diverse environmental conditions. This research aimed to assess the potential and stability of fresh root yield, starch content, and starch yield in promising cassava lines series 2018 across 14 environments under field conditions during 2023–2024. Three promising lines, CMR61-51-39, CMR61-52-113, and CMR61-52-134 with 3 check varieties, DOA Rayong5, DOA Rayong9 and Kasetsart50, were evaluated using a randomized complete block design with 4 replications. The potential and stability of genotypes were assessed using GGE biplot analysis. The results revealed that CMR61-52-134 exhibited high potential and stability in fresh root yield, starch content and starch yield, with an average fresh root yield of 5,868 kg/rai, starch content of 22.4%, and starch yield of 1,359 kg/rai. Therefore, CMR61-52-134 was selected as an elite line for further study to obtain field management practice recommendation.

Evaluation of Yield and Texture Quality in 2017 Edible Cassava Hybrids

Kusuma Rodpeawpan — 2025-12-16

Evaluating the yield performance of new cassava varieties under diverse environmental conditions is a crucial step in identifying promising varieties for dissemination to farmers. The objective of this research was to evaluate the yield potential and textural quality of 2017 edible cassava hybrids across multiple environments. A randomized complete block design in three replications was conducted from May 2022 to May 2023 across six environments—Rayong, Khon Kaen, Sukhothai, Lop Buri, Kanchanaburi, and Songkhla provinces—using four edible cassava hybrids (CMRE60-03-02, CMRE60-03-13, OMRE60-01-02, and OMRE60-02-12) and two check varieties (Hanatee and DOA Rayong2). The results from combined analysis of variance indicated that the OMRE60-01-02, CMRE60-03-13, and CMRE60-03-02 lines had similar average fresh root yield of 4,794, 4,538 and 4,207 kg/rai, respectively. These three varieties showed significantly higher average fresh root yield than the two check varieties, being 70, 61 and 49% higher than Hanatee, and 57, 48 and 38% higher than DOA Rayong2, respectively. The GGE biplot analysis indicated that the OMRE60-01-02 line had the highest average fresh root yield and high yield stability, while the CMRE60-03-13 line exhibited lower yield stability but no significant difference in average fresh root yield with the OMRE60-01-02 line. Meanwhile, Hanatee exhibited the highest yield stability but the lowest yield. Steamed cassava from the CMRE60-03-13 line had a higher textural quality than that from Hanatee and OMRE60-01-02. Therefore, the hybrid cassava line CMRE60-03-13 is suitable for recommendation to farmers due to its high yield and desirable textural quality when steamed.

Comparative Analysis of Percentage Disease Index and Area Under the Curve for Classifying Northern Corn Leaf Blight Severity

Theerawut Wongwarat — 2025-12-16

Northern corn leaf blight (NCLB, Exserohilum turcicum) is one of the most significant foliar diseases of maize, directly affecting sweet corn yield. Accurate assessment of disease severity is essential for screening resistant lines. This study compared the effectiveness of the percentage disease index (PDI) and the area under a disease progress curve (AUDPC) in evaluating the severity of NCLB in sweet corn. The experiment was conducted on the sixth generation (S₆) of self-pollinated hybrid sweet corn at the Chiang Mai Field Crops Research Center from December 2021 to February 2022. E. turcicum was artificially inoculated, and PDI was assessed at two time points: 28 and 55 days after planting (DAP). The AUDPC was then calculated and analyzed using the receiver operating characteristic (ROC) curve and Youden index to determine the critical threshold for disease severity classification. The correlation analysis revealed that PDI at 28 DAP was unsuitable for classifying disease severity, whereas PDI at 55 DAP and AUDPC based on observations at both 28 and 55 DAP showed a statistically significant correlation. Furthermore, the threshold value determined by AUDPC, in conjunction with ROC curve and Youden index was 910.88, with an area under the ROC curve (AUC) of 1, indicating highly accurate discrimination between resistant and susceptible sweet corn genotypes. Therefore, AUDPC combined with ROC curve and Youden’s index was more effective and reliable than using PDI at 55 DAP alone and can serve as a valuable tool in future research on breeding sweet corn resistant to NCLB.

Inducing Substances and Plant Defense Mechanisms Related to Pest Resistance in Tobacco with Scopoletin Extracts from the Morinda citrifolia L. (Noni) Fruits

Khemmikar Khompatara — 2025-12-16

Scopoletin is a secondary metabolite found in many plants. It possesses antioxidant properties and inhibits the growth of microorganisms. This research aimed to extract scopoletin from Thai noni (Morinda citrifolia L.) fruit to investigate its potential role in inducing compounds and mechanisms related to pest resistance in tobacco plants. The extraction was performed using the maceration method with ethanol as the solvent. The extract was then separated by column chromatography using silica gel as the stationary phase and a mixture of ethyl acetate and hexane (0–60% v/v) as the mobile phase. The presence of scopoletin in each fraction was detected by TLC under UV light at 365 nm. The fraction containing scopoletin was further purified using 2% methanol in dichloromethane as the mobile phase. The purified compound was identified using TLC, UV-visible spectroscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The results confirmed that the obtained yellow crystal were scopoletin, with a yield of 0.038±0.01%. A resistance induction assay was performed by infiltrating scopoletin into tobacco leaves at concentrations of 100, 500 and 1,000 μM. The treatment stimulated the production of salicylic acid and increased the activities of phenylalanine ammonia-lyase, glucanase and peroxidase, with peak responses observed at different time points. These findings suggest that scopoletin isolated from Thai noni fruit may functions as a plant elicitor that enhances pest resistance in tobacco by activating signaling molecules and defense-related enzymes.

Production of Cassava Starch-based Biofilm Using Lignin and Nanocellulose from Durian Husk as Additives

Kanoksak Loiloes — 2025-12-16

Biofilm made from cassava starch is not durable for packing usage due to its easy breaking and short lifespan. A large amount of durian shells was useless and unutilized by industry; therefore, they were chosen to produce additives for biofilm production. This research aims to enhance the durability of cassava starch-based biofilm by incorporating lignin and nanocellulose extracted from durian husk in biofilm. The result indicated that the lignin and nanocellulose extracted from durian husk had a lignin content of 39.5% and nanocellulose of 10% by dry basis. Cassava starch-based biofilms were prepared with varying concentrations of durian husk lignin and nanocellulose, along with 30% glycerol by weight. The biofilm containing 3% lignin exhibited the best physical and chemical properties, including a tensile strength of 142.51±5.21 kgf/cm², film elongation of 10.81±0.53%, moisture content of 7.97±0.18%, and water solubility of 4.88±0.65%. The oxygen permeation rate is 109.1±15.48 cm³/m²/day, similar to the biofilm without additives (109.5±34.71 cm³/m²/day), a thickness of 0.185±0.00 mm and a color change (∆E) of 41.89±0.85. Cassava starch biofilms with 3% lignin from durian husk and 30% glycerol were more durable and can be used for dry food packaging because of their better physical properties.