Agricultural and Biological Engineering

Growth performance of green cos lettuce under differential light intensities in controlled vertical hydroponic cultivation

2025-11-20T19:47:48+07:00

The increasing popularity of closed-system hydroponic cultivation has led to the need for optimizing environmental conditions to achieve uniform and high-quality crop production. One of the most important factors affecting plant growth is light intensity, which directly influences photosynthesis and nutrient accumulation. This study aimed to investigate the growth response of Green Cos lettuce (Caesar) under different light intensities in a controlled hydroponic environment and to record the growth parameters of the plants. The experimental procedure began with seed germination and seedling development, which took 28 days before transplanting into cultivation layers. The system consisted of three layers with identical environmental conditions, including nutrient solution pH, electrical conductivity (EC), air temperature, water temperature, relative humidity, and photoperiod, all monitored by sensors. The only difference among the layers was the number of LED grow lights used. Layer 1 was equipped with two lights, Layer 2 with three lights, and Layer 3 with four lights. Each light was an LED Grow Light Eco 18W (Flux PPF: PAR + PPF (400–800 nm) 27 µmol/s). Data was collected every five days from September 15, 2025, to October 15, 2025, for a total of 31 days, resulting in seven measurement intervals. Growth parameters recorded included leaf number, leaf size, plant height, and canopy width, as well as leaf color and appearance. The results showed that light intensity had a significant effect on the growth of Green Cos lettuce (Caesar). Plants grown in Layer 3, which received the highest light intensity, exhibited the best growth performance, with larger and longer leaves, uniform plant structure, and a healthy overall appearance. The average canopy width at maturity was 32.7 ± 1.98 cm for Layer 3, 29.0 ± 1.07 cm for Layer 2, and 23.8 ± 1.05 cm for Layer 1. The canopy width of plants in Layer 3 was 12.8% and 37.4% greater than those in Layers 2 and 1, respectively, while Layer 2 showed a 21.9% increase compared to Layer 1. The percentage increase of canopy width was calculated using the formula [Greater canopy width – Smaller canopy width) / Smaller canopy width] × 100. However, in all layers, the leaf characteristics are not very uniform; some leaves are curled and wrinkled, but most are complete. These findings indicate that optimizing light intensity plays a crucial role in enhancing the growth and quality of hydroponically grown Green Cos lettuce. The optimal light intensity for Green Cos (Caesar) in this study was 150 µmol/m²/s, achieved using four LED grow lights.

Research and development of environmental and Carbon Dioxide control machines to accelerate the growth of Vanda orchid seedlings from tissue culture

2026-03-04T10:57:17+07:00

The Thai government’s Thailand 4.0 policy emphasizes innovation-driven economic growth, particularly in the orchid industry. Currently, orchid farmers face a bottleneck in the first stage of nursing Vanda orchid seedlings, which typically takes 6 to 12 months. This research aimed to develop an environmental control system using modified atmospheres and specific light spectrums to accelerate growth. The study consisted of two phases: 1) developing the prototype environmental control machine, and 2) evaluating growth under varying CO₂concentrations (1,000, 1,500, and 2,000 ppm) and light treatments (natural light vs. LED). Results indicated that seedlings grown at 1,500 ppm CO₂ under natural light (shaded with 50% and 70% shading net) achieved optimal growth in terms of root and leaf count. Most importantly, this treatment allowed seedlings to reach the secondary nursing stage by the third month, effectively reducing the nursing duration by half.

Development of fresh galangal washing machine using pressurized water spray

2025-09-16T12:29:51+07:00

The purpose of this research was to design and perform an evaluation of the galangal washing machine using pressurized water spray at water flow rates of 10, 20, and 30 l/min and speeds of 30, 50, and 70 rpm. The result of this research comparing washing the galangal by farmers and a machine found that the operating capacity was 33.22 and 122.5 kg/h, the washing efficiency was 90.95% and 35.78%, and the percentage of damage was 0.08% and 1.09%, respectively. In the future, improvements should be made to increase the washing efficiency of galangal by increasing the washing time, and a water circulation system should be added to reduce water waste.