Juro Miyasaka

Light Environment Optimization for Lettuce Growth in Plant Factory

Abstract Plant factory is a crop production system which is isolated from outside environment. Fluorescent lamp is popularly used in the plant factory, however, the spectrum of fluorescent light is broad and some portion of them is not necessary for photosynthesis. On the other hand, LED (light emitting diode) has narrow band width and is getting common these days. The final goal of this project was to develop a new light apparatus with LEDs optimized for vegetable production in plant factory. The specific objective was to investigate the effective light quality for growing plant more healthy and rapidly. The effect of light provided by various light qualities provided by the combination of LEDs(blue, green, red) on the photosynthesis rate, growth and morphogenesis of lettuce (Lactuca sativa L “Greenwave”.) were evaluated and the response compared with those of plant irradiated by fluorescent lamps. Photosynthesis rate of lettuce was greater in monochromic red light and the mixed light with red and blue LEDs. Stem length increased in monochromic red and blue light and decreased in mixed light. Fresh weight of lettuce was increased in monochromic red and fluorescent light.

Experimental Analysis of Tread Pattern Effects on Tire Tractive Performance on Sand using an Indoor Traction Measurement System with Forced-slip Mechanism*

An indoor traction measurement system was redesigned to improve the measurement of tractive performance for off-road tires and to compare experimental tire traction results with those of a tire performance simulation. The system comprises a soil bin, a mixing and compaction device, and a single wheel tester with a forced-slip mechanism. The range of available slip is further extensible than that of a conventional system. Tractive performance of four automotive tires with smooth, lug, rib and block tread patterns was tested on sand. Experimental results show that the tire with lug pattern or block pattern exhibited higher drawbar pull than other tread patterned tires for slip greater than 17.8%.

Analysis of Elastic Wheel Performance for Off-road Mobile Robots using FE—DEM

Abstract For this study, we applied a finite element-discrete element method (FE-DEM) to predict the tractive performance of an elastic iron wheel for mobile robots running on sand. We developed our program, where FEM is applied to a wheel and a subsurface soil layer, and where DEM is applied to the surface soil layer where the contact interaction between the tire and soil is greatest. The developed FE-DEM tool was found to have sufficient accuracy to predict the performance of an elastic wheel running on deformable soil. Moreover, parametric analysis was applied for those parameters of the rigidity of the tread part of the wheel, the surface soil layer thickness, and the lug height. The effect of rigidity of the tread part was negligible for 1-5 MPa. The surface soil layer thickness was found to have no significant effect on tractive performance. The lug height showed a strong effect on the tractive performance of the wheel, but the effect on net traction seemed to be degraded concomitantly with the increase in lug height.

Tri-axial Contact Reaction at the Tire-Soil Interface

Abstract The contact stresses between a tire and sand were measured with a tri-axial force sensor embedded on the tread surface of the tire. The results showed that the sensor could detect normal and tangential contact reactions with sufficient accuracy. Moreover, we observed a forward shift of the rotational angle for which both normal and longitudinal tangential stresses are maximum. There were three points of measurement on the lateral direction of tire tread, and the tractive performance of a tire in terms of gross tractive effort, drawbar pull, and running resistance could be obtained through integration using the detected contact forces.

Optimization of Fertilizer Application Schedule: Utilization of Digestate after Anaerobic Digestion as Liquid Fertilizer

Abstract Anaerobic digestion, which is a series of processes to break down organic matter without oxygen is used for waste treatment. Organic wastes with high moisture content, such as livestock excreta, food waste, kitchen garbage, and so on are broken down by microorganisms, and biogas can be obtained. Digestate, which is produced as a byproduct, has rich nutrient and can be used as fertilizer. However, it must be applied in large quantities because the concentrations of nutrient in it are much lower than chemical fertilizer. The objective of this study is to develop a method, which determines the optimum fertilizer application schedule in order to establish minimum digestate utilization system, which consists of slurry spreaders, vacuum trucks for transportation, and reservoirs. In order to achieve this objective, the working hours in each farm field was calculated through the simulation, and the necessary number of vacuum trucks could be obtained in order not to occur idle time.

Control for Microwave-Driven Agricultural Vehicle: — Tracking System of Parabolic Transmitting Antenna and Vehicle Rectenna Panel —*

Abstract This microwave-driven vehicle receives microwave power from a system with a magnetron and a parabolic antenna. Running paths, vehicle power consumption, turning angle, and the parabolic antenna depression angle were measured to assess the transmitting system orientation control. The system detects the vehicle position and turns the parabolic antenna to the vehicle. However, the maximum rotation speed of the transmitter turntable was 8.04° /s for a 2 m distance. The transmitter can follow the vehicle at speeds up to 0.14 m/s, but the maximum vehicle speed was 0.26 m/s with the microwave power supply. The low microwave electricity reception efficiency (ca. 5 %) was nevertheless higher than in earlier experiments using a horn antenna instead of a parabolic antenna.

The effect of light quality on growth of lettuce

Abstract Plant factory is a plant production system with controlled temperature, carbon dioxide concentration and light environment to enhance plant growth efficiently. Fluorescent lamp is popularly used in a plant factory, however, the spectrum of fluorescent light is broad and some portion of them is not necessary for photosynthesis. On the other hand, LED (light emitting diode) has narrow band width and is getting easy to use these days. The final goal of this project is to develop a new light apparatus with LEDs for plant factory. The specific objective is to investigate the effective light quality for growing plant more rapidly. The effect of light generated by monochromic and mixed radiation from LEDs (blue, green, red) on the response of lettuce ( Lactuca sativa L.) were evaluated and compared with the effect of lettuce irradiated by fluorescent lamps. Photosynthesis rate of lettuce increased in monochromic red light and the light mixed with red and blue light. Number of leaves decreased in monochromic blue light. Fresh weight of lettuce was increased in monochromic red and fluorescent light, but monochromic red light significantly decreased dry weight rate. In the view of energy saving, LED is much better than fluorescent lamp. Especially, red LED is good.

Effect of different durations of root area chilling on the nutritional quality of spinach

Abstract It has been proposed that cold acclimatization of the plant body enhances the nutritional value of leaf vegetables; however, little is known about the optimal duration of cooling required to enhance the quality of factory-processed vegetables. The ideal low temperature acclimatization period increases ascorbic acid and sugar content without increasing the nitrate ion concentration for a given root area. Here, we investigated the ascorbic acid and sugar contents in spinach with a given root area subject to chilling for different durations; 2, 4, 5, 6, and 7 days. Ascorbic acid and sugar content levels remained stable at the beginning of chilling; however, after 6 days, the levels of both parameters doubled compared to those in the control (no chilling). In comparison, nitrate ion concentration gradually decreased with increasing acclimatization period. Spinach plants acclimatized for 7 days showed similar results as those acclimatized for 6 days. Our results show that the optimal duration for root area chilling to produce high quality spinach is 6 days, when controlling the temperature of the nutrient solution under plant factory conditions.

Current state and research trend in light environment for plant factory

Plant factory has been attracting attention as a new system of food production, and there are approximately 130 commercially operated facilities in March 2012 in Japan. Currently, leafy vegetables are mainly produced in plant factory. However, not only year-round and agricultural chemical free production but new researches focused on high value-added vegetable production and raw material production for pharmaceutical compounds have been studied. This report outlines the recent trends in research on high-value-added plants using light environments.

Development of Web System for Crop Management of Potherb Mustard ‘Mizuna’ using Ruby on Rails

Abstract Estimation of shipment of agricultural products is important to markets for stable distribution to shops and consumers. The authors have been studying optimization of shipment of Potherb Mustard ‘mizuna’ in Nantan District, Kyoto, Japan. In this report, development of web application as a base system of this optimization was introduced. The features of the web application and its development were shown, though the optimization program has not been integrated to this platform.