Hiroshi Shimizu

Computer-Vision-Based System for Plant Growth Analysis

A computer vision system with a CCD camera and an infrared lighting apparatus was developed to conduct noncontact, three-dimensional plant growth analyses. The infrared lighting apparatus was designed to obtain plant images in the dark by exposing plants to wavelengths of 800 nm and greater. Processing algorithms were developed to extract plant outlines, detect node positions, and produce thinned lines from images. The system was capable of resolving interimage differences of 5% of a pixel, or 0.025 mm.

The application of blue light as a growth regulator

Alternatives of agricultural chemicals such as growth retardant is awaited from the nenvironmental point of view. Blue light would have potential to shorten plant height, and growth nanalysis may make effective timing and period of application of blue light clear. And it will be one of the basic data to construct a quantitative model to describe the relation between internode and/or nstem elongation and light condition. This technique would provide growers with an environmental nfriendly ways to regulate plant growth of ornamental crops. nExperiments were conducted in a controlled environment cabinet that equipped temperature ncontrol, eight controllable fluorescent lamps, blue LEDs. A turn table was used to increase efficiency nof experiments. A CCD camera which had sensitivity in infrared region and an infrared illuminator nwere employed to obtain an image of plants during day and night.. The plant images were obtained nevery 10 minutes over three weeks. nTwo light conditions were planned for the experiments, that is to say, Exp I :12hrs light(0600 to n1800), 12 hrs dark(1800 to 0600) with 4 hrs night interrupt(2200 to 0200) by a fluorescent lamp, and nExp.II : 12hrs light(0600 to 1800), 12 hrs dark(1800 to 0600) with 4 hrs night interrupt (2200 to 0200) nby blue LEDs (0400 to 0600). It was observed that the growth speed of internode length was slow nunder in the light period, and it became fast in the dark, and that the average value of the amount of ninternode elongation per day was reduced even to about 60% by blue LED, and that the inhibitory neffect of internode elongation by blue LED was maintained not only in the night interruption period nirradiating blue LED but in the dark and light periods following it.

Simulation of greenhouse energy consumption

The energy cost of greenhouses is a major concern in greenhouse management during winter time. Greenhouse energy consumption per day can be reduced by lowering the greenhouse temperature since energy consumption is approximately a linear function of the difference between inside and outside air temperature of the greenhouse. However, lower greenhouse temperature requires longer growth period. Total energy consumption is the product of these two factors, and is not simply calculated. Greenhouse energy consumption is estimated using a model developed in this project.

Estimating Cuticle Resistance of Seedling Shoot Tips Based on the Penman-Monteith Model

Morphological characteristics of seedlings such as height and size uniformity are important requirements in transplant production and are affected by temperature at the plant shoot-tip. Plant temperature is described by the energy budget equation based on the Penman-Monteith model. The energy budget equation of a plant shoot-tip consists of environmental factors and the shoot-tip cuticle resistance. The energy budget equation was algebraically modified to an equation that expresses the relationship between Vapor Pressure Deficit (VPD) and ambient air temperature (Tair) — plant shoot-tip temperature (Tp). This same relationship was also obtained by a simple experiment where VPD was regulated at constant Tair. Comparing the coefficient of these two equations, the cuticle resistance of plant shoot-tips was calculated. The experiments were conducted using Campanula ‘Birch Hybrid’, Campanula carpatica ‘Blue Clips’, and Geranium dalmaticum. The values of cuticle resistance of each plant are 524.9, 157.2 and 57.8 s/m, respectively.

Simulation of Plant Shoot-Tip Temperature Based on Penman-Monteith Model

Abstract A model that predicts a plant shoot-tip temperature using five environment factors was constructed and simulation study was performed using the developed model to search the most effective environment factor which influences the shoot-tip temperature. The ambient air temperature was found to be the most effective to increase and decrease the shoot-tip temperature compared to changing glazing materials and shortwave radiation coming to the plant canopy.