This paper addresses the problem of detecting bruises on strawberry fruit surface. Bruises were caused in a controlled manner on the freshly harvested fruits. The intensity level of reflection from the bruised and non-bruised surfaces were measured and analyzed by using a spectrometer within the range of 600 to 1000 nm. The particular wavelengths critical for bruise detection were determined and spectral images were acquired with suitable filters. The effective wavelength with the constant differences between bruised and non-bruised areas was selected as 945 to 975 nm.
The image subtraction was carried out between bruised and non-bruised strawberries acquired with 960 nm and 860 nm filters respectively. Two methods of image subtraction are proposed, first between the images of the same samples for recognizing the possibility of bruise detection and, second between test and standard strawberry images for online sorting.
The former method has confirmed the possibility of bruise detection by using NIR image processing. The judgment result from the latter method has agreed with the visual judgment for online sorting of strawberries.

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Multiplication ratio (number of average of harvestable propagules per stock plant, M) and electric energy consumption per propagule (E_p) at four levels of planting density (59, 118, 236 and 473 m^-2) were investigated for sweetpotato (Ipomoea batatas (L.) Lam.) vegetative propagation in a closed transplant production system. After n multiplication cycles, total number of harvestable propagules (N_n) and electric energy consumption per propagule (E_{p, n}) in the system were estimated by using mathematical models. Single nodal cuttings were used as propagules and grown to 14 days under photosynthetic photon flux of 140, 200 and 320μ mol·m^-2·s^-1 during 1 to 5, 6 to 10 and 11 to 14 days after planting, respectively. Other environmental conditions included photoperiod of 16 h·d-¹, air temperature of 29°C, and CO₂ concentration of 920μmol·mo1^-1. At the planting densities of 59, 118, 236 and 473 m^-2, M were 5.9, 6.4, 3.8 and 2.3, respectively, and E_{p, 1} were 0.41, 0.19, 0.16 and 0.13 kWh (electricity cost : 6.2, 2.9, 2.4 and 2.0 Yen), respectively. Results suggest that production can be optimized and electricity cost can be reduced by manipulating planting densities.

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A binocular stereovision system has been developed to estimate growth variables of a transplant population. In the present study, the image analysis system was improved by adopting a three-layered artificial neural network model (ANN model) based on a back-propagation algorithm. Inputs of the ANN model were average height, leaf area, projected leaf area, and mass volume of the transplant population obtained from the image analysis system. Outputs of the ANN model were average height, number of unfolded leaves, leaf area, and fresh and dry masses of the transplant population, which give a more accurate assessment of the transplant growth status than that obtained from the image analysis system. The number of nodes in the hidden layer of the ANN model was determined through trial and error. The growth variables thus obtained from the ANN model using a sweetpotato (Ipomoea batatas (L.) Lam.) transplant population were more accurate than those obtained from a regression model. The image analysis system, after being improved by using the ANN model, successfully identified the transplant growth status with a high degree of accuracy.

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Evapotranspiration rate (ET) of a sweetpotato transplant canopy (TC) under artificial light was measured at three levels (0.1, 0.3 and 0.5ms^-1) of air current speed (ACS) in a wind-tunnel-type growth chamber and at leaf area indices (L) of 0.9, 1.5, 2.6 and 4.0. The ET was measured based on the weight change over time of a transplant tray, consisting of 72 transplants, soil mixture, water and a plug tray. The Penman-Monteith model (P-M) was used for estimating aerodynamic conductance (g_a) above the TC based on the measured ET and canopy conductance (g_c). It was found that ET of the sweetpotato TC increased as ACS and L increased. The increase in ACS increased g_a above TC. Increase in L increased the g_c and also g_a. Understanding the effect of ACS on ET makes it possible to control ET in the transplant production system with artificial light (TPSAL) by manipulation of ACS. Effects of ACS on the net photosynthetic rate and growth of TC should be further investigated to determine the optimum ACS in the TPSAL.

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Dry mass production and leaf area in relation to leaf injury and superoxide dismutase (SOD) were evaluated for eggplant (Solarium melongena L.) and pepper (Capsicum annuum L.) seed-lings grown in continuous light at different intensities with metalhalide and high-pressure sodium lamps.
Continuous light-induced leaf injury occurred in eggplants even at 50μmol m^-2 s^-1 PPFD. When the 2nd leaf unfolded under daily 12h light-12h dark cycle, the eggplants were transferred to three levels of light intensity; 100 (low), 250 (medium), 480 (high) μmol m^-2 s^-1. After 8days, the SOD activity in the 3rd leaves showing no leaf injury at low light intensity was higher than that showing chlorosis or necrosis at high light intensity. However, after 16 days when the seedlings grown at low light intensity developed leaf-necrosis, SOD activities decreased to a low level, similar to those at medium and high light intensities. SOD activity increased gradually with time under continuous light up to the point of leaf injury, and decreased rapidly thereafter. These results suggest that the superoxide radical is associated with leaf injury.
In contrast, pepper plants grew vigorously without any leaf injury, and the dry weight was the highest at a light intensity of 300-400 μmol m^-2 s^-1 and the largest leaf area at 150-200 μmol m^-2 s^-1. SOD activity in pepper plants was relatively lower and more stable compared to that of eggplants, and the pepper plants also seemingly well adapted to continuous light at an optimum intensity of 300 μmol m^-2 s^-1 for dry mass production in a closed environmental system.

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The effects of sucrose and agar concentration in the media, and light intensity on growth and carbon absorption were observed using the plantlets of sweet potato (Ipomoea batatas (L.) Lam.), The stem cuttings with one leaf dissected from in vitro cultured plantlets were cultured under 12 degrees of combinations of three sugar levels (5, 20, and 45 gl^-1) and two agar levels (5 and 10 gl^-1) in medium, and two levels of PPFD (50 and 100 μmol m^-2 s^-1) maintained at an air temperature of 25±1°C and a carbon dioxide concentration of 1, 000 μmol mol^-1. The dry weight of the plantlets increased as the sugar concentration and/or light intensity increased. Under high agar concentration, the shoot growth declined, but the root growth accelerated. Absorbed molar quantity of carbon dioxide was more in high concentration of agar or high light intensity. The plantlets which was inhibited the sugar absorption by the high agar concentration seemed to depend more on CO₂ as a carbon source. It may be suitable that the media contain high sugar and agar concentration in early stage for heterotrophic or mixotrophic growth of the plantlets, and then CO₂ concentration and light intensity are gradually raised for their mixotrophic or autotrophic growth according to the status of the plantlet.

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Addition of paclobutrazol (PAC) to modified MS medium induced prptocorm-like body (PLB) formation from rhizome segment cultures of Cyrnbidium kanran Makino (terrestrial type). The combination of BA with PAC reduced the number of PLB. Application of BA induced shoot (protocorm-like pseudobulb with short leaves) without root. Single addition of 10μMBA had a significant effect on induction and increased the number of shoots. PAC in culture medium inhibited BA-induced leaf formation from rhizome cultures.
Application of GA₃ to PLB cultures of epiphytic type Cymbidium (C. Hiroshima Golden Cup 'Sunny Moon') resulted rhizome formation. GA₃ treatment at 100μM was effective for rhizome formation from FLE cultures. Single addition of 10μMPAC was effective for proliferation of PLB from 'Sunny Moon'.

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In the future, robots will be able to do many kinds of agricultural operations. However, it is difficult to consider that robots automatically perform all kinds of operations instead of human because of the complexity of agricultural operations. In other words, robots will be engaged in agriculture with human in the future. Therefore, it is considered that human cooperative agricultural robot systems are required.
An essential element for a human cooperative robot is a sensing system which can detect the circumstances around a robot so that the robot can carry out its task safely and efficiently.
Final goal of this research is to develop an external sensing system for human cooperative agricultural robots. In this paper, a sensing system consisted of a laser scanner and infrared sensors was manufactured and tested. The laser scanner was mounted on a lift moved up and down at a distance of 300 mm to capture a three-dimensional distance data. The infrared sensors were used to detect the existence of human.
From the experimental results, not only the distance to an object but also the shape of the object was detected by moving the laser scanner up and down. The human motions including location, speed and direction were detected based on the information obtained from the laser scanner and the infrared sensors.

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