Year-round tomato cultivation needs high-quality seedlings with stem length and node position of the first flower truss controlled at suitable values. Generally, shade avoidance syndrome (SAS) promotes stem elongation and alters flowering time under natural sunlight. The objective of this study was to develop a method for controlling the stem elongation and flowering of tomato seedlings in a closed seedling production system (CSPS) with light emitting diodes (LEDs). We conducted two experiments to investigate how the artificial light environment induces SAS to control stem elongation and flowering. In Experiment 1, which examined the effect of end-of-day light (EOD-light), the phytochrome photostationary states (PSS) of the treatments were 0.56 for EOD-blue treatment, 0.89 for EOD-red (R) treatment, and 0.13 for EOD-far red (FR) treatment. Stem elongation was promoted more with EOD-FR treatment compared to the control. No significant differences among the treatments were observed for the node position of the first flower truss. Therefore, although the EOD-FR treatment did not promote flowering, it did induce SAS. In Experiment 2, which examined the effect of FR light quantity in the CSPS, we reproduced light environment conditions within the canopy at the time of the second nursery in a greenhouse and investigated how much the R/FR ratio induced SAS by adjusting the FR light quantity. The light environment conditions were tested at 150 nmol m-2 s-1 of total photosynthetic photon flux density with four FR light quantities (0, 50, 100, or 150 nmol m-2 s-1). There was no significant differences among the treatments for the node position of the first flower truss, and the stem elongation with FR50, FR100, and FR150 treatments was greater than that at FR0. These results suggested that the PSS, which was less than or equal to 0.72 during the light period (16 h), induced SAS. Thus, light environmental control with LEDs with EOD-FR or a low R/FR ratio is not suitable for the CSPS because it does not promote flowering of tomato seedlings.

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Marker-assisted selection (MAS) using four (SmX, SmY, SmY1, and SmY2) sequence characterized amplified region (SCAR) markers linked to the sex determining locus were performed in Actinidia chinensis (cv ‘Rainbow-Red’). The relationship between the SCAR markers and the sex was investigated. No SmX signal was detected, and SmY, SmY1, and SmY2 were mainly detected in males. Regarding the sex determination precision of each marker in 182 ‘Rainbow-Red’ seedlings, SmY1 was 95%, SmY was 77%, and SmY2 was 68%. Further, we investigated the existence of these markers in twenty six A. chinensis, A.deliciosa, and A.rufa varieties. These markers might not be detected in several varieties, and is believed to improve the efficiency of kiwifruit breeding programs. Especially SmY1 has great potential in enhancing kiwifruit breeding programs using ‘Rainbow-Red’ as the breeding material.

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The relationship between the concentration of a nutrient solution and the growth of Elatostema involucratum Franch. & Sav., hydroponically cultured from bulbils, was investigated. Transplants of E. involucratum were supplied with 0.25 units (low concentration) or 0.5 units (high concentration) of Enshi nutrient solution. However, in the high concentration treatment, the concentration of the Enshi nutrient solution from 0 to 14 days after transplantation was 0.25 units. The length of the main stem and internodes with the low concentration treatment was significantly longer than that with the high concentration treatment at 49 days after transplantation. Changes in the number of nodes after transplantation were not significantly different between the low and high concentration treatments. The stem diameter with the low concentration treatment was significantly larger than that with the high concentration treatment at 64 days after transplantation. In addition, the top and root fresh weight with the low concentration treatment was significantly higher than that with the high concentration treatment at 64 days after transplantation. The number of stems from bulbil and the number of lateral shoot were not significantly different between the low and high concentration treatments. In addition, the growth of transplants cultured with 0.13 or 0.25 units after transplantation was similar. Therefore, a suitable concentration of a nutrient solution in the hydroponic culture of E. involucratum was considered to be 0.25 units or less.

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A new type of water stress sensor for plants is recommended for appropriate water irrigation. This sensor simply consists of a strain gauge (base dimensions of 3.5 mm width × 8.5 mm length) and a thin sheet of neoprene rubber (rubber hardness: 65). The sensor is wound around a plant stem with suitable tension and can measure a physical quantity corresponding to the change in circumference of the plant stem. In this paper, the sensor output characteristics (the relationship between the change in the sensor output and the change in the length of rubber) upon loading and unloading were investigated in experiments using a universal testing machine. The mechanical behavior of the sensor output upon loading was different from that upon unloading in response to the change in length of the rubber. The sensor output characteristics were unaffected by the rubber width (varying from 5 to 10 mm) and the length of rubber (varying lengths above 20 mm) but were strongly affected by the initial tensile tension. Sensor sensitivity increased with the initial tension according to a quadratic function. The characteristic differences between the sensor and a conservative diameter sensor were experimentally clarified by measuring changes in the stem of a citreous tree over a period of a week. The tendency of the behaviors of the outputs of the two sensors accorded well (correlation coefficient of 0.95). Consequently, it is shown that the sensor can measure simply and finely the changes in diameter of a stem and is available for estimating plant water stress.

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The effects of ultrasonic pressure on the growth and antioxidant activity of Raphanus sativus L. sprouts (Japanese radish sprouts) were studied. Sprouts were grown under four different ultrasonic pressures (40 kHz; 0, 33.4, 78.9 and 136.4 kPa). The fresh weight per plant decreased with the increase in ultrasonic pressure, resulting from the decrease in water content. However, the total polyphenol content and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity are independent of ultrasonic pressure. Therefore, both values increase with the increase in ultrasonic pressure for per fresh weight of sprout. In conclusion, the application of ultrasound to the roots of Japanese radish sprouts is an effective method to increase the total polyphenol content.

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Plant foliage depth data obtained with a Kinect for Windows sensor were used to estimate the light-intercepting characteristics of tomato and paprika plants. As a qualitative measure of plant growth, we calculated plant cover ratios per unit area (Ra), defined as the ratio of the area of a horizontal projection of the foliage for a unit plant to the floor area occupied by the plant. To obtain an additional metric for the light-intercepting characteristics of the plants, termed Rp, Ra values were calculated at 1 cm increments starting from the top of a plant to provide an integrated value, Ra’; Rp was then calculated by taking the distance from the plant top to the point at which the value of Ra’ was 80 % of the Ra value for the plant and dividing this distance by the vertical distance from top to bottom of the plant foliage. Analyses using dummy plants and tomato plants showed that Ra values increased and Rp values decreased as the total foliage area increased and light was less able to penetrate downward through the array of leaves. Changes in leaf angle also affected Ra and Rp values. Dummy plants with their leaves horizontal had larger Ra values and smaller Rp values than when the leaves were inclined downward. A comparison of data at sunrise and sunset for paprika plants cultivated in a greenhouse showed that Ra values were larger and Rp values were smaller at sunrise, compared with their respective values at sunset. These relationships are in agreement with changes in leaf attitudes, which were more horizontal at sunrise and slightly drooped at sunset.

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