Ten out of 11 varieties of pungent radish in Japan had a higher content of isothiocyanate (pungent component) in the squeezed juice than Aokubii Daikon (general green-necked radish), and intense spiciness. The leaf shape, root shape, and root color varied, and no constant tendency was observed. However, because of their small size, low water content, high hardness, high brix value, and high sucrose content, they were all considered to belong to the northern radish. The content of isothiocyanate per squeezed juice of the test varieties was highest in ‘Kyoto Yakumi’ and also in Hamadaikon. A strong positive correlation was found between the dry matter ratio and amount of isothiocyanate, and varieties with a lower water content tended to have more isothiocyanate. There was a marked difference in the sugar composition among varieties, and the ratio of the sucrose content was particularly high in ‘Matsudate Sibori’ and Hamadaikon. It was suggested that the difference in sugar composition could be used as an index to show the relationships among varieties.

To clarify the effect of setting organic photovoltaic (OPV) panels on tomato fruit production, we examined the yield, fruit quality, plant growth, and photosynthetic characteristics of tomatoes in greenhouses with OPV (OPV greenhouse) and without OPV (control greenhouse) during fall-winter and spring-summer cultivations. We installed 86 and 106 OPV panels on the OPV greenhouse for fall-winter and spring-summer cultivations, respectively. During both cultivations, solar radiation inside the OPV greenhouse decreased compared with the control greenhouse. Although there was no significant difference in yield between the control and OPV greenhouses in both cultivations, fruit dry matter weight in the OPV greenhouse was 23% lower than in the control greenhouse in the fall-winter cultivation with lower solar radiation. We also investigated plant growth and photosynthesis-related traits in both greenhouses during fall-winter and spring-summer cultivations. The results showed that photosynthesis-related traits decreased in the OPV greenhouse for both cultivations, whereas plant growth decreased significantly during fall-winter cultivation compared with spring-summer cultivation as with the fruit dry matter weight. These results indicate that OPV panels reduced the fruit dry matter weight and plant growth in periods of low solar radiation, suggesting that solar sharing in tomato cultivation is effective when solar cells are removed during periods of low solar radiation and installed during periods of high solar radiation.

Foods rich in functional components are increasingly attracting attention. The beet, belonging to the family Amaranthaceae, is rich in betalain pigment, an antioxidant, and its demand as a functional vegetable is likely to increase in the future. Because of its polyembryony, a number of seedlings commonly grow from a beet seed, requiring some form of thinning. To confirm the effect of thinning on spring sowing red beets, this study examined the effects of the harvest time and different number of sprouts on the yield, shapes/sizes, and quality of the roots and above-ground parts. During the same growing period, although each red beet grew larger with fewer numbers of sprouts per mulch hole, the yield of the root was not affected. The betalain content per 100 g dry weight was higher in those with four or more seedlings at the optimum harvesting time than in the other test plots. This suggests that the number of sprouts and thinning affect the shapes/sizes and quality of red beets. Furthermore, considering the biomass, the estimated betalain production per 10 a was the highest in those with three seedlings in the overripening stage, suggesting that betalain can be obtained the most efficiently. Based on this, it became clear that the size of the roots is affected during the same growing period by thinning according to the purpose of red beet use, such as thinning more when importance is placed on the size of the roots harvested as a fresh vegetable or processed food, and thinning less when the betalain content is the focus as an ingredient for cosmetics or pharmaceuticals.

We investigated the effects of irradiation from a light-emitting diode (LED) on the growth of cut carnations using the standard-type carnation ‘Moon Light’ and spray-type carnation ‘Cherry Tessino’ in a warm climate region in Japan, where carnations are heated in winter. We examined the effects of irradiating carnations with light from a red or far-red LED all night or for 16 hr of an extended day on the number of days from pinching to flowering, number of flowers harvested, and flower quality, from the first pinching in July to the end of cultivation in June the following year. Irradiation with light from both a red and far-red LED accelerated growth compared with the control treatments. Light from the far-red LED was more effective at this than that from the red LED, and the all-night treatment was more effective than the 16 hr treatment in shortening the number of days from pinching to flowering and increasing the number of flowers harvested. Irradiation with light from the far-red LED also adversely affected the quality of the flowers harvested. For example, it promoted the production of soft flowers and insufficient number of lateral flowers in the spray-type carnation ‘Cherry Tessino’. The results suggest that red LED irradiation can be used to promote flowering in winter/spring-cropped cut carnation cultivation without quality loss.

The whole harvest cultivation method for one-year-old asparagus plants (new cultivation method) does not require occupying the field for a long time, as it shortens the growing period, compared with conventional methods. In this case, the harvest time is until May or June of the year following planting. Therefore, it is necessary to consider appropriate succeeding crops. This study examined the chemical properties of soil and allelopathic activity of the field after the harvesting of asparagus produced by the new cultivation method (after, the new cultivation method). We also planted various succeeding crops in the ridges and furrows of the field after the new cultivation method, and compared their growth and yields. The chemical properties of soil and allelopathic activity were within ranges that did not negatively affect each succeeding crop. Furthermore, among these crops, the yields of those in ridges and furrows of the field after the new cultivation method were equivalent, excluding cherry tomatoes, being similar to the mean yield in Japan. Regarding the suitability of succeeding crops for the whole harvest cultivation method for one year-old plants, crops other than asparagus can be cultivated in fields after harvesting by this method.

Effects of the number of leaders per tree and fruit numbers per leader on early yields and fruit quality were investigated in Japanese pear (Pyrus pyrifolia (Burm.f.) Nakai) ‘Hosui’ trees trained with a V-shaped trellis system. The trees of two leaders and four leaders reached to the top wire with a height of 3.6 m in the 2nd year of planting, and the trees of six leaders reached to the top in the 3rd year. The early yields were more than 3 t・10 a^–1 in the 3rd year of planting regardless of the number of leaders. Bearing more fruit attained more yields, but the fruit was smaller and tended to be of lower Brix. The fruit size of the V-shaped trellis was significantly smaller than that of the traditional pergola system, even when the fruit number was limited to 8 fruits per leader. When the crop load was set at 12 fruits per leader with the V-shaped trellis, the Brix was similar to that using the traditional system. The fruit at a higher position on the V-shaped trellis had an earlier harvest time than at a lower position and tended to be of smaller size. Interquartile ranges of fruit weight and Brix were similar between V-shaped trellis and pergola systems. Considering early yields and the fruit quality during the first 5 years after planting, four leaders per tree and 12 fruits per leader would be suitable for the cultivation of Japanese pear ‘Hosui’ with the V-shaped trellis system.

Computational fluid dynamics (CFD) analysis was used to model a single pipe house with a low eave height (less than 2 m), taking into account the effect of planting, and to reproduce the internal environment. As a result, it was possible to capture the temperature change of the internal air in both windy and windless conditions, while there was disagreement between the analyzed and measured values. The model was also used to estimate the relationship between the ratio of roof vent opening and the heat exhaust effect to reduce the internal temperature. The results showed that the smaller the roof vent opening ratio, the more heat was accumulated regardless of windless or windy conditions, and the larger the roof vent opening ratio, the higher the heat removal effect. However, this effect did not change significantly in the range of 12 and 16% of the floor area. This indicates that an aperture ratio of about 12% or more of the floor area is effective for ventilation of greenhouses with a similar shape.

Effects of slightly acidic electrolyzed water volatilized by a forced-air vaporizing system on plant growth and the control of powdery mildew in cucumber seedlings were investigated. The volatilization of electrolyzed water was automatically done for 12 h from 18:00 to 06:00 in specific on- and off-cycles. Thereby, it was considered possible to reduce application. The volatilization effectively avoided the attachment of excessive water to the leaves and also suppressed the spread of infection. However, the volatilized electrolyzed water caused a visible physiological disorder on the leaves and pericarp, especially when it was continuously applied at intervals of a 10-min application and 20-min suspension cycle. When the on- and off-cycle was prolonged to 10 and 110 min, respectively, the physiological disorder did not occur but progression of the disease was not prevented. Progression of the disease was inhibited on the application of a 10-min on- and 50-min off-cycle but leaf growth was also retarded. In addition, spread of the disease symptom was not well-inhibited by volatilization after appearance of the disease symptom. Both growth inhibition of the leaves and expansion of the disease symptom were avoided by spraying fungicides at the young seedling stage, and then volatilizing the electrolyzed water with a 10-min on- and 50-min off-cycle when the plants reached the maturing stage.

In this study, the relationship between characteristics of the fruiting mother shoot and inflorescence number was investigated in 7 citrus cultivars (‘Aoshima unshu’, ‘Shiranuhi’, ‘Setoka’, ‘Harehime’, ‘Seinannohikari’, ‘Tsunokagayaki’, and ‘Reikou’) for 2 years. In all citruses investigated in this study, absolute values of the correlation coefficient between the characteristics of the fruiting mother shoot and numbers of sprouting buds, vegetative shoots, or inflorescences were less than 0.5. In decision tree analysis, the number of total inflorescences, which is the sum of leafless and leafy inflorescences, was high in the thin fruiting mother shoots of ‘Aoshima unshu’ and in the thick ones of ‘Reikou’. In ‘Shiranuhi’, ‘Harehime’, ‘Seinannohikari’, and ‘Tsunokagayaki’, the numbers of total inflorescences were high in the long shoots. In ‘Setoka’, total numbers of inflorescences were higher in shoots in a certain length range. In decision tree for leafless inflorescence, numbers of inflorescences were higher in short shoots of ‘Aoshima unshu’ and ‘Setoka’, and in long ones of ‘Harehime’ and ‘Seinannohikari’. In ‘Shiranuhi’ and ‘Reikou’, numbers of leafless inflorescences were higher in the thinner shoots and, in ‘Tsunokagayaki’, numbers of leafless inflorescences were higher in the downward ones. In decision tree analysis for the number of leafy inflorescences, numbers of leafy inflorescences were higher in the longer shoots of ‘Aoshima unshu’, ‘Shiranuhi’, ‘Setoka’, and ‘Tsunokagayaki’. In ‘Harehime’, ‘Seinannohikari’, and ‘Tsunokagayaki’, numbers of leafy inflorescences were higher in the thicker shoots.

We used near-infrared spectroscopy to predict the number of seeds of ‘Koyama New Summer’, a bud mutation of Izu ‘Hyuganatsu’ (Citrus tamurana hort. Ex. Tanaka), and validated its prediction accuracy. The calibration lines for soluble solid content, number of developed seeds, number of total seeds, developed seed weight, and total seed weight prediction were generated from the 730–970-nm spectra after the second derivative to evaluate the accuracy of the calibration lines. The accuracy of the calibration lines was assessed to be high for four measurement items, excluding the developed seed weight. Although the calibration sample had few fruits near the boundary value of five or six seeds, the percentages of correct and incorrect answers were calculated from the predicted and measured values, with five or fewer total seeds as fruits with few seeds and six or more seeds as fruits with many seeds, and the percentage of correct answers was as high as 92.0%. The potential for incorrect prediction of fruit with a high seed count as fruit with a low seed count would lead to complaints from consumers, but this incorrect prediction did not occur. The accuracy of the calibration line constructed using the spectra obtained by irradiating five fruit sites with near-infrared light was rated high. There were a few incorrect answers, but they were considered unlikely to be a problem. The calibration lines were prepared and evaluated using fruit from three collection years. The calibration lines were evaluated to be highly accurate when using the 2020 production year with the highest number of total seeds and the 2018 production year with the lowest number of total seeds as the calibration samples. The results suggest that the seed number prediction can be improved using a variety of samples from seedless to many-seeded. Conclusively, it was shown that near-infrared spectroscopy could be used as a selection technique to ensure a stable supply of ‘Koyama New Summer’ as seedless or containing few seeds.

Crispness of persimmon flesh was evaluated by a swing-arm texture device. A conical probe was inserted into the flesh, and horizontal and vertical vibrations of the probe were separately monitored from 0 to 51,200 Hz. The vibrations were used to calculate the energy texture index. Out of the seven persimmon varieties tested, sensory tests showed that three varieties: ‘Taishuu‘, ‘Neo sweet’, and ‘Reigyoku’, were more crisp than the other varieties: ‘Maekawa-Jiro’, ‘Matsumotowase-Fuyu’, ‘Shinsyuu’, and ‘Kanshu’. There was a significant positive correlation between the energy texture index of horizontal vibrations and the sensory score. However, the sensory score was found to be influenced by the flesh firmness. Vibration ratios were obtained by dividing the horizontal by vertical vibrations, which were correlated with the elasticity index and sensory score. The vibration ratios calculated in 3,200–4,480 or 4,480–6,400–Hz frequency bands were especially useful for evaluating the crisp texture of each variety. In addition, the food friction index obtained by the swing-arm device had a highly significant positive correlation with the sensory score for flesh firmness and also with the elasticity index. The food friction index may be used for evaluating the flesh firmness of persimmon. These results show that the swing-arm device for texture evaluation can simultaneously measure both crisp texture and flesh firmness with single probe penetration. Furthermore, a scatter plot of the food friction index on the horizontal axis and vibration ratio on the vertical axis makes it possible to classify the flesh texture characteristics of persimmon varieties.