Fifty-two local Japanese chili pepper varieties (Capsicum annuum) were subjected to polymorphism analysis using the RAPD method to analyze their genetic relationships. The phylogenetic tree based on the UPGMA method was classified into five clusters (I–V) with two subclusters in cluster IV. Clusters I and II consisted of four varieties from the ‘Fushimi’ variety group in Kyoto and ‘Kenzaki Namban’ from Ishikawa, cluster III consisted of upward-fruiting varieties for spice, and subcluster IV-a consisted of varieties developed for ornamental use and varieties with characteristic fruit colors, while sub-cluster IV-b, which consisted of the largest number of cultivars, was composed of a mixture of various fruit types. The remaining cluster V was composed of bell-blocky type large-fruited varieties. As the result, analogical and genetic relationships of Japanese local chili pepper varieties were revealed, and some of them were consistent with historical facts in the literature.

A pollination method using pollen irradiated with gamma-rays (γ-rays) was applied to induce gynogenesis. For this study, the apple cultivars ‘Fuji’, ‘Jonathan’, and ‘Indo’ were used as seed parents. ‘Golden Delicious’ was used as a pollen parent. The pollen was irradiated with 500 Gy by γ-rays. After investigating the fruit set percentages and seed appearance of sampled fruits, we used SSR markers to elucidate the derivation of seedlings raised from the obtained seeds. The method was insufficient to obtain seedlings showing gynogenesis. However, irradiation might have induced embryonic development and abortion of most growing embryos and seeds by pollination with irradiated pollen. Most embryos degenerated about 50 days after pollination: the end of June. Therefore, embryos must be rescued before the timing of gynogenesis. Obtaining individuals showing gynogenesis using the irradiated pollen method requires fruit set first. For this experiment, ‘Indo’ was considered a suitable cultivar because of its high fruit set percentage. However, ‘Jonathan’ was judged as unsuitable due to its low fruit set percentage. Self-fertilized individuals were completely removed by emasculation. However, self-fertilized individuals numbered less than one out of 100 pollinated flowers. Therefore, increasing the number of flowers without emasculation must be more efficient than emasculating flowers because emasculation operations require much labor. Furthermore, after growing the seedlings, the derivation of the seeds should be investigated using the SSR marker. The results clarified that some pollen fertility was maintained after 500 Gy of γ-rays. However, individuals produced from irradiated pollen were very few. Such individuals numbered less than 5 out of 700 pollinated flowers. Therefore, 500 Gy of γ radiation may have been appropriate as the exposure dose. Future studies should clarify procedures of pollen tube growth, fertilization, embryogenesis, and abortion of embryo growth. Acquisition of individuals derived from gynogenesis by embryo culture is necessary.

The association between the flower color and anthocyanin composition of petals was investigated in 9 cultivars of Salvia splendens Sellow ex Schult. and S. coccinea Buc’hoz ex Etl. ‘Flamenco Red’ and ‘Acapulco’ had reddish flower colors and the same major pigments: pelargonidin 3-O-(6-O-caffeoyl)-glucoside-5-O-(6-O-malonyl)-glucoside, pelargonidin 3-O-(6-O-caffeoyl)-glucoside-5-O-(4,6-O-di-malonyl)-glucoside, pelargonidin 3-O-(6-O-p-coumaroyl)-glucoside-5-O-(6-O-malonyl)-glucoside, pelargonidin 3-O-(6-O-p-coumaroyl)-glucoside-5-O-(4,6-O-di-malonyl)-glucoside. The chemical structures of anthocyanins in ‘Flamenco Red’, ‘Flamenco Rose’, and ‘Flamenco Salmon’ were compared. ‘Flamenco Rose’ petals did not contain the acylated anthocyanin combined with two malonic acid molecules, one of the main anthocyanins in ‘Flamenco Red’. ‘Flamenco Salmon’ petals did not contain the acylated anthocyanin combined with p-coumaric acid, one of the main anthocyanins in ‘Flamenco Red’. Also, the total amount of anthocyanins decreased in ‘Flamenco Salmon’. These factors may have affected the color tone. In ‘Flamenco Purple’ and ‘Fujipulco’, both flowers were purple in color, but the major anthocyanins were different. The major anthocyanins of ‘Fujipulco’ were: cyanidin 3,5-diglucoside, pelargonidin 3,5-diglucoside, cyanidin 3-glucoside-5-malonylglucoside, cyanidin 3-glucoside-5-malonylglucoside, and pelargonidin 3-glucoside-5-malonylglucoside. The present study is the first to report the presence of these four anthocyanins in cultivars of S. coccinea.

Direct seeding of onions leads to increased susceptiblity to meteorological conditions because it results in a longer growing period of about two weeks than transplant cultivation. Therefore, we investigated the effect of the combination of local fertilization consisting of nitrogen, phosphoric acid, and potassium, and a top-dressing of nitrogen and potassium on the growth and yield of directly sown onions in Tokachi, Hokkaido. In addition, the effect of the difference in soil moisture due to rainfall on growth and yield with the above fertilization methods during the experimental year was investigated. The results differed depending on the year of the experiment, and it was shown that the difference in top-dressing of nitrogen and potassium on the growth was affected by the amount of precipitation. Consequently, we inferred that the difference in fertilization method did not lead to an increase in the weight of bulbs due to the difference in nutrient uptake during each experimental year. Our results suggest that if rainfall occurs after the top-dressing application in the middle of June and the onions absorb the fertilizer component, the weight of bulbs would increase.

Due to recent global warming, the occurrence of flowering disorder is increasing in the open field cultivation of Japanese pear in warm regions such as Kyusyu. In the present 5-year study, we verified the effectiveness of spring fertilization, which is expected to reduce the occurrence of flowering disorder in ‘Hosui’ and ‘Kosui’ cultivars. In both cultivars, changing the fertilization season from autumn to spring improved the freezing resistance and reduced flowering disorder steadily over 5 years, while not affecting the fruit quality. In contrast, fertilizing in both autumn and spring did not improve freezing resistance or reduce flowering disorder. In conclusion, spring fertilization is an effective and practical cultivation technique to reduce flowering disorder.

In the production of satsuma mandarin (Citrus unshiu Marcow.) in Japan, mulch cultivation, which induces drought stress in trees, is often used for high-quality fruit production. However, there are cases in which drought stress has not been induced because rainwater flows into the root area, and the roots extend out of the mulching sheet. Therefore, I have developed ‘shielding-mulch cultivation’ (‘S. mulch’), a method of mulching the planting row and surrounding the root area with an exclusive plastic sheet (‘S. sheet’, width: 500 mm; thickness: 1.5 mm; length: 30 m; material: high-density polyethylene) under drainage-designed field conditions. This study verified the usefulness of this technology. The effects of drought stress on trees and soil moisture in the root area under ‘S. mulch’ and conventional mulch cultivation were investigated. As a result, the maximum water potential in the leaves (ψmax) of ‘S. mulch’ was controlled to –0.7 to –1.0 MPa, which is appropriate for high-quality fruit production. On the other hand, ψmax of conventional mulch cultivation was not suitable for high-quality fruit production. In addition, the soil moisture of ‘S. mulch’ was lower than that of conventional mulch cultivation during the fruit growth period. As is characteristic of fruit with induced drought stress, the fruit of ‘S. mulch’ at harvest had a higher sugar content, slightly higher acidity, and smaller fruits with a strong reddish skin color as compared with fruit produced with conventional mulch cultivation. Therefore, it was suggested that ‘S. mulch’ can stably produce high-quality fruits by reliably inducing drought stress.

To develop a new cultivation system that enhances yield by increasing the amount of photosynthesis while avoiding an increase in temperature and any associated damage, we evaluated the effect of a cultivation system wherein dense planting is only conducted in the summer, which is the initial stage of cultivation, pinching in autumn, and reducing planting density to the same level as conventional cultivation systems in winter. This experiment was conducted on cherry tomatoes. Additionally, we estimated the optimum leaf area index (LAI) and planting density necessary to maximize the amount of photosynthesis. Our study confirmed that a greenhouse environment was effective at lowering temperature and increasing humidity due to the increased transpiration that resulted from dense planting. The yield per plant throughout the entire period remained the same as that in the beginning, suggesting that the yield per area markedly improved. This is believed to be due to the fact that in summer, the amount of photosynthesis increased with increases in LAI and the sink strength of the plant community, as well as a decrease in the number of damaged, mainly cracked, fruits. Additionally, the integrated photosynthesis amount by each LAI was estimated from the amount of solar radiation, relative light intensity on the plant community, and light-photosynthesis curve. The optimum planting density (5.21 plants・m^–2 in summer) was estimated from LAI that maximized the amount of photosynthesis.

Using the bolting rate data in autumn planting onion in Tonami City, Toyama Prefecture, and Joetsu City, Niigata Prefecture, which are snow-covered areas in winter, this paper examines a bolting rate estimation model. The model uses two indexes, VD and VD_LN: VD is the value integrating the daily temperature response of vernalization, and VD_LN is the value integrating the product of the daily temperature response and number of leaves to include the effect of plant size on bolting. The coefficient of determination, R², in the nonlinear regression to the approximate curve with the bolting rate was investigated for VD and VD_LN by varying the periods of integration. When VD was used, R² was under 0.25 in all cases, and the rate of bolting could not be estimated accurately. On the other hand, using VD_LN, R² was around 0.75 at the maximum in the integration until January 20, or 80 days after planting when all the data of Tonami and Joetsu were used. R² was over 0.95 in the integration until February 20 or later, or until 120 days or more after planting when only the data of Tonami were used. Therefore, the effectiveness of the model using VD_LN was indicated. Practically, VD_LN > 490 at 140 days after planting was shown as a threshold of bolting incidence in Tonami.

To develop potted flower production of Veronica ornata (Plantaginaceae), which is a useful genetic resource endemic to Japan, the effects of pinching season and node order on flowering time and quality were investigated. As the pinching season become later, the flowering become later in the experiment using the potted flower ‘NG-1’. Also, as the pinching season become later, the accumulation of heat units until flowering was decreased. Regarding the potted flower quality at harvest, as the pinching season become later, the node number to flowering and the shoot length were decreased. In the case of a higher pinching position, flowering became earlier, the accumulative temperature to flowering was decreased, and the node number to flowering and shoot length were decreased. Flowering shoots were increased by pinching in all seasons and the node order in this experiment. Blind shoots were also increased by pinching at the end of June or with a low node order. These results indicate that the flowering time and quality can be controlled by means of pinching timing and the node order on potted flower production of V. ornata. Shipping of the potted flowers may be possible in early September for Respect for the Aged Day by means of pinching above 2 or 3 nodes from the base at the end of May.

We have investigated the effect of foliar urea sprays applied at the end of August and early September to promote early growth of ‘Shimizu-hakuto’ peach. The leaf color value measured by SPAD increased on urea application compared with the control. The size of the ovary was larger and the leaf color value was higher the next year. However, there was no significant difference in the fruit set. In order to confirm the distribution and utilization of nitrogen components derived from foliar spraying, ¹⁵N-labeled urea was sprayed twice on a 6-year-old pot-planted tree from late August to early September. We noted the rapid transportation of ¹⁵N to each part of the tree. A total of 28.9% of the nitrogen attached to the tree was absorbed. The absorbed nitrogen was translocated to other parts such as branches and roots, and distribution rates in flower buds, current shoots, and one-year-old wood in December were higher than in other parts. In the next year, the utilization rate in new tissues such as leaves and young fruit was about 3%, respectively.

The effects of storage in a high-humidity refrigerator, which creates low-temperature and high-humidity conditions, on the weight, elongation, and quality of young asparagus (Asparagus officinalis L.) stalks were investigated. After 11 hours of storage, the decrease in weight and length of young stalks was significantly smaller in the high-humidity refrigerator than in the normal refrigerator, indicating that the high-humidity refrigerator was effective in repressing weight loss of young stalks during storage. To clarify the effect of storage in each refrigerator on the quality of young stalks on subsequent display at sales outlets, young stalks stored for 0–72 hours in each refrigerator were kept in water in a refrigerated showcase for 3 days. Although no significant difference between the normal and high-humidity refrigerators was observed in terms of the quality of young stalks after 3 days of display, storage in the high-humidity refrigerator suppressed an unfavorable rapid increase in weight of young stalks during display that is observed in the normal refrigerator, suggesting its effectiveness as a short-term refrigeration technique immediately after harvest. As the storage period in the high-humidity refrigerator increased, the amount of weight and elongation of young stems after storage in the refrigerated showcase became smaller, and their sugar content increased. These results indicate the usefulness of the high-humidity refrigerator for storage of asparagus and the possibility of applying the high-humidity and low-temperature storage to maintain the quality of asparagus during the display period.

Attenuated total reflection (ATR)-Micro electro mechanical systems (MEMS)-infrared (IR) spectroscopy was applied to determine total free sugar content in fresh juice of fruit, with only one independent variable without direct water subtraction. The reference values of the total free sugar content were determined using high-performance liquid chromatography (HPLC). After the spectra of tomato and strawberry juice samples (n = 21 and 11, respectively) were measured, smoothing of ATR-MEMS-IR spectra was processed, and each calibration was generated using absorbance at 1032 cm^–1 and 1000 cm^–1 with a correlation coefficient of 0.98 and 0.98, respectively. The sugars of tomatoes were mainly glucose and fructose, and those of strawberries were sucrose, glucose, and fructose, and these results corresponded to the absorption of sucrose occurring at a lower wavenumber than those of glucose and fructose. These calibrations predicted other sample lots. Nevertheless, they were predicted well with a root mean square error (RMSE) of 0.22 (n = 13) and 0.46 g/100 mL (n = 13), respectively. Moreover, Bland-Altman plots were within limits of agreement (LOA). Water solutions of sucrose, glucose, and fructose also showed high correlation coefficients (1.0) between the concentration and absorbance at these wavenumbers with high sensitivity.

Silver thiosulfate complex (STS) treatment of Delphiniums (Delphinium elatum) with strong ethylene sensitivity is fundamental for growers before shipping cut flowers. However, early flower drop owing to inadequate STS treatment is often reported by markets to growers. Since high humidity owing to rainfall before and after harvest possibly causes inadequate STS treatment, the effects of relative humidity (RH) before harvest, and temperature and relative humidity during STS treatment on the absorption of STS solution and silver content of cut flowers were investigated. Potted D. elatum plants were held for 6 days before harvest in a phytotron under different RH conditions. STS solution absorption by flowers cut from plants under high-RH conditions was higher than that of flowers harvested under low-RH conditions. The stoma size of the sepals of flowers harvested under high-RH conditions was significantly larger than that of flowers harvested under low-RH conditions. STS treatments were performed at 23°C-70%, 23°C-80%, 30°C-70%, and 30°C-80%. At a given temperature, STS solution absorption at low-RH was greater than that at high-RH. The effects of RH conditions before harvest and during pulse treatment on STS solution absorption were then compared. When treated with STS under high-RH, RH encountered before harvest did not affect STS solution absorption. When treated with STS under low-RH, cut flowers harvested from plants under high-RH absorbed more STS solution than cut flowers harvested under low-RH.