To develop an effective method to raise apple saplings, we investigated the effect of gibberellin paste on shoot elongation of current-year apple saplings. When 100–200-mg paste containing 2.7% gibberellic acid was applied near the shoot tip 2–3 times after spring grafting to August, shoot elongation of the columnar apple ‘Wijcik’ was promoted under both greenhouse and field conditions. In contrast, shoot elongation of ‘Fuji’ was not promoted by the application schemes under field conditions where shoots grew vigorously, but was promoted in a greenhouse experiment using pot culture where shoot-growing activity was weaker. However, 5-times-application of 100-mg gibberellin paste after sprouting to August significantly increased shoot length compared with non- or 3-times-applied saplings. This effect was consistently confirmed in non-columnar cultivars ‘Fuji’, ‘Shinano Sweet’, and ‘Shinano Gold’ and columnar apples ‘Wijcik’ and Morioka 74. This application also increased lateral shoots of all cultivars except Morioka 74. As a result, we found that 5-times-application of gibberellin paste during the growing season significantly increased shoot elongation of current-year-old apple saplings

This study assessed effects of irrigation on the occurrence of fruit sunburn injury of eggplant ‘Senryo’. In fields of growers, the rate of fruit sunburn injury occurrence was higher in fields with a low mass water content. In a research field, a treatment was prepared with pF 2.0 or pF 1.6 at the beginning of irrigation during March–June, when injury occurs most often. The difference in the occurrence rate between the two plots was small. Furthermore, when the beginning points of irrigation were set to pF 2.3 and pF 1.6, results showed a higher xylem exudation rate in the pF 1.6 plot. The occurrence rate was significantly lower in the pF 1.6 plot (35%) than in the pF 2.3 plot (43%). However, in the greenhouse with a low soil humus content (20.0 g・kg^–1), the occurrence of sunburn injury was significantly higher than in greenhouse B, where the soil humus content was 30.5 g・kg^–1. Therefore, organic matter was applied continuously for three years in greenhouse A. The results showed that the soil humus content was increased to 26.0 g・kg^–1. The rate of sunburn injury occurrence in greenhouse A was lower than that in greenhouse B, where organic matter had not been applied for three years. The results presented above suggest that the beginning point of irrigation that can reduce sunburn injury occurrence is pF 1.6–2.0. Before planting, the humus content should be raised or maintained by applying of organic matter to improve physical properties of soil.

Fertilization methods in which the nitrate concentration in leaves is low and yield is high in the cultivation of chinese chive in an andosol were investigated. The nitrate concentration in the leaves and nitrate nitrogen (N) content in the soil rose as the N content of the basal and additional chemical fertilizer increased A total of 600 kg・a^–1 of compost with a comparatively high C/N ratio in which N was slowly mineralized, was applied, and the nitrate-N content in soil and nitrate concentration in leaves were low, and the yield was high. The nitrate-N content and available N in the soil before planting were analyzed, and the amount of N which was subtracted from the standard application amount (2 kg・a^–1 N) was applied. Furthermore, controlled-release fertilizer was additionally applied, resulting in the nitrate concentration in leaves being relatively low and the yield being high. Based on these results, we propose a fertilizer application system using 600 kg・a^–1 of compost, a reduced amount of N-based fertilizer, by analyzing the nitrate-N content and available N in the soil before planting, and the additional application of controlled-release fertilizer, as a new fertilizer management method for chinese chive in an andosol to reduce the nitrate concentration in leaves and increase the yield.

In this study, to further clarify the mechanism of mulching treatment-induced β-cryptoxanthin accumulation, the effects of mulching on the expression of carotenoid metabolic genes were investigated in the flavedo of satsuma mandarin ‘Aoshima unshiu’ during fruit maturation from September to November. The results showed that the β-cryptoxanthin content in the flavedo was not significantly affected by the mulching treatment in September. However, the mulching treatment enhanced the β-cryptoxanthin content in October and November, in which the β-cryptoxanthin content in the flavedo was 1.9-fold and 1.4-fold higher than that of the control, respectively. Gene expression results showed that expressions of CitPSY, CitPDS, CitZDS, CitLCYb2, CitHYb, and CitZEP, involved in carotene and xanthophyll syntheses, were higher than in the control in September and October. In particular, expression levels of CitLCYb2, CitHYb, and CitZEP in the mulching treatment were much higher than in the control. In November, expressions of CitLCYb1 and CitLCYb2 were significantly up-regulated by the mulching treatment. Both enzymes of CitLCYb1 and CitLCYb2 participated in the biosynthesis of β-carotene; especially the expression level of CitLCYb2 in the mulching treatment was particularly high from September to November. These results suggest that the up-regulation of β, β-xanthophyll biosynthetic genes led to an increase of the β-cryptoxanthin content in the flavedo treated with mulching. In addition, it was suggested that the high expression of CitLCYb2 played an important role in the marked accumulation of β-cryptoxanthin in the mulching treatment.

Our aim was to reduce labor in persimmon tree husbandry and establish a simple cultivation method for the workability of persimmon bud thinning, fruit thinning, harvesting, and pruning, which are the main tasks on cultivating persimmon trees. So, we compared the workability of V-shaped trellis training and flat trellis training in a joint training system with the customary practice of the open center natural form of persimmon cultivation. The working time per 10 ares was the shortest for the joint V-shaped trellis for all tasks. Furthermore, the rate of increase in heart rate or the proportion of AC3 or higher was higher based on the Ovako Working Posture Analyzing System, and the surface myoelectric potential during harvesting was also the lowest for the joint V-shaped trellis. These findings suggest that the joint V-shaped trellis for persimmon is a training method that reduces the burden loaded on workers.

In this study, we evaluated the growth and fruit production of ‘Akatsuki’ peach trees trained to a tree joint V-shaped trellis system (JV-trellis) applied at two distances of 150 and 200 cm between planting rows. In addition, given the strong tendency for enlargement of the lateral branches close to the main trunk, we examined the effects of the timing of pinching shoots and autumn pruning on lateral branch growth in JV-trellis. We found that the crown expansion and height of trees trained using JV-trellis were earlier and lower, respectively, than those recorded in the control modified open-center system. However, no significant differences in growth or productivity were detected with respect to the two planting distances in JV-trellis. In the 4^th year (6 years old), the yield of the JV-trellis trees was 2.8 t・10 a^–1, which represents an increase of 20% compared with trees cultivated using the modified open-center system. However, we detected no significant differences between the fruit quality of fruit produced using JV-trellis and modified open-center systems. Furthermore, pinching shoots until 45 days after full bloom and pruning until 1 month after harvest were effective measures for controlling the growth of branches, although it was insufficient to reduce branch growth. In conclusion, the JV-trellis ‘Akatsuki’ system is considered to be applicable for attaining early yields of ‘Akatsuki’ peach, although it would be difficult to continue stable production in the long term, unless effective lateral branch management technology is established to reduce the growth of lateral branches.

In this study, we developed a convolutional neural network (CNN)-based classification model to count the number of leaves of direct-seeded onions using images captured by a 100 million pixel aerial camera mounted on a drone in an outdoor field. Firstly, since there were several other types of vegetation, such as weeds, in outdoor fields, we evaluated the effect of removing non-onions from the training data on the classification model. It was demonstrated that it was not necessary to define classes such as weeds, as they appear infrequently, when performing CNN using images captured in outdoor fields. Secondly, in the validation of classification model-2, it was determined that the model could not be sufficiently modified to extract features due to the small sample size, which led to biased results. Therefore, in order to correct the imbalance between the classes of development data in this study and include a wide range of features in each class, we split the data set into two classes based on the number of leaves. As a result, the classification of the model was improved and it was concluded that this modelling approach could be used to detect seedlings with fewer than four leaves in onion cultivation.

We investigated a method to estimate the amount of photosynthesis and fruit load of strawberries. The amount of photosynthesis was expressed as dry matter production, which was calculated by multiplication of light use efficiency and intercepted light. The total amount of light received was estimated using Kinect, which can be easily and temporally measured in the field for the same plants. The fruit load was expressed by the increase in fruit dry matter, and was estimated using the fruit enlargement curve created in this study. The estimated changes in dry matter production fluctuated depending on the direct light receiving leaf area measured by Kinect, the amount of solar radiation, and light use efficiency. The change in the amount of increase in fruit dry matter was markedly influenced by the fruit set condition of the fruit cluster. By comparing these values, we considered the time when the plants were enriched or exhausted. In order to verify the validity of the estimation, comparing the ratio of increase in fruit dry matter in dry matter production, the value of actual measurement remained higher than that estimated, but the trend was similar. In the future, it will be necessary to collect and verify survey data, and it was suggested that photosynthesis and fruit load can be estimated using the proposed method. Furthermore, it was shown that the value obtained by subtracting the fruit load from photosynthesis could be used as an index indicating the enrichment or exhaustion of plants.

To elucidate the effects of brine fulvic acid on hydroponically grown leaf lettuce, the endogenous plant hormones indole-3-acetic acid (IAA), trans-zeatin (tZ), isopentenyl adenine (iP), gibberellin₁ (GA₁), gibberellin₄ (GA₄), and abscisic acid (ABA) were quantified. After 39 days of hydroponic cultivation, the above-ground weight of the plants was significantly increased in the brine fulvic acid treatment. The concentration of IAA was 7.3 times higher in the largest leaf in the brine fulvic acid treatment than in the control treatment. tZ concentration in the root zone tended to be higher in the base zone in the control treatment, whereas in the brine fulvic acid treatment, it tended to be higher at the apical zone. The iP concentration was higher in roots in the brine fulvic acid treatment. The GA₁ concentration was lower in leaves than in roots, but was higher in roots in the brine fulvic acid treatment. The GA₄ concentration was lower in both leaves and roots in the brine fulvic acid treatment. Overall, the GA₁ concentrations were higher than GA₄ concentrations in roots, with the C-13 hydroxylation pathway being dominant. The GA₁ concentration was higher in the new leaves than in the largest and outer leaves in both the control and brine fulvic acid treatment, and it was about twice as high in the control treatment and about seven times as high in the fulvic acidic treatment. ABA concentrations were generally higher in leaves in the brine fulvic acid treatment. The highest value of 209 pmol・g^–1 FW was noted in the outer leaves.

To improve flower opening and vase life of Dutch iris (Iris × hollandica) cut flowers after cold-dry storage, we investigated the effects of silver thio-sulfate complex (STS), as an alternative to expensive gibberellin (GA₃), and the combination of STS and benzyladenine (BA). The flowering rate at 0.2 mM STS treatment before dry storage at 5°C for 5 days was 60%, higher than 0% in the control (tap water) but lower than 100% in 100-ppm GA₃. The vase life of cut flowers treated with STS or GA₃ was extended from 4.0 to 5.0 days, but it was shorter than those treated with 100-ppm BA, i.e., 5.8 days. STS or BA treatment after storage promoted the flowering rate and extended vase life more than the control, but GA₃ treatment decreased the flowering rate to 20%, and did not extend the vase life. The combination treatment of STS and BA before storage extended the vase life by 2.5, 1.7, and 1.1 days, compared with the control, STS, and BA, respectively. The effect of STS plus BA was not significantly different from that of the combination of GA₃ and BA. The cut flowers pre-treated with the combination of STS and BA showed accelerated flowering and a prolonged vase life even after storage at 5°C for 15 days. The cost of STS treatment per 5 mL at 0.2 mM was estimated to be 0.04 Japanese yen, which was lower than that of 2.3 yen for 100 ppm GA₃. Therefore, the combination treatment of STS and BA can be recommended as an economical method to improve postharvest quality after cold-dry storage in cut Dutch iris.

We would like to introduce and promote open field cultivation of vegetables, such as directly sown onions, in regions devastated by the Great East Japan Earthquake in Fukushima Prefecture. In particular, directly sown onions, in contrast to transplanted onions, do not require a greenhouse to grow seedlings. This can significantly reduce the time spent on raising seedlings and settled planting. In the field, the growth period of directly sown onions is longer than that of transplanted onions. It is important to reduce damage caused by weeds after sowing, since growth immediately after sowing is slow, which makes it easy for weeds to compete with the crop. Therefore, this study examined the influence of both the single and combination of multiple herbicides on growth and yield of direct-sown onions in autumn in Fukushima Prefecture. The herbicidal effect of a single treatment of dazomet or prosulfocarb was insufficient for some weed species. We demonstrated that weed control can be achieved by spraying prosulfocarb in combination with either dazomet (which can be used up to 14 days before sowing) or cyanazine (which can be used after sowing and before emergence). The results of this study show that weeds can be controlled by combining multiple herbicides without having any effect on growing onion crops or the final yield, by sowing the onion crop directly in the fall.

Onions for food processing are required to have certain properties, such as large bulbs, high-yield after being peeled, and in the case of producing sauté, a low bulb moisture content. In order to meet these demands, the new long-day and late-maturing F₁ cultivar ‘Surarippu’, which has a broad elliptic bulb shape and high dry matter content, has been bred. At our breeding site, the bulb shape index (ratio of bulb height to diameter) of ‘Surarippu’ was 1.15, which was higher than that of ‘Super-Kitamomiji’ (0.91, SKM), a leading late-maturing cultivar in Hokkaido. This means that the bulb of ‘Surarippu’ has few inedible parts, i.e., neck and basal plate. Therefore, the yield of edible parts increases after peeling and trimming. The dry matter content of ‘Surarippu’ (11.6%) was about 1.5 percentage points higher than that of ‘Kitamomiji2000’, a leading mid-maturing cultivar similar in shape to SKM, which led to heat treatment time reduction by 11 percentage points. Throughout the entire process, the use of ‘Surarippu’ led to an improved processing yield. When stored under suitable conditions, ‘Surarippu’ can be supplied for processing until late April of the following year. Furthermore, ‘Surarippu’ is resistant to Fusarium basal rot, the same as SKM (resistant), and its bulb weight and yield at the breeding site were approximately 1.45 times SKM’s. ‘Surarippu’ has many unique characteristics complementing the demands of the food processor, and is adaptable to a wide range of production areas in Hokkaido. Therefore, it is expected that the use of ‘Surarippu’ will expand in the food industry.