To select cultivars to produce doubled haploids (DHs) efficiently in an anther culture, a total of 28 apple cultivars (25 cultivars and 3 rootstock cultivars) were investigated to assess their callus formation rate, embryo formation rate, shoot formation rate from embryo, and efficiency of shoot multiplication and acclimatization. The callus formation rates of ‘Red Astrachan’, ‘Kinsei’, ‘Tsugaru’, ‘Golden Delicious’ (‘GD’), ‘American Summer Pearmain’ (‘ASP’), ‘Gala’, ‘Rome Beauty’, and ‘Jonathan’ were high, but ‘JM2’ and ‘King of Tompkins’ formed no callus. Regarding the embryo formation rates, ‘ASP’, ‘Rome Beauty’, ‘M.9’, and ‘Starking Delicious’ (‘SD’) were high, but ‘GD’, ‘JM2’, ‘King of Tompkins’, ‘Ralls Janet’, and ‘Smith’s Cider’ formed no embryo. Regarding the shoot formation rate from embryos, ‘Senshu’, ‘Tsugaru’, and ‘Sansa’ showed high values, but ‘Fuji’, ‘Jonathan’, and ‘Wijcik’ did not form shoots at all. The rate of shoot formation from anthers showed a high–low order of ‘Senshu’, ‘SD’, ‘ASP’, and ‘Tsugaru’. Multiplication and acclimatization of the shoots were not easy. Many individuals died. Eventually, only ‘Senshu’ and ‘SD’ acclimatized. Therefore, cultivars that produced DHs efficiently were ‘Senshu’ and ‘SD’. The results indicated that all processes of “embryo formation”, “shoot induction”, and “shoot multiplication and acclimatization” are important for obtaining DHs in apple anther cultures.

A new method of inducing fruit abscission by incubating detached ovaries and fruits in agar medium was developed in citrus. Ovary and fruit abscission in the satsuma mandarin, ‘Kiyomi’, hyuganatsu, and ponkan during early physiological fruit drop was characterized using this method. For primary physiological fruit drop, the abscission of detached ovaries could be divided into three patterns, including an early type in hyuganatsu, a medium type in ‘Kiyomi’, and a late type in satsuma mandarin and ponkan. The cumulative abscission ratio of four species and cultivars was over 80% at 96 h after treatment. However, for secondary physiological fruit drop, the initiation of fruit abscission was earliest in hyuganatsu, and latest in satsuma mandarin. The cumulative abscission ratio was highest in ponkan at 84% and lowest in hyuganatsu at 6%. The pattern of abscission was different for primary and secondary physiological fruit drop in the four species and cultivars. High temperature promoted the abscission of detached ovaries and fruits in satsuma mandarin and ponkan. Leaf attachment suppressed fruit abscission in ‘Kiyomi’, hyuganatsu, and ponkan at 7 weeks after anthesis in 2012 and ponkan at 5 weeks after anthesis in 2013. Ovary and fruit abscission in four species and cultivars during early physiological fruit drop was characterized by incubating detached ovaries and fruits in agar medium.

Dead flower buds were frequently observed in the Japanese pear cultivar ‘Kosui’ (Pyrus pyrifolia) when trees were cultured under open field conditions in the southwestern regions of Japan. To elucidate the causes of dead flower buds, we studied the effect of nitrogen (N) supplements using two experimental designs that included trees grown in pots and in the field. First, we investigated the effect of applying chemical N fertilizer during the winter using potted trees (controlled temperature experiment). We also investigated the effect of applying livestock waste compost during the fall-winter months on flower bud freezing tolerance and on the N and sugar contents of flower buds from trees cultivated in the field. In controlled temperature conditions, the percentage of dead flower buds significantly increased when N fertilizer was applied in December and January. In field conditions, compost application in the fall-winter months significantly reduced the freezing tolerance of flower buds concomitant with a significant increase in the percentage of dead flower buds compared to compost application in the spring. Application of compost in the fall-winter months resulted in a significantly higher N content compared to that in spring. In contrast, the relationship between the sugar content and freezing tolerance of flower buds is unclear. This potential connection remains to be elucidated in the near future. Collectively, these results suggest that compost application during the fall-winter season can adversely affect freezing tolerance through an increase in the N content, thus promoting dead flower buds.

The consumption of vegetables and fruits rich in potassium (K), such as melons and strawberries, is restricted in chronic kidney disease (CKD) patients. Therefore, we attempted to produce low-K strawberry fruits through management of a KNO₃ fertilizer in nutrient solution from anthesis to the harvest period. A general trend of decreasing K content in fruit was observed with the decrease of KNO₃ concentration in the nutrient solution. Among four strawberry cultivars, the fruit of the ‘Toyonoka’ exhibited a K reduction of about 64% when plants were grown in nutrient solution with KNO₃ at 1/16 of the normal level. Citric acid and ascorbic acid contents of ‘Toyonoka’ fruit were reduced with decreasing KNO₃ concentrations in the nutrient solution. Although the reduced NO₃⁻ of the nutrient solution was adjusted by using Ca(NO₃)₂ to obtain low-K strawberries, growth, yield, and quality did not vary with this adjustment. Compared with the typical level of K in strawberry fruit of 170 mg/100 g FW (Standard Tables of Food Composition in Japan, 2011), a 23.5% decrease (130 mg/100 g FW) in K was found in 1/32 level of KNO₃. The K contents of plant parts suggested that the low KNO₃ level was responsible for the low K absorption, which may have affected the translocation and accumulation of K into fruit. Therefore, 1/32 level of KNO₃ in nutrient solution lowers the fruit K content considerably.

Harvesting of asparagus spears is hard work because farmers have to harvest spears in a crouching posture. We previously developed electric long-shafted shears and a large-wheeled cart to improve the harvest posture, and we reported that the visibility of spears can be improved by modified branch training using string, without any yield or quality reduction. In the present study, we investigated the harvest efficiency, harvest posture, and subjective burden with electric long-shafted shears and a large-wheeled cart under modified branch training methods (the new standing harvest method) for labor-saving asparagus spear harvesting. Two male subjects in their 30s and 60s harvested spears for 60 min using (standing harvest) and without using (control) the new standing harvest method. The harvest efficiency of the new standing harvest method was 18% lower than that of the control. In the standing harvest, subjects had to pull the shears up to take the harvested spear from the shears with their left hand after each spear was cut (“take”). The subjects needed time for the “take” action, and the time necessary to harvest a spear with the electric long-shafted shears was longer than that required for the control. We also evaluated the harvest posture using the Ovako Working Posture Analyzing System (OWAS). For the subject in his 30s, action category(AC)2 and AC3 accounted for 72% and 14% of the postures recorded in the control, respectively, whereas in the standing harvest, AC1 and AC2 accounted for 57% and 41%, respectively. For the subject in his 60s, AC2 and AC3 accounted for 41% and 58% of the postures recorded in the control, respectively, whereas in the standing harvest, AC1 and AC2 accounted for 27% and 70%, respectively. Unfavorable postures during harvest were reduced by the new standing harvest method. The subjective physical burden on the subjects was evaluated using a modified Borg scale after 60 min of harvesting using and without using the new standing harvest method. The subjective physical burden in both subjects was highest (> 8) at the waist in the control, whereas the scores were lower than 3 in the standing harvest. Thus, the new standing harvest method reduced harvest efficiency, but resulted in substantial improvements in posture and reduced the physical burden on the subjects.

Contamination of vegetables with cadmium (Cd) is a worldwide problem. Three pot experiments were carried out to reduce the Cd content in fresh fruit of 52 Japanese pepper (Capsicum annuum L.) cultivars. The first experiment was carried out to select low Cd pepper cultivars after growing on a 2.1 Cd mg·kg⁻¹ contaminated soil. The second experiment was carried out to select low Cd-accumulating pepper rootstocks while the third experiment was carried out to evaluate grafting as a tool to reduce Cd in fresh peppers. The ability of pepper cultivars to accumulate Cd in fresh fruit was significantly different. The Cd content ranged from 0.018 to 0.088 mg·kg⁻¹ of fresh weight (FW). Among the pepper rootstocks cultivated in Japan, the cultivar ‘Daisuke’ was selected as a low-Cd accumulating rootstock. The grafting of cultivar ‘Ace’ onto ‘Daisuke’ rootstock reduced the Cd content by 40% in fresh peppers. However, other trace elements such as Fe, Mn, and Zn, which are important for human nutrition, were also reduced by 20%, 29%, and 42%, respectively.

The roles of plant hormones in the early growth of pepper fruit (Capsicum annuum L.) were investigated. An exogenous hormone treatment study indicated that cytokinin (CK) was more effective at stimulating early fruit growth in two lines than auxin or gibberellin (GA). Endogenous levels of CKs, 3-indole-acetic acid (IAA), and GAs in young pollinated and unpollinated fruit of four lines (two with medium-sized and two with small fruit) were also investigated. In pollinated fruit, the level of trans-zeatin riboside (tZR) increased with fruit size. In unpollinated fruit, tZR did not increase in any lines. IAA levels decreased gradually after flowering and did not differ between pollinated and unpollinated fruit in any lines. Levels of GA₁ in unpollinated fruit of the lines in which unpollinated fruit were relatively well enlarged were slightly higher. In the line in which unpollinated fruit could not enlarge, GA₁ levels of all samples were lower than the others. These results indicate that tZR is important in the early enlargement of pollinated pepper fruit, and that GA₁ is involved in early fruit enlargement, especially in unpollinated pepper.

Pungency in peppers is due to the presence of the alkaloid capsaicin and its analogues, collectively known as capsaicinoids. These compounds are only produced in the Capsicum genus and function as deterrents to mammals from consuming the pepper fruits. Pungency in pepper is qualitatively controlled by the Pun1 locus, which encodes a putative acyltransferase enzyme. Mutations in the Pun1 gene result in a loss of pungency, and several Pun1 loss-of-function alleles have been identified in sweet peppers to date (pun1^1–3). However, variations in pun1 alleles have not been completely elucidated. In the present study, we report a new type of loss-of-function pun1 allele, named pun1⁴, in a Japanese sweet pepper cultivar, ‘Nara Murasaki’ (C. annuum). Sequence analysis at the Pun1 locus revealed that this type of Pun1 allele is caused by a single adenine nucleotide insertion in the second exon region. This insertion is unique to ‘Nara Murasaki’ and is not present in wild-type Pun1. This insertion causes a frameshift mutation and a change in the amino acid sequence, resulting in a truncated protein. The results of gene expression analysis indicated that the expression of Pun1 in ‘Nara Murasaki’ was hardly detectable, while the transcripts of this gene were strongly expressed in a pungent cultivar. In a co-segregation test, the pun1⁴ genotype perfectly co-segregated with non-pungency in 103 F₂ population plants of a cross between ‘Nara Murasaki’ and a pungent cultivar. ‘Nara Murasaki’ and a DNA marker to distinguish the pun1⁴ allele will be informative for understanding the domestication process of sweet peppers.

In the tomato (Solanum lycopersicum), the position of the inflorescence on the stem is known to affect the number of days to first anthesis and has commonly been characterized by the leaf-number (ordinal number from the oldest leaf) of the leaf just below the inflorescence (LEAF-BI) only by the appearance after extension of the stem near the inflorescence. Some examples showing that this evaluation was not suitable were observed by the authors. To confirm the reproducibility of the observation, experiments were conducted in which 4 cultivars were sown in a greenhouse 12 times from Oct. 2008 to Aug. 2010. Based on the vertical positional relationship between the base of the first, second, or third inflorescence and the base of the last initiated leaf before inflorescence primordium on the growing point (L-LEAF, the true guide for determining the inflorescence position), the L-LEAFs of ‘My Lock’ plants in all growth periods and ‘House Momotaro’, ‘Momotaro 8’, and ‘Super Fast’ plants in the non-high-temperature growth periods were always just above the inflorescences, that is, the LEAF-BIs were always the leaves below the L-LEAFs. In contrast, the L-LEAFs of all cultivars except ʻMy Lockʼ in the high-temperature growth periods were often just below the inflorescence, that is, the LEAF-BIs were often the L-LEAFs. Comparing the leaf-number of LEAF-BI and that of L-LEAF demonstrated that the former often overestimated the inflorescence positon among growth periods and cultivars. In temperature treatments with ‘House Momotaro’, such a positional switch of the L-LEAF was reproducible. External observation indicated that the stem on the L-LEAF side and the stem on the inflorescence side extended non-uniformly and the position of the L-LEAF was determined by which side extended faster. Collectively, the LEAF-BI is not a leaf identified morphogenetically, and to identify the position of the inflorescence, the leaf-number of L-LEAF, not LEAF-BI, should be used.

Transport of water into cells is mediated by plasma membrane intrinsic protein (PIP) families of aquaporin, which are involved in petal cell expansion during flower opening. In this study, we performed comprehensive characterization of aquaporin family genes and analyzed the expression of PIP genes in petals of opening flowers to examine the role of PIPs in flower opening in the carnation (Dianthus caryophyllus L.). A database search of the genome sequence revealed the existence of 26 aquaporin genes with 8 members of the PIP subfamily in the carnation ‘Francesco’. The expression of all the PIP genes was validated by the existence of expressed sequence tags, and expression analysis by quantitative reverse transcription-PCR showed that DcPIP2;1 and DcPIP1;1 are the two major PIP isoforms expressed in petals of the ‘Pure Red’ carnation. The transcripts of these two genes were also detected abundantly in other floral tissues including the calyx, style, receptacle, and ovary, as well as stems and leaves. The expression of DcPIP2;1 and DcPIP1;1 in petals was maintained at a high level throughout the flower opening process. These data suggest a putative role of these PIPs in petal growth for flower opening.

Cut hydrangea (Hydrangea spp.) flowers are marketed at two different harvest stages, the fresh- and antique-stages. Flowers cut at the fresh-stage are harvested just after the coloring of decorative sepals is completed before flowering, and flowers cut at the antique-stage are harvested when the decorative sepals develop green and/or red colors after flowering. In almost all cultivars, an increase in the hydraulic conductance of the stomata (stomatal conductance) of the abaxial side of decorative sepals occurs during the transition from the fresh to the antique-stage. We investigated the relation between the stomatal conductance increase and the severity of the damage to decorative sepals. The degree of stomatal conductance increase regressed with the severity of the damage occurrence to the antique-stage decorative sepals before harvest. The relation between the stomatal conductance increase and vase life of antique-stage cut hydrangea flowers was also investigated. Abscisic acid (ABA)-treated antique-stage cut flowers exhibited lower stomatal conductance on the abaxial side of decorative sepals than control cut flowers. A photoperiodic change in the transpiration was observed in the control cut flowers, but not in ABA-treated cut flowers. These ABA treated cut flowers had longer vase lives than control cut flowers. To achieve minimal damage before harvest and longer vase life in the antique-stage during cut hydrangea flower production, screening for stomatal conductance non-increasing cultivars would be desirable. Since the stomatal conductance of antique-stage decorative sepals showed a highly significant correlation with fresh-stage decorative sepals, these can be used as an index in screening for stomatal conductance non-increasing cultivars.

The flowering response to monochromatic light and flowering-related genes underlying this response need to be characterized to efficiently use light-emitting diodes for lighting culture. The flowering response to far-red light has been well studied in long-day cut flowers, but there have been few studies investigating the response to blue light. Flowering and the expression of the G. paniculata homologs of the FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 genes (GpFT, GpSOC1) were not previously promoted in Gypsophila paniculata, an important long-day cut flower, ‘Bristol Fairy’ under long-day conditions with blue light. In the present study, we found that flowering was promoted in another G. paniculata ‘Million Star’, under long-day conditions with blue light, suggesting that there is variation in G. paniculata’s flowering response to blue light. Therefore, we analyzed the expression of GpFT and GpSOC1 in the ‘Million Star’. The expression of GpFT and GpSOC1 was promoted with flowering in ‘Million Star’ under long-day conditions with blue light in contrast to ‘Bristol Fairy’. We next analyzed the G. paniculata homologs (GpFKF1, GpGI) of FLAVIN-BINDING KELCH REPEAT F-BOX 1 and GIGANTEA genes, which participate in the flowering response to blue light. GpFKF1 and GpGI amino acid sequences were well conserved; gene expression showed a diurnal rhythm with different peaks under short-day and long-day conditions, as previously observed in Arabidopsis thaliana. GpFKF1 interacted with GpGI. There were no important differences in GpFKF1 or GpGI amino acid sequences between the two cultivars. Our results suggest that variation in the flowering response to blue light is associated with GpFT and GpSOC1, rather than GpFKF1 and GpGI.

Physiological and psychological effects of rose aromas have been reported. Many of these reports focused on the effect of rose essential oils, but the effect of rose fresh flowers on humans has not been sufficiently reported. We were also interested in the possibility of using rose hydrosol, a byproduct of the rose essential oil manufacturing process, for aromatherapy. In this study, the physiological and psychological effects of rose ‘Wishing’ fresh flowers and their hydrosols on humans were evaluated. R–R power spectral analysis of heart beats revealed the sedative effect of the fresh flowers’ scent. On the other hand, hydrosols did not show such an effect. Gas chromatography (GC) and GC-mass spectrometry (GC-MS) analysis indicated the possibility that the sedative effect of the fresh flowers’ scent was derived from β-caryophyllene, phenylethyl acetate, and 3,5-dimethoxy toluene. It is possible that fresh rose flowers may be an alternative to rose essential oils in aromatherapy.

We investigated the relationship between shoot apex morphology and anthesis time in five cultivars of Chrysanthemum morifolium flowering in summer. Fluctuating weather conditions in nature make stable production of agricultural crops difficult. The timing of floral induction and flower formation are determined by environmental factors such as day length and temperature. Although genetic analyses using model plants have provided a lot of knowledge regarding the molecular mechanism of flowering, it is difficult to apply to agricultural plants growing in the field because of the inconstant weather and lack of molecular analysis tools of many farmers. A simple morphological marker that enables farmers to predict anthesis time is useful for stable production of field-grown crops. We examined the shoot apex morphology of five Chrysanthemum morifolium cultivars weekly. Measurement of the shoot apex diameter by image analysis software showed that the shoot apex enlargement can be separated two phases, early slow-growth and later rapid-growth phases. We defined the developmental stages of the shoot apex in C. morifolium and found that the diameter of the shoot apex and developmental stages had a proportional relation. Each cultivar had a different inclination in an approximation straight line in the later rapid-growth phase. Comparison of the shoot apex morphology and weather records revealed different responses to the ambient temperature among the cultivars. The data suggest that weekly observation of the shoot apex makes it possible to characterize the cultivar and can be used to predict anthesis time. This is useful as a simple morphological marker for stable production of C. morifolium grown outdoors.

Physiological qualities of F₁ hybrid tomato seeds affected by the growing season; maturity stage at 40, 45, 50, 60, and 70 days after cross-pollination (DAP), and storage in plastic bags at 0°C for four months were studied. The characteristics of seeds from early harvested fruits (45 DAP) that subsequently ripened at ambient temperature (28 ± 2°C) for ten days (designated as “45+ripening”), were also investigated. Higher light intensity, and a wider range of night and day temperatures and relative humidity (RH), but lower night temperature and RH, were observed in the winter season compared to the rainy season. The winter climate delayed physiological maturity of the seeds by 10 days, indicated by the highest weight of dried seed, percentage germination and germination index which occurred at 60 DAP. On the other hand, in the rainy season physiological maturity occurred at 50 DAP. The proportions of irregularly shaped seeds, abnormal seedlings and weak seedlings were independent of fruit and seed maturity, while the amount of speckled seeds significantly increased with an increase in seed development on either the mother plant or the 45+ripening. Fresh (non-stored seeds) and stored seeds of the fruits harvested at 45+ripening and at 60 DAP showed the same quality. The number of fresh ungerminated seed in the seeds of 45 and 50 DAP was markedly reduced after four months storage at 0°C.