著者

Miyu Yamaguchi Amane Yamazaki Masako Akutsu

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-097, (Released:2023-11-28)

---

Strawberries, the most economically well-known berry crop, are known for their taste, nutritional value, and antioxidant compounds. Various spatiotemporal or seasonal factors are known to affect the strawberry pollen germination rate; however, determinating which factor most influences the variation in the pollen germination rate remains challenging. This study aimed to determine the optimal pollen germination media and pollen short-term storage methods in the Japanese strawberry cultivars ‘Shindai SUS-1’ and ‘Shindai BS8-9’. Each strawberry pollen was incubated for 3 h in the dark on a solid medium with 1.5% agar and different sucrose and boric acid concentrations. The pollen germination rate was then investigated. The optimal pollen germination medium for both cultivars was 1.5% agar, 10% sucrose, and 0.1% boric acid. The small amount of strawberry pollen used in this study was collected immediately after flowering in the morning. Therefore, we also investigated a method for collecting a large amount of pollen while maintaining pollen activity. For both cultivars, the pollen germination rate for dry pollen, incubated for 24 h with silica gel after the petals and calyx were removed, was the same as that of the fresh pollen collected immediately after flower collection. In addition, dry pollen was more efficient in terms of short-term storage than fresh pollen. For ‘Shindai BS8-9’, the germination rate for dry pollen was also higher than that of the fresh pollen when stored in vacuum at −25, 4, 15, 20, and 25°C for 3 and 7 days.

著者

Chairat Techavuthiporn Amnat Jarerat Chonlada Singhkai Hataitip Nimitkeatkai

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-092, (Released:2023-11-02)

---

The effects of UV-C treatment on physicochemical quality, bioactive compounds and antioxidant activity of okra (Abelmoschus esculentus L.) during storage were investigated. Okra pods were exposed to UV-C irradiation dose at 1.5, 3.0 or 6.0 kJ·m−2 before storage at 10 ± 2°C for 12 days. The results showed that UV-C treatment had a significant effect on okra bioactive compounds, such as ascorbic acid, total phenolic, flavonoid contents and antioxidant activity. The highest values of these compounds were observed in okra treated with 6.0 kJ·m−2 UV-C irradiation. A statistical analysis of the data demonstrated that mucilage had a favorable association with antioxidant capabilities and bioactive substances in response to UV-C treatment. Moreover, UV-C treatment also effectively maintained the quality of okra during storage, as evidenced by lower weight loss and higher firmness without incidence of decay. Therefore, postharvest UV-C treatment can be a potential approach to enhance bioactive compounds and maintain the quality of okra during storage.

著者

Toshihiko Sugiura Makoto Takeuchi Takuya Kobayashi Yuta Omine Itaru Yonaha Shohei Konno Moriyuki Shoda

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-085, (Released:2023-11-02)

---

The growing-degree-days (GDD) model for pineapple was developed to predict flowering and harvest dates; however, it has not been adapted to the climate in Japan’s growing regions, where air temperatures fluctuate over a wide range, and the prediction accuracy is low. The present study aimed to develop models for predicting flowering and harvest dates with high accuracy by analyzing a large phenological dataset from Japan’s main (Nago) and warmer (Ishigaki) production areas. The number of days between budding and flowering decreased at air temperatures of up to approximately 25°C and remained constant above 25°C. The number of days between flowering and harvest decreased until approximately 23°C. The effect of day length on both days to flowering and harvest was small. The relationship between air temperature and the developmental rate after budding to flowering and after flowering to harvest was modeled using the GDD and exponential function models, both with upper limits. The GDD model with an upper limit temperature was more accurate at predicting flowering and harvest dates compared to the conventional GDD model. In particular, the prediction accuracy of the harvest date was dramatically improved. Because the relationship between the developmental rate until flowering and the air temperature was exponential rather than linear, the exponential function model provided a more accurate prediction of the flowering date. The root-mean-square errors of the most accurate models were 3.7–6.1 days for predicting the flowering date and 6.1–10.2 days for the harvest date. We believe that these models will be useful for planning shipments of pineapple in regions with wide temperature ranges, such as Japan, and for cultivation management in response to climate change.

著者

Masahiko Fumuro

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-078, (Released:2023-10-31)

---

To investigate the practicality of using own-rooted trees in pot culture, the growth, yield, and fruit quality of pot-planted ‘Irwin’ mango trees, propagated by air layering versus grafting, over an 11-year period after planting were measured. The trunk diameter of the own-rooted trees propagated by air layering was significantly smaller than that of the grafted trees propagated by conventional methods until six years of age, after which there was no significant difference between the two tree types. The trunk diameter of the own-rooted trees was significantly greater than that of the scion diameter of the grafted trees after seven years of age. The total length of green branches was significantly longer in the own-rooted trees than in the grafted trees after nine years, and the number of leaves was significantly greater on the own-rooted trees than the grafted trees after six years. The height of the own-rooted trees was 35 cm shorter than that of the grafted trees. The fresh and dry weights of the leaves, green branches, thick branches, scaffold branches, and fine roots of the own-rooted trees were significantly greater than those of the grafted trees. However, the fresh and dry weights of the trunks and thick roots of the own-rooted trees were significantly smaller than those of the grafted trees. The weights (fresh and dry) of the aboveground parts of whole own-rooted trees were significantly greater than those of the grafted trees, but the weights of the underground parts did not differ significantly between the two tree types. The T-R ratio (the weight of the aboveground part of the tree excluding the leaves/the weight of the underground part of the tree) of the own-rooted trees was significantly greater than that of the grafted trees. The yield per tree of the own-rooted trees was significantly lower than that of the grafted trees for two years after fruiting; however, this difference resolved after 10 years. The average yield per unit land area over nine years was 2.46 kg·m−2 for own-rooted trees and 2.32 kg·m−2 for grafted trees. The numbers of fruits per tree did not differ significantly between tree types, except during years 4 and 5. The average fruit weight did not differ significantly between the tree types up to nine years, with one exception in year 5. However, the average fruit weight of the own-rooted trees was significantly greater than that of the grafted trees after 10 years. Fruit quality did not differ significantly between the two tree types. Since the height of the own-rooted trees was shorter, and their growth and yield were equal or greater than those of the grafted trees, pot culture using own-rooted trees of ‘Irwin’ mango appears to be highly beneficial.

著者

Katsuhiko Inamoto Tanjuro Goto Motoaki Doi

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-102, (Released:2023-10-31)

---

Three rose varieties, ‘Meivildo’, ‘Meikatana’, and ‘Korcut0122’ were grown using an “arching” method for three years. The relationship between temperature and light intensity, and the yield and quality of cut flowers, were analyzed. Flowering flushes were observed 18 times in ‘Meivildo’ and ‘Meikatana’ and 16 times in ‘Korcut0122’ during the experimental period. In three varieties, significant negative linear regressions between the interval of flowering flush (growth period, GP) and the mean temperature per GP were observed. Significant positive correlations and linear regression were observed between the number of cut flowers per plant and the mean temperature in ‘Meivildo’ and ‘Meikatana’, and the total light integral per GP (TLI) in ‘Korcut0122’. In three varieties, significant positive correlations and linear regressions were observed between the total cut flower weight per plant, and the mean daily light integral per GP (DLI) and TLI. Highly significant positive correlations and linear regressions were observed between the daily gain in flower weight (DGW) of cut flowers per plant (the total cut flower weight divided by the number of days of GP) and the mean DLI in all three varieties. In ‘Meivildo’ and ‘Meikatana’, cut flower weight per stem had significant negative correlations and linear regression with mean temperature and positive ones with TLI, while ‘Korcut0122’ showed no significant correlation with the three environmental factors. Significant positive correlations and linear regressions existed between the specific cut flower weight (the cut flower weight per stem length) and TLI in all three varieties, and negative ones existed between the specific cut flower weight and mean temperature in ‘Meivildo’ and ‘Meikatana’. The relationship between the results in this experiment and previous reports on the relation between the environment and cut flower yield quality are discussed. Finally, we present the significance of the method used in this experiment for 1) prediction of flowering and shipping of cut flowers, 2) evaluation of differences in characteristics among the rose varieties, and 3) contribution to the development of a growth model.

著者

Akira Yamazaki Ao Takezawa Kazusa Nishimura Ko Motoki Kyoka Nagasaka Ryohei Nakano Tetsuya Nakazaki Munetaka Hosokawa

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-094, (Released:2023-10-17)

---

Chili pepper is cultivated in the absence of fruit-promoting treatments or insect pollinators. The fertilization ability of both males and females, as well as natural self-pollination ability under high temperatures, are necessary for autonomous set fruit under high temperatures. The reproductive traits related to autonomous self-pollination ability and fertilization ability of both males and females after pollination under control (CK) and high temperature (HT) treatments were investigated in this study. ‘Takanotsume’ (TK) showed a significantly higher percentage of autonomous fruit set than ‘Peruvian Purple’ (PP) in both CK and HT treatments, suggesting that TK has a strong autonomous fruit set regardless of temperature. On the other hand, the percentage of autonomous fruit set of PP was 0% in the HT treatment, while autonomous fruit set was observed in the CK treatment. Therefore, TK had autonomous fruit set ability even at high temperatures when PP did not have any. TK had more pollen on the stigma than PP, suggesting that TK has a higher ability for autonomous self-pollination. Flower morphology was not considered a factor in the autonomous self-pollination of TK. In contrast, TK tended to release more pollen than PP. One factor that can support autonomous self-pollination is pollen dispersion. A significant difference was observed in the fruit set rate during artificial pollination between the treatments (CK and HT) of the pollen parent and the cultivars (TK and PP) of the seed parent. In fact, female fertility in TK was higher than that in PP, regardless of the temperature condition. Almost no fruit set of PP was observed via autonomous self-pollination in the HT treatment, but fruits were set by artificial pollination using both the pollen and pistil of PP in the HT treatment. This result is consistent with the finding that PP exhibits decreased autonomous self-pollination at high temperatures. The higher autonomous fruit-set ability of TK than PP under high temperatures may be attributed not only to superior female fertility, but also to its autonomous self-pollination ability under high temperatures. Therefore, pollen dispersal ability under high temperatures was considered a key factor for autonomous fruit-set.

著者

Kazuki Yamazaki Rika Kitamura Tomohiro Suzuki Takeshi Kurokura Kenji Yamane

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-079, (Released:2023-10-14)

---

Gladiolus (Gladiolus spp.) florets exhibit low ethylene sensitivity. Accordingly, the wilting of their tepals is an ethylene-independent process. Both trehalose and cycloheximide can extend the vase life of gladiolus florets. Floral senescence is probably regulated by programmed cell death. However, senescence-related genes have not been thoroughly investigated, except in ethylene-sensitive species. In this study, we analyzed the expression of senescence-associated genes by conducting transcriptome (RNA-seq) analysis. First, we examined the effects of 0.1 M trehalose (Tre), 300 μM cycloheximide (CHI), and 50 μM chloramphenicol (CAP) treatments on postharvest quality and senescence-related gene expression in gladiolus ‘Fujinoyuki’ cut florets. The Tre and CHI treatments extended the vase life of gladiolus florets by about 1 day, i.e., 30% of Cont. Tepals were sampled at 0 days (0d) and 2 days (2d) post-treatment. The RNA-seq analysis of floret tissues generated 81,136 unique sequences. Moreover, 2,892, 4,670, and 57 differentially expressed genes were identified from the 0d_Control (Cont) vs 2d_Cont, 2d_Cont vs 2d_CHI, and 2d_Cont vs 2d_Tre comparisons, respectively. Gene Ontology (GO) analysis suggested that cysteine-type endopeptidase activity was significantly higher for 2d_Cont than for 0d. Additionally, the 0d vs 2d_Cont comparison showed the cell wall-related GO terms were more enriched for 2d_Cont. The Kyoto Encyclopedia of Genes and Genomes analysis revealed an increase in the expression of sucrose synthesis-related genes in the 2d_Cont samples. Among the genes involved in starch and sucrose metabolism, the genes mediating cell wall degradation were more actively expressed in the 2d_Cont samples than in the 2d_CHI samples. The fragments per kilobase per million reads (FPKM) values were used to select candidate senescence-related gene families, including the cysteine protease, invertase, peroxidase, pectinesterase, and transcription factor (NAC [no apical meristem (NAM), Arabidopsis transcription activation factor (ATAF), and cup-shaped cotyledon (CUC)] and WRKY) families. The expression levels of transcription factor genes, including NAC 048, 68, 073 and WRKY 6, 11, 24, were validated by qPCR. The expression of these NAC and WRKY transcription factor genes was upregulated by CHI, suggesting their involvement in senescence or side reactions in gladiolus tepals. This study revealed several candidate genes and associated GO terms for senescence of cut florets, but further study is needed, especially on key genes, including transcription factors.

著者

Kazuma Okada Masato Wada Taku Shimizu Shigeki Moriya Kazuyuki Abe

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-101, (Released:2023-10-14)

---

The Tall Spindle apple (Malus × domestica Borkh.) planting system achieves high early and sustained yields and excellent fruit quality. This system requires high-density planting (1,000–1,500 trees/acre) of highly branched (feathered) nursery trees, which increases the total cost of nursery trees purchased. To supply large quantities of highly feathered nursery trees at low prices, the nursery cycle should be shortened to one year. However, it is difficult to naturally obtain one-year-old nursery trees with sufficient feather number and length. Repeated spraying with 6-benzyladenine (BA) has been used as a conventional method to induce feather formation in apple nursery trees. We recently demonstrated that gibberellin A3 (GA3) treatment also increases the feather number on young apple trees. Here, we investigated the effects of GA3 (0, 100, 500, and 1,000 μM) and BA (0, 75, 150, and 300 mg·L−1) combinations on the production of well-feathered trees over a one-year cycle. Among the 16 GA3 and BA combinations, repeated (7 or 9 times) spraying with 1,000 μM GA3 + 300 mg·L−1 BA solution (3 or 5 mL) was the most effective method for producing highly feathered nursery trees of ‘Fuji’/JM7 over a one-year cycle. In two trials, trees treated with 1,000 μM GA3 + 300 mg·L−1 BA had 0.9–1.0-fold greater terminal shoot lengths, 1.5–1.9-fold greater feather numbers (≥ 1 cm), 2.0-fold greater feather numbers (≥ 5–< 50 cm), 1.1–1.2-fold greater feather lengths, and 0.9-fold greater trunk diameters than those treated with 300 mg·L−1 BA (conventional method). The feathers of trees treated with 1,000 μM GA3 + 300 mg·L−1 BA were predominantly 1–30 cm long (≥ 94.5%), and only few large feathers were observed. Thus, compared with the conventional method, treatment with 1,000 μM GA3 + 300 mg·L−1 BA facilitated the production of highly feathered nursery trees over a one-year cycle. It also reduced the time and labor cost required to obtain a large number of well-branched nursery trees needed for high-density plantings such as in the Tall Spindle system.

著者

Tomohiro Kondo Hirokazu Higuchi

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-093, (Released:2023-10-11)

---

Passion fruit has edible arils with a complicated structure. Each aril has three different membranes; an external membrane, an internal membrane with a fimbriate structure at the basal area, and a transparent membrane that completely envelops the seed. It was reported that juice quality, including organic acid and sugar contents, varied depending on the extraction method. So, organic acid and sugar are potentially localized inside the aril. In this study, using three cultivars (purple passion fruit, yellow passion fruit, and ‘Summer Queen’, a hybrid variety between the two), juice qualities of different aril parts were determined. The aril was separated into three parts, that is, the outer pulp (OP), the distal part of the inner pulp (DIP), and the basal part of the inner pulp (BIP). The OP included the external membrane and the juice held by this membrane. The DIP surrounding the seed and the BIP was a fimbriate structure attached to the internal membrane. In all varieties, titratable acidity (TA) and citric acid content at DIP were higher than those at OP and BIP, although there were some differences among the varieties. Malic acid content did not vary among the parts. Total soluble solid content (TSS) at BIP was the highest among the parts, and glucose, sucrose, and fructose contents at DIP were lower than those at BIP. Purple passion fruit had a high juice content at OP and the yellow cultivar had high juice content at DIP, while the hybrid between the two showed intermediate characteristics. Organic acid and sugar were localized inside the aril in the passion fruit cultivars; the citric acid content and TA at DIP were higher than those at OP and BIP, and TSS at BIP was higher than those at DIP and OP. Therefore, adjusting the juice extraction intensity may be needed depending on the required juice quality.

著者

Yang Yang Sho Ohno Yoshiyuki Tanaka Motoaki Doi

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-069, (Released:2023-08-23)

---

Generally, Asteraceae flowers such as chrysanthemums and gerberas, are low ethylene-sensitive and do not exhibit petal wilting and abscission. However, previous research found that the flowers of dahlia, an Asteraceae member belonging to the tribe Coreopsideae, are ethylene-sensitive and show abscission layer development in petal-ovary boundaries. In this study, we investigated the ethylene sensitivity of 17 ornamental Asteraceae species belonging to different tribes by measuring the petal drawing resistance and vase life after 1–3 μL·L−1 ethylene exposure for 20 h. Although more than half of the tested species did not respond to ethylene, several species showed ethylene-sensitive petal wilting and abscission of fresh ray florets. Ethylene-sensitive petal wilting occurred in only two species (Calendula officinalis L. and Osteospermum L.) of the tribe Calenduleae, while ethylene-sensitive petal abscission occurred mainly in six species (Bidens ferulifolia D.C., Coreopsis lanceolata L., Cosmos atrosanguineus (Hook) Voss., Cosmos bipinnatus Cav., Cosmos sulphureus Cav. and Dahlia Cav.) of tribe Coreopsideae and one species (Helianthus annuus L.) of the tribe Heliantheae. In these species, abscission petals maintained their turgidity, and this process could be detected by measuring the petal drawing resistance of the ray florets. The reduction in petal drawing resistance, associated with abscission layer development in the petal-ovary boundaries, was observed only in these ethylene-sensitive species. The results of this study suggest that the ethylene sensitivity and petal senescing patterns in Asteraceae flowers may be associated with the phylogenetic classification at the tribe level.

著者

Natassia Clara Sita Asuka Kousaka Risa Tamoi Chiaki Ozawa Iriawati Yoshikazu Kiriiwa Katsumi Suzuki

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-072, (Released:2023-08-23)

---

Intumescence injury is a physiological disorder characterized by abnormal outgrowth of epidermal and parenchymal cells on the adaxial and/or abaxial surfaces of leaves. The purpose of this study was to examine cultivar differences in the incidence of intumescence injury, the relation between different calcium (Ca) conditions and intumescence injury, and to investigate countermeasures against intumescence injury in tomatoes. We grew tomato plants under different Ca nutrient conditions and treated them under high relative humidity and low ultra-violet light conditions to investigate intumescence injury incidence. The degree of intumescence injury varied among different tomato cultivars under a normal Ca condition with 4.5 me·L−1 of Ca. Intumescence occurred in cultivars that showed no injury incidence under the normal Ca condition when they were grown with a low Ca nutrient solution containing 0.5 or 2.5 me·L−1 of Ca. Intumescence injury incidence decreased in cultivars that showed high incidence under the normal Ca condition when they were grown with a high Ca nutrient solution containing 9.5 or 24.5 me·L−1 of Ca. The differences in the incidence of intumescence among cultivars was marked with different Ca nutrient solution concentrations. There was a negative correlation between the degree of intumescence injury and the Ca content in tomato shoots. Foliar spraying with Ca was found to reduce the incidence of intumescence injury. It was suggested that intumescence injury in tomatoes can be mitigated by using cultivars in which intumescence is less likely to occur, increasing the Ca concentration of shoots by providing more Ca nutrients to the plant, and spraying Ca solution directly on the leaves.

著者

William Viera Takashi Shinohara Atsushi Sanada Naoki Terada Kaihei Koshio

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-081, (Released:2023-08-23)

---

Passion fruit (Passiflora edulis) is a tropical fruit that can be consumed fresh or processed. It is a typical respiratory climacteric fruit which is highly perishable because of the loss of water that causes dehydration and thus shrinkage, affecting the fruit appearance; in addition, some quality traits such as fruit weight, firmness and vitamin C content can also be influenced. Therefore, this fruit has a short shelf life. Storage in low temperatures has been assessed to extent the passion fruit shelf life remaining its fruit quality traits; however, information about the application of the hypobaric method in this fruit is null. The objective of this research was to evaluate the physical and chemical characteristics of the yellow and purple passion fruit under hypobaric storage conditions in low temperature. Results showed the hypobaric method had a positive effect in decreasing fruit weight loss, declining the loss of firmness, and reducing the degradation of vitamin C during the storage period. It decreased the evolution of ethylene which is positive to delay fruit senescence, and the production of CO2. Finally, it was the only method which avoids the shrinkage completely in the purple passion fruits (‘Gulupa’, ‘Summer Queen’, and ‘Ruby Star’) and showed minor shrinkage in ‘POR1’ (yellow passion fruit). This method is considered as a promising technique to improve fruit storage.

著者

Yoshimi Yagishita Masayoshi Nakayama

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-083, (Released:2023-08-11)

---

There are light-yellow flower cultivars of sweet pea (Lathyrus odoratus L.), but no deep-yellow ones. Observation of sweet pea flowers under ultraviolet and blue light suggested that carotenoids are responsible for the light-yellow coloration. We carried out both spectroscopic and high-performance liquid chromatography (HPLC) analyses of floral extracts of a light-yellow cultivar, ‘Artemis’, and revealed that the responsible pigments are not flavonoids, but carotenoids, among which acylated lutein is a major component. Because lutein is the pigment responsible for the deep-yellow color of flowers in other plants, we expect to be able to generate deep-yellow flower cultivars of sweet pea. The R and C loci are complementary genes regulating biosynthesis of anthocyanin pigments responsible for the cyanic coloration in sweet pea flowers. In progenies obtained by crossing ‘Artemis’ and a white cultivar, ‘Diana White’, whose genotype is RRcc, the F1 plants had a red flower phenotype only, and the F2 plants had four coloration phenotypes that were white, yellow, red and a combination of yellow and red. Furthermore, the F1 plants, obtained by crossing ‘Artemis’ and another yellow cultivar, ‘Stella’, had a combination of yellow and red flower phenotype only. These data indicate that the genotype of ‘Artemis’ is rrCC and the yellow coloration trait is regulated by a single recessive gene, y, and furthermore, that the y gene is not in linkage with the R or C allele. The theoretical segregation ratio of the F2 plants’ phenotypes obtained by crossing ‘Artemis’ as one parent in the case that Y, R and C loci are independent of each other are presented. We also found some cyanic color cultivars containing higher amounts of carotenoids than ‘Artemis’.

著者

Gang Ma Lancui Zhang Kan Murakami Masaki Yahata Masaya Kato

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-082, (Released:2023-08-11)

---

‘Miyagawa-wase’ (Citrus unshiu Marcow.), an early-season citrus variety, is rich in multiple nutrients and widely consumed in Japan. In ‘Miyagawa-wase’, when the pulp reaches maturity and is ready to eat, the peel is still a greenish color because of the relatively high temperature in the harvest season. In this study, to improve the coloration of ‘Miyagawa-wase’ peel, we treated the fruit with 1-naphthaleneacetic acid (NAA) after harvest. The results showed that postharvest treatment with NAA was effective to induce chlorophyll degradation and carotenoid accumulation in ‘Miyagawa-wase’ peel during storage. In the NAA treatment, the reduction in the chlorophyll contents after harvest was in parallel with decreases in the expression of chlorophyll biosynthetic genes (CitGGDR, CitCHLH, CitCHL27, CitPORA, and CitCAO) and an increase in chlorophyll degradation gene CitPPH. The contents of the major carotenoids, β-cryptoxanthin and 9-cis-violaxanthin, were increased by the NAA treatment through upregulation of the expression of carotenoid biosynthetic genes (CitPSY, CitPDS, CitZDS, CitLCYb2, and CitHYb) after harvest. In addition, it was found that the positive effect on degreening in the NAA treatment was inhibited by the ethylene antagonist 1-MCP. In the combination treatment using NAA and 1-MCP, the total chlorophyll content was much higher, while the contents of β-cryptoxanthin and 9-cis-violaxanthin were lower compared with NAA treatment alone, indicating that the acceleration of degreening by NAA may be caused by ethylene. The results presented in this study suggest that postharvest NAA treatment is an effective method for improving the peel coloration in early-season citrus varieties.

著者

Katsuya Ohkawa Natsumi Ogata Akane Shibasaki Takahisa Tanaka Ryo Itabashi Chie Kouno Takanori Saito Hitoshi Ohara Satoru Kondo

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-064, (Released:2023-08-11)

---

To elucidate the inhibitory effect of ethephon on the occurrence of water-soaked disorder in Japanese pear ‘Akizuki’ (Pyrus pyrifolia Nakai) fruit, we sprayed fruits with 100 mg·L−1 ethephon solution approximately 120 DAFB in the 2012, 2014, 2015, 2016, and 2017 seasons. Ethephon treatment reduced the incidence and degree of water-soaked disorder at commercial harvest time. There was no significant difference in fruit size or soluble solids content between the ethephon-treated fruits and the control fruits, except for fruit size in the 2012 season. During the nine-day storage period after harvest, water-soaked disorder did not develop in either the ethephon-treated fruits or the control fruits. In addition, flesh firmness and soluble solids content did not differ between the ethephon-treated fruits and the control fruits during the storage period. Ethylene production increased sharply in the ethephon-treated fruits a few days after the ethephon treatment, in contrast to the control fruits. Sucrose content in the ethephon-treated fruits was higher than that in the control fruits on day 10 after treatment. Sorbitol content in the ethephon-treated fruits was lower than that in the control fruits on days 10 and 20 after treatment. Water-soluble, Na2CO3-soluble, and total pectin contents were not affected by the ethephon treatment. Hemicellulose, cellulose, and starch contents in the ethephon-treated fruits decreased earlier than those in the control fruits. Sucrose content was lower, but sorbitol and glucose contents were higher, in water-soaked tissue than in sound tissue. These results suggest that ethephon treatment rapidly induces changes in the contents of fruit’s internal components and accelerates fruit maturation, thereby alleviating factors that cause water-soaked disorder in ‘Akizuki’.

著者

Raymund Julius G. Rosales Songsin Photchanachai Chanulak Khanobdee

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-042, (Released:2023-08-11)

---

This study investigated the role of dry matter (DM) and adhesiveness (or stickiness) and their relationship with the physicochemical and antioxidant properties of raw and steamed pumpkins. Through path analysis, raw pumpkin with a high DM value yielded a positive correlation with total flavonoid contents (TFC) and Ferric Reducing Antioxidant Power (FRAP) value in its raw form, and contained high total soluble solids and 2,2-diphenyl-2-picryl-hydrazyl (DPPH) activity in its steamed form. DM showed a correlation with total phenolic compounds (TPC) and DPPH activity. A sticky pulp generated high DM, TPC, TFC, and antioxidant capacity. The TPC and TFC were positively correlated with the antioxidant capacity. There was no relationship between cell structure, and starch granule characteristics of the raw pulp and cooked DM or stickiness. Therefore, DM and stickiness may be used as quality indicators of chemical contents and antioxidant capacity in pumpkin and could support pumpkin improvement programs.

著者

Daiki Matsumoto Ryohei Yamazaki Misato Kasai Satoshi Taira Ryutaro Tao

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-087, (Released:2023-07-19)

---

Prunus fruit trees of the Rosaceae family exhibit S-RNase-based gametophytic self-incompatibility (GSI), which enables pistils to reject self-pollen by suppressing pollen tube elongation. In other plant species with S-RNase-based GSI, it has been shown that this suppression consists of two steps: first, slowing down of pollen tube elongation in the middle part of the style and second, complete arrest involving programmed cell death. To characterize the suppression pattern of incompatible pollen tubes in Prunus, we observed pollen tube elongation of ‘Satonishiki’ sweet cherry (Prunus avium) in ‘Satonishiki’ and ‘Rainier’ pistils on agar plates and ‘Satonishiki’ and ‘Rainier’ pollen tube growth in pistils on ‘Satonishiki’ cut branches. Incompatible selfed pollen tubes delayed penetration into the stigma in both experiments. Observation of pollen tubes in pistils on agar plates was difficult 24 h after pollination (HAP) due to wilting of the styles, while observing them on cut branches was possible up to 72 HAP. In the pistils on cut branches, ‘Satonishiki’ pollen tubes barely elongated in self pistils from 32 to 48 HAP when compatible ‘Rainier’ pollen tubes reached the base of a style, but resumed growth after 48 HAP and reached the base of the style. An RNase activity staining indicated that S-RNase was inactive 48 HAP. Finally, we observed pollen tube elongation in the style-grafted pistils on the cut branches. ‘Satonishiki’ pollen tube elongation was accelerated when the upper one-third of the self-pollinated styles was grafted onto compatible ‘Taishonishiki’ pistils. These results indicated that the suppression of incompatible pollen tube elongation in P. avium was consistently reversible. We discuss the suppression mechanism of incompatible pollen tube growth and the possibility of artificial control of Prunus self-incompatibility.

著者

Toshihiko Sugiura Noriaki Fukuda Taiga Tsuchida Mio Sakurai Hiroyoshi Sugiura

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-076, (Released:2023-07-04)

---

The future impacts of climate change on the yields of staple crops have been widely investigated. However, owing to insufficient data compared to that available for staple crops and the complexity of the quality determination process, the relationship between quality changes in horticultural crops and climate change has not been quantified, and potential future changes in fruit quality are not well understood. We conducted temperature treatment experiments to quantify the sensitivity of apple quality to air temperature and collected quality indices records through field observations to propose a model for estimating apple quality indices from the air temperature. In the temperature treatment experiment, ‘Fuji’ apple trees were placed in glass chambers set at a constant temperature of 17.3–25.6°C from 110 days after full bloom (DAFB). The fruits were harvested at 170 DAFB to measure the quality indices. The results indicated that the acidity and ratings for blush, peel ground color, starch disappearance, and watercore were all significantly lower at higher air temperatures. The relationship between these quality indices and air temperature could be linearly approximated. Sugar content and fruit firmness were not clearly affected by the air temperature. In addition, data from field observations conducted at experimental orchards in Aomori and Nagano Prefecture over 50 years (1970–2019) were analyzed. The relationship between fruit quality indices at 170 DAFB and the mean temperature in the 60 days from 110 DAFB in Aomori and Nagano was similar to that observed for the chamber experiment results, and no significant difference was observed in the slope of the linear regression equation between the chambers and orchards. A model was developed to estimate the fruit quality indices based on air temperature by accumulating daily amounts of change in quality indices calculated from daily mean temperatures using the results of experimental and field observations. The model could be used to assess the impact of future long-term temperature increases on apple quality indices.

著者

Jazmín Pérez-Pazos Amparo Rosero Enrique Vergara Rocío Gámez

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-017, (Released:2023-06-20)

---

The sweet potato is a highly important crop in terms of food security worldwide, its nutraceutical properties have increased demand, generating new market opportunities. The availability of disease-free planting material ensures success in establishing this crop, achieving higher yield and better quality. This study aimed to improve the production system of high-quality planting material in greenhouse conditions through the evaluation of three mixtures of substrates based on peat, vermicompost, rice husk, and coconut substrate in different proportions; the best treatment was subsequently evaluated in the acclimatization process of in vitro plants. The substrates were characterized physicochemically and their effect on growth parameters in sweet potato seedlings was determined. For the acclimatization process of in vitro plants, the best mixture of substrates and a humid chamber during the first eight days of growth was compared to the conventional technique. A substrate composed of peat, vermicompost, and rice husk (3:1:1) resulted in the best seedling development. The proposed in vitro plant acclimatization strategy produced seedlings with good growth, high survival rates (92%), and a good multiplication rate (3.53) compared to the conventional strategy (peat without a humid chamber). The use of an optimal substrate and the incorporation of a humid chamber during the first days of growth guaranteed adequate ranges of temperature and relative humidity that kept the vapor pressure deficit of the leaves below critical levels (< 1.2 kPa). Increased efficiency in the production of high-quality planting material with carefully controlled phytosanitary conditions can make an important contribution to improving global disease management strategies in sweet potato cultivation.

著者

Hiroshi Matsuda Hirokazu Higuchi Naoki Miyaji Masanori Okabe

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.QH-057, (Released:2023-06-10)

被引用文献数

1

---

The salak fruit (snake fruit) contains one to three seeds covered with an aril. The size of the fruit primarily depends on the number of seeds. Fruits with more seeds grow larger and attain higher commercial value in fresh markets owing to their superior appearance. In eastern Thailand, during the hot period in the early rainy season, the fruit set of salak decreases, which is empirically believed to be caused by high night temperatures. In this study, we pollinated and incubated salak spadices at various temperatures (18–36°C) to determine the optimal post-pollination temperature range needed to produce valuable fruits. Chronological pollen-tube elongation in the pistil and development of the early embryo and endosperm were then observed anatomically, followed by fruit-set estimation. At ≤ 21°C, pollen-tube elongation was limited. At 24–27°C, although elongation was slow, pollen tubes attained embryo sacs in > 60% of florets within 36 h after pollination. Pollen tubes elongated fastest at 30–33°C and attained embryo sacs within 12 h after pollination. At 36°C, the difference in the elongation speed tended to be higher among the pistils. The percentages of ovules with developing embryos were the highest at 27°C at 48 h after pollination; zygote and early embryos were observed in 10.8% and 55.9% of the ovules, respectively, and the primary endosperm nucleus, dispersing endosperm nucleoplasm, and free endosperm nuclei were observed in 8.6%, 38.7%, and 19.4%, respectively. The second highest percentage was observed at 24°C. The percentages tended to decrease at 30°C and decreased significantly at ≥ 33°C. At ≥ 30°C, shriveled embryo sacs were observed. The estimated fruit-set percentage based on embryo development as the consequent fruit set was the highest (≈80%) at 27°C, while the second highest percentage (≈75%) was at 24°C. At ≥ 30°C, the estimated percentage decreased to less than half that at 27°C. Fruits containing three seeds were expected to grow in the range of 17.6–28.0% at ≤ 27°C. One- or two-seeded fruits were expected to grow at ≥ 30°C. Limited fruit set was expected at 36°C. Our results indicate that salak prefers relatively cool temperatures of approximately 25°C for the fertilization and set of valuable fruits.