A long vase life of cut flowers is valued highly by consumers. Cut Eustoma flowers have gained popularity during recent decades in Japan but there are few studies on the postharvest physiology and technology of the flowers. The vase life of cut Eustoma flowers is not long and varies among cultivars. Ethylene is involved in flower senescence and pollination accelerates this process. The Eustoma inflorescence has many flowers and buds; therefore, to improve the postharvest quality of Eustoma inflorescence, promoting bud opening as well as delaying senescence of the open flower are important. This review summarizes the factors affecting vase life and describes effective treatments for cut Eustoma flower stems to extend their vase life.

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To induce haploid plants in Citrus maxima (Burm.) Merr. ‘Banpeiyu’, we evaluated the effect of pollination with soft X-ray-irradiated pollen on fruit set and seed development, and carried out ovule culture. When ‘Banpeiyu’ pummelo pistils were pollinated with X-ray-irradiated pollen of ‘Fukuhara’ sweet orange [C. sinensis (L.) Osbeck], the exposure doses affected the fruit set. The number of seeds per fruit was also affected by the exposure dose, and tended to decrease as the dose increased; however, all developed seeds obtained from these crosses were diploid. In the ovule culture of ‘Banpeiyu’ pummelo, six embryoids shown haploidy were obtained in all treatments. One haploid plantlet with 9 chromosomes was regenerated from an embryoid in a culture of ovules established 40 days after pollination with 400 Gray (Gy)-irradiated pollen of ‘Tosa-buntan’ pummelo (C. maxima). This haploid was suggested to be derived from ‘Banpeiyu’ pummelo by random amplified polymorphic DNA (RAPD) and cleaved amplified polymorphic sequence (CAPS) analysis.

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The effects of global warming have been observed in several crops as changes in temperature-dependent processes, such as dormancy in perennial fruit trees. We exposed potted Japanese pear ‘Housui’ plants to 600 chilling hours (CH) below 7.2°C, which is below the theoretical requirement. Such low chilling accumulation was initiated at different times (three treatments) and carried out during four consecutive seasons in order to observe the influence of these factors on the incidence and severity of floral primordia necrosis, water dynamics, phenological, and morphological changes during dormancy in lateral mixed buds, which is comprised of vegetative and reproductive primordia, obtained from the current season’s shoots. The submitted amount of chilling temperatures brought about the release of dormancy stage, regardless of seasonal variations in the duration to accumulate 600 CH, but caused a remarkable increase of floral primordia necrosis and a great increase in the number of floral primordia as a consequence of the development of new inflorescences; however, these morphological changes did not increased number of opened flowers because of the progression of floral primordia necrosis. Consecutive seasons of mild winter conditions anticipated the incidence of floral primordia necrosis. The results obtained from magnetic resonance imaging in the buds of plants subjected to low chilling accumulation showed low water mobility and water content especially in scales compared to plants grown under natural conditions. In contrast, increased water mobility and relative content were observed in specific portions of the bud base in treated buds, which was more accentuated in the mixed buds of plants grown for several seasons under mild winter conditions. Moreover, abnormal functional water movement inside dormant mixed buds might result in the necrosis of floral primordia, giving way to the development of new inflorescences.

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The amount of phenolic compound contained in the chestnut pellicle determines the degree of adhesiveness between the pellicle and kernel. The difficulty involved in pellicle removal in Japanese chestnut results from the accumulation of a large amount of phenolic compound in the pellicle. A new Japanese chestnut cultivar, ‘Porotan’, has a pellicle that is easily removed, like Chinese chestnut. In this study, the phenolic content of ‘Porotan’ pellicles was quantified and compared to those of Japanese (‘Kunimi’ and ‘Tsukuba’), Chinese (‘Houji 360’ and ‘Miyazakishinaguri’), and interspecific hybrid (‘Riheiguri’) chestnuts. Even though total phenolic content in ‘Porotan’ was highest among the cultivars measured, the ‘Porotan’ pellicle could be removed quickly. On the other hand, the phenolic content in a water-soluble extract, which shows the amount of phenolic compound accumulated on the inner surface of the pellicle, was low for ‘Porotan’ comparable to Chinese chestnut. Similar to total phenolic content, the phenolic content in an alcohol-soluble extract of ‘Porotan’, which shows the amount of phenolic compound accumulated in pellicle tissue, was highest among the cultivars. These results showed that the accumulation of phenolic compound on the inner surface of the ‘Porotan’ pellicle was low despite a large amount of phenolic compound in the pellicle tissue, and that the low accumulation of phenolics on the inner surface of the pellicle resulted in weak adhesion between the pellicle and kernel in ‘Porotan’.

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The carotenoid metabolism enzyme zeaxanthin epoxidase (ZEP) is a key regulator of carotenoid accumulation in Citrus fruit. The expression level of the gene encoding this enzyme, ZEP, influences varietal differences in the conversion of zeaxanthin to violaxanthin during fruit development. To determine how this gene is regulated, we investigated the structure of its alleles and analyzed allele-specific ZEP expression in heterozygous Citrus fruit. Four independent genomic sequences were isolated from a BAC library of Satsuma mandarin (Citrus unshiu Marc.). All ZEP gene sequences in Satsuma mandarin consisted of 16 exons and 15 introns. Genetic analyses of hybrid populations and analyses of sequence variations identified that two of the sequences were alleles from the ZEP-1/-2 locus, and others were from different locus/loci, ZEP-3/-4, for which allelism has not been confirmed. The ZEP-4 allele was expressed in young-stage fruit, but not in mature-stage fruit, while ZEP-1/-2 alleles were expressed as fruit matured. Our results showed that the newly identified isoform, ZEP-4, did not contribute to the accumulation of violaxanthin during fruit maturation. Expression levels of ZEP-1/-2 alleles in the fruit of three heterozygous Citrus cultivars were compared using allele-specific RT-PCR. Transcripts of ZEP-1 alleles were more abundant than those of ZEP-2 alleles in all three cultivars. Sequence diversity among the 5' UTRs of ZEP alleles was also analyzed. The implications of sequence diversity with respect to diversity of the expression and phylogenetic relationships among ZEP genes in Citrus are discussed.

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Persimmon (Diospyros kaki Thunb.) accumulates soluble condensed tannin (CT) in fruit which is responsible for its astringency trait. In this study, we analyzed the CT composition in persimmon fruit with phloroglucinol, and identified and characterized novel epigallocatechin-3-O-gallate-phloroglucinol (EGCG-P) adducts as one of the main CT components of persimmon fruit. Analysis with phloroglucinol in persimmon cultivars revealed the different tendencies of the CT composition and component ratio among the four astringency types (PCNA, PVNA, PVA, and PCA), which are categorized by their patterns of astringency loss. The concentration of the main CT component in persimmon fruit, epigallocatechin-3-O-gallate (EGCG), was particularly different among astringency types. Further analysis of the fruit at various maturation stages will help in understanding the different mechanisms of CT accumulation among astringent types. Our results demonstrated that the phloroglucinol methodology is useful for CT composition analysis in persimmon fruit and will contribute to future studies on the astringency trait in this fruit.

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Chives (Allium schoenoprasum) continuously produce leaves during spring and summer, and continue to develop leaves in winter, although growth is slow (evergreen). They do not produce well-defined bulbs, whereas asatsuki (A. schoenoprasum var. foliosum) forms bulbs with leaf desiccation in summer. Bulb formation of F₁ progenies of chives × asatsuki and BC₁ plants obtained by crosses with asatsuki was investigated in this study. No F₁ progenies formed bulbs. The bulb formation of BC₁ was classified based on the bulbing ratio into two phenotypes, e.g. non-bulb-forming and bulb-forming types; however, the variation persisted in obvious bulb-forming and non-bulb-forming individuals. The index of the maximum thickness of scale leaves was an alternative to clearly segregate the BC₁ progenies into three types, e.g. no bulb formation, intermediate, and bulb-forming phenotypes. These results indicate that more than two recessive genes are involved in the bulb formation of chive.

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We examined the permeability of roots of Dutch ‘Dundee’ and Japanese ‘Reiyo’ varieties of tomato seedlings to nutrient solutions and potassium ions. Seedlings were grown under 5 different conditions: (1) Seedlings were grown in Otsuka-A nutrient solution adjusted to an electric conductivity (EC) of 2.4 dS·m⁻¹, and on the experiment day their roots were permeated with EC 2.4; (2) before the experiment day the EC was changed to 7.2 dS·m⁻¹, and then roots were permeated with EC 7.2 in the experiment; (3) roots were permeated with potassium chloride (KCl) solution whose water potential was equivalent to EC 2.4 in the experiment; (4) before the experiment day the EC was changed to EC 7.2, and then roots were permeated with KCl solution whose water potential was equivalent to EC 7.2 in the experiment; and (5) roots were permeated with that KCl solution whose water potential was equivalent to EC 7.2 in the experiment. We measured the root permeability of seedlings grown in each solution, and the water potentials of exudates by using a pressure chamber and an isopiestic psychrometer. The nutrient solution or potassium solution in the chamber was forced into the plants under pressure. We then measured the quantity of extraction from the cutting surface of the root and root surface area to calculate root permeability. As a result, we found that, except in the KCl permeability experiment with a water potential equivalent to EC 2.4, the Japanese variety had greater permeability of nutrient solution and potassium. On this basis we conjectured that the Japanese variety ‘Reiyo’, whose root permeability was high, is able to assimilate more water and nutrients than the Dutch variety ‘Dundee’. On this basis we found that differences in root permeability can be considered one reason why ‘Reiyo’ grows larger than ‘Dundee’ in the initial part of its growth period.

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To obtain physiological data on bolting in Chinese cabbage (Brassica rapa L. pekinensis Group), we conducted seed vernalization treatment using six cultivars of Chinese cabbage with different maturity times, and an experiment on spring cultivation using eight strains with different bolting properties. Soluble sugar content and peroxidase (POD) activity in seedlings in the vernalization plot that were in the flower bud differentiation stage were high in early-maturing cultivars followed by mid-season cultivars; nitrate reductase (NR) and catalase (CAT) activities were high in early-maturing cultivars compared to the control, which did not encounter low temperatures. A correlation was recognized between bolting (number of days from sowing to bud emersion) and the values of soluble sugar content and POD, NR, and CAT activities in strains with different bolting properties during the differentiation stage 15 days before bud emersion. These results show that soluble sugar content and POD, NR, and CAT activities in the flower bud differentiation stage in Chinese cabbage participate in flower bud differentiation, and it is considered that these properties are physiological indicators of bolting.

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The indoor display life of potted carnations ‘Annemarie’ is limited to 12 days because of its low flowering ability under low-light conditions (15 μmol·m⁻²·s⁻¹ PPFD, 20°C). When commercially grown potted carnations were transferred to indoor (low-light) conditions, dry weight and total soluble carbohydrates (TSC) decreased during the first 6 days after transfer (DAT), remained constant until 10 DAT, and then increased at 14 DAT. Glucose, fructose, and sucrose contents decreased markedly during the first 6 DAT and then gradually decreased. Pinitol content was unchanged until 10 DAT and then slightly increased at 14 DAT. After 30 days in indoor conditions, the concentrations of fructose, glucose, and sucrose in leaves declined to barely detectable levels, while the pinitol content was unchanged. By the end of 30 days, pinitol accounted for 79% of TSC. In another experiment, potted carnations were grown under water-stress conditions (0.21 m³ water/m³ soil) for 14 days. Compared with plants grown under ample water conditions (0.41 m³water/m³ soil), water-stressed plants showed lower water potential and increased the contents of pinitol, glucose, and TSC in the leaves; however, the differences in water potential and soluble carbohydrate level disappeared after plants were supplied with ample water. To optimize flowering, we thinned the number of florets to 20, 50, or 80 per plant. Compared with plants with 50 or 80 florets, plants with 20 florets per plant showed higher chlorophyll fluorescence ratio (Fv/Fm) in their leaves and had more flowers per plant. In addition, we evaluated the effects of low-light conditions (15 μmol·m⁻²·s⁻¹) and high-light conditions (alternate cycles of 15 μmol·m⁻²·s⁻¹ for 2 days and 150 μmol·m⁻²·s⁻¹ for 1 day) on flowering. At 20 DAT, flowers in the high-light treatment showed higher TSC than those in the low-light treatment; however, levels of pinitol were significantly higher in plants grown under low-light conditions. These results suggested that thinning flower buds and growing plants under high-light conditions could alleviate the carbohydrate shortage that occurs in indoor conditions, and could improve the quality and display life of potted carnations. We discuss the roles of pinitol in carnation plants under stress conditions.

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