The purpose of this study was to clarify the plant growth and fruit quality of blueberry in a controlled room under artificial light. Cultivars used were a northern highbush ‘Blueray’, and two southern highbush, ‘Misty’ and ‘Sharpblue’. A comparative study was carried out of growth characteristics, photosynthetic potential and fruit quality analysis in different growing environments, in particular focusing on plants growing in a glasshouse under natural sunlight and plants in a controlled room under artificial light. Environmental conditions of the controlled room under artificial light were 15 to 25°C, 50 to 70% humidity, 150 to 350 μmol·m⁻²·s⁻¹ light intensity, and a 10-hour photoperiod from the primary experiment. In these growing environments, normal fruits developed from all the tested cultivars by successful growth without decreasing plant vigor and leaf photosynthetic ability until fruit harvesting time compared to the cultivars grown in the glasshouse under natural sunlight condition. Moreover, it was confirmed that high-quality fruits could be harvested in a controlled environment to increase fruit production with high SSC % and high anthocyanin content but low acid % in ‘Blueray’ and ‘Misty’, but not ‘Sharpblue’. Finally, this report presents the possibility of high-quality blueberry production in a controlled environment under artificial light conditions with some cultivars.

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To understand the factors affecting the incidence of blossom-end rot (BER), the effect of the Ca/K ratio (4/12–12/4, in me·L^–1) in nutrient solutions and Ca concentration in fractions in the distal part of young tomato fruits immediately before BER symptoms appear were investigated for three seasons. The rate of BER incidence increased with a decrease in the Ca/K ratio in the supplied solutions in the summer and spring, but little difference was observed in the winter. Ca concentration was highest in winter and lowest in summer, and the concentration in fractions decreased with a decrease in the Ca/K ratio of the solutions. When the results of all three experiments were pooled, among the fractions, water-soluble Ca concentration was found to have the highest significance in the relationship to BER incidence. The risk of BER incidence in rapidly growing tomato increased to a critical level when water-soluble Ca in the distal part of the fresh fruit decreased to less than 0.20 μmol·g^–1 FW. Multiple-regression analysis revealed that the concentration of water-soluble Ca, which is predominantly recovering apoplastic or cytoplasmic Ca²⁺, and total Ca, which has been translocated during fruit development, are significantly affected by solar radiation and Ca concentration in the supplied solution rather than air temperature.

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The origin of a spontaneous triploid asparagus plant from crosses of 2x × 2x was investigated by SSR and flow cytometric analyses. One hundred and twenty-four progeny were obtained from crosses between a diploid female ‘Gold Schatz’ and a diploid male ‘Hokkai 100’. SSR analysis proved that two and one genes were transmitted from the maternal and paternal parents, respectively, at each SSR locus of one progeny, 07M-61, whereas one gene each was from the female and male parents in the other diploid progeny. Triploidy of 07M-61 was confirmed by flow cytometric analysis. It was suggested that the triploid plant was derived from fertilization between an unreduced egg and reduced sperm nuclei, given its SSR genotypes. It was also suggested that the unreduced maternal gamete was derived from first division restitution (FDR) or second division restitution (SDR) with chiasma occurrence during meiosis. There were no noticeable morphological differences between the triploid and diploid progeny.

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Low-cost heating is needed to reduce chilling injuries, heating costs, and CO₂ emission during greenhouse tomato production. To acquire information about the physiological and morphological effects of root-zone heating, an economical option at low air temperatures, we grew tomato plants on a nutrient film technique hydroponic system in a heated nutrient solution. We investigated the effects of short-term root-zone heating after transplanting and long-term heating until harvest. We measured short-term plant growth, nutrient uptake, root activity (xylem exudation and root respiration rates), root indole-3-acetic acid (IAA) concentration, internal root structure, and long-term fruit weight and dry matter distribution. The minimum root-zone temperature was maintained at 16.6°C, while the minimum air temperature (5.9°C) and the minimum root-zone temperature in the control (5.8°C) were lower than optimal. After 7 days of root-zone heating, root dry weight and relative growth rate increased compared with those of the control, accompanied by increased mineral nutrient uptake and xylem exudation. These changes may explain the increased shoot growth after 21 days of heating. In roots, development of the epidermis and stele, including the xylem, was promoted by heating, in contrast to previous research on root-zone cooling at high air temperature, which promoted xylem-specific development. Although the proportion of dry matter distributed to the fruit was not changed by root-zone heating, individual fruit size and total yield were higher than in the control due to a higher total dry weight in the heating treatment. Our results suggest that root-zone heating is an effective low-cost heating technology at low air temperature because of its effects on root activity, growth, and fruit yield, but that the mechanisms may differ from those in root-zone cooling at high air temperature.

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Some flowers including rose open in a rhythmic fashion during specific times of the day. We used time-lapse cinematography to understand the mechanism of rhythmic opening and perception of light in cut rose flowers. Cut rose flowers exposed to a 12 h light/12 h dark photoperiod started opening shortly before the light period had begun and stopped during the light period even when their leaves were removed, indicating that petals and/or sepals perceive light and synchronize flower opening to photoperiods. This rhythmic opening could be seen in constant darkness even though the time of flower opening shifted to an earlier point in constant darkness compared with the 12 h photoperiod, but it was not observed in constant light. We also evaluated the effect of exposing cut flowers first to a 12 h photoperiod and then shifting them to an 18 h photoperiod. During the 12 h photoperiod, flower opening started shortly before the light period had begun and stopped during the light period, while in the 18 h photoperiod, it proceeded in the middle of the dark period. These results suggested that changes of light to darkness or vice versa were important signals for the start and maintenance of rhythmic flower opening. In addition, we found that even a petal removed from a rose flower showed rhythmic growth when exposed to a 12 h light/12 h dark photoperiod, showing that petals could perceive light and synchronize their growth to the photoperiod.

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For determination of the endogenous and exogenous causes of somaclonal variation in in vitro culture, a bioassay system was developed using the variegated Saintpaulia (African violet) ‘Thamires’ (Saintpaulia sp.), having pink petals with blue splotches caused by transposon VGs1 (Variation Generator of Saintpaulia 1) deletion in the promoter region of flavonoid 3',5'-hydroxylase. Not only true-to-type but also many solid blue and chimeric plants regenerate in vitro-cultured explants of this cultivar. Using multiplex PCR that enables the determination of these variations, we attempted to evaluate the effects of four candidate triggers of mutation: pre-existing mutated cells, shooting conditions in vitro or ex vitro, cutting treatment of explants, and addition of plant growth regulators (PGRs) to the medium. The percentages of somaclonal variations among total shoots regenerated from leaf segments and stamens were 46.6 and 56.5, which were higher than the percentages expected from pre-existing mutated cells (3.6 and 1.4, respectively). These results indicate that pre-existing mutated cells are not a main cause of somaclonal variations. The percentage of somaclonal variation was independent of culture conditions for mother plants; the mutation percentages of adventitious shoots regenerated from ex vitro- and in vitro-grown leaves were 9.2% and 8.5%, respectively. In addition, the percentage of somaclonal variations of adventitious shoots regenerated under in vitro conditions from the in vitro grown mother plants was also low, at 4.9%. This indicates that the in vitro condition itself is not a main cause of somaclonal variation. However, when adventitious shoots were regenerated from 10 × 5-mm cut-leaf laminas on a PGR-free medium, the percentage of somaclonal variation was 26.4%. In addition, the percentage of somaclonal variations dramatically increased when PGRs were added to the medium for both leaves and leaf segments (39.9 and 46.6, respectively). The bioassay system using Saintpaulia ‘Thamires’ will enable the screening of many environmental factors because of its rapidity and ease of use and will facilitate the development of a new tissue culture technology for avoiding mutation.

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Mature pollen grains of Lilium cultivar, with their germ pores folded in upon themselves, were observed under a scanning electron microscope (SEM). The conventional pretreatment process requires aldehyde fixation, dehydration, drying and metal sputtering for SEM observation. These complicated and laborious procedures can considerably alter the morphology of pollen grains. In order to omit this conventional pretreatment process, we established a novel technique utilizing an ionic liquid (IL) that is composed solely of ions, namely, a liquid salt that can remain in a molten state even at room temperature. IL-treated pollen grains could be observed under vacuum conditions without artifacts, and furthermore, a satisfactory SEM image could visualize pollen grains in a wet state. The possible direction of future studies on ionic liquids in the SEM field is also discussed.

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Premature softening during low-temperature storage is a major issue in the red kiwifruit (Actinidia chinensis Planch.) cultivar ‘Rainbow Red’. The objective of this study was to investigate the effect of low temperature on ethylene sensitivity in this cultivar. We demonstrate how ethylene preconditioning at 4°C and 25°C interacted with more rapidly ripening at the lower temperature in ‘Rainbow Red’ kiwifruit. The expression of ripening-related genes ACS1, ACO3, EIL4, ERF14, and PGB was at the basal level during ethylene preconditioning at 4°C and 25°C, and rapidly increased with ethylene treatment following ripening. These results suggest that low-temperature storage enhances ethylene sensitivity in ‘Rainbow Red’.

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Asparagus has a short shelf life. A temperature of 0–2°C with a relative humidity of 95–100% is well known as the ideal storage environment for asparagus spears. The quality of spears stored in a snow vault and snow mount (Snow) was compared with those stored in an electric refrigerator (Refrigerator). Asparagus spears of ‘Grande’ and ‘Gijnlim’ were stored in Snow and Refrigerator for 0, 2, 5, 10, and 20 days; then, 1) physical and external appearance characteristics such as hardness, weight, and surface color, and 2) features of internal quality such as Brix, sugar, ascorbic acid, and rutin content in the spears were investigated. Although temperature and relative humidity fluctuated largely in the ranges of 3–6°C and 65–85% in Refrigerator, those in Snow were almost completely stable at 0–1°C and 100%. In ‘Grande’, the weight of the spears stored in Refrigerator decreased dramatically compared with that of spears stored in Snow. The external appearance of ‘Gijnlim’ spears was preserved until the 10th day, but loose tips were observed on the spears in both Snow and Refrigerator on the 20th day. ‘Grande’ spears stored in Refrigerator turned slightly brown and wilted at the surface of the basal part compared with Snow-stored spears. No loose tips were observed on ‘Grande’ spears. There was also no significant difference in the internal quality of spears between those stored in Snow and Refrigerator, in both varieties. CO₂ emissions in snow storage were reduced to half of those in refrigerator storage in LCA analysis and no CO₂ emissions were identified during the storage period in Snow. From the perspectives of energy utilization and quality preservation, snow appears to be one of the better alternatives for spear preservation than use of a refrigerator.

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