The effect of water stress on the number of first-flush flowers was investigated in Meiwa kumquat trees. Treatments of soil water deficit (SWD), soil water deficit combined with mist (SWM), and non-treated controls (CONT) were established in a greenhouse in 2009 and 2010. The leaf water potential in SWD and SWM decreased significantly after 10 d of the treatment. In 2009, the number of first-flush flowers in SWD and SWM was 133.8 and 142.4, respectively, and these were significantly greater than that in CONT. Second- or third-flush flowers were significantly greater in CONT. In 2010, the number of first-flush flowers increased with a decrease in the leaf water potential down to −1.7 MPa. It was also positively correlated with leaf abscisic acid (ABA) content, but did not significantly change once ABA levels exceeded 5 nmol g−1. These results suggest that water stress increases the number of first-flush flowers. The severe water stress represented by leaf water potentials below −1.7 MPa, or over 5 nmol g−1 of leaf ABA content, did not appear to have the same effect. Approximately 150 flowers per 100 nodes of shoots appeared to be the maximum number of first-flush flowers produced by Meiwa kumquat trees.
We investigated whether it is possible to produce vinblastine by irradiation of blue light (B, 440 nm) and ultraviolet A light (UVA, 370 nm) to Catharanthus roseus for domestic production of vinblastine using an environmentally controlled room with artificial lighting, such as a plant factory. Catharanthus roseus plants were cultivated under red light (R, 660 nm) for 28 d and then were cultivated under 3 light quality treatments: UVA supplemented with R, B, or R for 7 d. At 3 d after treatments, vinblastine content in the leaves increased sharply under UVA supplemented with R compared with R alone. The vinblastine content under B was 1/6 of that under UVA supplemented with R. Vinblastine content increased as the UVA intensity was increased from 0 to 10 Wm−2. UVA irradiation to the leaf discs made from the younger leaves raised the vinblastine content in the leaf discs more than those from the aged leaves. Therefore, UVA light should be irradiated to the young plants at early vegetable stage. For the domestic production of vinblastine, we proposed that the cultivation method of irradiating young plants with 10 Wm−2 UVA for more than 3 d.
Japanese honeysuckle is an evergreen vine that grows naturally in Japan and East Asia. The buds and leaves of this plant are used as crude drugs known as Kinginka and Nindou, respectively, in Japan and East Asia. The medicinal compounds are chlorogenic acid and luteolin, which have antiviral, anticancer, anti-inflammatory, and antioxidant activities. The optimal environmental conditions for growing Japanese honeysuckle have remained unknown thus far. The aim of this study was to investigate the effects of supplemental lighting in winter greenhouse on growth and production of medicinal compounds in Japanese honeysuckle. For that purpose, we cultivated Japanese honeysuckle plants in a greenhouse using supplemental lighting from high-pressure sodium lamps. During the experiment, the daily light integral was maintained at 10 mol m −2 d −1 by controlling the irradiation period of supplemental lighting from the evening until midnight. The total dry weight and total leaf area of plants subjected to 55 d of supplemental lighting were significantly higher than those in control plants. The number of flower buds was significantly higher in treated plants, and then, there was no difference in the concentration of chlorogenic acid and luteolin between the two groups. In conclusion, supplemental lighting is a useful method for winter cultivation of Japanese honeysuckle that increases the yield of flower buds and does not decrease the concentration of main medicinal compounds.
Improving the yield and quality of crops is imperative within agriculture. Both traits depend on gene expression and metabolic activities that are affected by environmental factor, and are therefore complex and variable. Transcriptome analysis is a helpful method to understand gene expression profiles in vivo; however, most crops are in fact cultivars for which there is little genetic information. In this study, we determined gene expression profiles of Perilla frutescens var. crispa f. viridis, a cultivar of green perilla. We compared the transcriptome gene sequence of P. frutescens in leaves and roots after 7, 14, and 35 d of growth with the gene sequences of other plants in public databases. Green perilla showed the highest similarity to Mimulus guttatus (Lamiales). Genetic information for approximately 13,000 genes was evaluated, and many of these genes have been classified into the organism's biological processes using Gene Ontology analysis. De novo-based gene expression levels and other plants-based gene expression levels were similar in 90% of genes. Results suggest that information from public databases can assist in analyzing the genetic information of cultivars. This method will be a platform for providing rapid and cost-effective options for use in commercial agriculture.
Several studies have reported that the circadian rhythm of leaf lettuce (Lactuca sativa L.) is approximately 24 h and that the fresh weight of Greenwave, a cultivar of leaf lettuce, is larger under the light-dark period of 22 h or 24 h. In this study, we investigated the optimal light-dark cycles for Greenwave and the deciding factors of optimal light-dark cycles by cultivation experiments under several light-dark conditions in plant factory. By optimization of light-dark cycles, we obtained the optimal light-dark conditions for the light/dark ratio (L/D) of L/D=2 and the light-dark period of 15-22 h (T15-T22). In addition, the higher growth rate on T21 and T22 conditions was suggested to be related to the decrease in leaf starch concentration at night. The results in this study suggests that the cultivation of leaf lettuce under light-dark conditions reduce running costs in plant factory with artificial lighting (PFAL).
Understanding the effect of light on stomatal behavior is mandatory for plant cultivation under controlled environmental systems. In this study, the effects of LED light quality and intensity on daily stomatal conductance (gs), stomatal aperture movement and stomatal density were investigated in petunia (Petunia×hybrida Vilm.) plants under a semi-closed system. Three petunia cultivars, namely ‘Coral’, ‘Purple’ and ‘Red’, were grown under different light quality and quantity for 1 month and then all the parameters were measured. Results showed that ‘Coral’ exhibited overall higher gs than ‘Purple’ and ‘Red’. Light quality significantly affected gs, width of stomatal aperture and stomatal density of all cultivars. The effect of light quality on gs and width of stomata aperture was strongly depended upon cultivar and time of day and there was a two-way interaction. Light intensity did not affect daily fluctuation pattern of gs but did affect the amplitude of the fluctuation. In contrast to the effect of light quality, the effect of light intensity was independent of cultivar and time of day. There was no obvious correlation between gs and width of either adaxial or abaxial stomata apertures during photoperiod. Light intensity significantly affected stomatal density which could partially explain an increasing of gs in response to increasing light intensity.
Monoecious cucumber (Cucumis sativus L.) produces male and female flowers on the same plant, but application of ethylene promotes expression of female flowers. In the early bisexual stage, all flower buds contain primordia for both stamens and pistils and sexual differences are established by the selective arrest of sexual organ primordia. The expression of six cell cycle-related genes [Cs Cyclin A (CsCycA), CsCycB, CsCycD3; 1, CsCycD3; 2, Cs Cyclin-dependent kinase A (CsCDKA), and CsCDKB] was analyzed in male and female flower buds to investigate cell cycle activity in sexual organs. CsCycA was expressed specifically in the area containing arrested stamen primordia (ACASP) in female flower buds, but was barely detected in male flower buds. Expression of the other five genes was detected in the ACASP but not in pistils of female flower buds. Expression of all six genes was elevated transiently following the application of 2-chloroethylphosphonic acid (ethephon), an ethylene-releasing agent, to the shoot apices. The correlation of expression of these genes with the formation of female flowers suggests they play a role in the arrest of stamens of female flowers in monoecious cucumber plants.
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