Japan Agricultural Research Quarterly: JARQ
Online ISSN : 2185-8896
Print ISSN : 0021-3551
ISSN-L : 0021-3551
Current issue
Displaying 1-9 of 9 articles from this issue
REVIEWS
Agricultural Environment
  • Yasumi YAGASAKI
    Article type: review-article
    2022 Volume 56 Issue 3 Pages 219-227
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    Two recently developed models of radio-cesium (RCs) transfer from soil to rice grains that were parameterized and ready-to-use for paddy fields in Fukushima were reviewed to establish model-based countermeasures for food safety management in Fukushima. A probability density function model of the transfer factor from soil to rice grains based on soil exchangeable potassium (K) was compared with that of a rice grain RCs concentration model on the basis of the concentration of soil exchangeable RCs and soil exchangeable K. The relevance between these two models was demonstrated using soil exchangeable RCs as a quantitative index of the availability of soil RCs and observed data. The results indicate that the probability density of the transfer factor is affected by soil exchangeable RCs and that the use of a log-normal distribution in the model is justified by the observed distribution pattern of soil exchangeable RCs. This finding improves the accountability of the differences in the modeled probability densities for different regions and helps design countermeasures using the two models for different purposes, such as precautions for K fertilization or conservative risk assessment of shipping restrictions.

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Agricultural Engineering
  • Masahiro OHNISHI, Tomoko FUKAI, Tomohiko OTA
    Article type: review-article
    2022 Volume 56 Issue 3 Pages 229-236
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    We developed an arm-raising work assistance tool and evaluated its ability to mitigate the effects of the workload during grape cultivation. The tool comprises a hip belt, arm supports, and connectors linking them. This tool supports the arms when held at any height while keeping the wearer’s elbows pulled in. When performing berry thinning using the tool, the percent maximum voluntary contraction (%MVC) of the deltoid muscle was found to reduce by approximately 30%-80% without reducing the efficiency. Seven out of eight workers reported that using the tool made their work easier.

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Horticulture
  • Ryosuke YAMANAKA, Hiroki KAWASHIMA
    Article type: review-article
    2022 Volume 56 Issue 3 Pages 237-243
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    In Japan, several protected horticultural farms depend on nonrenewable sources of energy, such as fossil fuels. However, widespread consumption of fossil fuels causes global warming, and fluctuations in fossil fuel prices may adversely affect farm management. Thus, new low-cost energy-saving techniques have been developed recently. For instance, a multilayered thermal curtain fabricated from nanofiber enhanced the thermal insulation of greenhouses, thereby reducing fossil fuel costs by approximately 35%-51%. Additionally, a local heating technique, which selectively heats areas surrounding the tomato shoot apexes and flower clusters using hanging warm air ducts, has been applied to reduce energy consumption in cherry tomato or tomato cultivation, reducing reduced fossil fuel costs by approximately 10% compared with the conventional method using ground-fixed warm air ducts. Furthermore, a low-cost multivariable environmental control system, “YoshiMax,” simultaneously controlled the ambient temperature and CO2 concentration in a greenhouse along with the frequency of fertigation in response to solar radiation; this improved plant growth and reduced CO2 and fertilization costs. These and other similar techniques are expected to enable sustainable agricultural management. To increase the efficiency of energy use, it is also effective to increase yield per energy input via high-density planting using a movable bench, etc.

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ARTICLES
Biotechnology
  • Aki SAGISAKA, Ritsuko MURAKAMI, Kenji WATANABE, Hiromitsu TANAKA
    Article type: research-article
    2022 Volume 56 Issue 3 Pages 245-250
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    Sap-sucking insects, such as aphids, leafhoppers, thrips, and whiteflies, are vectors for > 70% of plant viruses. Presently, the development of insecticide resistance is causing a problem in agriculture worldwide as control of these insect vectors and of virus transmission is increasingly difficult. Insects lack an adaptive immune response system but use RNA interference (RNAi) functions as antiviral defense systems. Nevertheless, some viruses that infect insects encode proteins termed as viral suppressors of RNA silencing (VSR) proteins that can act against the RNAi systems. VSR proteins enable viruses to keep and increase in number in the body of the insects. The present study aimed to construct a VSR detection system for use in the detection of VSRs of viruses transmitted by insect vectors. The activities of VSR proteins were measured using a dual-luciferase reporter assay in S2 Drosophila cells. The analyses showed that HC-pro protein from Zucchini yellow mosaic virus had the highest level of activity among the tested VSR proteins. This methodological approach enables the detection of VSR proteins and measurement of VSR activities of insect viruses as well as plant viruses transmitted by insect vectors.

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Agricultural Environment
  • Atsushi MATSUMURA, Takuya MORISHITA, Shusuke NAKAI, Hiroyuki MASUMOTO, ...
    Article type: research-article
    2022 Volume 56 Issue 3 Pages 251-260
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    Soils are heterogeneous at a spatial scale because of variability in soil nutrients and physical factors. The present study was conducted to investigate the heterogeneity of soil physicochemical properties in differently managed fields to determine the key factors influencing the grain yield and β-glucan content of naked waxy barley. Two fields were compared—one upland field converted from a paddy (converted upland) and one conventional upland field (normal upland). In each field, the relationships between variables were examined using correlation analyses. The results showed that the converted upland had lower yield and β-glucan content than that of the normal upland. Soil water content was a significant factor in both fields, but greater effect was observed in the converted upland. The β-glucan content was negatively correlated with soil water content in the converted upland. Electrical conductivity or mineral N was positively correlated, whereas soil penetration resistance at the depth of 20 cm-30 cm was negatively correlated with the β-glucan content in the normal upland. Comprehensive analyses indicated that avoiding water damage is the priority for increasing the yield and grain β-glucan content of naked waxy barley.

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Food
  • Masatsugu TAMURA, Kanae HOSHI, Takahiro SAITO, Yoshimasa SASAHARA
    Article type: research-article
    2022 Volume 56 Issue 3 Pages 261-267
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    The present study aimed to investigate the in vitro starch digestion of cooked rice grain with added vegetable oils. Polished rice grain (400 g) was cooked with 500 mL of ultrapure water only or with one of six types of vegetable oils (cocoa butter [CB], coconut oil, corn oil [CO], olive oil [OO], palm oil, and rapeseed oil [RO]), and then was frozen and stored. The frozen grain was reheated using a microwave and used for texture analysis, in vitro gastro-small intestinal digestion, and microstructure observation. The cooked grain with added CB had significantly higher resistant starch content (0.70% d.b.) than the control (0.19% d.b.). Although the surface firmness and overall adhesiveness of the cooked grain were not significantly different between the samples, the overall firmness of the grain cooked in RO was significantly lower than that of all others. Cooked grain with added RO (70.35%) indicated a significant reduction in starch hydrolysis compared with the cooked grain with added OO (95.04%) and CO (83.94%) at 210 min of in vitro digestion. However, no difference was observed in tissue structure of the digested cooked grain between the samples.

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Forestry
  • Eko PRASETYO, Fajar SETIAWAN, WIDIYATNO, Mohammad NA’IEM, Haruka OHAS ...
    Article type: research-article
    2022 Volume 56 Issue 3 Pages 269-281
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    Indonesia, mainly Java, is home to the second largest area of Tectona grandis (teak) plantations globally; however, despite their importance, little is known about the impact of climate change on this tree species. Here, species distribution models were developed using estimated site index values of T. grandis on Java as the response variable, with seven bioclimatic variables and three soil characteristics as predictor variables. Three statistical approaches—generalized linear, general additive, and random forest models—were examined. Two global climate models with two representative concentration pathways (2.6 and 8.5) and time periods (the 2050s and 2070s) were also used to compare the effect of predicted future changes in the site index. Of the three models, random forest model showed the best fit, with precipitation as the important predictor of T. grandis growth followed by temperature. The model predicted that 12.6% of Java Island would experience an increase in climatic suitability, with northeast of Banten Province, northeast and northwest of Central Java Province, and northwest of East Java Province becoming the most suitable for T. grandis growth in both the 2050s and 2070s. These findings suggest that certain areas should be prioritized for the development of future T. grandis plantations on Java.

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Fisheries
  • Kazuya NISHIDA, Satoru N. CHIBA, Kay SAKUMA, Ryouichi HIGASHI, Nobuaki ...
    Article type: research-article
    2022 Volume 56 Issue 3 Pages 283-294
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    Distinguishing between Beryx splendens and Beryx mollis (Actinopterygii: Beryciformes) on the basis of external morphology is difficult, and a reliable method of differentiation must be established. In this study, we developed a multiplex polymerase chain reaction (PCR) method with species-specific primers for distinguishing B. splendens from B. mollis. In total, 146 specimens were collected in the North Pacific Ocean, East China Sea, and Southwest Indian Ocean. Provisionally, 115 specimens were identified on the basis of the number of pyloric caeca. Phylogenetic analysis was also performed by using the 146 partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene and sequences from a DNA database. Identification by the number of pyloric caeca was consistent with the result of the COI phylogeny, and we surmised that the use of the COI sequences was effective for the differentiation of the two species. Multiplex PCR with species-specific primers was subsequently developed on the basis of the partial COI sequences. All of the specimens used in the molecular analyses were successfully identified as B. splendens or B. mollis via electrophoresis of the PCR products amplified using the species-specific PCR primers.

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  • Haruo YAMAGUCHI, Minoru INOUE, Yuko TANIMOTO, Narumi SUMIDA, Masao ADA ...
    Article type: research-article
    2022 Volume 56 Issue 3 Pages 295-301
    Published: July 01, 2022
    Released on J-STAGE: August 13, 2022
    JOURNAL FREE ACCESS

    Dissolved nutrients, especially inorganic nitrogen (N) and inorganic phosphorus (P), are typically deficient in the coastal surface waters of temperate regions during warm seasons. Even under the conditions of inorganic N and P deficiencies, the planktonic diatom Chaetoceros tenuissimus sometimes forms blooms. The present study characterized, at the mRNA transcript level, the gene expression patterns in N- or P-limited cultures of C. tenuissimus to propose the molecular markers of N- and P-deficient states of C. tenuissimus. Gene transcriptions of nitrate transporter and glutamine synthetase appeared to be upregulated in N-limited cultures. Phosphate transporter and alkaline phosphatase transcriptions appeared to be induced under P-limited conditions. These results suggest that C. tenuissimus under the N-deficient state expresses a transmembrane nitrate transporter, uptakes nitrate effectively, and assimilates the N source rapidly via glutamine synthesis; P-deficient C. tenuissimus possibly supplements P sources from organic P compounds via hydrolysis actions of phosphatases and uptakes phosphate effectively through phosphate transporters.

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