Japan Agricultural Research Quarterly: JARQ
Online ISSN : 2185-8896
Print ISSN : 0021-3551
ISSN-L : 0021-3551
Current issue
Showing 1-10 articles out of 10 articles from the selected issue
REVIEWS
Horticulture
  • Takeshi KUNIGA
    Type: review-article
    2020 Volume 54 Issue 4 Pages 285-291
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    Light is one of the most important factors affecting plant growth. Although photosynthesis has been widely investigated, knowledge remains limited on how the quality of light influences the production of horticultural crops, especially fruits and vegetables. Here, we present a review of recent studies on how modification to light quality influences the production of these crops. The light environment contributes toward sustaining and regulating fruit and vegetable production. And light conditions are increasingly being modified with such artificial light as light-emitting diodes (LEDs), coupled with sheet mulching. These tools are useful for enhancing light-mediated growth and reproduction in plants. Thus, the physiological and biological responses of plants to light must be analyzed to advance our understanding of the molecular mechanisms underlying how light controls plant development.

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  • Atsushi KONO, Takeo SHIMIZU
    Type: review-article
    2020 Volume 54 Issue 4 Pages 293-298
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    Leaf trichomes confer pest resistance. Dense trichomes could also present a physical barrier to microorganisms, such as grapevine downy mildew caused by Plasmopara viticola on grape. Zoospores of P. viticola swim in water and enter stomata. Some wild Vitis accessions such as V. labrusca and V. cinerea have highly hydrophobic, dense, prostrate trichomes on the lower leaf surface that repel water and enhance resistance to downy mildew. Quantitative trait loci for leaf trichome density have been identified on LGs 5, 7, 8, and 15 of grapevine. A major locus on LG 5 was found in V. vinifera ‘Muscat of Alexandria,’ which has few leaf trichomes. Hairless alleles on LG 5 in historical V. vinifera cultivars reduce trichome density in the progeny of V. labrusca origin. Applying information on these loci in breeding programs would allow the introduction of this natural physical barrier against pathogenic microorganisms into cultivars.

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Animal Science
  • Rena YOSHITOSHI, Nariyasu WATANABE, Jihyun LIM
    Type: review-article
    2020 Volume 54 Issue 4 Pages 299-306
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    Livestock select places in a pasture that offer high-quality and nutritious grass, and these selections cause spatial heterogeneity and reduced productivity. To maximize the efficiency of pasture systems, it is important to understand the spatiotemporal information regarding livestock grazing behavior. In this review, we describe studies conducted to develop a simple tool for determining cow foraging behavior, and to predict the spatial distribution of cow excrement (dung) in a steeply sloping pasture. An accelerometry-based activity monitor, the Kenz Lifecorder EX (hereafter, the LC), was used to differentiate between foraging and other activities of beef cows. A linear discriminant analysis yielded good discrimination accuracy of the minute-based data of the LC. The combination of the activity timeline and GPS tracking data successfully revealed the spatiotemporal distribution of cow foraging activity in a sloping pasture. Both foraging activity and excretion play important roles in the nutrient cycling in pasture ecosystems. We found that the spatial distribution of cow dung could be predicted using a Bayesian approach in conjunction with a generalized linear mixed model incorporating conditional autoregressive terms with two parameters (green herbage biomass and distance from a water trough). Dung deposits tended to be distributed in areas with higher green herbage biomass and in areas located closer to the water trough. We also describe a new pasture survey method of detecting cow dung and weed positions in a pasture by using unmanned aerial vehicle (UAV)-based imagery.

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ARTICLES
Agricultural Environment
  • Eiko NAGAOKA-NAKAZONO, Nami UECHI, Hiroshi KATOH, Takashi FUJIKAWA, Sh ...
    Type: research-article
    2020 Volume 54 Issue 4 Pages 307-316
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    Citrus tristeza virus (CTV) commonly infects yuzu (Citrus junos) in most parts of the citrus-growing areas in Japan. This study examined the occurrence of CTV in the northernmost commercial citrusproducing areas of Japan. Colonies of the brown citrus aphid (Toxoptera citricidus) were detected within the areas investigated. However, 23 of the 41 trees that were examined by RT-PCR and both or either subject to stem-pitting observation and immunostrip testing were free of CTV. Several CTVfree trees were apparently more than 60 years old. A field trial revealed that all eight uninoculated seedlings tested negative for CTV at 52 months after transplanting. These results suggest that CTVfree yuzu production is possible in the Rikuzen-Takata and Ofunato areas of Japan.

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Agricultural Engineering
  • Hirofumi YAMASAKI, Mitsuhiro HORIO, Kohichi FUJITA
    Type: research-article
    2020 Volume 54 Issue 4 Pages 317-325
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    We studied the impacts of soil surface hardness and increased machinery body mass by the harvested crop relative to the fuel efficiency during traveling and driving for head-feeding combine harvesters. The fuel efficiency during traveling and driving increased with softness of the soil, showing a strong correlation with the index of hardness indicated in the Yamanaka model soil penetrometer. The index of hardness realizing fuel efficiency equivalent to traveling on the road was about 23 mm. Based on the fuel efficiency and index of hardness obtained in the testing, a relational expression between the index of hardness and fuel efficiency of the machinery provided for the testing was then figured out, thereby making it possible to correct the fuel efficiency during traveling and driving under any soil conditions. We also confirmed that fuel efficiency during traveling and driving increased with the mass of rough rice in the grain tank. We devised methods of testing and evaluating the fuel efficiency during traveling and driving, by correcting such conditions so as to make a fair comparison among different models.

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Social Science
  • Kenji HOSONO, Yuji YASHIMA
    Type: research-article
    2020 Volume 54 Issue 4 Pages 327-333
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    We aimed to clarify the competitive advantage of a vertically diversified brand chicken business as a method of creating a sustainable poultry business, using a part of Porter’s value chain framework to extract strengths and linkages of a company’s marketing in a case study of one enterprise adopting this business model. Company T1 achieved vertical diversification of its production, processing, distribution, sales, and restaurant businesses through its original brand chicken, produced on a directmanagement farm and cooperative farms under uniform quality control. T1 internalized its poultry farming and never abandoned this model, despite its low profitability, because its original brand H chicken was a high-quality product at the core of T1’s marketing strategy. We concluded that this high-quality original product resulted in a successful vertically diversified business within the poultry industry. To achieve this success, efforts are needed to maintain high levels of quality using sophisticated human resource approaches.

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Horticulture
  • Ryutaro AIDA, Naonobu NODA, Satoshi YOSHIOKA, Mitsuru DOUZONO, Mai TSU ...
    Type: research-article
    2020 Volume 54 Issue 4 Pages 335-340
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    Transgenic chrysanthemums (Chrysanthemum morifolium) with blue flower colors have already been created, and are expected to be commercialized. However, cultivated chrysanthemums are known to cross with wild species native to Japan, and careful studies are needed to assess the risk of these transgenes escaping into wild Chrysanthemum populations. We previously reported on the transmission of transgenes from the model cultivar ‘Taihei’ to interspecific progeny. For this study, we used the recently developed cultivar ‘Sei Arabella’ and a promising breeding strain (T37) as transgene hosts, and performed crosses between these lines and the wild species Chrysanthemum japonense var. japonense. We found relatively high seed set rates (20.6%-83.4%) after artificial, reciprocal pollinations, and the inheritance and segregation of the transgenes in the hybrid progeny were confirmed by PCR. Some of the transgenic progeny exhibited blue flower colors and contained modified anthocyanins, like their transgenic parents. These results were similar to those obtained with ‘Taihei’ and thus suggested that the risk of transgenes escaping to wild species could be quite high. Therefore, it will be important to investigate techniques to reduce this risk.

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  • Hiroko SHIMIZU-YUMOTO, Yumi UJIIE, Takayuki OGAWA
    2020 Volume 54 Issue 4 Pages 341-348
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    In Japan, cut Sarcandra glabra branches with fruit are used as a New Year’s decoration, but frequent fruit drop reduces ornamental value. This study investigated the effects of the harvest season, postharvest treatments, and shipping conditions on the fruit drop of branches, in order to propose a suitable postharvest handling method for the shipment of cut S. glabra branches. Ethylene treatments accelerated fruit drop, especially in cut branches on which the pericarp turned red early in the growing season. Silver thiosulfate complex (STS), an ethylene action inhibitor, was effective in reducing fruit drop regardless of ethylene treatments. However, treatment with 1-methylcyclopropene (1-MCP), another ethylene action inhibitor, increased the cumulative percentage of dropped fruit after seven days with or without ethylene treatment. A synthetic auxin, 1-naphthaleneacetic acid (NAA), had an effect similar to that of STS, but NAA tended to accelerate leaf abscission. Treatments with 0.03 to 1.0 mM STS for three days at 10°C reduced fruit drop. Treatments with 0.03 to 0.1 mM STS for three days at 23°C also reduced fruit drop, but the cut ends of branches turned brown with more than 0.3 mM STS. For pretreatment with tap water, the cumulative percentage of dropped fruit after simulated shipment at 10°C increased earlier than at 2°C. Pretreatment with STS strongly suppressed fruit drop after simulated shipment at 2°C and 10°C. Sugar and antibacterial agents in the vase solution were also effective in reducing fruit drop. Finally, the cut branches of S. glabra were treated with 0.1 to 0.3 mM STS for three days in the grower’s stockroom, and then dry-transported by reefer container at 2°C for 11 days. As a result, the cumulative percentage of dropped fruit from the branches was very low for ten days in a quality test room.

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Forestry
  • Kyotaro NOGUCHI, Sasitorn POUNGPARN, Suthathip UMNOUYSIN, Pipat PATANA ...
    2020 Volume 54 Issue 4 Pages 349-360
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    Fine roots are a key component of belowground carbon dynamics in forest ecosystems. However, information on fine root dynamics in mangrove forests is still limited. Therefore, in this study we examined the biomass and production rates of fine roots by using soil coring and an ingrowth core method, respectively, at soil depths of 0 cm-40 cm in Avicennia alba and Rhizophora apiculata stands in Ranong Province, southern Thailand. In these stands, the fine root biomass was ca. 3.4 kg m−2 and 1.4 kg m−2, respectively, while fine root production rates were ca. 450 g m−2 year−1 and 740 g m−2 year−1, respectively. Fine root biomass was not significantly different between the surface (0 cm-20 cm) and subsurface (20 cm-40 cm) soil in both stands. The fine root production rate was also similar between the soil layers in the R. apiculata stand, whereas it decreased with soil depth in the A. alba stand. The patterns of vertical distribution of fine root production rates probably reflected the species characteristics of A. alba and R. apiculata, and suggested that fine root production in the subsurface soil contributes significantly to belowground carbon dynamics, especially in R. apiculata.

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Fisheries
  • Shinsuke MORIOKA, Katsuhisa TANAKA, Tatsuya YURIMOTO, Faizul M. KASSIM ...
    Type: research-article
    2020 Volume 54 Issue 4 Pages 361-368
    Published: October 01, 2020
    Released: November 25, 2020
    JOURNALS FREE ACCESS

    We analyzed the gonadal development and age of the spotted scat (Scatophagus argus) in the Matang Mangrove Forest Reserve, Malaysia. Histological analysis of gonads indicated that few females and males in the mangrove estuarine system were sexually mature, with few specimens having sizes greater than the typical maturation size (> 140 mm in total length for females, > 110 mm in total length for males). These observations suggested that S. argus do not mature sexually in the mangrove estuary. Growth analysis using age information from otolith increments suggested that S. argus moved or are carried into the mangrove estuary during the late tholichthys larval stage at a size of about 12 mm-14 mm in total length (ca. 37 days old), and that the fish use the estuary as a nursery ground before sexual maturation. The period of sojourn in the estuary is for a maximum of ca. 290 days for females by the size of ca. 160 mm-180 mm in total length and ca. 155 days for males by the size of ca. 110 mm in total length. After these nursery periods, grown specimens reaching sexual maturity are considered to leave the estuary habitats.

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