Japan Agricultural Research Quarterly: JARQ
Online ISSN : 2185-8896
Print ISSN : 0021-3551
ISSN-L : 0021-3551
Volume 54 , Issue 2
Showing 1-11 articles out of 11 articles from the selected issue
REVIEWS
Food
  • Junichi MANO, Reona TAKABATAKE, Kazumi KITTA
    Type: review-article
    2020 Volume 54 Issue 2 Pages 113-119
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    The varieties of commercially available genetically modified (GM) crops are rapidly increasing, and this situation demands analytical methods capable of detecting recently developed GM crops. Here we review our research activities to develop and validate new analytical methods for recently distributed GM crops. For the screening analysis of GM content in analytical samples, we developed real-time PCR-based quantitative methods for two GM maize events, MIR604 and MIR162. To accurately analyze GM content irrespective of the commingling of stacked GM events, we developed the group testing method. For the comprehensive analysis of various GM events, the real-time PCR array method was established. In November 2016, the Consumer Affairs Agency of Japan released the standard testing manual including these new testing methods to ensure the validity of the food labeling system in Japan. Given the expected increase in the number of GM events to be analyzed in the future, we need to keep working toward the realization of simple and comprehensive detection and quantification methods that can be used for the increasing number of these events.

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Horticulture
  • Atsushi ITO, Eiko NIWATA, Chihomi KON, Mitsuru HACHIYA
    Type: review-article
    2020 Volume 54 Issue 2 Pages 121-127
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    For a year-round supply of high-quality garlic, a technological system that combines the post-harvest curing of bulbs and long-term storage is essential. For long-term storage after harvesting and curing, storage at a subzero temperature effectively suppresses germination and rooting. However, after being delivered from a storehouse through distribution and sales to consumers, instances of “concavities on the surface of scales” of garlic bulbs have been witnessed when kept at ambient temperature. As a method of suppressing the occurrence of concavities, we focus on curing after harvesting. We confirmed that the incidences of concavities after storage at subzero temperatures are greatly reduced by introducing a tempering method that ventilates hot air during the daytime and ambient temperature air overnight. And based on the demands of growers, we showed how the tempering method can be applied at production sites. These results are summarized in the “PostHarvest Processing Manual for a Year-Round Supply of Garlic” and utilized at production sites.

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ARTICLES
Crop Science
  • Minoru ICHIHARA, Tohru TOMINAGA, Masayuki YAMASHITA, Hitoshi SAWADA
    Type: research-article
    2020 Volume 54 Issue 2 Pages 129-135
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    In this study, we aimed to evaluate the levels of resistance of Lolium multiflorum populations to glyphosate and glufosinate in Japanese pear orchards in Hamamatsu City, Shizuoka Prefecture, Japan, and determine the efficacy of several foliar-applied herbicides to control this weed during several growth stages. Bioassays using glyphosate-potassium (1.08-2.70 kg ai ha-1) and glufosinate (0.60-1.00 kg ai ha-1) were conducted, and the survival rates of L. multiflorum populations after foliar application were 11.1%-53.3% and 0.0%-5.6%, respectively. After treatments with several foliarapplied herbicides in the early growth stage (at a plant length of about 5 cm) with the maximum dosage, the survival rate of plants treated with glyphosate-potassium (38.9%) was not significantly different from that of plants receiving no treatment (100%). However, the survival rates of plants treated with quizalofop-ethyl (0.0%), glufosinate (17.8%), and glufosinate-P-sodium (18.9%) were significantly lower than that of plants receiving no treatment. In the middle growth stage (at a plant length of about 35 cm), although the survival rate of plants treated with quizalofop-ethyl (8.3%) was significantly lower than that of plants receiving no treatment (100%), the survival rates of other plants were not significantly different from that of plants receiving no treatment. These results indicate that L. multiflorum has developed resistance to glyphosate and glufosinate in the orchards, and suggest that the foliar application of quizalofop-ethyl (0.74 kg ai ha-1) is particularly effective for the control of this weed.

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  • Takahiro HARA, Ryoma TAKESHIMA, Katsuhiro MATSUI
    Type: research-article
    2020 Volume 54 Issue 2 Pages 137-143
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    Preharvest sprouting (PHS), caused by rain after maturity, leads to a severe degradation of buckwheat quality. We previously reported the PHS tolerance of several natural resources and landraces in Japan, and have bred PHS-tolerant lines. Here, we investigate the rates of PHS in our breeding lines and leading cultivars in Japan. The new lines ‘Kyukei 28’ and ‘Kyukei 29’ had better PHS tolerance than all leading cultivars. To reveal the PHS tolerance inherited by these lines, we performed genetic analysis using crosses between these lines and a self-compatible line, ‘Kyukei SC7’. The rate of germination in F2 segregating lines showed different segregation patterns, suggesting that major tolerance genes in ‘Kyukei 28’ (KY28) are recessive and those in ‘Kyukei 29’ (KY29) are dominant. This information could help to accelerate the breeding of buckwheat lines with PHS tolerance and develop DNA markers for the selection of tolerant lines.

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  • Peter Lyod P. SABES, Mathias Mawo LON, Mchuno Alfred PETER, Jumpei MAR ...
    Type: research-article
    2020 Volume 54 Issue 2 Pages 145-151
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    Silicon (Si) application is considered one means of cultural management having beneficial effects on the control of rice diseases. Carbonized rice husk (CRH)—a cost-effective biochar derived from a by-product of rice production—has been proposed as Si fertilizer as well as for promoting carbon sequestration in soil. This experiment was conducted in an irrigated paddy field in Tsukuba, Japan, to evaluate the potential effects of CRH application on sheath blight among four treatments (two levels of CRH application at 1.5 and 3.0 t ha-1, a spray of fungicide with flutolanil, and the control without any application). The results demonstrated that CRH at 3.0 t ha-1 increased rice Si content by 9% and regulated sheath blight development in the plant community to some extent after inoculation, whereas CRH at 1.5 t ha-1 showed no clear impacts on rice plants and fungal pathogen development. The fungicide application with flutolanil had the lowest rate of sheath blight development, but did not affect rice Si content. The results suggest that CRH application at 3.0 t ha-1 or more could be an option for integrated management of sheath blight without negative effects on rice yield.

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Agricultural Engineering
  • Kosuke HAMADA, Yoshiyuki SHINOGI, Tomoyuki TANIGUCHI, Hidetoshi MOCHIZ ...
    Type: research-article
    2020 Volume 54 Issue 2 Pages 153-162
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    Enhanced irrigation efficiency is necessary to address water shortages, and precise estimation of soil water movement by simulation models is essential. Previous studies have suggested that soil hydraulic properties, which are important factors of soil water movement, differ spatially in the horizontal and vertical directions. However, most of studies have estimated soil water movement by considering soil hydraulic properties only along the soil profile. In the present study, we defined soil hydraulic conductivity and soil water retention as soil hydraulic properties, and conducted soil water movement simulations considering the spatial (horizontal and vertical) differences in soil hydraulic properties.

    The simulation model also estimated soil temperature to include water vapor transfer in the estimation of soil water movement. We validated the model by comparing simulated and observed results from a pot experiment, and comparing the soil water movement and soil temperature in two cases of applying the soil hydraulic properties: spatial application and vertical application. The results showed that the simulated soil temperature differed from the observed values due to the uniform application ofthermal conductivity of soil. Our findings indicated that the differences in soil water movement between both cases increased with the number of irrigations.

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  • Takeshi KUROYANAGI
    2020 Volume 54 Issue 2 Pages 163-170
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    Windbreaks constitute a traditional methodology adopted to reduce heat loss from greenhouses. In this study, the influence of a windbreak on the heat loss from a heated greenhouse was investigated. Energy balance and leakage measurements were conducted simultaneously at a plastic-film-covered greenhouse with a forced air heater and a single-layer thermal curtain. A windbreak covered with a plastic net (porosity of 0.60) was built 7.0 m away from the windward side of the greenhouse. The heat transfer coefficients of the greenhouse were derived from the cases where the net was rolled up and deployed on the windbreak. The overall heat transfer coefficient of the entire greenhouse (U value) was reduced by the net-covered windbreak. The reduction increased as the windspeed increased: the windbreak reduced the U value by 11.9% at a windspeed of 0.5 m s-1, and by 22.4% at a windspeed of 3.0 m s-1. The effect of the windbreak on the U value was mainly due to the wellknown dependency of leakage on windspeed. The windbreak also influenced the U value owing to the reduction of the overall heat transfer coefficient of the greenhouse cover (K value) in windy and radiative cooled conditions.

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Social Science
  • Wenhao WU, Guosheng WU, Changbin YIN, Hsiaoping CHIEN
    Type: research-article
    2020 Volume 54 Issue 2 Pages 171-177
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    This study aims to examine the revenue effects of rice contract farming for small high-value rice farmers and explore the constraints on the adoption of contract farming in China using a face-to-face survey questionnaire as the main instrument of data collection. A probit model and ordinary least-squares (OLS) regression analysis were used to estimate the likelihood of participation in contract farming and the impact of contract farming on rice farmers’ income, respectively. A total of 78 household questionnaires collected in Wuchang was considered valid for analysis. This study proves that participating in contract farming is an effective way of increasing rice farmers’ income, after control for observable and unobservable household characteristics. Specifically, contract farming contributes toward enhancing the rice farm-gate price and cost-profit ratio. The results also reveal that rice farmers with organic or green planting experience are more likely to participate in contract farming.

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Animal Science
  • Hiroki MATSUI, Kiyoshi TAJIMA, Hisao ITABASHI
    Type: research-article
    2020 Volume 54 Issue 2 Pages 179-183
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    The effect of bromochloromethane-cyclodextrin (BCM-CD) on the microbial community structure in the rumen of steers was examined in this study. Two animals were fed a diet supplemented with BCM-CD (1.0 g/100 kg body weight/day) for two weeks, while two other animals were fed a basal diet during the same experimental period to serve as controls. Two 16S rRNA gene clone libraries were constructed from the rumen fluid of both the control and BCM-treated animals. DNA sequences from the libraries were searched for homology. The statistical differences between both libraries were examined by LIBSHUFF analysis. The DNA sequences of each library were taxonomically classified and the proportion was calculated. A total of 107 (control) and 110 (BCM-treated) clones were analyzed, and the Chao-1 species estimate was 1.6-fold higher in BCM-treated samples. LIBSHUFF comparison showed a statistically significant difference between the two clone libraries. No methanogenic archaeal clone was detected in the BCM-treated clone library. Within Firmicutes, the proportion of Lachnospiraceae clones in the BCM-treated library was 4.5-fold higher than that in the control library. The proportion of Prevotellaceae clones was 1.7-fold higher in the BCM-treated library than in the control library. These results suggest that BCM-CD indirectly affects eubacterial community in the rumen.

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Forestry
  • Koichi TAKENAKA, Buruh ABEBE, Ryuichi TABUCHI
    Type: research-article
    2020 Volume 54 Issue 2 Pages 185-191
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    The development of forest monitoring methods for the plantation eucalypt forests in Ethiopia is crucial as eucalypts play an important role in the country’s wood supply. We assessed the stand structure and estimated the total stem volume of a 30-year-old Eucalyptus globulus forest in the highlands (>3000 m altitude) of northern Ethiopia. Census data were collected from 186 trees, of which 28 trees were destructively sampled. The forest stand density was 581 trees ha−1, mean ± SD diameter at breast height was 21.2 ± 6.4 cm, and mean ± SD predicted tree height was 22.0 ± 4.2 m. The estimated stem volume was 269.7 m3 ha−1. An allometric model to predict tree height was derived using the measured diameter at breast height of the sampled trees. Moreover, an allometric model was developed to estimate stem volume for standing trees in order to describe the relationship between the stem volume and diameter at breast height squared × tree height (incorporated as a compound variable), using data on 38 trees for which height could be measured reliably. The findings suggest that the diameter at breast height alone can be used to estimate stem volume, and thus may be useful for simple forest monitoring in the study region. This study is one of the few to assess the stand structure and stem volume of a high-altitude Eucalyptus plantation.

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Fisheries
  • Shinsuke MORIOKA, Katsuhisa TANAKA, Tatsuya YURIMOTO, Faizul M. KASSIM ...
    Type: research-article
    2020 Volume 54 Issue 2 Pages 193-199
    Published: April 01, 2020
    Released: April 14, 2020
    JOURNALS FREE ACCESS

    Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) were determined for the spotted scat (Scatophagus argus) in the Matang Mangrove Forest Reserve in Peninsular Malaysia. The ratios from fish samples along with those obtained from samples of their potential food items (i.e., mangrove leaves in the estuary, coastal phytoplankton, microphytobenthos) revealed wide variations, indicating that S. argus utilizes various food items between the coastal area at the river mouth to the inner mangrove estuary. The carbon isotope ratio in the fish body tended to be lower in fish sampled from the inner estuary as compared with fish at the river mouth. The carbon isotope ratio values of the fish body were relatively high in small fish (<20 mm in total length [TL]) but lower in fish of 20-100 mm TL, and relatively higher in fish >100 mm TL. These findings strongly suggest that small-sized S. argus (<20 mm TL) migrate from the outer coastal area into the mangrove estuary and utilize the mangrove estuary habitat as their nursery grounds before eventually returning to the river-mouth area as their growth progresses.

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