Japan Agricultural Research Quarterly: JARQ
Online ISSN : 2185-8896
Print ISSN : 0021-3551
ISSN-L : 0021-3551
Current issue
Displaying 1-11 of 11 articles from this issue
REVIEWS
Agricultural Environment
  • Toru IWANAMI
    Article type: review-article
    2022 Volume 56 Issue 2 Pages 105-120
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    Citrus greening (huanglongbing) is established in majority of the subtropical and tropical citrus-producing areas of the world. In Japan, the disease causes damage to citrus grown on the subtropical islands and threatens the major citrus production areas on the main islands of Kyushu, Shikoku, and Honshu. Since the initial identification of the disease on a small island near Taiwan, wide-ranging programs and collaboration among scientists, plant quarantine officials, and administrators to combat the disease have been undertaken. This paper reviews the history of the disease and development of countermeasures in Japan. The scientific insight and crucial technical tools that promote control practices are summarized. Implications for the control of the disease in other countries and future research directions are also discussed.

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Animal Science
  • Kikuyasu NAKAMURA
    Article type: review-article
    2022 Volume 56 Issue 2 Pages 121-127
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    In Southeast and East Asia, Leucocytozoon caulleryi, a protozoan of the order Haemosporida of the phylum Apicomplexa, causes anemia, hemorrhage, and mortality in young chickens, and anemia and hemorrhage with egg drop and soft-shelled eggs in layer hens. Leucocytozoonosis caused by L. caulleryi is a notifiable infectious disease in Japan because of the damage it causes to the poultry industry. During the summer, biting midges (Culicoides arakawae) transmit this protozoan to chickens. This review provides the etiology, pathology, and diagnosis of L. caulleryi infection in chickens.

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ARTICLES
Agricultural Environment
  • Rikiya NIRA, Prapit SANGTONG, Takao FUJIMOTO
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 129-135
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    Applying organic material to soil is an important management method for sustainable crop production. We investigated its effect on soil nitrogen (N) mineralization in two experiments using the 15N isotope dilution method. In Hokkaido, Northern Japan, we applied wheat (Triticum aestivum) straw to Brown Andosol (BA; US Soil Taxonomy: Andisols) and Brown Lowland soil (BLs; US Soil Taxonomy: Inceptisols). The gross rate of N mineralization increased in BA with wheat straw and adequate inorganic N, supporting the general recommendation for the application of additional N fertilizer. The relationship between the microbial biomass N (x) and the gross rate of N mineralization (y) was y = 0.234e0.0751x (R2 = 0.815) in BA and BLs sampled during the growth season of a subsequent maize (Zea mays) crop. In long-term experiments with organic material application to Ultisols in Lop Buri, Central Thailand, the gross rates of N mineralization were higher in organically treated soil at a water-holding capacity (WHC) of 27%-41% and similar among soils at WHC ≈ 20%. The rates in Lop Buri soil were higher than those in Hokkaido soils, despite the former’s lower total carbon levels. The results suggest high specific microbial activities in Lop Buri soil.

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  • Ayaka FUCHIKAMI, Myra SHIN, Hiroyuki MASUMOTO, Ryoji KOUKATA, Hayato T ...
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 137-146
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    This study investigated the biofumigation effects of Brassica juncea crop on soil nitrification and soil bacterial communities under gray lowland soil conditions. Treatments included incorporating B. juncea containing high levels of glucosinolate (GLS) or Sinapis alba containing low levels of GLS and unamended control. Nitrification activity was evaluated using soils collected at the sweet corn transplantation (8 days after incorporation) and tassel emergence stage (46 days after incorporation). Sweet corn growth, yield, and nitrogen status were compared among treatments. Additionally, soil bacterial community structure in initial soils and soils at maize transplantation were investigated using next-generation sequencing. The results showed that incorporating B. juncea plants did not inhibit soil nitrification at the transplanting and tassel emergence stages, and apparent differences in sweet corn yield and nitrogen uptake were not observed among treatments. Differences between treatments regarding the effects of the incorporation on the soil bacterial abundance were observed in some bacterial families, but the abundances of nitrifying bacteria were not statistically different. Our results showed that incorporating B. juncea, which has a high GLS content, into sweet corn cultivation soil changed the abundance of certain soil bacterial families; however, nitrification inhibition effect is not expected under gray lowland soil conditions.

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Agricultural Engineering
  • Xuan GU, Rui WANG, Tianlai LI, Hui XU
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 147-161
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    To identify an energy-saving solution to cool Chinese solar greenhouses during summer nights, we present a design for a seasonal ice storage system that uses a storage tank to store winter cold energy in water to serve as a source of cold air in the summer. The parameters of the seasonal ice storage system were designed based on the cooling demand of the greenhouse in the summer. To optimize the cooling effect in the heat exchange system, a computational fluid dynamics model was developed to select the size of the heat transfer pipes, and a validation experiment was conducted in the greenhouse. The impacts of the insulation material and size of the heat exchange pipes on system performance have been discussed. The field experiment was conducted in Shenyang to validate the performance of the ice storage system. The best cooling effect in cultivation area was 6.7°C, and the average temperature difference between the beginning and end of the run in the greenhouse was 4.4°C. This system increased heat exchange performance while lowering air temperature in the greenhouse.

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Horticulture
  • Kyutaro KISHIMOTO
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 163-170
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    Temperature, an environmental factor affecting cut flowers' physiological state, is expected to affect scent emission. We investigated scent emission from carnation cut flowers of two scent types (Dianthus caryophyllus L.), exhibiting fruity (because of methyl benzoate) and spicy (because of eugenol) scents, at various temperatures (10°C, 15°C, 23°C, and 28°C). Cut flowers harvested on the day of flower opening were used for analysis. Scent emission was significantly higher at 23°C and 28°C than at 10°C and 15°C until 1 or 2 days but was significantly lower at 8 and 10 days postharvest. Methyl benzoate emissions decreased faster than eugenol emissions. Considering the lower limit of noticeable scent, as per previous sensory evaluations of carnations, scent lasted the longest at 10°C and 15°C. After ~5 days of pretreatment at 10°C, scent emission was slightly improved at 23°C than at 23°C. Such cut flower management at 10°C before sale may contribute to the persistence of scent at room temperature in consumers' homes after sale. Various factors, including the suppression of scent substrate consumption, regulation of scent emission from the cuticle, and influence on the expression of scent emission–related genes, may affect the retention of scent emission because of low temperature.

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Animal Science
  • Konosuke OTOMARU, Shoko OISHI, Yu FUJIMURA, Katsuhisa NAGAI, Shinya YA ...
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 171-176
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    This study aimed to assess the effect of ascorbic acid supplementation on fecal immunoglobulin A (IgA) in calves. A total of 30 Japanese Black calves were assigned to the supplementation and control groups. The supplementation group received 1,000 mg/day of ascorbic acid orally from 2 to 4 weeks of age (n = 15), whereas the control group did not (n = 15). Blood and fecal samples were collected at 2 and 4 weeks of age. There is no significant difference in the values of hematological and biochemical parameters between the two groups. The fecal IgA concentration in the control group decreased from 2 to 4 weeks of age, whereas it increased in the supplementation group from 2 to 4 weeks of age. The difference between the groups was statistically significant at 4 weeks of age (P < 0.05). These results suggested that ascorbic acid supplementation to calves may increase IgA production in the intestinal tract.

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Forestry
  • Yasuhiro OHNUKI, Jumpei TORIYAMA, Eriko ITO, Shin'ichi IIDA, Naok ...
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 177-187
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    Forests with a tropical monsoon climate are often influenced by extreme climatic phenomena. We investigated the differences in actual water content of surface soils in a lowland evergreen forest (EF) and deciduous forest (DF) in Cambodia, yearly from 2014 to 2016. The average soil water content values were higher for lowland EF than for DF, showing a distinct difference in the dry seasons. A major reason for this were the differences in soil type and thickness: Acrisols have an average thickness of 7 m, whereas Plinthosols, Arenosols, and Leptosols have an average thickness of 1 m; thicker, fine-textured soils contain and supply substantial amounts of water even in dry seasons. In the lowland EF site, some ponds were near the stream water during an average year's dry seasons because the groundwater levels were close to the soil surface year-round. However, in extreme climate, such as “El Niño” in February 2016, all ponds in the EF dried up, and the surface soils contained no water at several points of higher elevation. At the lowland DF site, even during “El Niño,” the surface soil water content did not reach zero; this could be due to their high water-holding capacity and low evapotranspiration, and the effect of no understory vegetation. On average, the lowland DF site showed lower values than the lowland EF site, especially in Leptosols, which are quite thin. Soil water content fluctuation is important for understanding Cambodia's unique forest landscape; specifically, lowland EF and DF form a mosaic in a similar monsoon climate. We presented the variations of soil water content spatially, seasonally, and interannually, which were mainly explained by soil thickness and partially by soil type and texture. The spatial variations in the 4-ha plot corresponded well with the tree species characteristics.

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Fisheries
  • Tomoyuki SHIKATA, Goh ONITSUKA, Hiroshi SHONO, Makiko HIRAI, Daiki INO ...
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 189-198
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    The summer blooms of Karenia mikimotoi have recently tremendously damaged aquaculture industries in the Bungo Channel, western Japan. We statistically extracted meteorological variables correlated with the magnitude and timing of the summer bloom in Uwajima Bay and Saiki Bay located in the eastern and western coasts of the channel using data for ~13 y until 2017. We conducted field investigations in 2017 to understand the water quality characteristics in both bays. Meteorological conditions were almost totally similar, but K. mikimotoi population dynamics were different to varying degrees from year to year between both bays. Bloom timing significantly correlated with air temperature in March and April in Uwajima Bay and Saiki Bay, respectively. Bloom magnitude negatively correlated with hours of bright sunshine for 10 days before the bloom peak in Uwajima Bay and positively with precipitation and negatively with wind speed 5-10 days before the bloom peak in Saiki Bay. Field investigations showed that water temperature and salinity were always higher in Uwajima Bay and that nutrient concentration fluctuations were different in both bays. The present study indicates a possibility that meteorological factors influence K. mikimotoi population dynamics by means of water quality and local physical processes in both bays.

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  • Toshiyuki TANABE, Yosuke MIYAZAKI, Kenji NOHARA, Nobuaki SUZUKI, Takao ...
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 199-209
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    Establishing sampling techniques for juveniles of tuna species is essential for understanding their ecology and population dynamics because only individuals showing rapid growth during larval and juvenile stages are able to survive. This study is the first report on the successful sampling of juveniles of tuna species using the larva catcher (LC)-type trawl net, a pelagic trawl gear with a 10 × 10-m mouth opening, 40-m total length, and 5 × 5-mm mesh size. It was used in a research cruise in May-June 2009. The LC net was horizontally towed for 30 min at depths of 0 m-10 m at speeds of about 1.8 m/s. Overall, 66 and 163 juveniles of Pacific bluefin tuna (PBT) and yellowfin tuna (YFT) were collected; the standard length (SL) of the PBT and YFT ranged from 15.0 to 29.7 mm and 11.7 to 34.8 mm, respectively. The total operation time for the trawls of the LC-type net was much shorter than that of the usual trawls; therefore, a larger number of operations can be conducted in a day. We concluded that the LC-type trawl net can be used for collecting tuna juveniles because of its catchability and ease of operation.

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Biomass Utilization
  • Aye Aye THINN, Yooichi KAINOH
    Article type: research-article
    2022 Volume 56 Issue 2 Pages 211-217
    Published: April 01, 2022
    Released on J-STAGE: May 11, 2022
    JOURNAL FREE ACCESS

    We examined the nutritional value of different diets on the longevity and reproductive performance of black soldier flies (Hermetia illucens) under laboratory conditions. In addition to water only (W) (control group), four diets were used: sugar and water (SW); pollen, sugar, and water (PSW); pollen, honey, and water (PHW); and honey and water (HW). The PSW group exhibited the highest reproductive performance because it had the longest oviposition period, largest number of clutches and hatched clutches, largest number of eggs laid/female, and greatest male and female longevity. Nevertheless, the highest hatching rate was found in the SW group. The number of successfully hatched eggs (fertilized) was the greatest in the PSW and HW treatments, but the differences between diets (SW, PSW, PHW, and HW) were nonsignificant.

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