Japan Agricultural Research Quarterly: JARQ
Online ISSN : 2185-8896
Print ISSN : 0021-3551
ISSN-L : 0021-3551
Current issue
Displaying 1-7 of 7 articles from this issue
REVIEWS
Crop Science
  • Akira FUKUSHIMA
    Article type: review-article
    2024 Volume 58 Issue 4 Pages 177-183
    Published: October 01, 2024
    Released on J-STAGE: October 21, 2024
    JOURNAL FREE ACCESS

    A decrease in the number of farmers, enlargement of the management scale, and diversification of rice usage are predicted for rice cultivation in Japan. Conventionally, branded rice varieties with weak lodging resistance are cultivated under low-nitrogen conditions to produce low-yield, high-priced rice with a taste suitable for household consumption. In contrast, it is more effective to cultivate varieties with strong lodging resistance under high-nitrogen conditions to produce high-yield rice for commercial use and livestock feed. Cold regions (Tohoku region) are suitable for producing high-yield rice, although cold weather reduces variation in cultivation systems. For large-scale farms in cold regions, direct seeding, sparse transplanting, and late transplanting are promising strategies. We discuss the future directions of rice breeding and cultivation technologies for commercial use and livestock feed in cold regions.

    Download PDF (880K)
  • Koji NAKAGOMI
    Article type: review-article
    2024 Volume 58 Issue 4 Pages 185-192
    Published: October 01, 2024
    Released on J-STAGE: October 21, 2024
    JOURNAL FREE ACCESS

    To breed rice cultivars with kernel-cracking resistance, we selected new standard cultivars for evaluation. Among 21 cultivars rated from “resistant” to “weak” in Tohoku, Hokuriku, and western Japan, we regarded “Ouu 431,” “Ukei 1210,” “Eminokizuna,” and “Yamadawara” as resistant. We selected two resistant lines, namely, “IRSL 30” and “IRSL 37,” as breeding materials from the chromosome segment substitution lines of “Itadaki” (Oryza sativa L.) × donor Oryza rufipogon and identified a major QTL, qCR8-2, responsible for cracking resistance by QTL analysis using F4 individuals derived from “Itadaki/IRSL 30” and “Itadaki/IRSL 37.” “Chugoku PL2,” which was selected from the progeny of “Itadaki/IRSL 37,” has qCR8-2 in an “Itadaki” background. It had better palatability and a lower broken rice ratio during milling compared with “Itadaki.” In this case, improved cracking resistance led to improved palatability and milling traits.

    Download PDF (1358K)
Animal Science
  • Tomoya YAMADA, Mitsuru KAMIYA, Mikito HIGUCHI
    Article type: review-article
    2024 Volume 58 Issue 4 Pages 193-196
    Published: October 01, 2024
    Released on J-STAGE: October 21, 2024
    JOURNAL FREE ACCESS

    Fat depot-specific differences in adipose tissue growth (adipogenesis) are an important factor in the production of beef cattle. Japanese black (Wagyu) cattle are characterized by high adipogenic ability. This review will discuss fat depot-specific differences in adipogenesis among subcutaneous, visceral, and intramuscular depots of fattening Wagyu based on our previous studies. We show that anatomical sites of adipose tissue affect adipocyte size. We also show that fat depot-specific differences in adipogenesis are affected by the expression of adipogenic transcription factors. In addition, we show that fat depot-specific differences in adipokine gene expression are affected by adipocyte size. Furthermore, we show that macrophages infiltrate into adipose tissues in a fat depot-specific manner. These results suggest that fat depot-specific differences in adipogenesis affect body fat distribution in fattening Wagyu.

    Download PDF (846K)
ARTICLES
Agricultural Environment
  • Yuriko HAYANO-SAITO, Masahiko KUMAGAI, Mitsuru NAKAMURA, Tarou SUZUKI, ...
    Article type: research-article
    2024 Volume 58 Issue 4 Pages 197-204
    Published: October 01, 2024
    Released on J-STAGE: October 21, 2024
    JOURNAL FREE ACCESS

    Breeding rice crops that are resistant to rice blast is a protective and viable strategy. The proper characterization of the phenotypes of resistance (R) genes to leaf and panicle blast contributes to effective resistance breeding. However, observer subjectivity complicates the evaluation of panicle blast-resistance phenotypes. Hence, we evaluated panicle blast-resistance phenotypes using the number of panicles classified by the location of damage to the panicle tissues. Six cultivars/lines carrying Pi35, pi21, Pi34, Pi39(t), Pb1, and qPbm11, which conferred quantitative resistance, including Pb1 and qPbm11, panicle resistance genes and loci, respectively, were evaluated. These cultivars/lines were planted in the field, and disease progression of panicle blast was investigated. Our data revealed that the severity of spikelet damage differed among the cultivars/lines. In addition, the panicle number of damaged spikelets approximately two weeks after heading was correlated with the panicle number of damaged rachises and necks approximately four weeks after heading. These results suggested that the severity of spikelet damage is crucial for assessing R gene-mediated panicle resistance. Our results provide essential information on panicle blast progression and provide insights into the role of R genes in panicle blast.

    Download PDF (1112K)
  • Muthuvel JOTHI, Junpei TAKANO, Lingaraj SAHOO
    Article type: research-article
    2024 Volume 58 Issue 4 Pages 205-214
    Published: October 01, 2024
    Released on J-STAGE: October 21, 2024
    JOURNAL FREE ACCESS

    Boron (B) is an essential micronutrient required for optimal plant growth and development. Seed yield and quality are often compromised in plants grown under limited soil B. Indian mustard (Brassica juncea L.) is one of the most susceptible plants to B limitation. In this study, twenty-seven Indian mustard genotypes were grown in hydroponic culture with different B concentrations, and growth performances were evaluated based on their root and shoot growth. Geeta, RH406, and Maya were found to be low-B tolerant, moderate, and sensitive genotypes, respectively. In Geeta, root meristem cells showed higher viability than RH406 and Maya under low B conditions. Geeta had a significantly higher B concentration in the root and youngest opened leaf (YOL) than Maya and RH406. The pectin levels in the cell wall of the root and the YOL varied across different genotypes under different B conditions. The pectin levels in the cell wall of YOL were lowest in Geeta and highest in Maya under sufficient B conditions. Based on these results, we suggest that a higher B uptake and translocation and possibly lower pectin levels are the key factors responsible for low B tolerance in B. juncea genotypes.

    Download PDF (4090K)
Forestry
  • Eriko ITO, Bora TITH, Borin TO, Junko NAGAKURA
    Article type: research-article
    2024 Volume 58 Issue 4 Pages 215-232
    Published: October 01, 2024
    Released on J-STAGE: October 21, 2024
    JOURNAL FREE ACCESS

    Forest degradation often leads to soil degradation. To clarify the impacts of large-diameter tree cutting and in situ sawing operations on forest site characteristics, we investigated forest floor characteristics and soil physicochemical properties at sites where logging had already been performed of a lowland dry evergreen forest on sandy acrisol soil in central Cambodia. Transects were staked along the direction where individual trees had fallen after being felled approximately 10 years prior, and each transect was divided into five subplots (control, stump, timber, unused trunk, and crown) representing different sections of the fallen tree. A temporary supply of organic matter associated with cutting activity mitigated soil degradation; however, this effect was limited. Differences in soil physicochemical properties between the control subplots and the logging-affected subplots were particularly pronounced in the reduction of the concentrations of exchangeable bases (Ex·Ca2+ and Ex·Mg2+) and corresponding pH(H2O), although some soil properties were conserved (Ex·K+ and total N stock). These results suggested that a continuous supply of litter from standing trees was effective in mitigating soil degradation and that the preservation of pre-existing juvenile trees at cutting was essential for sustainable forest use. Our findings also indicated that sandy acrisol soils are vulnerable to disturbance from logging. Future research on forest restoration in degraded soils is needed.

    Download PDF (24138K)
Fisheries
  • Yosuke TANAKA, Atsushi TAWA, Taiki ISHIHARA, Yosuke MOCHIZUKI, Hiroshi ...
    Article type: research-article
    2024 Volume 58 Issue 4 Pages 233-245
    Published: October 01, 2024
    Released on J-STAGE: October 21, 2024
    JOURNAL FREE ACCESS

    In this study, we estimated prey availability in the early life stages of Pacific bluefin tuna (PBF) based on their mouth gape size, collected in two spawning grounds, the Pacific Ocean around the Nansei Islands and the Sea of Japan. The increase in mouth gape sizes was investigated using laboratory-reared PBF larvae and juveniles. Thereafter, we compared the mouth gape size of PBF with the body size of prey larvae, including PBF, collected in field surveys in the spawning grounds of PBF conducted in 2017 and 2018. We defined the collected larvae smaller than the mouth gape, mouth width, and 1/3rd the body length (BL) of PBF as potential prey larvae (PPL), which have the potential of being captured and ingested by PBF. The number of PPL in each sampling station was estimated for PBF of 8, 10, 15, 20, and 30 mm BL size classes as predatory PBF. The density of PPL increased for PBF larger than 20 mm in BL, suggesting that prey availability could change drastically for PBF larvae and juveniles larger than 20 mm BL.

    Download PDF (1610K)
feedback
Top