Springer Science and Business Media LLC Acta Medica Okayama 0971-5894 2026 Suppression of salt-enhanced apoplastic flow by salicylic acid in rice EN Md. Asadulla Al Galib Graduate School of Environmental and Life Science, Okayama University Maoxiang Zhao Graduate School of Environmental and Life Science, Okayama University Toshiyuki Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshimasa Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshihiko Hirai Graduate School of Environmental and Life Science, Okayama University Yoshitaka Nakashima Graduate School of Environmental and Life Science, Okayama University Shintaro Munemasa Graduate School of Environmental and Life Science, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Yoshiyuki Murata Graduate School of Environmental and Life Science, Okayama University Salinity enhances apoplastic flow, resulting in an increment of Na+ uptake and a lower K+/Na+ ratio. Salicylic acid (SA) plays an important role in improving salinity tolerance in plants. The effect of exogenous SA on apoplastic flow in salt-treated rice seedlings was studied using an apoplastic tracer, 8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS) in light. Application of NaCl at 25 mM to the hydroponic solution significantly increased PTS uptake, while 25 mM NaCl did not affect seedling growth. Application of 25 mM NaNO3 increased PTS uptake to the same degree. Salinity significantly increased sodium (Na+) content but had no significant effect on potassium (K+) content, resulting in a lower K+/Na+ ratio. The application of SA at 0.05 mM and 0.1 mM to the hydroponic solution reduced Na-enhanced PTS uptake. Salicylic acid at 0.05 mM and 0.1 mM significantly reduced Na+ content and slightly increased K+ content in the shoots of rice seedlings, resulting in a higher K+/Na+ ratio. However, SA at up to 0.1 mM did not increase SA contents in shoots under salt stress. These results suggest that exogenous SA reduces Na+ uptake by suppressing Na+-enhanced apoplastic flow in rice seedlings. These findings provide insight into modulation of Na+ transport pathways from roots to shoots by SA and may allow us to utilize brackish water for rice cultivation and to improve salt-tolerant rice through suppression of salt-enhanced apoplastic flow by chemicals such as salicylic acid. No potential conflict of interest relevant to this article was reported.

Springer Science and Business Media LLC Acta Medica Okayama 0718-9508 2025 Suppression of Na+ Uptake Via Apoplastic Flow by Chitosan in Rice EN Maoxiang Zhao Graduate School of Environmental and Life Science, Okayama University Md. Asadulla Al Galib Graduate School of Environmental and Life Science, Okayama University Toshiyuki Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshimasa Nakamura Graduate School of Environmental and Life Science, Okayama University Yoshihiko Hirai Graduate School of Environmental and Life Science, Okayama University Yoshitaka Nakashima Shintaro Munemasa Graduate School of Environmental and Life Science, Okayama University Izumi C. Mori Institute of Plant Science and Resources, Okayama University Yoshiyuki Murata Graduate School of Environmental and Life Science, Okayama University Purpose: Chitosan enhances tolerance to salinity in rice. Apoplastic flow plays a crucial role in the accumulation of sodium (Na+) in rice under salinity. This study investigated the effects of exogenous chitosan on apoplastic flow and Na+ uptake in NaCl-treated rice seedlings. Methods: We employed an apoplastic tracer, trisodium salt of 8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), in order to evaluate apoplastic flow in rice (Oryza sativa L., cv. Nipponbare) seedlings that were hydroponically grown in the solution containing NaCl (0 and 25 mM), and chitosan (0 mg L− 1, 10 mg L− 1, and 50 mg L− 1). Results: Application of 25 mM NaCl significantly increased PTS uptake and Na+ content in shoots but did not affect K+ content, resulting in a lower K+/Na+ ratio although 25 mM NaCl did not affect the seedling growth. The application of chitosan suppressed Na+-enhanced PTS uptake and Na+ accumulation in shoots without affecting the K+ content, which led to a higher K+/Na+ ratio. Moreover, chitosan did not affect the reducing sugar content or electrical conductivity in the solution containing NaCl. Conclusions: These results suggest that application of chitosan suppressed Na+-enhanced apoplastic flow to reduce Na+ uptake in rice seedlings. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2071-1050 15 1 2022 Interspecific Variability in Growth Characteristics and Phytoremediation of Cu by Free-Floating Azolla Macrophytes 497 EN Muhammad Shahbaz Akhtar Department of Environmental Sciences, Forman Christian College University Sohaib Aslam Department of Environmental Sciences, Forman Christian College University Allah Ditta Department of Environmental Sciences, Shaheed Benazir Bhutto University Bedur Faleh A. Albalawi Department of Biology, University of Tabuk Yoko Oki Department of Environmental Management Engineering, Graduate School of Environmental and Life Science, Okayama University Yoshitaka Nakashima Department of Environmental Management Engineering, Graduate School of Environmental and Life Science, Okayama University The phytoremediation potential of aquatic plants, particularly for Cu, is scarcely reported in the pertinent literature. In this regard, differential growth behavior and phytoaccumulation ability of three free-floating Azolla species (A. japonica, A. pinnata, and A. hybrid) were evaluated in a climatically controlled (a temperature of 25/20 degrees C, light/dark 16/8 h, a light intensity of 60 mu mol m(-2) s(-1), and a relative humidity of 65%) microcosm study. Azolla plants were exposed to solutions having three Cu concentrations (0, 3, and 6 mg L-1) under two incubation periods (4 and 8 days). Different Cu treatments significantly reduced Azolla biomass during both incubation periods and A. pinnata was the most sensitive species. Azolla plants grown in aqueous solutions showed substantial variations in Cu removal capacity. Higher bioconcentration values displayed by Azolla plants indicated that these plants can be deployed as potential plants for Cu removal from Cu contaminated water. Nevertheless, the plants exposed to higher Cu concentrations displayed color changes and root detachment due to Cu phytotoxic effects which may also ultimately lead to plant death. Significant correlations between Cu removed from the aqueous solutions and Cu contents of plant biomass indicated that Cu phytoremediation by Azolla plants was due to the phytoaccumulation mechanism because the removed Cu from aqueous solutions was accumulated in plant biomass. Introduced Azolla species, i.e., A. hybrid, displayed comparable Cu removal efficiency with naturally grown Azolla species, i.e., A. japonica and A. pinnata. Tested Azolla species proved to be suitable candidates to remediate Cu contaminated water and can be deployed for phytoremediation. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2073-4441 14 13 2022 Backwater Effect of Clogging of Aquatic Plants at Fine-Particle Screens on Inland Flooding in Okayama 1980 EN Takumi Inaba Graduate School of Environmental and Life Science, Okayama University Kumiko Tsujimoto Graduate School of Environmental and Life Science, Okayama University Yoshitaka Nakashima Graduate School of Environmental and Life Science, Okayama University In low-lying Okayama city, Japan, the heavy rainfall frequency and intensity have recently increased, subjecting the city to inland flooding. Another factor increasing the inland flooding risk is fine-particle screen clogging by aquatic plants at drainage pump stations, which obstructs drainage and causes backwater. In this study, water level simulations were conducted in drainage pump station channels to clarify the inland flooding risks with and without aquatic plant clogging-induced backwater at fine-particle screens. In the Urayasu West Drainage Pump Station channels, without backwater, no inland flooding occurred under an initial water level of 70% of the channel depth and a 40 m(3)/s discharge. However, when backwater deeper than 0.2 m occurred under the same conditions, inland flooding occurred, indicating an increased inland flooding risk associated with backwater. Additionally, we conducted an aquatic plant distribution survey in the main Okayama city channels and proposed six priority control sections based on sections with thriving aquatic plants. Although no previous inland flooding studies have considered aquatic plant clogging-induced backwater at fine-particle screens, aquatic plants cause clogging problems and drainage obstructions at water control facilities worldwide. Therefore, this study reveals the importance of conducting water level simulations and distribution surveys in areas other than Okayama city. No potential conflict of interest relevant to this article was reported.

岡山大学全学教育・ 学生支援機構 Acta Medica Okayama 2432-9665 6 2021 農業分野における外国人技能実習生に対する日本語教育の現状と課題ー教材開発に向けた予備調査の結果から一 191 205 EN Takami Mohri Institute of Global Resource Development, Okayama University Yoshitaka Nakashima Graduate School of Environmental and life Science, Okayama University 10.18926/63358 外国人技能実習生に対する日本語教育の課題として、介護職以外はH本語能力の受け入れ条件がないこと、受け入れ機関によって日本語教育の時間数や内容が異なること、一般的な初級教材の使用が中心で、専門分野に特化した教材開発には至っていないこと等が挙げられる。本稿では技能の専門領域の中でも「農業分野」における教材閲発のニーズを分析するために、技能実習生を受け入れている企業において実習中のベトナム人技能実習生2人、インドネシア人3人技能実習生に予備調査としてアンケート調査およびインタビュー調査を行った結果を報告する。調査の結果、来H後2年以上を経た現在は、全員から仕事上で日本語が理解できず困ることはあまりないが、渡H帥に農業分野に特化した日本語学習が必要であったという回答があった。さらには、視覚面で理解が促進できる動画教材のニーズが高いことがわかった。今後は、本調査の結果をもとに特定業種の技能実習生向けのICTを利活用した教材開発を進める予定である。 No potential conflict of interest relevant to this article was reported.

岡山大学環境理工学部 Acta Medica Okayama 2187-6940 22 1 2017 岡山地方気象台観測露場移転による気温低下量の推定 61 64 EN Takeshi Miura Graduate School of Environmental and life Science, Okayama University Yu Ueda Graduate School of Environmental and life Science, Okayama University Hidenori Morita Graduate School of Environmental and life Science, Okayama University Hidetaka Chikamori Graduate School of Environmental and life Science, Okayama University Masahiro Kurokawa Yoshitaka Nakashima Graduate School of Environmental and life Science, Okayama University Yoko Oki Graduate School of Environmental and life Science, Okayama University 10.18926/fest/54863 Statistical change in official temperature records at Okayama City caused by relocation of meteorological observation field of Meteorological Agency was evaluated. The observation field of Okayama local meteorological observatory was moved to the Tsushima Campus of Okayama University from the downtown area of Okayama City in March, 2015. Comparison between the air temperature records measured at meteorological agency station and the records at Tanjo Pond in Tsushima Campus, showed 0.56 ℃ drop in annual average before and after relocation. Moreover, comparison between the records of Okayama local meteorological observatory and that at the surrounding meteorological observing 9 stations showed 0.55 ℃ drop in annual average. Those results suggest that the relocation dropped annual average of air temperature by about 0.6 ℃. No potential conflict of interest relevant to this article was reported.