Strengthening countermeasures to mitigate chalky rice grains under high-temperature stress: a lesson from the hottest summer of 2023 in Hokuriku, Japan

In a rapidly warming world, high-temperature stress during grain-filling often aggravates rice grain quality in Japan. Recent hot summer, especially in 2023, caused enormous damage to rice grain appearance of the premium Japanese cultivar, ‘Koshihikari’, which is not so tolerant to high-temperature...

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Main Authors: Tsutomu Ishimaru, Tadashi Tsukaguchi, Daryong Kim
Format: Article
Language:English
Published: Taylor & Francis Group 2025-07-01
Series:Plant Production Science
Subjects:
Online Access:https://www.tandfonline.com/doi/10.1080/1343943X.2025.2513441
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author Tsutomu Ishimaru
Tadashi Tsukaguchi
Daryong Kim
author_facet Tsutomu Ishimaru
Tadashi Tsukaguchi
Daryong Kim
author_sort Tsutomu Ishimaru
collection DOAJ
description In a rapidly warming world, high-temperature stress during grain-filling often aggravates rice grain quality in Japan. Recent hot summer, especially in 2023, caused enormous damage to rice grain appearance of the premium Japanese cultivar, ‘Koshihikari’, which is not so tolerant to high-temperature stress, in the Hokuriku region. Previous studies revealed that a complex combination of factors such as climatic conditions, plant nitrogen status, water management, and the cultivar’s level of heat adaptation greatly affect the incidence of chalky rice grains. Application of nitrogen fertilizer to maintain plant nitrogen status would be a practical countermeasure to mitigate the incidence of chalky grains induced by high temperature, owing to a close correlation of grain protein content with perfect grains. Among the classes of storage proteins, 13kDa prolamin is considered a key component, highlighting the critical roles of not only carbon but also nitrogen metabolism in the chalky phenotype under high-temperature stress. Depending on water availability, continuous irrigation with running water or saturated and surface-dry water conditions can be adopted to create cooler paddy environments. Numerous efforts to develop heat-adaptative cultivars have been associated with the retention of high percentages of first-grade quality grains, even in the hottest year of 2023. Genetic and physiological factors that contribute to good grain appearance under high-temperature stress must be, however, further elucidated for most of the heat-adaptative cultivars. This review provides the latest information on optimum cultivation techniques and heat-adaptative cultivars that can mitigate the incidence of chalky grains induced by high temperatures in Japan.
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spelling doaj-art-30891dc774de4b4fbc2ae6ff4dcf52e02025-08-20T03:58:14ZengTaylor & Francis GroupPlant Production Science1343-943X1349-10082025-07-0128319520910.1080/1343943X.2025.2513441Strengthening countermeasures to mitigate chalky rice grains under high-temperature stress: a lesson from the hottest summer of 2023 in Hokuriku, JapanTsutomu Ishimaru0Tadashi Tsukaguchi1Daryong Kim2Joetsu Research Station, Central Region Agricultural Research Center, National Agriculture and Food Research Organization (CARC/NARO), Joetsu, JapanFaculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, JapanJoetsu Research Station, Central Region Agricultural Research Center, National Agriculture and Food Research Organization (CARC/NARO), Joetsu, JapanIn a rapidly warming world, high-temperature stress during grain-filling often aggravates rice grain quality in Japan. Recent hot summer, especially in 2023, caused enormous damage to rice grain appearance of the premium Japanese cultivar, ‘Koshihikari’, which is not so tolerant to high-temperature stress, in the Hokuriku region. Previous studies revealed that a complex combination of factors such as climatic conditions, plant nitrogen status, water management, and the cultivar’s level of heat adaptation greatly affect the incidence of chalky rice grains. Application of nitrogen fertilizer to maintain plant nitrogen status would be a practical countermeasure to mitigate the incidence of chalky grains induced by high temperature, owing to a close correlation of grain protein content with perfect grains. Among the classes of storage proteins, 13kDa prolamin is considered a key component, highlighting the critical roles of not only carbon but also nitrogen metabolism in the chalky phenotype under high-temperature stress. Depending on water availability, continuous irrigation with running water or saturated and surface-dry water conditions can be adopted to create cooler paddy environments. Numerous efforts to develop heat-adaptative cultivars have been associated with the retention of high percentages of first-grade quality grains, even in the hottest year of 2023. Genetic and physiological factors that contribute to good grain appearance under high-temperature stress must be, however, further elucidated for most of the heat-adaptative cultivars. This review provides the latest information on optimum cultivation techniques and heat-adaptative cultivars that can mitigate the incidence of chalky grains induced by high temperatures in Japan.https://www.tandfonline.com/doi/10.1080/1343943X.2025.2513441Chalky grainsgrain-fillingheat adaptationhigh-temperature stressrice
spellingShingle Tsutomu Ishimaru
Tadashi Tsukaguchi
Daryong Kim
Strengthening countermeasures to mitigate chalky rice grains under high-temperature stress: a lesson from the hottest summer of 2023 in Hokuriku, Japan
Plant Production Science
Chalky grains
grain-filling
heat adaptation
high-temperature stress
rice
title Strengthening countermeasures to mitigate chalky rice grains under high-temperature stress: a lesson from the hottest summer of 2023 in Hokuriku, Japan
title_full Strengthening countermeasures to mitigate chalky rice grains under high-temperature stress: a lesson from the hottest summer of 2023 in Hokuriku, Japan
title_fullStr Strengthening countermeasures to mitigate chalky rice grains under high-temperature stress: a lesson from the hottest summer of 2023 in Hokuriku, Japan
title_full_unstemmed Strengthening countermeasures to mitigate chalky rice grains under high-temperature stress: a lesson from the hottest summer of 2023 in Hokuriku, Japan
title_short Strengthening countermeasures to mitigate chalky rice grains under high-temperature stress: a lesson from the hottest summer of 2023 in Hokuriku, Japan
title_sort strengthening countermeasures to mitigate chalky rice grains under high temperature stress a lesson from the hottest summer of 2023 in hokuriku japan
topic Chalky grains
grain-filling
heat adaptation
high-temperature stress
rice
url https://www.tandfonline.com/doi/10.1080/1343943X.2025.2513441
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AT daryongkim strengtheningcountermeasurestomitigatechalkyricegrainsunderhightemperaturestressalessonfromthehottestsummerof2023inhokurikujapan