Critical air temperature and sensitivity of the incidence of chalky rice kernels for the rice cultivar “Sai-no-kagayaki”

Rice grain quality degradation and economic loss due to global warming in Japan

“…According to Masutomi et al (2015) [13], the occurrence of CRG, I [%], is estimated by the following equation:…”

“…Because the starch granules of endosperm in CRG are loosely packed, the numerous air spaces between starch granules cause random light reflections to create a chalky appearance [8]. Several studies have shown that high temperatures during the ripening period of rice increase the occurrence of CRG [8,[11][12][13] due to the lack of starch substrates in the endosperm [14], down-regulation of some starch synthesis-related genes [15], and up-regulation of starchdegrading amylase-encoding genes [15,16]. Hence, there is a great concern that global warming will increase the occurrence of CRG in Japan.…”

“…To assess the effects of high temperatures on the occurrence of CRG, several types of models for estimating the occurrence of CRG have been developed. A major type of the models is statistical models of non-linear relationship between the occurrence of CRG and temperatures during the ripening period [8,13,20]. A feature of these simple statistical models is that they can be easily developed for any variety and applied to any area without much loss of accuracy in estimations, if input data, including temperature, CRG occurrence, and flowering date, are available for the varieties and regions.…”

Countermeasures for heat damage in rice grain quality under climate change

“…The major types induced by high temperature exposure are milkywhite, basal-white, and white-back grain (Nagato & ebata, 1965) (Figure 3). Masutomi et al (2015) quantified the critical air temperature during 30 d after heading (dAH) at which chalky rice began to occur (T cr ), as well as the sensitivity of chalky grain incidence to air temperature changes above the T cr (S t ), using the heat sensitive cultivar 'Sainokagayaki. ' They clarified that basal-white grains have both a lower T cr (25.1 °C) and a higher S t (10.3% °C −1…”

Large-scale evaluation of the effects of adaptation to climate change by shifting transplanting date on rice production and quality in Japan

“…One major cause of the recent apparent decline in rice quality is the increase of white immature kernels due to high temperature, which tends to occur when the average temperature during the 20 days after the heading date is higher than 26 or 27 C Morita et al, 2016 . Several studies have attempted to develop a model for estimating the incidence of white immature kernels from meteorological factors e.g., Nagahata et al, 2006;Nakagawa et al, 2008;Wakiyama et al, 2010;Masutomi et al, 2015;Yoshida et al, 2016 . Most of these studies, however, focused on the field or regional scale or on a specific cultivar.…”