Effect of High Temperature at Ripening Stage on the Reserve Accumulation in Seed in Some Rice Cultivars

AbstractThis work aimed at determining whether high temperature intermittent drying followed by tempering at ambient temperature could preserve the seed viability and vigor.JaponicaandIndicarice seeds with 21.2 % and 22.6 % wet moisture contents (w.b.) were dried at 50 ºC and 60ºC for either 5, 10, 15 or 20 minutes, followed by tempering at 25ºC for 45 minutes. Each drying cycle was repeated until the rice seeds were dried to 12.0 % (w.b.). The drying rate was improved and the total in-dryer time was reduced in the intermittent drying when compared to continuous drying, due to the tempering process. The seed vigor was significantly reduced by intermittent drying at 60 °C with all exposure times, although the seed still kept the ability to germinate for both rice cultivars. The intermittent drying at 50 ºC for 5 minutes per drying cycle preserved the seed vigor ofJaponicarice well, while inIndicarice, the intermittent drying at 50 ºC up to 20 minutes could still be able to maintain the seed vigor.

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Starch Morphology and Metabolomic Analyses Reveal That the Effect of High Temperature on Cooked Rice Elongation and Expansion Varied in Indica and Japonica Rice Cultivars

Agronomy ◽

10.3390/agronomy11122416 ◽

2021 ◽

Vol 11 (12) ◽

pp. 2416

Author(s):

Nnaemeka Emmanuel Okpala ◽

Mouloumdema Pouwedeou Potcho ◽

Muhammad Imran ◽

Tianyue An ◽

Gegen Bao ◽

...

Keyword(s):

High Temperature ◽

Low Temperature ◽

Oryza Sativa L ◽

Effect Of Temperature ◽

Japonica Rice ◽

Rice Cultivars ◽

Starch Granules ◽

Cooked Rice ◽

Temperature Regimes ◽

Badh2 Gene

Rice (Oryza sativa L.) is mainly grouped into indica and japonica varieties. The aim of this study was to investigate the effect of temperature on cooked rice elongation, cooked rice expansion, and rice fragrance. This study was conducted in three growth temperature chambers with indica cultivar Basmati 385 (B385) and japonica cultivar Yunjingyou (YJY). Grains of B385 grown in low-temperature regimes had the highest cooked rice elongation and expansion, whereas the grains of YJY grown in high-temperature regimes had the highest cooked rice elongation and expansion. Starch granules of B385 grown in low-temperature regimes were more compact and bigger, compared to grains grown in medium- and high-temperature regimes. Conversely, the starch granules of YJY grown in high-temperature regimes were more compact and bigger, compared to those grown in medium- and low-temperature regimes. Metabolomic analyses showed that temperature affected the rice metabolome and revealed that cyclohexanol could be responsible for the differences observed in cooked rice elongation and expansion percentage. However, in both B385 and YJY, grains from low-temperature regimes had the highest 2-AP content and the lowest expression levels of the badh2 gene. The findings of this study will be useful to rice breeders and producers.

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