Abstract
Amino acid content in grains is an important nutritional quality trait in rice. High temperature can affect rice quality by accelerating grain filling. However, there is limited information available on the influence of high temperature on amino acid content in rice grains, especially under natural conditions. In this study, grain-filling traits and amino acid content in the grain of two rice cultivars (Luliangyou 996 and Lingliangyou 268) were compared between two years (2016 and 2017) with contrasting temperatures during the early grain-filling period under field conditions. Average daily mean temperature during the period of 0–5 days after full heading in 2016 (30.1 °C) was 5.4 °C higher than that in 2017. Initial, maximum, and mean grain-filling rates were 42–307% higher in 2016 than in 2017 for Luliangyou 996 and Lingliangyou 268. The time taken to reach the maximum grain-filling rate and active grain-filling duration were 6.3–10.7 d shorter in 2016 compared to 2017 for Luliangyou 996 and Lingliangyou 268. Grain weight was equal to or significantly higher in 2016 than in 2017 for Luliangyou 996 and Lingliangyou 268. N accumulation and N content in the grain were significantly lower in 2016 than in 2017 for both cultivars. The grain contents of all detected amino acids, except for methionine in Luliangyou 996, were significantly lower in 2016 than in 2017. Our study suggests that high temperature during the early grain-filling period can result in an accelerated grain-filling process, reduced N accumulation and content in rice grains, and consequently reduced amino acid content in the grain.
Highlights
Rice is the staple food for more than half of the world’s population[1]
Basic research in genetics and genetic engineering research has led to useful information for enriching amino acid content in crops including rice[7]
It has been well documented that high temperature during grain filling can accelerate the grain-filling rate in rice, resulting in loosely packed rice starch granules, decreased head milled rice rate, and increased abnormal and chalky rice grains[10]
Summary
Rice is the staple food for more than half of the world’s population[1]. In China, rice production and consumption are the highest in the world, and China accounts for nearly one-third of the global rice market[2]. Enhancing amino acids in the grain is one of the major objectives for improving the nutritional value of rice[6]. Especially during the grain-filling period, is one of the dominant environmental factors affecting rice quality[9]. There is limited information available on the effect of high temperature during the grain-filling period on amino acid content in rice grains. Grain-filling traits and amino acid content in grains of two rice cultivars were compared between two years that differed due to a heat event during the early grain-filling period under field experiment conditions. The main objective of this study was to determine the influence of natural high temperature during the early grain-filling period on amino acid content in rice grains
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