Abstract
Seed filling is crucial for seed vigor and starch accumulation and structure. Differences in hybrid rice seed vigor were evaluated in field experiments, conducted across two sites in 2017 and 2018, under different seed filling temperatures along with the underlying mechanisms related to the seed filling characteristics and starch accumulation and structure. Significant differences in the seed vigor parameters were revealed, with different seed filling characteristics observed under different temperatures. When averaged across cultivars, the seeds with a low seed filling rate and long seed filling duration obsessed 11.9% higher germination percentage (GP) and 22.7% higher vigor index (VI) than those with a high seed filling rate and short seed filling duration. Moreover, a high seed filling rate and short seed filling duration significantly decreased the total starch and amylose contents and increased the amylopectin content. Additionally, when averaged across cultivars, the relative crystallinity and starch granule diameter obtained with a high seed filling rate and short seed filling duration were 3.8% and 15.1% higher, respectively, than those with a low seed filling rate and long seed filling duration. In summary, it can be speculated that seed filling characteristics determine hybrid rice seed vigor by affecting starch accumulation and structure.
Highlights
Rice (Oryza sativa L.) is one of the most important crops in China
The objectives of this study were to evaluate the differences in seed vigor of hybrid rice under different temperatures during seed filling and to explore the mechanisms associated with such variations with regard to seed filling characteristics and starch accumulation and structure
Previous studies have reported that the decrease in grain weight due to high temperature has been ascribed to the shortening of the grain filling duration[20,21,27]
Summary
Rice (Oryza sativa L.) is one of the most important crops in China. With increasing human populations and decreasing areas of agricultural land, the promotion of rice production, especially hybrid rice production, is essential in China[1]. Previous studies have reported that the grain growth of hybrid rice is associated with certain grain filling characteristics[6,7]. Seed filling influences seed growth and development and affects the seed quality of hybrid rice. Cai et al.[17] reported that different morphologies of rice starch were observed during grain filling period and affected grain quality. We hypothesized that seed filling characteristics contributed to the variations in seed vigor of hybrid rice by affecting starch accumulation and structure. The objectives of this study were to evaluate the differences in seed vigor of hybrid rice under different temperatures during seed filling and to explore the mechanisms associated with such variations with regard to seed filling characteristics and starch accumulation and structure
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