Open Access

ARTICLE

Grain Photosynthesis and Filling Characteristics of Rice Varieties with Different Grain Weights

Jinge Li^1,2, Chuyao Wang^1,2, Fangbo Cao^1,2, Min Huang^1,2,*, Jiana Chen^1,2,*

1 Rice and Product Ecophysiology, Key Laboratory of Ministry of Education for Crop Physiology and Molecular Biology, Hunan Agricultural University, Changsha, 410128, China
2 National Engineering Research Center of Rice, College of Agronomy, Hunan Agricultural University, Changsha, 410128, China

* Corresponding Authors: Min Huang. Email: ; Jiana Chen. Email:

Phyton-International Journal of Experimental Botany 2025, 94(7), 2155-2165. https://doi.org/10.32604/phyton.2025.066940

Received 21 April 2025; Accepted 27 June 2025; Issue published 31 July 2025

Abstract

Grain filling is a critical determinant of yield and quality in rice. This study aims to clarify the association between grain photosynthesis and the filling rate of rice varieties with different grain weights, providing a theoretical foundation for optimizing grain-filling processes. Two rice varieties with similar growth duration but different grain weights were selected: a large-grain variety, Lingliangyou 268 (L268), and a small-grain variety, Ruiliangyou 1053 (R1053). Differences in grain filling, grain photosynthetic rate, and grain chlorophyll content were systematically examined during the filling stage. Results showed significant differences in grain-filling, grain photosynthetic rate, and grain chlorophyll content between large-grain and small-grain rice varieties. The grain photosynthetic rate of L268 was a significantly higher than R1053. L268 also exhibited significantly higher initial grain filling rate, maximum grain-filling rate, and mean grain filling rate compared to R1053. Throughout the grain filling period, L268 showed higher grain chlorophyll content (including chlorophyll a, chlorophyll b, and total chlorophyll) than R1053. The increase in chlorophyll content, particularly total chlorophyll, enhanced the grain photosynthetic rate during the early and middle stages of grain filling significantly. These findings suggested that rice varieties with higher grain weights exhibited stronger panicle photosynthetic capacity due to their higher chlorophyll content. The enhanced grain photosynthetic rate contributed to improved grain filling and increased grain weight.

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