@article{Xu2026, 
author = {Yanan Xu and Yi Tao and Chang Ye and Deshun Xiao and Song Chen and Guang Chu and Chunmei Xu and Jianliang Huang and Danying Wang},
title = {Model development and feature parameter extraction to capture variations in rice leaf color changes during the later reproductive period},
year = {2026},
journal = {Journal of Integrative Agriculture (JIA)},
volume = {25},
number = {6},
pages = {2353-2361},
keywords = {rice, leaf color change, grain filling, model, feature parameters},
url = {https://www.sciopen.com/article/10.1016/j.jia.2025.03.011},
doi = {10.1016/j.jia.2025.03.011},
abstract = {The change in leaf color during the later reproductive period of rice is directly related to photoassimilate accumulation and nutrient reuse, and it ultimately affects grain filling and yield. This study aimed to explore an assessment model that depicts the leaf color change process, and extract parameters that can precisely distinguish differences in leaf color changes among different treatments and varieties. A total of 31 rice varieties were selected as the field experiment materials in 2019 and 2023. The SPAD values of the flag, 2nd and 3rd leaves were measured after heading, and they were normalized to the leaf color index (CI). A functional model for the variation of leaf CI with time (t) in the late reproductive stage of rice was established based on CI=at2+bt+c, and seven color change parameters were extracted for the quantitative comparison and assessment of leaf color changes, including three time related parameters for color change (onset time, T0; midpoint time, T50; and color change duration, T100); one leaf color index (final value of CI, CIf); and three parameters related to the color change rate (the rate during T0−T50, R1; the rate during T50−T100, R2; and the mean color change rate, Rm). In 2023, Chunyou 927 (CY927) with a dark leaf color and Yongyou 1540 (YY1540) with a normal leaf color were used as materials, and three N fertilizer amounts were applied to explore the effects of N fertilizer on the leaf color change process through the established assessment system. The T0 of the flag leaf was delayed by 2.6−3.0 d compared to the 2nd and 3rd leaves. The CIf of the flag leaf was 12.12 and 21.15% higher than those of 2nd and 3rd leaves, respectively. In addition, the R1, R2 and Rm of the 3rd leaf were 10.75–19.82%, 17.99–20.09% and 18.23–11.61% higher than the flag and 2nd leaves, respectively. Rice yield was significantly positively correlated with T0, positively correlated with T50 and T100, and negatively correlated with R1, R2 and Rm. The average T0, T50, and T100 of rice varieties with yields higher than 8,000 kg ha−1 were 6.8, 22.2, and 31.8 d, respectively, with a CIf of 0.563 and an Rm of 0.015 d–1. N applications delayed T0 by 4.5–6.2 d, reduced Rm by 30.06–32.33%, and increased CIf by 35.78–39.69%. The established leaf color change model and extracted parameters quantitatively depicted the leaf color change process during the later reproductive period. They also effectively distinguished the differences in leaf color change among leaf positions, rice varieties and N treatments. This approach is valuable for selecting and cultivating high-yield and nutrient-efficient rice varieties, as well as for analyzing the underlying mechanisms.}
}