ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Crop and Product Physiology
This article is part of the Research TopicCrop Diversity Strategies for Enhanced Weed Suppression, Forage Productivity, and Resource Use Efficiency in Marginal GrasslandsView all articles
Quantifying germination cardinal temperatures of ten forage legumes using nonlinear regression models
Provisionally accepted
Mengyao ShiYumeng HuRuoxi JiaXinli ZhaoJiahui TanHaoyang TengYiran HanYihao GaiZitong LeiYichen Yuan
Shangzhi Zhong
Juan Sun
Qibo Tao*- Qingdao Agricultural University, Qingdao, China
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Forage legumes play a pivotal role in livestock production, environmental protection, sustainable cropping systems, and various industrial applications. Understanding the germination thermal requirements of forage legumes is necessary for optimizing their sowing and production. The response of germination rate to temperature can be described by non-linear regression models. In this study, ten constant temperatures (from 0 to 45°C with 5°C interval) were considered and two non-linear regression models (intersected-lines and quadratic polynomial) were applied to quantify cardinal temperatures and thermal range for ten important forage legumes. Both germination percentage and speed of germination were low in hot and cold temperatures outside the range of 15 to 25°C for these species. Notably, significant inter-specific variations in thermal requirements were identified. Alfalfa (Medicago sativa), yellow medick (Medicago falcata), and erect milkvetch (Astragalus adsurgens) demonstrated high thermal plasticity, with low minimum temperature (or base, Tb), high maximum temperature (Tm) and wide thermal ranges. Conversely, sweet clover (Melilotus officinalis) exhibited a preference for cooler regimes, characterized by the lowest optimum temperature (To) and Tm thresholds. Niuzhizi (Lespedeza potaninii) and white clover (Trifolium repens) were identified as thermophilic, requiring higher temperatures for optimal germination, as evidenced by their higher To and Tm thresholds. While genus Vicia and red clover (Trifolium pratense) were best adapted to moderate thermal environments. Furthermore, germination speed-related parameters were more sensitive to temperature fluctuations than the germination percentage. Among different models, intersected-lines was superior for prediction of cardinal temperatures of ten forage legumes based on lower root mean square of error (RMSE) and higher coefficient of determination (R2). No statistically significant relationship between cardinal temperatures and germination parameters was observed. The findings from this research provide a scientific basis for improving sowing practices and regional selection, which is vital for cultivation and production. The successful identification of these cardinal temperatures is also crucial for development of plant growth and biomass prediction models that simulate growth and estimate yield under current and future climate scenarios.
Keywords: Cardinal temperature, Forage legumes, Germination rate, Non-linear regression models, thermal range
Received: 27 Nov 2025; Accepted: 14 Jan 2026.
Copyright: © 2026 Shi, Hu, Jia, Zhao, Tan, Teng, Han, Gai, Lei, Yuan, Zhong, Sun and Tao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Qibo Tao
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