Identification and Evaluation of Thermotolerance in Broccoli Seedlings Based on a Multi-Trait Phenotyping System
by
,
Xuaner Li
1,†, 
Yongyu Zhao
1,†,
Tiemin Xu
1,2,
Xigang Feng
1,2,
Fengqing Han
1, 
Dongna Wen
1,
Yumei Liu
1,
Wenzheng Gao
1,
Zhiwei Zhao
2 and
Zhansheng Li
1,*
1
State Key Laboratory of Vegetable Biobreeding, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China
2
Shouguang R&D Center of Vegetables, Chinese Academy of Agricultural Sciences, Shouguang 262700, China
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Biology 2025, 14(8), 1093; https://doi.org/10.3390/biology14081093
Submission received: 31 July 2025
/
Revised: 15 August 2025
/
Accepted: 19 August 2025
/
Published: 21 August 2025
(This article belongs to the Special Issue Unraveling the Molecular Mechanisms of Development and Stress Tolerance in Vegetables)
Simple Summary
As extreme heat events become more common due to global climate change, the ability of crops to survive high temperatures is increasingly important. Broccoli, a cool-season vegetable, is especially vulnerable to heat during the seedling stage, which can affect yield and quality. In this study, we developed a quick and effective way to identify which broccoli cultivars are more heat tolerant. By examining plant health indicators like cell damage and chlorophyll levels, we tested 14 common broccoli varieties and found that some, like ‘Yanxiu’, recovered well from heat, while others were more sensitive. Our findings can help farmers and breeders choose better varieties for hot climates and guide future development of heat-tolerant broccoli.
Abstract
To establish a systematic approach for evaluating heat tolerance at the seedling stage in broccoli, we investigated 14 representative cultivars cultivated in China. Physiological indicators such as electrical conductivity, malondialdehyde, proline, and chlorophyll content were measured before and after heat stress, alongside phenotypic scoring of heat injury, to characterize the differential thermotolerance among genotypes. The results indicated that significant differences (p < 0.05) in heat tolerance at the seedling stage were observed among different broccoli cultivars after heat stress treatment at 40 °C. Among them, Yanxiu exhibited the strongest heat tolerance, followed by Meiqing, Naihanyouxiu, Meiao 7172, Feicui 5, Guowang 11, Zheqing 80, Zhongqing 15, Zhongqing 318, Zhongqing 319, and Qianghan. Lvxiong 90, Zhongqing 11, and Zhongqing 16 were the least heat tolerant. Pearson’s correlation analysis demonstrated that the seedling heat tolerance of different broccoli cultivars was significantly negatively correlated with electrical conductivity, with a correlation coefficient of 0.542 (p < 0.05). In this study, a rapid and robust method for determining the heat resistance response of broccoli was established, providing a scientific basis and technical support for the identification of the heat resistance of new broccoli cultivars and the selection and breeding of heat-tolerant cultivars in China.
