关键词: 蚕豆, 盐胁迫, 耐盐性筛选, 多指标评价, 衣康酸

Abstract:

【Objective】Salt stress limits the stable and increased yields of faba beans (Vicia faba L.) on saline-alkali soils. This study aims to improve the efficiency and accuracy of distinguishing salt tolerance differences among various materials at early stages by combining indoor germination assays with field observations. Additionally, it evaluates the potential of exogenous itaconic acid (IA) at different doses and acidic treatments to alleviate salt stress during the germination stage, providing complementary pathways for early prediction and exogenous regulation. 【Method】 Fifteen faba bean germplasm materials were selected for germination tests under 100 mmol·L^-1 NaCl conditions. Various indices, including relative germination rate (RGR), relative germination energy (RGE), relative root length (RRL), vigor index (VI), germination index (GI), and germination stress index (GSI), were measured. Comprehensive evaluation and classification were performed using the comprehensive membership value μ(X_i). Field trials were conducted on both saline-alkali and non-saline-alkali soils, tracking seedling emergence rate, Soil and Plant Analyzer Development (SPAD) values at the bud stage, flowering-stage salt injury index (SI), and 17 agronomic traits to form a field classification of salt tolerance. Stratified 5-fold cross-validation was employed to assess the performance of field-grade determination, using F1 metrics. For the IA treatment, three representative germplasms were selected, and a gradient of 0% to 1% IA was applied under 100 mmol·L^-1 NaCl. Acetic acid (CH₃COOH) and pH7.0 treatments served as controls to analyze the alleviating effects of IA on salt stress. 【Result】Significant differences were observed in all indices among the different classifications at the germination stage, showing strong discriminatory power across materials, with comprehensive scores showing a continuous gradient from salt-sensitive to salt-tolerant materials, allowing for classification. Field observations indicated that seedling emergence rates and SPAD values decreased in most materials under saline-alkali conditions, although some materials still performed well. Overall, germination-stage classification correlated well with field classification, with approximately 73% of materials showing consistency across both stages, suggesting that germination assessments are indicative of actual field salt tolerance. A supervised model built on key germination-stage traits (VI, RGE, RGR, and GSI) showed a moderate ability to predict field classification, achieving F1=0.50, Precision=0.46, and Recall=0.60 under stratified 5-fold cross-validation, providing quantitative support for early-stage screening of salt-tolerant germplasm. Low doses of IA (e.g., 0.01%) improved the germination vigor and root growth of the materials, but no similar effect was observed with equimolar acetic acid. When the external solution was adjusted to pH 7.0, the promoting effect of IA significantly weakened or disappeared, indicating that its alleviating effect is not only related to molecular structure but also closely associated with a weak acidic environment. Additionally, the effect exhibited variety-specific responses, with germplasm V434 showing higher responsiveness. 【Conclusion】 The combined evaluation of indoor germination assays and field observations effectively distinguishes salt tolerance differences among faba bean materials at early stages. Indices such as vigor index (VI), germination stress index (GSI), and relative germination rate (RGR) effectively reflect field-grade performance and improve initial screening efficiency. IA demonstrates a dose-dependent, pH-sensitive alleviating effect during germination; however, its stability and applicability need further validation under complex saline-alkali stress and field conditions.

Key words: faba bean, salt stress, salt tolerance screening, multi-indicator evaluation, itaconic acid