Evaluation of saline-alkali tolerance in 71 soybean germplasms based on multi-method integrated analysis at the germination stage.

Authors

Yixin Tian, Qi Gao, Guanxiong Zhu, Chunyu Wang, Fangjing Hua, Chunyan Li, Pengpeng Cao, Fengju Gao, Jinying Zhu

Published in

PeerJ. Volume 14. Pages e21642. Epub Aug 24, 2026.

Abstract

Global soybean production is constrained by scarce arable land, and standardized evaluation tools remain lacking for natural mixed saline-alkali stress, the predominant abiotic stress under field conditions.
This study aimed to establish a comprehensive saline-alkali tolerance evaluation system for soybean germplasms via integrated multivariate statistical methods, and screen core and auxiliary indicators for efficient germplasm identification.
Seventy-one soybean germplasms were tested under 90 mmol/L mixed saline-alkali stress (NaCl:Na₂SO₄:NaHCO₃:Na₂CO₃ = 1:9:9:1, pH 8.2) simulating natural saline-alkali soil. We quantified the saline-alkali tolerance coefficients (SATC) of 13 morphological and physiological indicators, followed by coefficient of variation (CV), principal component analysis (PCA), subordinate function, cluster analysis and regression modeling.
Significant inter-germplasm variations in saline-alkali tolerance were detected, and indicators with CV > 0.35 (e.g., root length (RL), root fresh weight (RFW)) were screened as primary indices. PCA extracted five principal components with 87.18% cumulative variance contribution, and the integrated analytical pipeline categorized germplasms into five tolerance grades: eight highly tolerant, 24 moderately tolerant, 13 generally tolerant, 16 sensitive and 10 highly sensitive accessions. A high-precision prediction model was constructed (D = 0.290X ₁ - 0.026X ₂ + 0.438X₃ + 0.402X ₄ + 0.180X ₅ + 0.153X ₆ + 0.813X ₇ - 1.123; R² = 0.998, where X ₁-X ₇ represent the SATC of germination rate (GR), RL, RFW, total fresh weight (TFW), shoot dry weight (SDW), root dry weight (RDW), and total dry weight (TDW), respectively). A Chi-squared Automatic Interaction Detection (CHAID) decision tree model was further developed and validated using 10-fold cross-validation, yielding a cross-validation risk value of 0.003, which was comparable to the resubstitution risk value (0.002), indicating good generalization ability and low risk of overfitting. A novel five-dimensional overlapping analysis identified RFW as the core evaluation indicator, with RDW, TFW and R/S as key auxiliary indicators.
This study delivers a standardized, reproducible technical framework for large-scale screening of saline-alkali-tolerant soybean germplasms. It facilitates global saline-alkali land utilization, accelerates worldwide soybean stress-tolerance breeding, and provides a transferable paradigm for stress tolerance evaluation in other major crops.

PMID:
42668836
Bibliographic data and abstract were imported from PubMed on 30 Aug 2026.

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