Assessment of high-light adaptation and screening of superior oat germplasm

In the context of climate warming, high-light stress has become a major environmental constraint on crop photosynthetic efficiency and growth. Elucidating the physiological and morphological responses of oat seedlings to high light, together with the identification of tolerant germplasm, is therefore essential for enhancing oat adaptation to light-intensive environments.

Forty-eight oat (Avena sativa) accessions were assessed for high-light adaptability at the seedling stage. A preliminary light-gradient experiment using four representative accessions identified 1600 μmol·m^-2·s^-1 as an optimal light intensity for high-light stress screening. All accessions were subsequently exposed to this light regime, and nine traits were quantified, including plant height, leaf thickness, stem diameter, aboveground fresh and dry weights, SPAD value, net photosynthetic rate, proline (Pro) content, and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity. Correlation analysis, cluster analysis, the TOPSIS multi-criteria decision model, and structural equation modeling were integrated to comprehensively evaluate high-light adaptability.

High-light stress markedly suppressed seedling growth, with most growth-related traits exhibiting an overall decline. Based on the comprehensive evaluation index derived from the TOPSIS model in combination with cluster analysis, the 48 oat accessions were classified into four distinct high-light tolerance groups. Among these, Qingyongjiu 478 and Xizangbailang demonstrated superior adaptation to high-light conditions. Structural equation modeling further indicated that proline content, SPAD value, and stem diameter had significant effects on aboveground fresh weight formation, with total effects of -0.506, 0.475, and 0.470, respectively.

This study establishes a robust framework for evaluating high-light adaptability at the oat seedling stage, identifies key physiological traits governing biomass accumulation under high-light stress, and provides valuable germplasm resources and theoretical support for high-light tolerance gene discovery and oat breeding programs.