Kaolin-based particle film mitigates high light stress in native tree seedlings through anatomical and growth...

Deforestation and environmental degradation increase the need for effective strategies to improve seedling establishment in ecological restoration programs, particularly under high irradiance conditions. Although processed kaolin particle film (PKPF) has been widely used to mitigate abiotic stress in agricultural crops, its potential application to native forest species during restoration remains poorly understood. This study evaluated the effects of PKPF on anatomical, ultrastructural, and biometric traits of Cordia superba and Citharexylum myrianthum, two native Atlantic Forest species commonly used in restoration projects. Seedlings were grown under full sunlight with or without PKPF application and compared with greenhouse-grown plants. PKPF reduced leaf temperature, preserved chloroplast and mitochondrial ultrastructure, and promoted the accumulation of starch grains and plastoglobules. These responses indicate improved maintenance of cellular integrity and energy metabolism under high irradiance, contributing to enhanced stress tolerance during seedling establishment. Growth responses were more pronounced in C. superba, whereas C. myrianthum exhibited greater intrinsic tolerance to light stress. Overall, the results demonstrate that PKPF mitigates the adverse effects of excessive solar radiation by protecting cellular structures associated with photosynthetic performance and supporting seedling development. This study provides novel evidence for the use of kaolin-based technologies in native forest species and highlights their potential to improve restoration success under increasingly challenging environmental conditions.