Temperature and humidity are the key environmental factors affecting the storage life of seeds. To explore the feasibility and factors influencing ultra-dry storage of Pinus kesiya var. langbianensis seeds, the seeds were dehydrated to six different moisture contents (0.92–6.12%) and stored for one year. The effects of moisture content, packaging method, storage temperature, and pre-humidification method on the viability of ultra-dry seeds were systematically investigated using an orthogonal experimental design. The germination energy, relative electrical conductivity (REC), malondialdehyde (MDA), proline (Pro), total soluble sugar content, and fatty acid composition were determined. The results showed that moisture content and pre-humidification had significant effects on seed germination energy and vigor (p < 0.01). The germination energy of ultra-dried seeds was significantly negatively correlated with REC and MDA contents (p < 0.01) and significantly positively correlated with Pro content (p < 0.01). Based on the comprehensive indices, the optimal combination for seed germination energy was: 4.24% moisture content, self-sealing bag packaging, room temperature (25 °C) storage, and 20% polyethylene glycol (PEG) pre-humidification. Under the optimal moisture content (4.24%), the total sugar content of seeds was the lowest, while the fatty acid unsaturation index and oleic acid content were higher than those in the other treatments. Therefore, appropriate ultra-dry treatment can effectively maintain the seed vigor of P. kesiya var. langbianensis, and its protective effect is closely related to reducing membrane lipid peroxidation, accumulating proline, and regulating fatty acid unsaturation. This has important implications for forest seed conservation and germplasm management, particularly for long-term ex situ preservation of tree seeds in gene banks, supporting reforestation and biodiversity restoration efforts.
Sun et al. (Mon,) studied this question.