Effects of post-harvest natural drying on seed quality and endogenous hormones of Camellia oleifera

Camellia oleifera Abel. (C. oleifera), one of the four woody oil-producing plants in the world produces edible oils with high percentage of unsaturated fatty acid content in seeds. The mature C. oleifera seeds continue to undergo a series of physiological changes after harvest. To this end, the dynamic changes in nutrients, oil content, fatty acid composition, and endogenous hormone content in C. oleifera seeds under different natural drying times after harvest were investigated. The content of soluble sugar and soluble protein of C. oleifera seeds increased with the extension of natural drying, especially soluble sugar content increased nearly 2-fold at 30 d after post-harvest natural drying compared with that of the control group. The content of oil reached a peak (23.6%) at 30 d after post-harvest natural drying. During the post-harvest natural drying process, the relative content of palmitic acid and oleic acid increased, while the relative content of palmitic acid and linoleic acid decreased. Furthermore, the levels of unsaturated fatty acids (oleic acid, linoleic acid, linolenic acid, and arachidonic acid) increased significantly with increasing natural drying time. The overall trend of endogenous hormones SA, SL, and ACC concentrations increased with the post-harvest natural drying process. Furthermore, the concentration of SA, SL, and ACC were positively correlated with oil content. Altogether, post-harvest natural drying for 30 days significantly promoted the anabolism of oil and improved the quality of C. oleifera seeds. These findings provide a scientific basis for reasonable post-harvest treatment to improve Camellia oil yield.