Characteristics of Growth, Photosynthesis, C/N Ratio, and Antioxidant Capacity in the Seedling Stage of Aquilaria sinensis ‘Qinan’

In this study, <i>Aquilaria sinensis</i> 'Qinan', a strain of <i>A. sinensis</i> that easily forms agarwood, was selected and propagated by grafting seedlings. Existing research has mainly focused on the characteristics of agarwood formation, but little attention has been paid to the growth characteristics of <i>A. sinensis</i> 'Qinan'. In this study, the growth rate, photosynthetic capacity, leaf size, carbon and nitrogen contents, and antioxidant capacity were evaluated during the early growth stage in <i>A. sinensis</i> 'Qinan' and <i>A. sinensis</i> grafted seedlings. Compared with <i>A. sinensis</i>, <i>A. sinensis</i> 'Qinan' exhibited higher net photosynthetic rate (9.2 μmol m^-2 s^-1 in <i>A. sinensis</i> 'Qinan' and 7.8 μmol m^-2 s^-1 in <i>A. sinensis</i>) in the mature leaf. There were higher contents of secondary metabolites such as flavonoids and phenols, with stronger antioxidant capacity in <i>A. sinensis</i> 'Qinan'. Larger leaf area (43.9 cm² in <i>A. sinensis</i> and 30.1 cm² in <i>A. sinensis</i> 'Qinan'), higher nitrogen content (24.9 mg kg^-1 in <i>A. sinensis</i> and 23.7 mg kg^-1 in <i>A. sinensis</i> 'Qinan') in young leaves, faster growth rate, and larger biomass were observed in <i>A. sinensis</i>. The results indicate that differences exist in nutrient distribution during the growth process of <i>A. sinensis</i> 'Qinan' and <i>A. sinensis</i>, with more substances being used to synthesize defensive secondary metabolites in <i>A. sinensis</i> 'Qinan'.