Vegetative Propagation Performance of Stem Cuttings from a Camellia sinensis Tree Unpruned for Approximately 70 Years Compared with Cuttings from Regularly Pruned Tea Bushes: A Case Study

The vegetative propagation capacity of stem cuttings from long-unpruned, tree-form tea plants is poorly documented. This case study compared cuttings from a single, approximately 70-year-old, unpruned tree-form Camellia sinensis donor with cuttings from seven regularly pruned commercial tea bushes in the same plantation and evaluated the effects of cutting collection period and indole-3-butyric acid (IBA) concentration. Single-leaf, 8 cm long semi-hardwood cuttings were left untreated (control) or dipped at their basal ends in 500, 1000, or 1500 ppm IBA for 3 s and rooted in 100% perlite for 90 days. Overall, 2400 cuttings were evaluated; the direct factorial comparison included 960 cuttings collected from both donor sources in August and October, with the bush-form material restricted to the 30–50% slope class matching that of the tree-form donor. Survival, the combined callused-or-rooted response, and rooting were analyzed using bias-reduced binomial generalized linear models with a logit link, whereas four root and shoot growth traits measured in successfully rooted August cuttings were analyzed by two-way analysis of variance. Cuttings from the tree-form donor maintained 100% survival in August and October, but their rooting percentages were 25.00% and 0.00%, respectively, compared with 63.61% and 8.06% in the directly compared bush-form material. For rooting, donor source and cutting collection period were significant model terms, whereas the overall main effect of IBA concentration was not significant; the donor source × IBA concentration interaction was significant, but the donor source × cutting collection period interaction was not. IBA concentration significantly affected all four post-rooting growth traits, with a significant donor source × IBA concentration interaction only for aboveground fresh biomass. Thus, high cutting survival did not ensure successful adventitious rooting. Although the August results indicate that this particular mature donor can be propagated by stem cuttings under the conditions tested, the use of a single tree-form donor precludes population-level inference, and collection-period differences may also reflect seasonal environmental conditions experienced during the subsequent rooting periods. The findings should therefore be interpreted as case-specific evidence.