Potential of botanical biostimulants (peppermint, laurel, and rosemary extracts) to influence growth, physiological performance, antioxidant defense, and postharvest quality of hydroponically grown tuberose (Polianthes tuberosa L.): a preliminary inv

This study evaluated the effectiveness of botanical biostimulants in enhancing the growth, physiological performance, and postharvest quality of hydroponically grown tuberose (Polianthes tuberosa L.) cut flowers. Two nutrient solutions were compared: the conventional Hoagland nutrient solution (Solution A) and a modified nutrient solution supplemented with peppermint, laurel, and rosemary leaf extracts (Solution B). Plant growth, floral characteristics, vase life, biochemical traits, and antioxidant enzyme activities were assessed under both treatments. The results demonstrated that the botanical biostimulants significantly improved several growth and postharvest attributes compared with the conventional Hoagland solution. Peppermint extract at 15 mL L⁻¹ accelerated flower emergence (96.3 days), increased reducing sugar content (0.218), and induced the highest activities of peroxidase and catalase. Rosemary extract at 15 mL L⁻¹ significantly extended vase life (8.33 days), while rosemary extract at 5 mL L⁻¹ produced the highest number of florets (27.67). Laurel extract at 10 mL L⁻¹ significantly increased spike length (26.83 cm). In contrast, the control treatment (Hoagland solution) produced the highest number of bulblets. Pearson's correlation analysis revealed significant positive relationships among several growth and physiological traits. Leaf number was positively correlated with flower diameter (r = 0.373*), spike length (r = 0.412*), and fresh weight (r = 0.747**). Flower diameter showed positive correlations with fresh weight (r = 0.508**), peroxidase activity (r = 0.419*), and catalase activity (r = 0.419*). Flower number was positively associated with spike length (r = 0.511**), whereas peduncle length and bulblet number were positively correlated with reducing sugar content (r = 0.494** and r = 0.368*, respectively). A perfect positive correlation was observed between peroxidase and catalase activities (r = 1.000**). Principal component analysis identified five principal components explaining 76.86% of the total variation. Overall, the findings indicate that peppermint, rosemary, and laurel leaf extracts can serve as effective botanical biostimulants for improving the growth, physiological traits, and postharvest performance of hydroponically grown tuberose, highlighting their potential as sustainable supplements to conventional mineral fertilization.