Morpho-physiological response of water leaf (Talinum triangulare Jacq) to urea and Azomite

The cultivation of waterleaf (Talinum triangulare) is crucial to mitigate its overexploitation from the wild; however, optimal fertilizer strategies remain poorly explored. Azomite, a naturally occurring mineral complex, is gaining interest in sustainable agriculture for its ability to improve plant growth and stress resilience without the environmental footprint of synthetic fertilizers. This study evaluated the novel combination of urea nitrogen (N) and Azomite supplementation on the growth and physiology of waterleaf plants to determine a sustainable fertilization strategy. Using a 2 × 6 factorial completely randomized design, plants were subjected to six N rates (0, 50, 100, 150, 200, and 250 kg/ha) with or without Azomite (12.45 g/pot). The results revealed a critical threshold for urea application with rates ≥ 150 kg/ha inducing severe ammonium toxicity, culminating in complete plant mortality at 250 kg/ha. In contrast, 50 kg/ha N rate was identified as optimal, significantly (P < 0.05) enhancing morphological traits such as increasing plant height, stem diameter, leaf number and branch number by 21–300 %, and boosting fresh and dry biomass by 281 % and 154 %, respectively compared to the control. The synergistic application of 50 kg/ha N with Azomite further amplified these benefits driving the most robust improvements in plant architecture and photosynthetic capacity. This combination resulted in a photosynthetic rate of 6.41 μmol m⁻² s⁻¹ and a transpiration rate of 4.50 mol m⁻² s⁻¹ , significantly higher than all other treatments. Principal Component Analysis (PCA) confirmed that the 50 kg/ha N and 50 kg/ha N with Azomite treatments were strongly associated with superior growth and physiological performance. In conclusion, 50 kg/ha is the optimal urea-N rate for waterleaf, with Azomite supplementation providing significant synergistic growth benefits. This strategy offers a practical efficient solution for enhancing waterleaf productivity while minimizing the risks of nitrogen toxicity and environmental pollution.