Titanium dioxide nanoparticles alleviate phosphorus deficiency stress in apple plants

Titanium dioxide nanoparticles (TiO₂NPs) can influence various physiological processes in plant tissues. Phosphorus (P) deficiency can cause severely impair growth which may lead to lethal damage to plants, such as apple trees. The aim of this study was to investigate the role of titanium in nanometric form, in alleviating the consequences of P deficiency. One-year-old MM106 apple rootstock plants were divided into two groups: one was subjected to phosphorus deficiency (-P), while the other received balanced fertilization (+ P). Both groups were sprayed with TiO₂NPs at concentrations of 0, 10, 50, and 100 mgL⁻¹, along with a normal TiO at 100 mgL⁻¹ The results showed that 10 mgL⁻¹ TiO₂NPs were the most effective at enhancing various physiological and growth parameters in -P plants. These included increased leaf cytokinin (CK) content (isopentyl adenine), chlorophyll levels, root fresh weight, root network area, root length in the 2-6 mm range, and surface area per cm². These improvements contributed to the increased uptake of phosphorus, iron, and copper, which are essential for chlorophyll synthesis. The interplay of these factors, along with increased CK levels, improved vegetative growth and mitigated the adverse effects of phosphorus deficiency.