**3.4 Titanium nanoparticles (titanium dioxide TiO2 & anatase titanium dioxide AnTiO2)**

Wheat seed gluten and starch contents have responded favorably for using TiO2 NPs foliar applications and improved plant height, seed and ear numbers, ear weight, gluten and starch content, yield, biomass, and harvest index under drought stress [73]. Enhanced photosynthesis and increased the maize plant's capacity to absorb light under water deficit [74]. Applying nanoparticles and Gibberellic acid to basil plants effectively enhanced the rate of photosynthesis, enhancing their tolerance to drought stress [75]. Various doses and sizes (10–25 nm) of AnTiO2NP on the flax plant under water-scarce conditions responded favorably for growth, development, hydrogen peroxide (H2O2), malondialdehyde content, seed oil production, protein content, and

photosynthetic pigments [76]. The effects of TiO2 NP on onion seedlings have also been documented as they boosted SOD activity. TiO2 NP concentrations of 40 and 50 mg/ml, lowered the CAT and POD activities and secretion of amylase was reduced. However, seed germination and seedling growth were reduced at higher concentration of TiO2 NPs, whereas the effect was enhanced at lower concentration [77].


#### **Table 2.**

*Effects of nanoparticles on plants under drought stress.*

*Improvement of Abiotic Stress Tolerance in Plants with the Application of Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.110201*

#### **3.5 Silver nanoparticles (Ag NPs)**

Developing drought-tolerant cultivars and reducing drought stress is essential for maintaining food security [78]. Only a small amount of historical literature focused on the interaction between drought and Ag NPs. Diminishing the detrimental impacts of drought stress on *Lens culinaris* has been credited to the application of Ag NPs [68]. The study indicated that varying PEG and Ag NPs concentrations had a significant impact on seed germination, root length, and biomass. Hence, Ag NPs could help to reduce water stress that affects plant development and productivity [79].
