Effect of Nano-TiO 2 Composite on the Fertilization and Fruit-Setting of Litchi.

Titanium dioxide nanoparticles (nTiO 2 ) are widely used as fertilizers in agricultural production because they promote photosynthesis and strong adhesion. Low pollination and fertilization due to rainy weather during the litchi plant's flowering phase result in poor fruit quality and output. nTiO 2 would affect litchi during the flowering and fruiting stages. This study considers how nTiO 2 affects litchi's fruit quality and pollen viability during the flowering stage. The effects of nTiO 2 treatment on pollen vigor, yield, and fruit quality were investigated. nTiO 2 effectively improved the pollen germination rate and pollen tube length of litchi male flowers. The germination rate reached 22.31 ± 1.70%, and the pollen tube reached 237.66 μm in the 450 mg/L reagent-treated group. Spraying with 150 mg/L of nTiO 2 increased the germination rate of pollen by 2.67% and 3.67% for two types of male flowers (M1 and M2) of anthesis, respectively. After nTiO 2 spraying, the fruit set rates of 'Guiwei' and 'Nomici' were 46.68% and 30.33%, respectively, higher than those of the boric acid treatment group and the control group. The edibility rate, titration calculation, and vitamin C of nTiO 2 treatment were significantly higher than those of the control. The nTiO 2 -treated litchi fruit was more vividly colored. Meanwhile, the adhesion of nTiO 2 to leaves was effectively optimized by using ATP and BCS to form nTiO 2 carriers and configuring nTiO 2 complex reagents. These results set the foundation for future applications of titanium dioxide nanoparticles as fertilizers for agriculture and guide their application to flowers and fruits.