Effect of calcium oxide, zinc oxide nanoparticles and their combined treatments on growth and yield attributes of Solanum lycopersicum L.

Tomato (Solanum lycopersicum L. Syn Lycopersicon esculentum Mill.) occupies a significant position among vegetable crops. With the increasing population, the food supply is going to be short and will be causing a major problem. Therefore, the enhancement of crop production is necessary for food security. To enhance nutrient efficiency and yield in an agricultural field, nanotechnology can play a key role. In the present study, zinc oxide (ZnO) and calcium oxide (CaO) nanoparticles (NPs) were synthesized by following green synthesis i.e., by using water extract of Nigella sativa seeds. These particles were characterized by UV visible spectroscopy and particle size analyzer. A UV–visible spectrum of ZnO and CaO NPs showed absorption peaks at 230 nm and 220 nm respectively. The particle size of 50–60 nm and 5 to 10 nm was observed for ZnO and CaO nanoparticles respectively. Sterilized seeds of tomato were germinated and grown in pots, which were treated with foliar spray of ZnO, and CaO nanoparticles in various concentrations (50, 100, 200 ppm) with three replications separately. The effect of ZnO, CaO, and CaO + ZnO NPs was observed by measuring vegetative growth parameters (i.e. plant length, number of leaves/plant, leaf area/plant, fresh and dry weight of the whole plant) and biochemical parameters (i.e. titratable acidity, total phenolics and zinc and calcium metal content). Results revealed that nano-spray of CaO and ZnO NPs gave positive results on the physiological parameters of tomato plants. A combined effect of ZnO and CaO on S. lycopersicum was significantly higher as compared to the separate treatments of ZnO and CaO. The combined effect of ZnO + CaO with the concentration of 50 ppm gave positive results in shoot length, number of shoots, number of roots, yield/plant, fruit weight, and leaf area. Whereas, root length, plant weight, and fruit diameter were higher at 200 ppm of ZnO + CaO. Biochemical parameters were also improved by using the nano-spray application as CaO < ZnO < ZnO + CaO respectively. The research proved to be cost-effective, less toxic, and eco-friendly which will also be beneficial for future perspectives.