Effect of foliar application of nano-NPK and nano-micro elements on the growth, flowering, and biochemical composition of Zinnia elegans

Zinnia elegans, a widely utilized flowering plant for pots, cut flowers, bouquets, and gardens, necessitates macro- and micro-nutrients for optimal growth, development, and flowering. This study, conducted in 2023 and 2024, aimed to enhance the plant's growth and flowering response through foliar applications of Nano-NPK, Nano-micronutrients, and their combination.The results indicated that all treatments significantly affected the plant growth parameters (plant height, stem diameter, number of leaves, fresh and dry weights and root length) compared to control. In most cases, spraying with Nano-NPK 4 mL/L, and NPK + Nano fmicro-elements (4 mL/L ) increased the plant height, formation of leaves and branches per plant, the weights of the leaves, stem thickness to the highestvalues and exhibited the longest roots. The impact of nano fertilizers on flowering revealed that the highest number of flowering heads was recorded in plants treated with Nano-NPK + Nano-micro 2 and 4 mL/L and the largest flowering head size with Nano-NPK+ Nano-micro 4 mL/L. The Nano treatments significantly increased the fresh weight of flowers, especially with the mixture of Nano-NPK + Nano-micro at 4 mL/ L. Compared to the control, using of Nano fertilizers significantly increased all the flowering parameters. All the Nano-treatments significantly increased the contents of chlorophyll-a, b and total chlorophyll, and carbohydrates. The highest contents were obtained with Nano-NPK + micro-elements 4mL/ L and Nano-NPK at 4 mL/L alone.