Effect of nano NPK fertilizer, cytokinin, and gibberellic acid on vegetative growth and chemical constituents of Paulownia (Paulownia tomentosa L) plants

The investigation sought to examine the effects of nano NPK, cytokinin, and GA3 on the growth and chemical composition of Paulownia tree seedlings. The experiment comprised three treatments: Nano NPK at concentrations of 0 and 6 g L-1, applied monthly from April to September; cytokinin at concentrations of 0, 100, and 200 mg L-1, applied thrice in March, July, and September; and GA3 at concentrations of 0, 200, and 400 mg L-1, applied biannually in May and August. Plant sprayed with 6 g L-1 Nano NPK increased all vegetative and chemical parameters compared with control. Furthermore, plants sprayed with 200 mg L-1 cytokinin increase plant height to 96.67 cm, leaves number 31.22 leaf plant-1, stem diameter 5.56 cm, leaves area 277.83 cm2, nitrogen content in leaves 1.65 %, and total carbohydrate in leaves 8.94 % compared with control. In contrast, the plants sprayed with 400 mg L-1 GA3 plant height increased to 92.11 cm, leaves number 29.50 leaf plant-1, leaves area 257.90 cm2, nitrogen and phosphorus content in leaves 1.77- 2.80 %, and total carbohydrate in leaves 8.30 %. Nonetheless, plants treated with 200 mg L-1 GA3 exhibited an increase in total chlorophyll content in leaves to 24.40 mg g-1 fresh weight in comparison to the control group. Further investigation is necessary to ascertain whether higher concentrations than those employed in this study may produce better outcomes.