Split application of nano urea and conventional urea for optimizing nitrogen management in chrysanthemum under polyhouse conditions
Synthetic fertilizers have played a pivotal role in enhancing the crop productivity and quality; however, excessive dependence on conventional fertilizers, particularly urea, has led to low nutrient use efficiency, environmental contamination, soil fertility depletion, and associated ecological risks. Chrysanthemum is a high-value floricultural crop, is a heavy nitrogen feeder and its growth, flowering, and yield are strongly influenced by nitrogen availability. Nano urea, owing to its higher foliar absorption efficiency (80%) and controlled nutrient release, has emerged as promising alternative to conventional urea for improving nitrogen use efficiency. A factorial randomized block design experiment was conducted during 2022–2023 to evaluate the effect of split applications of urea and nano urea on growth, flowering, yield, and soil nutrient status of chrysanthemum under polyhouse conditions. Treatments comprised different doses of nano urea and urea applied at weekly, biweekly, and fortnightly intervals, starting after pinching and continued up to twelve weeks. Among the treatment variety combinations, T3V2 recorded the highest plant height (170.49 cm), flower diameter (16.23 cm), and vase life (27.60 days), whereas T3V1 produced the maximum plant spread (58.90 cm), cut flower yield (6.37 stems plant⁻¹), and benefit cost ratio (4.23) with improvements of 15–30% over urea treatments. This treatment also resulted in lower soil nitrogen, phosphorus, and potassium levels, reflecting improved nutrient uptake and reduced nutrient accumulation. The study highlights nano urea as a sustainable, high-efficiency nitrogen management strategy capable of improving productivity, profitability, and resource use efficiency in chrysanthemum cultivation.