Foliar Application of Nano-Urea Enhances Growth, Yield and Biochemical Quality of Tea (Camellia sinensis L.) in Northern Bangladesh

Abstract

Tea (Camellia sinensis L.) is one of the leading beverage crops in terms of economic value worldwide, and sustainable nitrogen management is critical for maintaining productivity and leaf quality. Tea is a nitrogen-demanding perennial crop, yet field-based evidence regarding the effectiveness of foliar nano-urea remains limited. This study was conducted in northern Bangladesh to evaluate the effects of four different rates of foliar nano-urea on vegetative growth, fresh leaf yield and biochemical quality of tea. The experiment was conducted using the commercial tea clone BT-2 in a randomized complete block design. The treatments consisted of an unfertilized control, recommended fertilizer dose (RDF), and nano-urea at 100, 200, 300 or 400 mL acre−1. Two successive application-harvest cycles were evaluated for growth traits, fresh leaf yield, chlorophyll, total polyphenols, flavonoids and caffeine. Compared with the control, foliar application of nano-urea significantly enhanced plant height, leaf length, leaf width, harvestable shoot numbers and fresh leaf yield. The higher rates (300–400 mL acre−1) also enhanced chlorophyll and key biochemical quality attributes. In comparison to RDF, nano-urea at 300–400 mL acre−1 performed statistically similarly for several growth, yield and quality traits. The present results provide field-based evidence that nano-urea application could potentially be used as a supplement instead of conventional fertilization to enhance canopy development and fresh leaf productivity while improving biochemical quality. These findings demonstrate that foliar nano-urea is an effective supplement to conventional nitrogen fertilization for improving tea growth and leaf quality under the agroecological conditions of northern Bangladesh.