Soil acidity is one of the major soil-degradation events throughout the world, and the long-term application of nitrogenous fertilizers is thought to be a main cause of soil acidity. In the present experiment, we collected soil and tea (Camellia sinensis L.) leaf samples from five representative tea gardens in Bangladesh and evaluated soil nutrient pools and biochemical properties of tea leaves. The results showed that there was a negative relationship between soil pH and the amount of applied nitrogenous fertilizers. Moreover, continuous application of traditional fertilizers over twenty-five years promoted not only the deficiency of phosphorus (P) and mineral-based cations, such as potassium (K⁺), calcium (Ca²⁺), and magnesium (Mg²⁺), but also increased manganese (Mn²⁺) and aluminum (Al³⁺) toxicity in soils, which suppressed the yield and quality of tea. Crucially, tea leaf production remained almost similar (average 1079.77 kg ha⁻¹) from 1995 to 2015, while the application doses of urea, TSP, and MoP increased by 24.69%, 18.92%, and 16.67%, respectively, in garden soils. However, the pH value of soil declined up to 24% from 1992 to 2020 in the tested gardens. Consequently, the availability of K⁺, P, Ca²⁺, and Mg²⁺ decreased by 56%, 25%, 55%, and 49%, respectively, in those tea garden soils. In addition, the quality of tea leaves was severely affected, as evident by the reduced levels of total flavonoids, polyphenols, soluble solids, vitamin C, vitamin B1, and vitamin B2. Moreover, free-radical scavenging activity (DPPH), caffeine, and tannin concentration were increased in tea leaves, which indicated that tea plants were potentially being stressed. Therefore, we study concluded that long-term application of traditional nitrogenous fertilizers can be an important regulator of lowering garden soil pH, which reduces native soil nutrient pools and thereby the yield and quality of tea leaves.

Tea (Camellia sinensis (L.) Kuntze) is a highly valued plant known for its refreshing taste, medicinal properties, and health benefits. It is an evergreen shrub or small tree belonging to the Theaceae family. The productivity and quality of tea leaves and liquor are strongly influenced by edaphic and environmental factors. However, the cultivation of tea faces significant challenges due to the increasing occurrence of drought associated with global warming and climate change. In this review, we have summarized the potential effects of drought on the growth, productivity, and liquor quality of tea. Drought exerts substantial impacts on the physiological, biochemical, and morphological features of tea plants. For instance, under drought stress, there is a reduction in leaf activity, including chlorophyll production, photosynthetic rate, and CO₂ uptake. Drought periods also lead to decreased shoot initiation and extension rates. However, it is important to note that responses to drought can vary depending on factors such as tea variety, cultivar diversity, agricultural management practices, and study techniques. While drought-induced biochemical damage may occur, it is often reversible, and the plant can recover upon rehydration. Irrigation strategies employed during dry periods have been shown to have a significant positive effect on tea yields, making it a promising option for enhancing productivity in drought-prone regions. Furthermore, the cultivation of drought-tolerant tea cultivars, along with the application of micro and macro-nutrients, as well as hormone treatments, can contribute to improving the post-drought recovery process. Studying the influence of drought on tea productivity offers an opportunity for frontier research, aiming to understand the intricate relationship between tea leaf productivity and liquor quality. Additionally, investigating the factors that contribute to stress recovery in tea plants holds promise for enhancing cultivation practices and ensuring the sustainability of tea production in the face of changing climatic conditions.