Natural variations and dynamics of macronutrients for 87 tea plant (Camellia sinensis) varieties throughout the growing seasons in Wuhan

The tea plant (Camellia sinensis (L.) O. Kuntze) is the most extensively consumed beverage crop in the world, with steadily increasing consumption over the last decade. Tea plantations are frequently over-fertilized to achieve enhanced growth and yield, which ultimately influences the soil acidification and compaction, resulting in low quality and yield. However, the effect of optimum nutrient concentrations in the leaves on tea yield and quality is poorly understood. In this study, the dynamics of macronutrients nitrogen (N), phosphorus (P) and potassium (K) levels, nutrient use and remobilization efficiencies, and nutrient requirements (NR) were quantified among the diverse tea plant varieties over the entire growing seasons. Leaf samples of two categories, young leaves and mature canopy leaves, were collected from 87 elite tea varieties during the growing seasons to illustrate their biological significance. The results revealed that the highest average N levels were observed in the 2nd spring tea, P levels in summer tea, and K levels in autumn tea in both young and mature leaves. The results further revealed that a higher average nutrient utilization efficiency for nitrogen (NUtE-N) was identified in the summer followed by autumn. The NUtE-P in autumn and the NUtE-K in the 1st spring tea were relatively higher. Nutrient remobilization efficiencies (NRE) (NRE < 0 and NRE > 0) for N, P and K within canopy leaves were calculated, indicating the alternative roles of sources and sinks during the growth period. Moreover, NRE < 0 was almost exclusively found in the spring and summer, whereas NRE > 0 was mainly observed in the autumn. In terms of requirements, N was the most required for optimal tea yield, followed by K, and then P. Seasonally, maximum N, P and K requirements were coincidentally observed in the 2nd spring tea, whereas the minimum were in summer tea, autumn tea and the 1st spring tea, respectively. Based on nutrient utilization, the nutrient requirements of tea plants and the understanding of natural variability in N, P and K dynamics were elucidated to address agronomic, economic and environmental issues.