Dynamic changes and genotypic variations of nitrogen concentration and remobilization for 20 tea plant (Camellia sinensis) cultivars throughout growing seasons

Abstract

Background: Tea plant ( Camellia sinensis ) is an evergreen perennial plant and characterized by a high nitrogen (N) requirement. There are roundly bud sprouting and leaves development for plucking and pruning annually, leading to continuous and substantial amount of N removal. Appropriate level of N application is closely related with high yield and top quality, therefore understanding the underlying mechanism is very crucial for development of optimized tea garden management practices according to genotypes’ requirement. Results: This study aimed to assess variation for dynamic N concentration, N remobilization efficiency (NRE) and N utilization efficiency (NUtE) changes during growing seasons among 20 tea plant cultivars at sufficient N level. The average N concentration varied between 31.05 and 44.2 g kg -1 in one bud with two leaves, between 22.67 and 29.42 g kg -1 in leaves attached to green-red stems, between 20.79 and 24.57 g kg -1 respectively. The dynamic changes of N concentration represented different profiles of ‘S’, ‘U’ and ‘S-like’-shape respectively. Specific NRE defined here is dependent on the development rounds and accompanied with N fluxes between leaves compartments. Nevertheless, the rates and order of N remobilization were inconsistent among genotypes during the entire growing seasons, which might be affected by the amount of N requirement and managed at whole plant level. The dynamic changes of average NUtE among cultivars followed an ‘S’-shape. NUtE addressed here was special for harvestable part and lower NUtE is highly associated with tea quality. Conclusions: The result revealed the annual growing rhythm and physiological character related with N indices, which was related with the amount and optimal time for N fertilization requirement dependent on tea plant genotype. An optimized NUtE should be optimized by combination of tea garden management and breeding practices to achieve economic benefit, N use efficiency and sustainable development.