Abstract: To explore nitrogen absorption and utilization by tea plant, micro-plot ¹⁵N labeling was carried out during 2012-2013 on a field experiment established in 2008 investigating interaction of plucking standards and N fertilization. Yield and quality related chemical compounds of spring tea shoots and ¹⁵N parameters (N uptake and N derived from fertilizer) were measured under two plucking standards (one bud with one expanding leaf and one bud with three expanding leaves) and two N fertilization levels (200 and 450 kg·hm^-2). The results showed that spring tea yields were mainly affected by plucking standards, being 1.8 to 2.1 times larger for standard of one bud and three leaves than for that of one bud and one leaf. Nitrogen fertilization levels had no significant effects on tea yields. The effects of plucking standards on the concentrations of quality related compounds such as amino acid, and especially the theanine, were greater than those of N levels. The contents of free amino acids in one bud and one leaf of plants supplied with N at 450 kg·hm^-2 were the highest among the four treatments. Nitrogen concentrations in mature leaves decreased while Ndff increased through the period from winter dormancy (sampled on 17 December) to the end of spring tea season (on 24 April), Ndff in the young shoots was affected by N levels much greater than by plucking standards through the spring tea season. The recovery rate of ¹⁵N in young shoots under low N level was the highest among the four treatments. The overall results indicated that N absorption was influenced by plucking standards and the N levels while N demand by plants subjected variable plucking standards was satisfied by the two N levels.

Key words: tea yield, ¹⁵N, plucking standard, N fertilization levels, qualities, utilization efficiency