不同施氮量对乌龙茶生长和生理的影响

以武夷肉桂为研究对象，研究不同施氮量对乌龙茶幼龄茶树生长和生理的影响。结果表明，幼龄茶树对氮肥的需求不强烈，其新梢生物量、根生物量和总生物量以及茶叶产量随施氮量的增加而下降。茶树新梢全氮、叶绿素、游离氨基酸、茶多酚和咖啡碱的含量随施氮量的增加而增加，而茶树碳氮比随着施氮量增加而下降；但施氮并没有影响茶树总碳含量。老叶叶绿素含量、根全氮和硝态氮含量、新梢总糖含量与施氮量呈二次曲线回归关系，适度施氮促进根对氮的吸收、老叶叶绿素合成和新梢总糖代谢，过度施氮则相反。新梢生物量与其硝态氮含量和游离氨基酸总量显著负相关；根生物量与根碳氮比和新梢咖啡碱含量显著负相关；茎叶生物量和总生物量与根含氮量显著正相关，但与新梢硝态氮和氨基酸含量显著负相关。过度施氮造成茶树生产力下降的主要原因是因为过度施氮极显著提高了茶树氨基酸代谢水平，使用于茶树生长的碳代谢产物（如总糖）减少，进而影响茶树的生长。

Effects of nitrogen application on growth and physiological characteristics of oolong tea plant Camellia sinensis

In this paper, a greenhouse experiment was carded out to study the effects of nitrogen application （0. 0, 0. 5, L 0, L 5, 2. 0, and 2. S g · pot^- 1 ） on growth and physiological characteristics of young oolong tea plants Camellia sinenis. The results showed that nitrogen was not necessary for the growth of the young plants, and the biomass of young shoots, biomass of roots, total biomass and yield decreased significantly with increasing nitrogen rates, while SPAD values and the contents of tissue nitrogen, total free a- mino acids, tea polyphenols and caffeine of young shoots inereased significantly with increasing nitrogen rates. However, nitrogen application had no effect on the total carbon concentration. SPAD value of mature leaves, the contents of tissue nitrogen, and nitrate nitrogen in the roots, as weU as total sugar concentration of young shoots, showed significant quadratic polynomial regressions with nitrogen application rates. Moderate nitrogen application promoted the nitrogen absorption of roots, synthesis of chlorophyU of mature leaves, and the metabolism of total sugar of young shoots, while excessive nitrogen application showed opposite results. The hiomass of young shoots was significantly negatively correlated with the contents of nitrate nitrogen and total free amino acids of young shoots, the hiomass of roots was also significantly negatively correlated with the C ： N ratio of roots and caffeine concentration of young shoots. Shoot biomass and total biomass of tea plant were significantly positively correlated with tissue nitrogen concentration of roots, but they were negatively correlated with nitrate nitrogen concentration of roots and the content of total free amino acids of young shoots. The results suggested that the productivity reduction of tea plants with excessive nitrogen application result from increased total free amino metabolism, and decrease of the C-compounds （e. g. total sugar）.