Andrey Vasilyevich Velikiy

Soil N deficiency is one of the main constraints limiting high tea yields worldwide, particularly in Russia. Besides, high dosages of N fertilizers are widely applied for tea plantations, resulting in agrogenic transformation of soils, environment pollution, and a decrease in the tea quality. One of the ways to reduce dosages of N fertilizers is the development of new cultivars with high N use efficiency. In this regard, the effect of genotype on biosynthesis and accumulation of valuable secondary metabolites in tea leaves was studied under optimal N supply and its deficiency in potted experiment. The study was conducted on the most promising local tea cultivars (Kolkhida and Karatum), grown on brown forest acidic soils in the humid subtropics of Russia. Using high-performance liquid chromatography, the contents of catechins, flavanols, alkaloids and theanine were evaluated in tea leaves. Our results showed that N availability stimulated the biosynthesis of theanine more than one order of magnitude and alkaloids (caffeine 3–5 times and theobromine 2–3 times) in both tea genotypes; however, it decreased the accumulation of several catechins and flavanols on average 1,5–2 times. Under optimal N supply, cv. Kolkhida displayed higher accumulation of theanine (by 30–60%) and gallated catechins (by 50%) in the leaves, however cv. higher accumulation of alkaloids (caffeine and theobromine) was observed in cv. Karatum (by 10–20%). N deficiency resulted in greater accumulation of simple and gallated catechins, as well as rutin in cv. Kolkhida, as compared to cv. Karatum. However, the content of the studied metabolites in cv. Karatum was more stable under different nitrogen levels, indicating its lower susceptibility to N deficiency.