REGULATORY EFFECT OF NITROGEN ON THE FORMATION AND ACCUMULATION OF SECONDARY METABOLITES IN DIFFERENT GENOTYPES OF CAMELLIA SINENSIS (L.) KUNTZE

Abstract

Soil N defi ciency 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 effi ciency. In this regard, the eff ect of genotype on biosynthesis and accumulation of valuable secondary metabolites in tea leaves was studied under optimal N supply and its defi ciency in potted experiment. Th e 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 chromatog-raphy, the contents of catechins, fl avanols, 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 (caff eine 3–5 times and theobromine 2–3 times) in both tea genotypes; however, it decreased the accumulation of several catechins and fl avanols on average 1,5–2 times. Under optimal N supply, cv. Kolkhida displayed higher accumu-lation of theanine (by 30–60%) and gallated catechins (by 50%) in the leaves, however cv. higher accumulation of alkaloids (caff eine and theobromine) was observed in cv. Karatum (by 10–20%). N defi ciency 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 diff erent nitrogen levels, indicating its lower susceptibility to N defi ciency.