Abstract
Biogenesis of caffeine in tea leaves was followed by tracer technique, and in order to examine the effect of nitrogenous fertilizer on cultivation, tea trees were cultivated for about three months during autumn to winter using a medium containing (15NH4)2⋅SO4 (Expt. I). It was thereby learned that about one-half of the 15N absorbed was stored in the root while the other half transited to the aerial portion. In the young leaves, 40% of 15N and 70% of it in old leaves were found in the protein. Fresh caffeine produced from the absorbed labeled nitrogen was only 0.46% (Tables III and V).
After three months of cultivation, a part of the tea trees was transplanted to 15N-free soil and further cultivated for about four months, until the following spring (Expt. II). It was found that 15N of proteins in the root decreased while concentration of 15N in the leaves showed general increase. This fact seemed to suggest that 15N stored in the root during autumn to winter had been utilized next spring for formation of caffeine. It was found also that incorporation of 15N into caffeine occurs much later than that into the proteins.
