Since the Meiji period, Japan has actively collected and preserved domestic and foreign genetic resources of tea for breeding. The National Agriculture and Food Research Organization (NARO), Japan possesses one of the world's largest genetic resources of tea collected from 14 countries and regions. To efficiently utilize these genetic resources for various research purposes, including breeding, it is crucial that the characteristics of these genetic resources are accurately understood. Recently, analyses of genetic diversity using DNA markers have been actively conducted. Moreover, analysis of the diversity of NARO’s genetic resources of tea using Simple sequence repeat (SSR) markers revealed a large extent of genetic differentiation between germplasms of domestic and overseas origin. The genetic diversity of the domestic accessions, as opposed to the foreign accessions, was limited. Therefore, to expand the genetic diversity of breeding materials, the utilization of genetic resources introduced from overseas is vital. Core collections of NARO’s genetic resources of tea were selected using the SSR marker genotype data. These core collections are very useful to exploit the abundant diversity of tea plants. Moreover, combining core collections and genome analyzing technology would enable the creation of new breeding materials and the identification of useful loci of important agricultural traits.

The roads leading to tea plantations in mountainous areas are usually narrow. Thus, only light trucks can enter the fields, making it impossible for tea farmers to use riding-type tea-managing machines. We invented a lightweight tea-field managing machine that can be carried by light trucks and only needs one person to operate it. It can work in contour hedgerows (1,600 to 1,800 mm), with a maximum tilt angle of 15°. To use this machine, tea fields need to have 1) a 2 m aisle on the machine moving side, 2) a 0.5 m aisle on the blade reverse side, and 3) an area of 2 m × 3 m for alighting and dismounting on the light truck cargo side. Compared with the control machines, the new machine helps 1) reduce effort, labor cost, and number of workers required, 2) shorten the total working time, and 3) improve work accuracy in the flat fields. The difference between the new and a control machine was unclear in terms of yield; however, the quality of unrefined tea obtained was almost the same.

An aroma extract obtained from matcha by diethyl ether extraction reproduced its characteristic aroma. However, the aroma dissipated after concentration with a Snyder column at 45 ℃, indicating that the key odorants of matcha are as volatile as diethyl ether. This study characterized key low-boiling-point odorants in matcha by gas chromatography–olfactometry (GC-O) and GC–mass spectrometry (GC-MS) using solid-phase microextraction (SPME). Five odorants were identified by GC-O: methanethiol, dimethyl sulfide (DMS), 2-methylpropanal (2-MP), 3-methylbutanal (3-MB), and 2-methylbutanal (2-MB). The concentrations of these key odorants (except methanethiol) were determined by GC-MS using stable isotopes: DMS (2.92–17.5 mg·kg^-1), 2-MP (0.06–11.1 mg·kg^-1), 3-MB (0.44–5.26 mg·kg^-1), 2-MB (0.97–7.08 mg·kg^-1). These key odorants would be affected by heating during manufacturing.