Yamakai

Yamakai is an open-pollinated seedling of Yabukita, trialled at the Shizuoka Prefectural Tea Experiment Station from 1949 and released to growers in 1967 — yet it has never carried a Cha Norin number or a Plant Variety Protection Act registration. What kept it out of the national registry was not quality but character: its aroma is strong, food-like and genuinely divisive, the kind of trait mid-century blenders had no use for in a cultivar meant to disappear into a uniform sencha blend. Decades later that same trait is exactly why single-cultivar producers seek it out. Shizuoka Prefecture never let it lapse either — it remains one of the prefecture’s recommended cultivars, and is sold today as sencha, fukamushi sencha, kabusecha and gyokuro, and, by a few specialist producers, even as kamairicha and black tea.

Lineage

• Yabukita (seed parent) — an open-pollinated seed taken from an existing Yabukita bush, not a controlled cross; the pollen parent was never recorded.

Yamakai is one of a small cohort of Yabukita-seedling selections carried through trials at the Shizuoka Prefectural Tea Experiment Station in the late 1960s under the internal breeding-line number Shizu-7166, alongside Suruga-wase (Shizu-7109), Kurasawa (Shizu-7111) and Fuji-midori (Shizu-7224) — plus a further line, Shizu-7132, which like Yamakai was never formally registered. Because each of these lines began as an unplanned open-pollination event on an existing Yabukita plant, none has a documented pollen parent. Two of the cohort did go on to found registered cultivars, though Yamakai itself is not recorded as having parented one: Kurasawa is the seed parent of Koshun (registered 2000, Kurasawa × Kanaya-midori), and the unnamed line Shizu-7132 is the seed parent of Tsuyuhikari (registered 2003, Shizu-7132 × Asatsuyu, crossed 1970).

History

The seedling that became Yamakai was taken into trial at the Shizuoka Prefectural Tea Experiment Station (now the Shizuoka Tea Research Center) in 1949. It was evaluated there for the better part of two decades before being named Yamakai and having its cultivation actively promoted across the prefecture in 1967 — the date this record uses as its public debut, though it corresponds to no national registration.

That absence is not an oversight. Japan’s first slate of nationally registered tea cultivars (茶農林, Cha Norin) was set in 1953 and has been added to steadily since; a full listing running from Cha Norin No. 1 through No. 52 (compiled in the reference table 附表1 茶農林登録品種一覧) contains no entry for Yamakai, and it is likewise absent from a separately compiled registry table of both Cha Norin and Plant Variety Protection Act cultivars. The Plant Variety Protection Act itself did not exist until 1978, more than a decade after Yamakai was already being planted commercially in Shizuoka; by the time tea varieties could be filed under it, Yamakai had long since been distributed to growers, which would have told against the novelty a Plant Variety Protection Act filing requires. So Yamakai holds neither registration — not because it was rejected, but because the two registries it might have entered were either the wrong shape for it or came too late.

What it does hold is prefectural recognition. Yamakai has its own entry in the Shizuoka Tea Industry Council’s “notable tea cultivar” guidebook, drawn from the same 『茶』 journal that is one of the better characteristics sources for Shizuoka cultivars generally, and it is named there among the prefecture’s recommended cultivars outside Yabukita. Commercial interest in it has never fully died: the Kagoshima Tea Experiment Station included Yamakai as one of thirteen major green-tea cultivars in a multi-year regional adaptability trial run at Mizobe, Aira district, from 1987, with comparative growth, frost-damage and yield data published across several instalments of 茶業研究報告 (Chagyo Kenkyu Hokoku, the Tea Research Journal) between 1989 and 1991 — evidence that even without a national number, breeders kept using it as a comparison point against Yabukita and other registered cultivars.

The Shizuoka Tea Industry Council’s leaflet on the cultivar settles both the kanji and the rationale: it writes the name 山峡 and explains it as a reference to the new shoots and the made tea both having a mountain-tea-like character. Secondary references wobble on each half — one Japanese site gives the kanji as 山狭, and an English-language reference attributes the name to the liquor’s colour resembling mountain-grown tea — but the prefectural source is the one the record follows.

Characteristics

Yamakai buds at the same time as Yabukita, which puts it in the medium (中生) band rather than early or late. Its cold resistance is rated medium, but that average conceals a specific weakness: in the Kagoshima regional trial, Yamakai was one of the cultivars that suffered conspicuously more frost damage than the group average, in company with Asahi and Uji-hikari, even though its own harvest timing was not markedly later than Yabukita’s. Disease resistance is mixed — weak against anthracnose and bacterial shoot blight, medium against blister blight and gray blight, and somewhat susceptible to the mulberry (white peach) scale insect. Mature leaves are deep green, slightly small and thin, with a diamond shape. Yield is rated やや多 — slightly higher than Yabukita — and it takes well to covered cultivation, which is a large part of why it has kept a following among kabusecha producers.

Made as sencha, the leaf rolls tightly to a good green colour and brews a clear green liquor with sweetness, umami and a refreshing finish; Japanese retailers note it performs particularly well in second and third flush, sometimes even outdoing Yabukita there. But the trait everyone comes back to is the aroma, and it is not a conventional green-tea aroma at all: English-language tasting notes describe something food-like — sour notes, mayonnaise, oil — while Japanese vendors reach for cured-ham-and-melon and roast-meat comparisons, and independent reviewers describe a gourmet raspberry-jam or red-fruit character depending on how it is roasted. Accounts agree this is polarising rather than universally pleasant, which is precisely the property that kept it out of uniform blends for decades and is now the reason single-cultivar sellers list it at all. Beyond straight sencha and fukamushi sencha, a few specialist producers also process it as kamairicha and even as black tea, chasing the same aromatic intensity through different routes.