Mie Ryokuho No. 1

Mie Ryokuho No. 1 (みえ緑萌1号) is a late-budding sencha and kabusecha cultivar bred in Mie Prefecture from an open-pollinated Yabukita seedling and registered in 1996. It exists because a prefecture whose fields are mostly Yabukita has its harvest and processing bunched into a narrow early-to-mid-season window, with little to fall back on for spreading the load or dodging late frost at picking time — and Mie’s breeders had few good late-budding lines to offer as an alternative. It buds five to seven days after Yabukita depending on location, and unlike many late cultivars bred with sencha alone in mind, it was explicitly trialled and released for kabusecha too. That dual billing fits its home prefecture: Mie is Japan’s third-largest tea-producing prefecture and the historic home of kabusecha cultivation. It carries no 茶農林 (Cha Norin) number — its only registration is under the Plant Variety Protection Act.

Lineage

• Yabukita ♀ — the seed parent. Mie Ryokuho No. 1 is an open-pollinated (natural-cross) seedling raised from Yabukita seed at the Mie Prefecture Agricultural Experiment Station’s tea branch, not a controlled cross, so its pollen parent was never recorded.

Like Sayamakaori and dozens of other prefectural releases from this period, this sits one step removed from a landrace selection: one parent, Yabukita, is documented, and the other is whatever pollen reached the flower in a nursery of Yabukita seedlings around 1960. No cultivars bred from Mie Ryokuho No. 1 turned up in the sources consulted, and it does not appear to have been used elsewhere as a breeding parent — its reach stayed within Mie.

It is worth naming alongside a separate, unrelated Mie cultivar that shares its naming pattern: Mie-uejima (みえうえじま／三重上島, Registration No. 11368, registered 2003). Mie-uejima is not a Yabukita seedling at all but a landrace (zairai) selection, picked out on a private grower’s own field in Ōdai-chō starting in 1985 by the breeder Uejima Chikashi (上嶋親), and it buds early rather than late. The two cultivars share nothing beyond a prefecture and a naming convention — easy to conflate on the strength of the name alone, genetically unconnected in fact.

History

Selection and trials

In 1960 (Showa 35), researchers at the Mie Prefecture Agricultural Experiment Station’s tea branch (三重県農業試験場茶業分場), in Kameyama, grew out open-pollinated seedlings raised from Yabukita seed and picked one out for further work. Individual-tree selection ran from 1971 to 1973 (Showa 46–48), and the line moved into selected-tree determination trials from 1974 (Showa 49). Regional adaptability trials for sencha use began in 1980 (Showa 55) at the Nansei tea trial site’s field in Ōdai-chō, Taki-gun (多気郡大台町) — coincidentally the same district where the unrelated cultivar Mie-uejima would later be selected, on a grower’s own field, a few years afterward. From 1983 (Showa 58) the trials were extended to test suitability for kabusecha specifically, reflecting Mie’s position as a major kabusecha-producing prefecture.

Registration

An application for registration under the Plant Variety Protection Act (種苗法) was filed on 8 March 1994 (Application No. 6649), and the cultivar was formally registered on 18 March 1996 (Heisei 8) as Registration No. 4954, with Mie Prefecture itself as the registrant. Four breeders are named on the registration: Ikeda Toshihisa (池田敏久), Tachibana Naoaki (橘尚明), Otani Kazuya (大谷一哉) and Yoshida Motojo (吉田元丈); the underlying research, credited to the first three, was published the same year as “チャ新品種「みえ緑萌1号」の育成” (Breeding of the new tea cultivar ‘Mie Ryokuho No. 1’) in the Mie Prefecture Agricultural Technology Center’s research bulletin, issue 24.

It never received a 茶農林 (Cha Norin) number. Checking MAFF’s own registry table of Cha Norin cultivars (附表１茶農林登録品種一覧 — numbers 1 through 52, spanning registrations from 1953 into the early 2000s) confirms Mie Ryokuho No. 1 is absent from it. That was a choice rather than a closed door: the same table shows prefectural programmes still taking Cha Norin numbers on either side of this registration — Saitama’s Musashikaori as 茶農林46号 in 1997, its Sainomidori as 茶農林50号 in 2003 — and Mie registered under the Plant Variety Protection Act instead.

Characteristics

Mie Ryokuho No. 1 is a late-budding cultivar. Compared with Yabukita, budding and harvest both come about five days later at the Kameyama trial site, and seven days later for budding, six for harvest, at Yokkaichi — the gap widening somewhat in the kabusecha-growing coastal districts. Growth habit is intermediate, vigour is strong, lateral spread is good, and early growth after planting is described as good. Young trees already outyield young Yabukita plantings — 117, 315 and 216 kg/10a in the fifth, sixth and seventh years after planting, against Yabukita’s 83, 172 and 142 — and the advantage holds in mature gardens: a sencha garden at Kameyama returned 407 kg/10a on the first flush and 375 kg/10a on the second, against Yabukita’s 304 and 288, while a kabusecha garden at Yokkaichi returned 510 and 577 kg/10a against Yabukita’s 476 and 349, the second-flush kabusecha figure in particular a wide margin.

Cold hardiness is rated as equivalent to Yabukita’s. Disease resistance is where it pulls ahead: the registration record rates it strong against red blight (赤枯病), moderately strong against split-bark-type frost damage and ring spot disease (輪斑病), and average against anthracnose (炭そ病) and mochi disease, while the prefecture’s own side-by-side trial specifically credits it with better anthracnose and ring spot resistance than Yabukita — a useful edge, given how vulnerable Yabukita itself is to both.

The cup is the main selling point. Aracha quality scores from the release trials put it ahead of Yabukita on every measure for both processing styles, with the widest margins in colour and aroma: as sencha (scored out of 100) it took 93.3 against Yabukita’s 91.1; as kabusecha (scored out of 50) it took 48.4 against 45.6. New leaf runs a somewhat deeper green than Yabukita’s, though slightly smaller and a little less glossy, which likely accounts for the colour advantage. Both the release literature and the independent reference 日本茶備忘録 single it out as particularly well suited to kabusecha on top of its baseline competence as sencha — an unusual dual billing, since most late-budding cultivars are optimised for one or the other, not both.

Outside Mie it is essentially undocumented. It has no page on Shinkoju’s roughly 80-cultivar single-origin shop reference — the predictable URL for it returns a 404, unlike its neighbour Mie-uejima, which does have one — and myjapanesegreentea.com’s cultivar registry lists it by name and registration year only, with no dedicated entry. That fits a cultivar bred to solve a specifically Mie problem — spreading Yabukita’s harvest load and shoring up disease resistance in a shade-tea district — and one that appears to have stayed there.