Meiryoku

Meiryoku is a medium-season sencha cultivar bred at the national tea research station in Kanaya, Shizuoka, and registered by the Ministry of Agriculture, Forestry and Fisheries in 1986 as Cha Norin No. 35. It was developed in the same programme, at the same station, that later produced Okumidori, Kanayamidori and Fushun, aimed at a cultivar that matched Yabukita’s timing and cup quality while improving on its two weakest points: anthracnose and ring blight resistance. It never displaced Yabukita commercially and shows up today mostly as a comparison variety in agronomic trials rather than on retail cultivar lists, but the breeding record behind it is unusually well documented for a cultivar of its size.

Lineage

• Yabukita ♀ (やぶきた) — the seed parent, contributing the mid-season timing and the cup profile Meiryoku was bred to match.
• Yamatomidori ♂ (やまとみどり, Cha Norin No. 10) — the pollen parent, a 1953-registered Nara Zairai selection.

Meiryoku is a controlled cross, not a landrace selection: both parents are themselves registered Cha Norin cultivars, crossed deliberately at the Tokai-Kinki Agricultural Experiment Station’s tea division in 1959. No cultivar bred from Meiryoku itself was found in the sources consulted.

Several reference sources — the Cha Norin registry table circulated by the retailer Minorien, and the Japanese Tea Sommelier’s master registry list — instead give the pollen parent as Z1, an unregistered breeding line rather than Yamatomidori. The peer-reviewed release paper, which reproduces the Ministry’s own 1986 registration dossier and gives a year-by-year breeding chronology, is unambiguous on Yamatomidori, and this record follows it (see conflicts in the frontmatter). Z1 is nonetheless worth naming, because it turns out to be a real and separately documented parent of two related cultivars from the same breeding programme, Fushun and Saeakari — see below.

History

The cross was made in 1959 at the Tokai-Kinki Agricultural Experiment Station’s tea division (the institution that later became the Tea Experiment Station and, still later, the National Research Institute of Tea), with the stated aim of breeding a high-quality, high-yielding, disease-resistant cultivar matched to Yabukita’s timing. Yabukita was the seed parent and Yamatomidori the pollen parent. A clonal line was selected from the resulting seedling population in 1965, and from 1967 it was carried under the strain number “Cha-hon F1NN52” through clonal comparison and trait evaluation trials. From 1977 it was retested at cooperating institutions under the strain name “Kanaya No. 6” (金谷6号), covering both regional adaptability and, specifically, resistance to frost-crack (laceration-type) winter injury.

It was named and registered by MAFF on 6 June 1986 as Meiryoku, Cha Norin No. 35. My Japanese Green Tea’s registry table separately lists a 1987 date under Japan’s old Seed and Seedling Law registered-cultivars list, distinct from the 1986 Agriculture and Forestry certified-cultivar registration — two different legal registrations rather than a factual disagreement between sources.

What Z1 was

Z1 was not a registered cultivar but a working breeding-line designation at the national tea research programme, bred from open-pollinated seed of Tamamidori (たまみどり, Cha Norin No. 4, itself a 1953 selection from Uji Zairai seedlings). It was already established enough by 1973 to be entered as a named comparison line — alongside Yabukita, Tamamidori, Beniifuji and roughly forty other registered cultivars and strains — in a cutting-rooting-ability trial run at the Makurazaki branch of the Tea Experiment Station, where it ranked at the top of the scale (10 out of 10) for ease of root strike. It was never itself registered, but it went on to become the seed parent of two later Cha Norin cultivars from the same breeding lineage: Fushun (Cha Norin No. 41, Z1 × Kanayamidori, crossed 1965 at Kanaya, registered 1991) and Saeakari (Cultivar No. 55, Z1 × Saemidori, crossed 1989 at Makurazaki, registered 2011/2012). Z1’s own parent, Tamamidori, is unrelated to either of Meiryoku’s real parents, so despite the shared station and the recurring appearance of “Z1” beside Meiryoku’s name in secondary sources, there is no documented lineage connection between Meiryoku and Z1’s descendants.

Later use in research

Meiryoku shows up repeatedly as a comparison cultivar in the decades after registration rather than as a commercial success in its own right. A 1992 sensory study set it against Yabukita and Okuyutaka in an open-day tasting with 129 visitors; Yabukita was preferred by the most tasters, followed by Okuyutaka, with Meiryoku third. A 1996 grafting trial used it as rootstock material and found that new-shoot development in the scion was shifted earlier when grafted onto Meiryoku roots, one of several rootstock-dependent effects the study recorded. A 2003 nitrogen-fertiliser trial run across Yabukita, Sayamakaori, Kanayamidori and Meiryoku found that Meiryoku held its new-shoot chemical composition better than the other three cultivars under reduced nitrogen application, pointing to a comparatively high tolerance for low-input cultivation. None of these studies describe wide commercial planting, and no English-language vendor or cultivar-guide page consulted for this record covers Meiryoku beyond a bare registry-table entry.

Characteristics

Meiryoku buds and is picked in almost the same window as Yabukita — the release paper places it as a medium-season cultivar with no meaningful timing gap, rather than giving a specific day offset. The tree grows upright and branches well, with a good bush spread. Mature leaves are long, narrow and oblong; the leaf colour is green with a faint yellow cast and less gloss than Yabukita. New shoots are somewhat slender with slightly thicker leaves, and the hundred-bud weight runs heavier than Yabukita’s. Cutting rooting is good and nursery propagation is straightforward, and the release paper describes vigorous, high-yielding growth through both the young-tree and mature stages, though no yield figure relative to Yabukita was found.

Disease resistance was the point of the cross. Anthracnose resistance is rated medium to somewhat strong, a clear improvement on Yabukita’s weak resistance, and resistance to ring blight (輪斑病) is rated strong, again markedly ahead of Yabukita. Cold hardiness overall is medium, but the cultivar is comparatively weak against frost-crack (laceration-type) winter injury specifically — the trait its later-stage trials from 1977 onward were designed to test. That anthracnose resistance did not prove absolute in practice: a later release paper for Saeakari (2011) notes that when Meiryoku was planted next to anthracnose-susceptible cultivars such as Sayamakaori and Okumidori, incidence on Meiryoku rose sharply, unlike Saeakari’s resistance, which held under the same conditions.

As sencha, Meiryoku’s quality is close to Yabukita’s: green in appearance, easy to shape, with aroma, liquor colour and taste rated roughly equal to Yabukita but with a fresher, more “refreshing” character. Chemically it runs higher than Yabukita in caffeine and total free amino acids and lower in tannin. It is recommended for warm-region cultivation — Tokai, Kinki, Shikoku and Kyushu — and, on the evidence available, has settled into a role as a well-characterised research and comparison cultivar rather than a cultivar many growers actually planted.