Sofu

Sofu is a Shizuoka cross bred to put an aroma into Japanese tea that no domestic cultivar had carried before: a sweet, jasmine-like floral note traceable to a single gene from its Indian-hybrid pollen parent. Crossed at the national tea research station in Kanaya using Yabukita as the seed parent and Shizu-Inzatsu 131 — itself descended from Assam stock — as the pollen parent, it was selected in 1977, named and filed for registration in 2002, and formally registered under the Plant Variety Protection Act in 2005. It is grown almost entirely for that aroma, in modest sencha and semi-fermented (oolong-style) lots out of Shizuoka’s Honyama and Kawane districts, rather than as a volume crop.

Lineage

• Yabukita ♀ — the standard Shizuoka cultivar, contributing the reliable vegetal base and general growing habit that most Yabukita crosses are bred to keep.
• Shizu-Inzatsu 131 ♂ (静印雑131) — an unregistered breeding line selected around 1944 from a seedling of “Manipur No. 5,” an Assam-type tea tree grown from seed brought back from India in the 1920s by Maruo Fumio, at the Shizuoka tea experiment station, where its development is credited to Arima Toshiharu. It never received a 茶農林 number of its own — the registration system did not exist until 1953 — but it is the parent that gives Sofu, and Fujikaori, their defining floral aroma.

Sofu is a controlled cross, not a landrace selection: both parents are documented, and the cross was made deliberately to move an assamica-type aroma trait into a sinensis-type garden plant. Fujikaori is the reciprocal cross of the same two parents — Shizu-Inzatsu 131 as the seed parent, Yabukita as the pollen parent — and shares the aroma trait; at least one further Inzatsu-131-line cultivar, Kondowase, is reported to carry it too, though that claim rests on a single source and is not independently confirmed here. No cultivar bred from Sofu itself is documented.

History

Selection at Kanaya

The cross of Yabukita and Shizu-Inzatsu 131 was made at the Tea Experiment Station’s cultivation department in Kanaya, Shizuoka (from 2001 part of the National Institute of Vegetable and Tea Science, now NARO’s Institute of Fruit Tree and Tea Science). An individual from that cross was selected in 1977 — though NARO’s own sources use that year differently, the variety database calling it the year the line was selected and the pedigree chart in its cultivar handbook labelling it the year of the cross, so the two are not stated separately here. The line was carried afterward under the working strain name Kanaya No. 21 (金谷21号).

Naming and registration

The strain was named Sofu (蒼風) and assigned the sequence number 茶農林49号 (Cha Norin No. 49) in 2002, the same year its Plant Variety Protection Act application (No. 14905) was filed, on 1 August 2002. The application was granted on 7 February 2005 as registration No. 12706. Sources disagree on which of these dates to call “registered” — see conflicts above; this record follows NARO’s own variety database and uses 2005.

The name is written with 蒼 (sō), a deep blue-green — the colour of indigo or new foliage — and 風 (fū), wind: “a clear wind,” chosen, by NARO’s own account, for the tea’s bright liquor colour and the cool sweep of its aroma.

The methyl anthranilate discovery

In 2004, Sawai, Yamaguchi and Tanaka, working out of the Kanaya and Makurazaki tea research stations, published gas-chromatography work in the Japan Agricultural Research Quarterly identifying the compound behind Sofu’s aroma: methyl anthranilate (methyl 2-aminobenzoate, C₈H₉NO₂), a grape- and jasmine-adjacent ester that had not previously turned up in any Japanese tea cultivar. It was present in Shizu-Inzatsu 131 and in Fujikaori as well, and the paper traced its origin to var. assamica. A follow-up NARO study mapped the trait to a single locus, provisionally named Mat, close to the RAPD marker TRWO-03S (genetic distance approximately 2.1 cM); it segregated cleanly 1:1 in an F1 population from the Yabukita × Shizu-Inzatsu 131 cross, consistent with simple dominant inheritance from the Inzatsu parent.

This is a different aroma route from the terpene alcohols — linalool and geraniol — that produce the muscat and rose notes typical of oxidised Japanese teas, black tea and most oolong-style cultivars generally. No source consulted here reports elevated linalool or geraniol in Sofu specifically; its floral character is instead credited squarely to methyl anthranilate.

Characteristics

Sofu is early-budding: NARO’s own cultivar entry gives it 6 days ahead of Yabukita to bud and about 4 days ahead to first-flush harvest in warm-region trials, and its cultivar handbook gives the plucking date as 4–7 days ahead. Because it is early, NARO recommends it only for warm districts with little risk of late frost — and its frost tolerance does not help matters. Resistance to blue-wilt frost injury (青枯) and split-bark frost injury (裂傷型凍害) is rated weaker than Yabukita, though resistance to red-wilt frost injury (赤枯) is on a par with it. That combination — an early flush pushed into the frost-prone window, on a plant that tolerates frost damage worse than the crop it was bred from — is the cultivar’s clearest agronomic weakness.

Disease resistance is mixed: strong against ring spot disease (輪斑病, Pestalotiopsis longiseta), moderately strong against anthracnose and red leaf blight (both better than Yabukita), medium against mochi disease, and weak against bacterial shoot blight (赤焼病). The tree habit is slightly open and spreading, and cuttings root well. Yield in mature plantings is reported comparable to Yabukita, though at least one grower account describes young bushes as slower to bush out, throwing fewer new shoots with heavier individual buds.

The cup is where Sofu earns its niche. Green tea from it carries a sweet, floral aroma with no real precedent among Japanese cultivars at the time of its release, though NARO’s own quality notes concede a somewhat strong astringency in the green-tea form. Growers who have made single-cultivar lots describe it in two stages — a young-leaf, sencha-like freshness up front, then a floral, muscat-and-citrus lift that follows, sometimes read as jasmine, sometimes as white flowers, occasionally with a cooling, menthol-like edge. It does not take deep steaming (fukamushi) well — the aroma is reported to fade under it — so it is generally processed as a normal or lightly steamed sencha, or pan-fired (kamairicha). NARO’s own recommendation is to keep the first flush as green tea and push the more astringent summer flush into semi-fermented (oolong-style) processing, where the aroma is reported at its strongest. Despite official recommended-cultivar status in Shizuoka since 2005, growers describe commercial planting as still minimal two decades on: Sofu persists mainly as small single-origin lots out of districts such as Ashikubo, Kawane, Tamakawa and Fuji rather than as an established block planting.