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Yamasenishiki

Parents: Norin No.22 (seed parent) and Norin No.1 (pollen parent). Crossed in 1944. Bred by Niigata Prefectural Agricultural Experiment Station (cross) → MAF Fukui Experiment Station → Tohoku Agricultural Experiment Station.

Ou No.225 OOU0002250

Pedigree

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Norin No.22 → Koshihikari Norin No.1 → Koshihikari Norin No.8 → Norin No.22 Norin No.6 → Norin No.22 Moritawase → Norin No.1 Rikuu No.132 → Norin No.1 Ginbozu → Norin No.8 Asahi → Norin No.8 Joshu → Norin No.6 Sen'ichi → Norin No.6 Rikuu No.20 → Rikuu No.132 Kamenoo No.4 → Rikuu No.132 Aikoku → Rikuu No.20 Norin No.22 → Honenwase Norin No.1 → Honenwase Norin No.22 → Hatsunishiki Norin No.1 → Hatsunishiki Norin No.22 → Yamasenishiki Norin No.1 → Yamasenishiki Norin No.22 → Koshijiwase Norin No.1 → Koshijiwase Norin No.22 → Yo 44 Norin No.1 → Yo 44 Norin No.22 → Yo 45 Norin No.1 → Yo 45 Norin No.22 → Yo 46 Norin No.1 → Yo 46 Norin No.22 → Yo 47 Norin No.1 → Yo 47 Norin No.22 → Yo 48 Norin No.1 → Yo 48 Norin No.22 → Yo 49 Norin No.1 → Yo 49 Yamasenishiki Ou No.225 Norin No.22 Kinki No.34 Norin No.1 Hokuriku No.4 Moritawase Rikuu No.132 Rikuu No.20 Kamenoo No.4 Aikoku Norin No.8 Kinki No.15 Norin No.6 Kinki No.9 Joshu Sen'ichi Ginbozu Asahi Koshihikari Etsunan No.17 ・ 32.6% Honenwase Etsunan No.14 Hatsunishiki Ou No.224 Koshijiwase Sei 40 Yo 44 Yo 45 Yo 46 Yo 47 Yo 48 Yo 49
The diagram shows this variety's own parents and the line that connects it to Koshihikari. Among the descendants only the main varieties are drawn; the other parent of each cross, and every descendant not drawn here, are listed in full below. Faint boxes are unnamed breeding lines.

Parents

Siblings

  • Koshihikari Etsunan No.17
  • Honenwase Etsunan No.14
  • Hatsunishiki Ou No.224
  • Koshijiwase Sei 40
  • Yo 44 Yo 44
  • Yo 45 Yo 45
  • Yo 46 Yo 46
  • Yo 47 Yo 47
  • Yo 48 Yo 48
  • Yo 49 Yo 49

Descendants

Relations are counted along the shortest line of descent. The rows in the diagram follow the order of crosses, so a variety with more than one path down can sit lower in the diagram than its relation here suggests.

Sixteen years to fix

At the Ministry's designated paddy rice breeding trial site in the Niigata Prefectural Agricultural Experiment Station, an artificial cross was made in 1945 taking Norin No.22 as the mother and Norin No.1 as the father; from the F3 in 1948 it was bred at the Ministry's Fukui Agricultural Improvement Laboratory, and from the F5 in 1950 selection and fixing were carried out by line breeding in Cultivation Section One of the Ministry's Tohoku Agricultural Experiment Station.

From the F7 in 1952 it was distributed to the relevant prefectures under the line name Ou No.225 while regional suitability was examined; in 1961 it stands at F16.

A line from the same cross as Koshihikari. Crossed in 1945, and still "under examination" at F16 in 1961.

Hatsunishiki was at F8 in 1953. Out of one cross, one line was carried to the eighth generation and another to the sixteenth.

Ishikawa made it a certified variety in 1956 and promoted it to recommended variety in 1959 when the certified category was abolished. Hiroshima planned adoption from 1962.

Its siblings appear in the same document

The Ishikawa section of this document also gives the reasons for adopting Honenwase, Hatsunishiki and Koshijiwase.

"Koshijiwase" has stronger resistance than Norin No.1 to leaf and panicle blast, sclerotial disease and root rot, and has been adopted as a recommended variety for the wet and semi-wet paddies throughout the prefecture, and for the lagoon-shore districts, where Norin No.1 cannot secure panicle number, replacing Norin No.1 and Shin No.6 there.

One prefecture, sorting four lines from one cross by the land they suit. Honenwase for the dry fertile flats, Hatsunishiki along the hills, Koshijiwase for wet paddies.

Koshijiwase has no historical document of its own. What is known of its character is known because it is written here.

Why Ishikawa let go of Norin No.1

Norin No.1 increased sharply after being adopted as a recommended variety in 1932 and became Ishikawa's principal variety. However, traits such as (1) high temperature sensitivity, (2) large tillering capacity, (3) blast and sclerotial resistance that are not strong and (4) somewhat weak culm became obstacles to high yield under post-war heavy fertilisation, leaving harvests unstable.

The weaknesses are counted off with numbers. "Large tillering capacity" appears as a defect because under heavy fertiliser the stems multiply too far.

Ou No.225 is "somewhat low-tillering". On shallow-tilled, degraded and autumn-declining paddies it yields more through a higher proportion of effective stems. The reverse of the trait called a defect.

In Hiroshima it was taken to cover the quality and stem-maggot weakness of Ginga No.1, the leading early variety there. One line, adopted by two prefectures for two different reasons.

Sources disagree

Which parent of Koshihikari was the seed parent

The NARO historical document states in words that Norin No.22 was the seed parent and Norin No.1 the pollen parent. Niigata Prefecture, which bred the variety, states the reverse. The diagram follows the historical document; Niigata's account is recorded here. We call neither wrong.

The year of the cross

The NARO documents appear to reproduce the prefectures' original applications for recommended-variety status and give 1945 — and the documents for Honenwase, Hatsunishiki and Yamasenishiki, all from the same cross, give 1945 as well, four in agreement. Niigata's own account says the cross was made in 1944 and that the 1945 planting was skipped for lack of hands. We use 1944 and note the discrepancy.

How the seed parent of Norin No.1 is written

The two spellings appear in the same NARO database, in the pedigree field and in the historical document respectively. We use the pedigree field's spelling and list the other.

How Kamenoo No.4 is written

We follow the NARO database. The commonly seen spelling uses a katakana no; we prefer the spelling we can cite.

On naming

Variety names are proper nouns. We use a name in this language only where a published source for it can be cited; otherwise the Japanese name stands.

What we have not yet confirmed

We have not looked below the top twenty

The site covers the twenty most widely planted varieties of the 2024 crop and the varieties that connect them back to Koshihikari. Many descendants exist below that line; we have not yet verified them against primary sources.

The year Masshigura was crossed

Neither Aomori Prefecture's table of recommended-variety characteristics nor the NARO database gives the year Masshigura (Aokei No.138) was crossed. The cross itself, Ou No.341 / Yamagata No.40, and its adoption as a recommended variety in fiscal 2004 are confirmed from primary sources; the year of the cross is not. For the same reason we do not say which parent was the seed parent. On 8 October 2026 we went back to the breeder's own side. The Masshigura page in the variety database of the Aomori Prefectural Industrial Technology Research Center's Agriculture and Forestry Research Institute carries a heading reading “The origin of Masshigura” — with nothing under it. Of the institute's bulletins, only No.42 (2015) onward are online, and the issue that would hold the breeding report for Masshigura is not among them. So the year of the cross is absent from the breeder's own published material as well.

Sources

The source document is in Japanese.

  1. イネ品種データベース検索システム「越南17号（コシヒカリ）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-10
  2. イネ品種データベース検索システム 交配系譜図「越南17号」 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-10
  3. イネ品種データベース検索システム「北陸4号（水稲農林1号）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-10
  4. イネ品種データベース検索システム 交配系譜図「北陸4号」 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-10
  5. イネ品種データベース検索システム「北陸4号を親とする品種一覧」（全263行） — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01
  6. イネ品種データベース検索システム 交配系譜図「近畿34号（水稲農林22号）」 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01
  7. イネ品種データベース検索システム 交配系譜図「近畿15号（水稲農林8号）」 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-10
  8. イネ品種データベース検索システム 交配系譜図「近畿9号（水稲農林6号）」 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-10
  9. イネ品種データベース検索システム 交配系譜図「陸羽132号」 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-10
  10. イネ品種データベース検索システム 交配系譜図「陸羽20号」 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-10
  11. コシヒカリのエピソード1 〜交配から系統の育成まで〜 — Niigata Prefectural Government ・ primary source ・ accessed 2026-09-10
  12. 新潟コシヒカリの軌跡 〜誕生から定着に至るまで〜 — Niigata Prefectural Government ・ primary source ・ accessed 2026-09-10
  13. 戦後日本のイノベーション100選「コシヒカリ」経緯 — Japan Institute of Invention and Innovation ・ accessed 2026-09-10
  14. あきさかりの良さを引き出す栽培法 — Fukui Prefectural Government ・ primary source ・ accessed 2026-09-10
  15. ぎふクリーン農業／県産品種 ハツシモ — Gifu Prefectural Government ・ primary source ・ accessed 2026-09-11
  16. 水稲「あさひの夢」の奨励品種採用（研究成果情報） — National Agricultural Research Center, NARO ・ primary source ・ accessed 2026-09-11
  17. コシヒカリのエピソード2 〜奨励品種への採用から〜 — Niigata Prefectural Government ・ primary source ・ accessed 2026-09-10
  18. コシヒカリBLの導入のねらい — Niigata Prefectural Government ・ primary source ・ accessed 2026-09-10
  19. イネ品種データベース検索システム「近畿15号（水稲農林8号）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-16
  20. イネ品種データベース検索システム「近畿9号（水稲農林6号）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-09-16
  21. イネ品種データベース検索システム「越南14号（ホウネンワセ）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01
  22. イネ品種データベース検索システム「奥羽224号（ハツニシキ）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01
  23. イネ品種データベース検索システム「奥羽225号（ヤマセニシキ）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01
  24. イネ品種データベース検索システム「近畿34号を親とする品種一覧」（全167行） — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01
  25. イネ品種データベース検索システム 交配系譜図「生40（越路早生）」 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01
  26. イネ品種データベース検索システム「越南12号（ヤマコガネ）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01
  27. イネ品種データベース検索システム「山陰47号（ヤエホ）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01