Home Rice
Obakowase
Parents: Ou No.187 (seed parent) and Norin No.1 (pollen parent). Crossed in 1933. Bred by Ou Testing Site (cross) → Miyagi Prefectural Agricultural Experiment Station (selection).
Tohoku No.42 TOH0000420
Pedigree
Skip the diagram and read the listParents
-
Ou No.187 seed parent
Sources: イネ品種データベース検索システム「東北42号（オバコワセ）」品種来歴文書
-
Norin No.1 pollen parent
Hokuriku No.4 ・ High yielding with good grain quality and eating quality; susceptible to rice blast
Sources: イネ品種データベース検索システム「東北42号（オバコワセ）」品種来歴文書
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.
Crossed at Ou, raised in Miyagi
In 1933 an artificial cross was made at the Ou Testing Site of the Ministry of Agriculture and Forestry Agricultural Experiment Station, taking "Ou No.187" as the mother and "Paddy Rice Norin No.1" as the father; in 1937 the F4 seed was received by the Miyagi Prefectural Agricultural Experiment Station as test material for the Ministry's designated paddy rice breeding trial, and it has been selected and bred there since, distributed to the relevant prefectures under the line name "Tohoku No.42" from 1942 to confirm regional suitability.
The cross was made in 1933 at the Ou Testing Site; the father Paddy Rice Norin No.1. It moved to the Miyagi Prefectural Agricultural Experiment Station at the F4, and was selected there.
The place that makes the cross and the place that selects are separate. Norin No.1 itself was the same (crossed at the Rikuu Branch, fixed in Niigata). That division is how the eight-district system begun in fiscal 1927 worked.
Stronger than both of its ancestors
It ripens slightly earlier than Rikuu No.132, and its habit resembles Norin No.1. Culm and panicle are somewhat longer, panicle number somewhat lower, a skewed panicle-number type with a strong culm; its disease resistance is stronger than Norin No.1's and Rikuu No.132's.
The varieties compared with it are Norin No.1 and Rikuu No.132. Rikuu No.132 is Norin No.1's father, so it is being compared with both its father and its grandfather.
its disease resistance is stronger than Norin No.1's and Rikuu No.132's
Stronger than either. The page for Norin No.6 notes that Norin No.1 failed to inherit blast resistance from Rikuu No.132. In Obakowase it is back.
The grain is about midway between Norin No.1's and Rikuu No.132's, and of good quality.
Grain size midway too. It sits between its father and its grandfather.
Destined for northern Miyagi and Iwate
This line is thought suited to the flat fertile land of northern Miyagi Prefecture and the flat fertile land of Iwate Prefecture.
Akita Prefecture is "examining adoption as a recommended variety from fiscal 1953". Three prefectures appear, and every one of them is still "examining" or "thought".
Sources disagree
How the seed parent of Norin No.1 is written
- Moritawase, written 森多早生 — 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」
- Moritawase, written 森田早稲 — 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
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
- 亀の尾4号 — 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」
- 亀ノ尾4号 (the common spelling)
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.
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- イネ品種データベース検索システム「東北42号（オバコワセ）」品種来歴文書 — Institute of Crop Science, NARO ・ primary source ・ accessed 2026-10-01