Chokai

A half sibling and an uncle at once

In 1942 at the Ou Testing Site of the Ministry of Agriculture and Forestry Agricultural Experiment Station an artificial cross was made taking "Paddy Rice Norin No.22" as the mother and "Rikuu No.132" as the father

The mother is Norin No.22 — Koshihikari's mother. The father is Rikuu No.132 — Paddy Rice Norin No.1's father, and so Koshihikari's paternal grandfather.

Rikuu No.132 × Moritawase → Norin No.1
Norin No.22 × Norin No.1  → Koshihikari
Norin No.22 × Rikuu No.132 → Tohoku No.56 (Chokai)

Sharing a mother with Koshihikari makes it a half sibling. Being a child of Rikuu No.132 also makes it Norin No.1's half sibling — so from Koshihikari's side, an uncle or aunt.

The same shape appears in Tonewase (Kanto No.41): a child of Norin No.8 (Koshihikari's maternal grandmother) and Norin No.1, half sibling and aunt together.

This time it happens on the father's side. Keep crossing within a narrow pedigree and one relationship comes to carry two names.

Blast chose the variety

In Akita Prefecture, mid-maturing varieties such as Norin No.17 (19,400 chō), Rikuu No.132 (8,500 chō), Shinko No.190 (12,300 chō) and Okunikuwase No.5 (13,700 chō) make up the bulk of cultivation, but blast resistance that is middling or somewhat weak is a fault common to these varieties.

The prefecture's planting at the time is laid out in chō. Norin No.17 at 19,400, Okuniku- wase No.5 at 13,700, Shinko No.190 at 12,300, Rikuu No.132 at 8,500. More than fifty thousand chō sharing the same weakness.

In 1952 blast was prevalent and the damage heavy in the north of the prefecture, and in the on-site trials conducted in that district the safety of Tohoku No.56 was confirmed.

Confirmed in the year the disease came, in the place it came to. Not a trial designed to test it — a disaster that served as the trial.

In this prefecture's rice growing, where blast always demands vigilance, it is judged a variety able to answer the farmers' wishes.

Grain quality somewhat poorer

Tohoku No.56 is a mid-maturing non-glutinous variety ripening a little earlier than Rikuu No.132 … the grain is medium and the grain quality somewhat poorer. Blast resistance is strong and there is considerable cold tolerance. Yields are high too, but the culm being somewhat weak it has the fault of lodging under heavy fertiliser and the like.

Grain quality somewhat poorer. Written down, and adopted anyway.

Strong against blast, cold-tolerant, high-yielding. Poorer in grain quality and in lodging. Which to take was decided this way in Akita in 1953.