At what generation it was handed on

A historical document records what generation the variety stood at when the document was written — "in fiscal 1955 it is the tenth hybrid generation", and so on.

Gather those lines and one thing comes into view. Varieties were handed on before fixing was finished.

The national stations handed them on at F1 to F4

The national station that made the cross looked after only the early hybrid generations and passed the rest to a prefecture. The documents say at what generation.

Document	Generation handed on	Year
Wakasa, Yamahonami (Etsunan No.15, No.18)	F1	1947
Paddy Rice Norin No.6 (Kinki No.9)	F3	1928
Paddy Rice Norin No.50 (Tohoku No.50)	F3	1938
Paddy Rice Fujisaka No.4 (Fukei No.19)	F3	1942
Paddy Rice Toono No.2 (Enkei No.3)	F3	1935
Paddy Rice Aiko No.2 (A-kei No.3)	F3 → F4	1934 → 1935
Obakowase (Tohoku No.42)	F4	1937
Natsuminori (Tohoku No.58)	F3	1944
Chokai (Tohoku No.56)	F3	1945

There is even a case of handing on at F1. Wakasa and Yamahonami: the year after the cross, the F1 seed went to Izumo, and the year after that Fukui entered it in an "F2 individual-selection trial".

Paddy Rice Aiko No.2 is finer still: it went to the Miyagi Prefectural Agricultural Experiment Station at F3, and the next year, at the very founding of the Ayashi Testing Site, the F4 was transferred there.

So it is not only that the place that crosses and the place that selects are separate — the work of fixing itself was handed to the prefecture.

A line name does not mean fixing is over

Document	Line name: year and generation	Generation in the year of the document
Koshihikari (Etsunan No.17)	1953, F8	—
Yamaseshirazu (Tohoku No.63)	February 1954	fiscal 1958, F12
Chokai (Tohoku No.56)	1950	fiscal 1953, F11
Chiyohikari (Tokai No.6)	February 1954	fiscal 1956, 11th
Azusa (Hokuriku No.56)	1952	fiscal 1955, F10
Yamahonami (Etsunan No.18)	1953	fiscal 1959, F13
Wakasa (Etsunan No.15)	1952	fiscal 1961, F15
Wakakusa (Etsunan No.39)	1960	fiscal 1964, F11
Mutsukogane (Fukei No.62)	fiscal 1961	fiscal 1963, F12
Harukaze (Kanto No.74)	fiscal 1964	fiscal 1967, F13
Mineasahi (Chubu No.17)	1973	fiscal 1980, F14

A line name was given, the seed went out to the prefectures, and the generations went on advancing. The documents close with the formula "…distributed to confirm regional suitability, and in fiscal N it is the Mth hybrid generation." Handed out, and still being fixed.

And then segregation was found, after it had gone out

One document records exactly that. Mineasahi's.

Moreover, as segregation in heading date was seen in the first year of distribution, re-fixing was undertaken, and from 1975 it was supplied as a fixed line.

(The character for "heading" is broken in the original; it is listed at flaws in the sources.)

In the first year it went out, the heading date was found not to be uniform. So the fixing was done again, and from two years later it was supplied afresh as a fixed line.

Line-named and distributed in 1973, re-fixed in 1975, F14 in fiscal 1980. No passage states "handed on before fixing was finished" more plainly than this one.

The same cross, fixed at different generations

Of the eleven lines out of Koshihikari's own cross, the two that went to Tohoku were fixed far apart.

	Year	Generation
Hatsunishiki (Ou No.224)	1953	F8
Yamasenishiki (Ou No.225)	1961	F16

Out of one cross, selected in the same Tohoku — eight generations apart. The selectors judged "this is settled now" at different times.

Fast-forwarding the generations

Ways of shortening a twelve- or fifteen-year job are in the documents too.

Two generations a year in warm country — Nikisakae (Saikai No.75)

to shorten the breeding period, the F1 was raised at the station's Ibusuki Testing Site from that winter into the following spring

Ibusuki, in Kagoshima. A Kyushu station using the winter at its own warm testing site.

Sent across prefectural lines — Mutsukogane (Fukei No.62)

In the spring of 1956 the F3 seed was sent to the Rice Breeding Section of the Kagoshima Prefectural Agricultural Experiment Station, where over two years the generations were shortened by direct-sown bulk culture in the nursery bed, advancing from F3 to F6. In 1958 the F6 panicles were moved to the Fujisaka Testing Site

Aomori → Kagoshima → Aomori. F3 to F6 in two years. A variety for cold country, fast-forwarded in warm country and brought home.

Using a glasshouse — the same document

in the winter of the same year the F1 generation was shortened in a glasshouse

In the winter of the year of the cross, the F1 is already moving.

For contrast, a case with no fast-forwarding: Paddy Rice Norin No.19 was crossed in 1929 and named in April 1941. Twelve years.

What to keep in mind when reading

• "the Mth hybrid generation" is the generation in the year of that document, not the generation at which breeding finished
• A line name does not mean fixing is over
• This site does not hold generations as data. It only quotes, in the page text, the generation a document gives. The same variety stands at a different generation in a document of a different year, so reducing it to one figure would be a lie