I. Research Notes

Spring wheats under the conditions of their old home, Sapporo, after their fifty year culture in Kyoto as winter crop

H. KIHARA

Kihara Institute tor Biological Research, Misima, Japan

Introduction

It is generally considered that the spring and winter habits of wheats are genetically determined. If the habits are really of genetical, they should not be changed unless a mutation occurs in the gene locus controling the habits. Neverthless, there are some reports which argue the presence of the habit shifts (for example, GLOUSCHCHENKO, I.E., WIS 41-42, 1976).

I have been continuously using those spring wheats as my research materials since I moved from Sapporo to Kyoto. Although those materials were grown as spring wheats in Sapporo before I actually began my research work in Kyoto, they have been grown wheats thereafter. This switch-over was done because the flowering as winter time of them meets with the rainy season, "tsuyu", in Kyoto, if grown as spring wheats.

Since then half a century has passed, and it seemed to be a good timing to test whether or not this duration was long enough to alter their genetical spring habit to the adapted winter habit. To substantialize this idea, the seeds of the above mentioned species of wheats of the Kyoto strains were recently sown in Sapporo to check any alteration in their original spring habit.

Material and Method

All the strains of the following five species of wheats are originally spring wheats from Sapporo. They have been grown as winter wheats in Kyoto and inbred since 1926.

For the control, the same five species which were inbred in Sapporo during the past 50 years by growing as spring wheats, were used. As the control for winter wheat, an American winter wheat variety "Gaines" which has been grown in Misima was used to see the response to spring growing in Sapporo.

All the above materials were sown at the Hokkaido University in Sapporo in heat sterilized soil on April 4, 1976, and the seedlings were planted in rows there on April 21.

Results and Discussion

1. Shooting:

Except a strain, "Gaines", all the tested strains normally grew and shooted ears. There was also no difference in the mode of ear development between the test strains and the control strains. "Gaines", which requires vernalization as a winter wheat, stayed in rosette form in this spring sowing test.

2. Pollen fertilities and seed fertilities:

The pollen and seed fertilities of the five species used in the present test could be compared between the conditions of Sapporo and Kyoto where they were grown as winter wheats. Table 1 shows the results obtained in Sapporo through the present test and the results obtained in Misima, grown as winter wheats.

From the comparison of the results, it is understood that the five species once adapted to winter sowing in Kyoto and Misima showed their original habit when switched back to Sapporo, their old home.

3. Discussion:

It has been revealed from the observations on ear differentiations that the autumn sowing for 50 years in Kyoto did not alter their habit of tested five species of wheat, from the original "spring" to the adapted "winter". Namely, the Kyoto strains of the five species differentiated their ears normally under the spring sowing condition in Sapporo, while the proper winter strain, "Gaines", stayed in rosette form under the same condition.

The combination of the subjects described above may justify to consider that a 50 year treatment of our spring wheats with successive winter growing and associated inbreedings did not alter the habit of those strains. Although half a century would not be long in the sense of evolutional chronology, the present experiment may support the concept that adaptation can not change any genes, but only mutations can do.

Literature Cited

GLOUSHCHENKO, I.E. 1976. Persistent modifications and their genetic importance for spring wheat breeding, Parts I, II and III., WIS No. 41-42

(Received Feb. 10, 1976)