晩抽系菜類の採種と逆淘汰に就いて

Abstract

1. An experiment was conducted concerning the degeneration of seeds caused by careless management, using Hikoshima Haruna as an example of slow-bolting Chinese cabbage.2. If the seed was sown too early, the plants grew fairly large, became somewhat insensitive to the low temperature which is a factor for seed stalk development and became susceptible to cold and diseases, resulting in a small harvest of seeds. If the sowing was done too late, seed stalks developed when the plants were young, and seed production was also decreased.3. The proper time for sowing Hikoshima-Haruna for seed production was Nov. 9th in 1949 for a warm winter, and Oct. 25th in 1950 for a cold winter, both about 10 days later than that of Nagasaki Chinese cabbage, an early variety used as a check.4. Considering the results of low temperature treatments it seems that Hikoshima-Haruna is more insensitive to low temperature, so that the flower bud differentiation was delayed longer and the leaves by that time were more profuse than those of the check variety.5. Weighing the seeds produced per plant, it was recognized that the earlier the seed stalk development and flowering the, greater the seed production. However, such seeds were subject to degeneration due to improper development. This relation became obscure when the sowing was properly delayed.6. A progeny test was conducted to know the bolting character of such plants by using seeds which were obtained from self-pollinated and intra-pollinated plants. It was ascertained that seeds obtained from early bolting mother plants produced early bolting crops, and that inbreeding also brought about bad harvest.7. From the experiments, it is concluded; (1) in stock seed production, the mother plants must be grown in heavy clay soils with precise care, and must be selected respecting to slow-bolting character; (2) in the case of commercial seed production, the sowing should be delayed properly and early bolting plants must be eliminated, to prevent the degeneration of seed as far as possible, thus enabling the production of high quality seeds in large quantities and at inexpensive cost which are the most importantfactors in seed production.