コルチヒン処理によって育成されたコモンベッチの倍数体

抄録

(1) In the gerrixinating seeds of a line of common vetch, studies were made in order to find the relation between the temperature and colchicine concentration inducing the chromosome doubling. Characteristics of induced autotetraploids were observed. (2) The temperature used were high (25'C), medium (16-17'C) and low (5-9'C), and the concentrations 0. 025% and 0. 05%The treatments w-ere made for 24 hours. (3) By the external appearance, the size of stomata and pollen grains of treated plants, the chromosome doubling was tentatively judged. It seems that the combination of suitably higher temperature and lower concentrat, ion was effective inducing the chromosome doubling. At higher temperature and higher concentration, a larger number of plants died. (4) In the next generation of plants treated and judged tentatively as 4 x, the 4 x strains and individrrals were determined. (5) Characteristics of 4 x, compared with those of 2x, are as follows. Il'he plant height, numbers of nodes and branches were almost the same or somewhat in:ferior. The leafiets show a deeper depression at the top and are rolled to some extent along the main vein. The flowering time was somewhat later, and the numbers of seed per pod were considerably smaller. The length and width of seed were larger but its thickness was rather smaller. (6) Chromosome numbers in root tips of 2x and 4x were 2n=12 and 2n=24 respectively. The chromosbme conjugation at Ist metaphase of PMC showed 6n in 2 x, while in 4 x there were observed most frequently 6rv, as well as other types of conjugation. In 4. x at ana-and telophases, the lagging chromosomes and in tetrad stage many polyads were found.