Cytological studies on the interspecific hybrids, Solanum tuberosum L. ×S. sp. Tayama-shu, and their applications to the breeding.

[摘要] 1) Cytological observations were carried out on the triploid hybrids obtained from the cross, tetraploid Solanum tuberosum var. Irish-Cobbler × diploid S. sp. Tayama-shu (this species is assumed to be S. geniocalyx or S. stenotomum), and their parents. 2) In the species Tayama-shu, 12II were arranged regularly in the equatorial plane at MI, and thereafter the chromosome behaviours preceeded normally. 3) In S. tuberosum L. var. Irish Cobbler 24I were arranged regularly at the Metaphase of the heterotypic division, as these situation have been recognized also in the division of other varieties of S. tuberosum exhibiting some irregularities in meiosis. In addition to this, from one to two quadrivalents or from one to three trivalents were often met with, and in the second division the fusion of both nuclear plates occurred in high frequency, resulting the formation of corresponding number of dyads together with tetrads. 4) At the Metaphase of the heterotypic division in F1 hybrids the chromosome configuration of (5-12)III + (0-8)II +(0-6)I were observed, and the average value of tri-, bi- and uni-valent chromosomes per cell calculated from about 40 cells and their standard deviation were 8.25±1.70, 3.18±2.05, and 3.18±1.46 respectively. At the beginning of homotypic division both apindles of all cells approached nearly, fused with each other. At Metaphase, they formed a single nuclear plate, divided equationally, thus resulting the formation of dyads instead of tetrads. 5) Supposed that they have the ability of fertilization, the dyads formed by such behaviours in meiosis will make the induction of polyploidal progenies possible.

[学科分类] 农业科学（综合）