1959 Volume 28 Issue 2 Pages 139-142
The induced autotetraploid (2n=48) rose campions (Lychnis coronaria DESR.) are vigorous usually with thicker stems, thicker leaves and larger flowers than the ordinary diploids, although they grow -very slowly at the rosette young stage in winter and then begin to bloom later for several days than the latter. The petals are so large and thick, even though the size of flowers in a plant fluctuates in wide range, that they do not wilt so soon as the diploids when they are cut for decoration. By nature, rose campions begin to shoot the long stems with flowers firstly on the second early summer season after sowing. And it is ascertained clearly that their pollen and seed fertility are much influ-enced or changed by environmental factors, espe-cially “temperature”, during their flowering season. The ordinary diploid plants are easily capable of producing a plenty of fertile pollen and seeds in the condition of wide range of environmental tempera-tures. On the other hand, the autotetraploids prefer to the narrower, cooler temperature range for pro-ducing good pollen and fertile seeds than the former usually. For example, the former is possible to increase pollen and seed fertility sufficiently in the wide range of 20_??_28°C, signed with the maximum point of a day temperature at Utsunomiya; and the latter, on the contrary, necessitates the narrow range 23_??_26°C. The causes of such a peculiar phenomenon, of which the autotetraploids are distin-guished clearly from the diploids regard to reproduc-tive-physiological properties, will be explained generally by assumption of the presence of modifying minor genes for fertility. These genes are considered to be much sensible for environmental temperature but are latent or inactive in the ordinary di-ploids properly and, firstly when they are duplicated by chromosomal doubling, they will come into force to modify or tighten the optimum temperature range for increasing fertility, resulting the special adaptation of autotetraploids for the same climatic conditions as those of the regions where their an-cestral plants were grown up. Then the autotetra-ploid rose campion is regarded as one of the typical “cool-loving” species for fertility which are originated from the mild climatic temperate zone such as the South European districts.
