Effects of temperature on spermatophyte male meiosis

摘要

Eleven forest tree species have been studied in order to investigate the duration of the diakinesis — telophase II phases of meiosis and to gather information on the sensitivity of the PMC's to extreme temperatures. The duration of meiosis was studied under natural conditions for 9 trees, and in laboratory experiments for 2 trees. Different methods for studying the duration of meiosis are compared and criticized. The planning of the experiments is discussed in relation to the reliability of the results.On the evidence of the material to be presented, the meiosis of Populus tremula proceeds faster than that of any other species studied. The idea that any phases of meiosis are proportional in duration in different spermatophyte species should be discarded. It is shown, at least for conifers, that the relative duration of some phases of meiosis is different from that for well-known cereals.Meiotic disturbances caused by very low temperatures will lead to permanent damage. There is no basis for the idea that this type of meiotic irregularity can heal. Evidence is presented of mass degeneration of PMC's under unfavourable conditions.