Physiological-genetical studies on seed germination

Abstract

Earlier work on germination has always taken an extended view of the process of germination, The process was regarded as commencing when tine mature dry seed is subjected to suitable conditions and ending when the young seedling appeared. In most of the earlier work the appearance of the seedling, was taken in the soil and this of course also included establishment of the plantlet.It is clear that the greater part of the process discussed in these researches includes growth purely and not germination in a stricter sense. Work in this laboratory has tended to narrow the definition and regard germination as taking place in three overlapping stages with a comparatively smooth progression from the dry seed to the activated embryo. In the order of their appearance the three stages may be said to be (Nelson and Macsween 1933):-a) Hydration of the colloids of the tests of the seed;b) Water intake by an osmotic mechanism through the hydrated tests which acts as a semipermeable membrane;c) "Vital" reactions involving energy release, and movement and reorganisation of plastic materials - more crudely respiration and growth.