RELATIONS OF GERMINATING SOY BEANS TO TEMPERATURE AND LENGTH OF INCUBATION TIME

Because much physiological study deals with plants that are secured from seeds, the conditions that prevail during the preliminary germination period constitute a very important part of such studies. Individual variability among the similar plants of an experimental series makes physiological experimentation very laborious, and presents one of the most difficult problems with respect to both technique and interpretation. Many recent experimenters have attempted to reduce variability through some sort of plant selection, and such selection usually begins with the seeds employed, -as when the seeds are chosen according to their genetic background and with reference to size, weight, color, etc. Young seedlings, just after germination, are commonly subjected to more or less rigorous selection according to size and general appearance, but especially according to apparent vigor. Such selection tends to restrict variability and furnishes experimental series of plants that are more nearly alike in their intrinsic physiological nature, as well as in their variability, than would be the case without selection. When young seedlings are selected for uniformity, the standard set of conditions that prevailed while germination was in progress becomes a basis for the selection. Consequently any advance in our knowledge of how specified lots of seed may be influenced in their germination performance by the environmental complex prevailing during the period of germination should be useful in the preparation of seedlings for experiments dealing with more advanced developmental phases. In this connection see GOODSPEED (11), CORRENS (5) , HAASIS (12), and TANG (36). Furthermore, a number of students (20) have presented evidence leading to the 1 Botanical contribution from the Johns Hopkins University, no. 118.