REST PERIOD STUDIES WITH SEEDS 5 



growth even during the early part of their rest, while others are 

 very difficult to force during any stage of their dormancy, and a few 

 can not be forced at all until the rest period is at an end. These 

 tests were made with twigs twelve to sixteen inches long which were 

 cut from trees and shrubs and kept standing in vessels of water 

 after treatment. Later, forcing tests were made with many of the 

 same species which were growing in pots. 1 These tests confirmed 

 the fact of a rest period in practically all trees and shrubs of the 

 temperate zone, and also demonstrated that twigs may be used for 

 forcing tests and the results be just as reliable as where pot-grown 

 plants are employed. 



Additional rest period studies at this Agricultural Experiment 

 Station were made with bulbs and herebaceous perennial plants. 2 These 

 studies apparently proved that bulbs have a pronounced period of 

 rest. The resting phase of bulbs was found to be so strong that 

 they can not be aroused into growth by any of the treatments tried. 



PRELIMINARY EXPERIMENTS WITH SEEDS 



The first of the rest period studies with seeds was begun in the 

 spring of 1907. Several species of seeds, representing both wild and 

 cultivated forms, growing in the vicinity of Columbia were collected 

 and planted at different stages of maturity to find if they would 

 grow at once. 



The object in collecting immature seeds was to discover if 

 possible just when the resting phase begins. It has been assumed 

 that the rest does not set in until the seeds are mature. While this 

 conclusion seems logical and appears to be warranted, there seems to 

 be no experimental proof in support of such a conclusion. If seeds 

 are able to grow before they are mature and not immediately after- 

 ward, it seems safe to conclude that the rest begins at the time of 

 maturity. If seeds do not grow when immature and also do not 

 grow immediately after maturity, such results would neither prove 

 nor disprove when the rest period sets in. If they are able to grow 

 before maturity and will not grow afterward, this would indicate 

 that the rest period sets in with the conclusion of the ripening 

 process. The process of germination in its last analysis is nothing 

 more than the resumption of growth on the part of the embryo which 

 has been dormant for a time. The use of the term "germination," 



1. Howard, W. L., Rest Period Studies with Pot-Grown Woody Plants. 

 Research Bui. No. 16, Mo. Agr. Exp. Sta. 1915. 



2. Howard, W. L., Rest Period Studies with Bulbs and Herbaceous Peren- 

 nial Plants. Research Bui. No. 15, Mo. Agr. Exp. Sta. 1915. 



