GERMINATION OF BARLEY POLLEN 



By Stephen Anthony, formerly Assistant, and Harry V. Harlan, Agronomist in 

 Barley Investigations, Office of Cereal Investigations, Bureau of Plant Industry, United 

 States Department of Agriculture 



INTRODUCTION 



The artificial germination of plant pollens has met with varying suc- 

 cess. As a whole, the pollen of the Gramineae has proved very difficult 

 to germinate. While experiments with the pollen of many plants have 

 resulted not only in ready germination but in satisfactory methods of 

 preserving the pollen for considerable periods of time, the results with 

 many of the Gramineae have been far from satisfactory. This is espe- 

 cially true of self-fertilized forms, for many of which no artificial germi- 

 nation of pollen has been secured. The pollen of corn, on the other 

 hand, was germinated readily by Andronescu (i)} It is believed that 

 the pollen studies reported herein record the first artificial germination 

 of barley pollen. 



These studies grew out of a series of observations made by the junior 

 author on the lateral florets of 2 -row barley. The stamens of these 

 florets are sometimes abortive, sometimes rudimentary, and sometimes 

 well developed, producing abundant pollen. In an attempt to classify 

 these variations, the question naturally arose as to whether or not this 

 pollen was viable in all cases, and for such determination a reliable method 

 of artificial germination obviously was desirable. It was to fill this need 

 that the investigation was undertaken. The senior author was asso- 

 ciated in barley investigations at that time, and the original project was 

 intended to be a joint study. As it turned out, however, practically all 

 of the laboratory studies were made by the senior author, while the field 

 experiments were contributed by the junior author. 



REVIEW OF THE LITERATURE 



The volume of literature on the germination of pollen is so extensive 

 that mention of only those papers having a special significance in their 

 relation to the present studies will be included. These, for the most part, 

 are cited at specific points in the text. According to older views, pollen 

 fell into three classes: (i) pollen for which water alone was necessary for 

 germination, (2) pollen which required, besides water, a chemical stimu- 

 lant, (3) pollen which germinated in a solution of sugar of various 

 concentrations. Mohl (8) in 1834 germinated pollen in wat^r. Van 



1 Reference is made by number (italic) to ''Literature cited," p. S3S-536- 



Journal of Agricultural Research, Vol. XVIII, No. lo 



Washington, D. C. Feb. i6, 1920 



tq iS-^S) KeyNo. G-184 



