432 Journal of Agricultural Research voi. xix, No.g 



EXPERIMENTAL METHODS AND MATERIAL 

 The first experiment by the present writer was a very elementary one 

 made in Minnesota in 191 1. It included yield only. Plants from which 

 the awns were clipped produced only 75 per cent of the yield of normal 

 plants. 



In this and the later experiments, sufficient spikes of the same age 

 were tagged on the same day. The method used was that described in 

 an earlier paper. ^ The awns on half the spikes were removed even with 

 the top of the upper most sheath as fast as they appeared. In clipping the 

 awns it was necessary to examine the heads each day for three or four days. 

 It is apparent that mechanical injuries might result from this opera- 

 tion which would affect the later growth of the spike. For this reason it 

 was thought desirable to trace the growth throughout the period from 

 flowering to maturity. The number tagged was sufficient for a sample 

 of two or three spikes per day from both the clipped and the normal 

 plants for a period of 30 days. In a preliminary experiment at Arlington 

 Farm, Va., in May, 1915, it was found that the taking of daily samples 

 was practicable. In July, 1915, a complete experiment was conducted 

 with the Manchuria barley at University Faim, St. Paul, Minn., and in 

 the summer of 191 6 a similar experiment was conducted at Aberdeen, 

 Idaho, with Hannchen barley, The weights, lengths, and diameters of 

 the kernels of the samples were obtained daily. The kernels were later 

 analyzed to determine the nitrogen and ash. The results from the two 

 varieties will be presented separately. 



EFFECT OF REMOVING THE AWNS FROM MANCHURIA BARLEY IN 



MINNESOTA 



The Manchuria is a 6-rowed variety of barley. It is awned, a vigorous 

 grower, and adapted to fairly humid climatic conditions. It cannot be 

 grown in the arid districts with success. The first sample at Minnesota 

 was taken on July i, 191 5; and samples were taken daily until August 7, 

 with the exception of five days. This was the only study conducted in 

 Minnesota. Table I shows the data obtained at St. Paul, Minn., in a 

 humid district, with the variety of barley best adapted to that district. 

 The samples taken in Minnesota differ from those taken at Aberdeen in 

 that they consist of a single spike each day. The weights and measure- 

 ments of the individual lateral and central kernels on one side of the 

 spike were taken under each of the headings "weight," "length," etc., 

 in Table I. The first column contains the weight and measurement of a 

 lateral kernel, the second contains those of the central kernel, and the 

 third contains those of the remaining lateral kernels at the same rachis 

 node. The kernels were studied in order from the base of the spike 

 upward. In the first line under each date are the data from the first 

 fertile florets at the base of the spike. In the second line are the observ^a- 

 tions on the florets at the node above. The last line contains the data 

 on the last fertile florets at the tip of the spike. 



1 Harlan, Harry V. daily development of kernels op hannchen barley from flowering 

 To maturity at ABERDEEN, IDAHO. In Jouf. A.gr. Research, v. 19, no. 9, p. 393-43°. 1920. 



