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JOIMALOFAGElirniAlRESEARCH 



Vol. XIX Washington, D. C, August 2, 1920 No. 9 



DAILY DEVELOPMENT OF KERNELS OF HANNCHEN 

 BARLEY FROM FLOWERING TO MATURITY AT ABER- 

 DEEN, IDAHO 1 



By Harry V. Harlan 



Agronomist in Charge of Barley Investigations, Office of Cereal Investigations, Bureau 

 0/ Plant Industry, United States Department of Agriculture 



INTRODUCTION 



Several years ago the author made a few elementary experiments on the 

 function of the awn in barley. In these studies the awns were cHpped 

 from some spikes and not from others. The effect on the development 

 of the kernels was so striking that in 191 5 a more elaborate experi- 

 ment was carried out by the author and Stephen Anthony. The develop- 

 ment of kernels on normal and clipped spikes was determined from 

 flowering to maturity. The method of study proved so satisfactory 

 that it led to other investigations in which it offered the same possibility 

 of application. The development of barley on dry land and on irrigated 

 land, the response to irrigation water, and the differences in varietal 

 behavior have all been studied by this means. The last study has been 

 undertaken since the resignation of Mr. Anthony. In these studies, 

 kernel growth has been used as an index of effect. Yield and size of 

 mature kernels, while probably a safe summary of the effects of varia- 

 tions of treatment or differences of types, do not throw much light on 

 the time when the effect occurred, or always on the reasons therefor. 

 This group of studies has been carried on with the idea that variations 

 from a basic growth curve showing the inception, duration, and degree 

 of response would be much more illuminating than the single observation 

 of the final result. 



A number of studies have been completed, and it is the intention to 

 publish the results of the special projects from time to time. The 

 results represent a normal growth curve. It is intended that this curve 

 shall form the basis of comparison in the later studies and that it shall 



1 These studies were made on the Aberdeen Substation, Aberdeen, Idaho, in connection with cereal 

 experiments conducted cooperatively by the Idaho Agricultural Experiment Station and the Office of 

 Cereal Investigations, Bureau of Plant Industry, United States Department of Agriculture. 



Journal of Agricultural Research, Vol. XIX, No. 9 



Washington, D. C. Aug. a. 1930 



«a Key No. G-199 



(393) 



