RESULTS OF SELECTION WITH SELF-FERTILIZED CROPS 127 



characters of the stems of cereals has been carried out at the 

 Minnesota Station (Garber and Olson, 1919). Number of fibro- 

 vascular bundles, area of sclerenchyma cells in the cortex and 

 bundle and other characters were studied in relation to lodging. 

 Stiffness and thickness of wall of the sclerenchyma seemed to be 

 associated in oats but no such relation was found in wheat and 

 barley. No other instance of a close association between any 

 one of the characters studied and lodging was obtained. 



Some correlations are of value in selection or in obtaining 

 accurate data. Thus, if one desires to classify a number of 

 selections according to comparative maturity, reliable results 

 may often be obtained by taking such notes as date of awn emer- 

 gence in barley and date of heading in wheat and oats. In years 

 favorable for normal development, a high correlation between 

 date of heading and maturity has been obtained. In unfavorable 

 years, date of heading is a more reliable indication of the inherited 

 differences between strains in relation to their normal period 

 of maturity than a note taken at maturity. 



In general, it seems safe to conclude that no one character 

 is closely enough associated with yield to be of selection value 

 in picking out the highest yielding strain. It is possible, how- 

 ever, in many crops to weed out the very undesirable plants by 

 inspection. The yield test must then be used to determine the 

 better pure lines. This seems reasonable when we realize that 

 yield is the final result of many growth characters. A strain which 

 excels in all characters, such as stooling, disease resistance, size of 

 seed, size of head, fertility, etc., naturally will be a high yielder. 

 As so many characters of which the above are only a few of the 

 more easily seen are essential to high yield, no single botanical 

 character is of great selection value. This has led to the present 

 method which is summarized as follows by Newman (1912): 



"Thus instead of basing the isolation of superior individuals purely 

 upon botanical or morphological characters as was formerly the case, 

 the principle has become to select a large number of individuals without 

 special regard to such characters." 



The value of these individuals is determined by the study 

 of yield continued over several years. 



Numerous experiments have proved the value of this method. 

 In this connection it is of interest to point out progress that has 

 already been made with self -fertilized crops. 



