84 



Purity of 

 sorts main- 

 tained by 

 mass-selec- 

 tion or 

 'rogueing. ' 



Value of a 

 special seed 

 plot. 



of the validity of such a claim is afforded in the mass-selection of heads made 

 in 1905 from an old pedigree sort originating from Grenadier autumn wheat 

 (50, p. 340). The sort in question was grown on an ordinary farm near 

 Svalof and the selection was made from the sheaf by one of the experts of 

 the Station. In making this selection care was taken to select only heads 

 which were typical and which contained fine, plump kernels. The seed from 

 the selected heads was sown in the large comparative trial plots in 1906 

 where it proved promising. The severe winter of 1908-09 also showed this 

 sort to be hardier than the mother sort, while in yield it excelled all others. 

 On the average of the past five years (1906-1910) it stands next to Extra 

 Squarehead II in yield as will be seen in the following table : 



The above instance illustrates two important facts, viz.: That it is 

 often possible to affect improvements by mass-selection and secondly, that 

 even pedigree sorts, at least in the case of wheat, when grown for a period of 

 years in the country, can often be still further improved upon. 



As a means of maintaining purity and constancy in all sorts, pedigree 

 sorts included, mass-selection is still recommended. Where this cannot be 

 done rogueing, that is removing all aberrant plants before harvesting, should 

 be followed. This practice is zealously followed each year by the Swedish 

 Seed Company with all its large cultures of autumn wheat grown on its farm 

 at Svalof. 



From the above discussion it follows that mass-selection by the farmer 

 in one form or another should be an annual task. By rogueing those fields 

 from which he intends to take his next year's seed the purity of his stock 

 may be maintained. By operating a special seed plot each year and selecting 

 therefrom a sufficient quantity of typical heads or panicles to provide seed 

 for the following year's plot not only will the purity and uniformity of the 

 stock be maintained with greater assurance, but in many cases further 

 improvement may actually take place. The use of such a plot on every 

 farm on which seed growing is being prosecuted is strongly recommended 

 by the Swedish experts. 



In making such selection the operator should be content with typical 

 plants and heads and should avoid extremes. The reasons for such precau- 

 tion have been amply demonstrated. 



