Richardson: Wheat Breeding 



141 



various factors on wiiich these important 

 qualities depend, wliether the\' conform 

 to the Mendclian scheme of inheritance, 

 and whether the\' are transmitted 

 independent! \' of other factors, or in 

 association, and, if so, how close the 

 association is. 



The aim of the wheat -breeder is 

 always an improvement in type, the 

 production of varieties possessing the 

 maximum of desirable qualities, and the 

 minimum of undesirable attributes. If 

 he knows that the desirable qualities he 

 is seeking are in two or more strains it is 

 his task to unite the desirable qualities 

 in the one strain. His most important 

 problem is to determine by analysis and 

 experiment the factors on which the 

 desirable characteristics depend. But 

 as soon as these factors have been deter- 

 mined, and their mode of inheritance 

 investigated, they can be brought under 

 control and associated together at the 

 breeder's will. 



SUMMARY. 



1 . The enriching and improving of the 

 soil has been the dominant note in our 

 system of wheat farming during the 

 past generation. 



2. There is reason to beheve that as 

 much attention might profitably be 

 given to the improvement of the plant 

 as there has hitherto been given to the 

 improvement in its environment. 



3. The primary aim of wheat impro\-e- 

 ment is the production of prolific varie- 

 ties. Other important considerations 

 are milling quality of grain, drought 

 resistance, and rust resistance. 



4. Extraordinary activity is being 

 displayed throughout the world in 

 wheat improvement. 



5. Varieties may be im]iro\'ed by 

 selection and cross-breeding. 



6. Every care should be taken by 

 farmers to get (a) the right variety of 

 wheat, (b) well-developed seed, (c) seed 

 from the most vigorous plants. 



7. The common beet containing 6 to 

 7 ])er cent, of sugar has been developed 

 into the sugar beet containing 20 to 25 

 per cent, of sugar by systematic selec- 

 tion. 



(S. Selection is based on variation. 



9. Most variations are small, and 

 diverge only slightly from the mean of 

 the species. Others are large, and vary 

 widely from the mean (mutations). 



10. There are two general methods of 

 selection: (a) mass selection, (b) indi- 

 vidual selection. 



11. "Mass selection" has been effec- 

 tively applied by farmers to the improve- 

 ment of their crops. It must be con- 

 tinuous and uninterrupted. 



12. "Individual selection" is more 

 complicated, and requires elaborate 

 records and trials for its successful 

 application. 



13. The introduction and acclima- 

 tization of certain foreign varieties is 

 likely to lead to valuable direct and 

 indirect results. 



14. New varieties may also be ob- 

 tained by cross-breeding. 



15. The immediate effects of cross- 

 breeding in wheats are (1) increase in 

 vigor of progeny, (2) a "breaking of 

 type." 



16. Mendel showed that the varia- 

 tions induced by cros.sing follow definite 

 laws. 



17. Mendel's results have been 

 generally confirmed by workers in 

 widely different fields of inquiry. 



18. The mode of inheritance of many 

 unit characters in wheat has been worked 

 out in detail. 



19. The mode of inheritance of other 

 characteristics in wheat of great prac- 

 tical importance has not yet been worked 

 out. 



20. The well informed wheat im- 

 prover may enter on his task of wheat 

 improvement without leaving much to 

 chance. 



