8 July, 1908.] Improvement of C crcals hy Selection and Crossing. 413 



it is more reasonable to suppose, in tlie absence of experimental evidence, 

 tnat the normal and natural self-fertilization of the wheat plant does not 

 account for such rapid diminution in the yield. Notwithstanding all that 

 has been written about the advantages of crossing and the disadvantages of 

 self-fertilization, it must be remembered that there are drawbacks to the 

 one and compensating advantages to the other. In the case of a natural 

 cross, if the pollen is brought from an inferior plant, or from a plant low 

 in vitality, then the resulting cross will have a tendency to degeneration. 

 Instead of increased vigor there may be diminished vitality, and deteriora- 

 tion may be due tO' undesirable crossing. On the other hand, the self- 

 fertilized plant such as wheat, runs practically no ri.sk from undesirable 

 •crossing and the in-and-in breeding to which it has so long been accus- 

 tomed, does not seriously affect it within a reasonable time. If its vigor is 

 maintauied, the natural mode of breeding is rot likely to impair it. And 

 this suggests another method of maintaining the yield, which would pro- 

 bably do away with the necessity for regeneration, and that is to select 

 the seed wheat so that only the best are .sown and all inferior grains 

 rejected. The larger .seeds with their greater food supply will give the 

 young plants a much better and more uniform start than the smaller seeds. 

 It is just as likelv for a strain to run out from the want of careful and 

 intelligent methods of seed selection, as it is from the inherent defect of 

 self-fertilization. 



It has been pointed out elsewhere that when the large seed from the 

 large ears was sown, it was 25 per cent, ntore prolific than the mixed 

 sample of the same variety, and this is equal to the increase obtamed 

 from repeating the cross. In the latter case the profit of producing the 

 regenerated stock is in the hands of the seedsmen, while in the former, 

 the farmer can select his own seed wheat. There is still another means 

 whereby the vigor of the type may be maintained and deterioration arrested 

 and that is by crossing different individuals of the variety to be improved. 

 It may seem at first sight, as if it were a hopeless task out of weakness 

 to produce strength, but the mere operation of crossing, in plants long 

 accustomed to self-fertilization, infuses nevv' life and vigor into the off- 

 spring — rejuvenates it, in fact. It is often stated that the mere growing of 

 , a varietv in the same locality \ear after vear tends to produce deterioration 

 and the evident remedv is a change of seed. Xo doubt a change of .seed, 

 if it is a better .seed, will likelv do good, but if the varietv has become 

 adapted to local conditions, selected graded seed would be likely to jirove 

 a sufficient change from ordinary seed. 



Mea.sures for Increasing the \ ield. 



If we confine our attention now, in conclusion, to the definite object 

 of the improvement of our wheat yield, there are various factors which 

 must be taken into account, in addition to the skilful cultixation of the 

 soil, a proper rotation and the use of suitable manures. 



/. Selection of Varieties. — It is a well-known fact that .some varieties 

 are much better adapted for certain conditions of soil and climate than 

 others, and this has led to the very common practice of variety testing. 

 It is only by growing different varieties for several years under similar 

 conditions and alongside those generally grown, that their suitability or 

 otherwise can be determined and their superiority shown in increased yields. 

 It is a most interesting and instructive sight to see a large number of 



