62 



SOME OP THE PRINCIPLES OF PLANT -BREEDING 



selection has been discontinued, and indeed this 

 is practically the only real criterion as to whether 

 a new race has been produced. For example, in the 

 case of the corn mentioned above as selected by De 

 Vries, that in seven years had 

 been increased from 12 to 20 in 

 the number of rows to the ear, 

 De Vries found that it required 

 only about three years of cul- 

 tivation without selection to 

 fall again to the original aver- 

 age of 12 to 16 rows. In a 

 case like this it would seem, 

 therefore, that no distinctly 

 new character had been added 

 as a result of selection, but 

 that the average of the race 

 had been increased by the 

 continuous selection under 

 isolation, and that when the 

 different individuals were al- 

 lowed to breed together 

 freely, without selection, the 

 mean of the race, as a whole, was again quickly 

 reestablished. 



Fig. 82. Centgeners of flax. Plats on right 

 bred for seed productiou, thus short and 

 very fruitful. Plats on left bred for fiber 

 production, thus tall and less fruitful. 

 (Notice difference in height is shown by 

 difference in height of man's hand.) 



Systematic methods of selection, or pedigree breeding. 



Two distinct methods of selection are in use, 

 which are termed (1) the nursery method, and (2) 

 the field method. The nursery method, which was 

 used first by Hallet about 1868, so far as the 

 writer is informed, consists in cultivating each 

 plant under the most favorable conditions possible 

 for its best development. By this method, with 

 wheat, for example, Hallet pursued the policy of 

 planting the individuals in squares a foot apart, 

 which would give the plant abundant opportunity 



for stooling, and also enable the investigator to 

 distinguish clearly each individual plant. In more 

 recent years this method has been strikingly em- 

 phasized by the work of Professor Hays, at the 

 Minnesota Experiment Sta- 

 tion, who, at the same time, 

 has modified the principle 

 somewhat into his centgener 

 method (Fig. 82). In Profes- 

 sor Hays' method, the progeny 

 of each plant, presumably 

 about one hundred individu- 

 als, are grown together in a 

 small plat or centgener, the 

 individuals being planted four 

 to six inches apart in the 

 case of wheat and small 

 grains. 



The field method, which was 

 emphasized by Rimpau about 

 1867, and has been used by 

 many investigators, consists 

 in selecting from plants 

 grown under normal conditions. The argument for 

 this method is that the plant will show what it will 

 do and its true worth only when it is grown under 

 the method of ordinary field culture. Both of these 

 methods depend on progressive or cumulative selec- 

 tion, the building up and adding together of small 

 improvements. 



Breeders who are conducting careful experi- 

 ments will find it necessary and desirable to use 

 what may be termed statistical methods of judging 

 their plants. While we are breeding possibly for 

 one primary improvement, as, for example, in- 

 creased yield, it is necessary, at the same time, 

 that we should keep the product up to the standard 



f.B.Form 

 41. 



m;..L^,3..TJ'l§J.. -^ 



Locality, ...Qj^tiA^l*WCrtflU...O.C.. 



COTTOlt-IJrDiriD UAtlJfOTMS. 



Year, 



Escperimenter, .Sr^Zt^ili^tfffJft^tfrrr^.. 



I 



V.Early, 



Uedium, 

 Xate, 

 V. Late. 



Bolls. 



V. l/axofi. 



Medium, 



Small, 



V. Small. 



y /A 



Opeaing, 



Good, 



Medium, 



Poor. 



Seed. 



Snl^th, 

 Tufted, 



or 

 Intcrme- 

 .diate. 



Size by 

 Weight. 



Covering. 



0,f 



lelt, 

 Good, 

 Fair, 

 Pp,or. 



Length, 





/s, 



jAs:.. 



; eh ape _ 



...C^VifXdSj*.. #]&*^___ 



No. locks__^_ ; No.'BcedB to lock_ft!."/fl,_; weight 10 bolls eced 



cotton ; No. of bolls opon'-_A^4^__i__ pn , ..Q^T JT 



Eesistance to — 



Disease: Very resistant, resistant, medium, slight, none. 

 Storm : Very resistant, resistant, medium, slight, none. 

 Insect: .Very resistant, resistant, medium, slight, none. - 



Basai, BbanOhes': .No M. • length *•_ Je5__ ; 



color __ ; smooth, rough, hairy; horizontal," 



ascc^ng, nearly erects 



Tloweks: Large, mo(!|?Cm, Bmall"; orange yellow, cr^fta, whitish ; TPol- 

 Jen— orange, deep yellow, yellow, cijilfln, whitish ; Petal spot— large^'i 

 small, li^e; deep red, red, pink, fiUnt. 



Leaves : Large, mo^m, small ; light or dark green ; :.___-; 



parted, smooth, glaucous, pub(^ent; Lobes— deep, medium, shallow j 

 Type— Sea Island, ui^d, intermediate. 



Fig. 83. A score-card for 



Very 

 Fine, 



Medium, 

 Coarse, 



Uni- 

 formity. 



Idit, 

 Good, 

 Fair, 

 Poor. 



Sttlbg, 

 Strong, 

 JUedium, 

 Weak. 



/O 



Drag. 



Stifing, 

 Strong, 

 Medium, 

 Weak. 



Yield 

 or Sked 

 Cotton. 



M9 



n 



Pee 



Cent of 

 Lint. 



S3J 



Total 

 Score. 



ys- 



FfiVlTFVLNESS : E.xcellent, good, medium, light medium, poor. 

 Type., 

 Selected for 



ESS : J!;.i:ceiieni;, gooa, n 



Form of Plant SZjfJ!*yaAC!t. 



.Shape : Very^^ood, good, incdiuni, poor. 



Height ^.ZAl.-^j. .. 



cotton. 



