PLANT -BREEDING 



PLANT -BREEDING 



1365 



ecessitv of intelligent selection of 

 seed is to be taken can hardly be 



wheat), etc. The 

 plants from whic 



°Tn'' ll' " I .iir .-lihird fruits selection has played a 



,„' , ;, .,,,,, ,,nt tliough here the process is slightly 



Mer' !^ .1..- -M.Ttion is usually limited to asingle 

 ^eneriti.'.n the best individual among many seedlings 

 birng'selec'ted and propagated by buds or grafts so that 

 further selection to fix and retai- ■'« 

 necessary. In this way was prod 

 cord grape, the Dana Hovey 

 etc. It must not be understoo 



apple, 



Duld 



of 



nf sele 



niong 

 ■dling 



pro- 



owing to the long 



I whole is a factor 

 1 should be clearly 

 f'tr improved or 

 .t be to select the 

 ■n>ni the best indi- 

 k'crease the num- 

 ely fail should he 

 depend upone°xaminrng "a number of fruits without ref- 

 erence to the plants on which they grew, and selectmg 

 that one for pr..l'n'j-;iti..n 



of prime iinpi>rt:iiioe in s.i..i;.in. . 

 recognized by every ■•>'•■ ''"'"' 

 pedigree plants. The ;inii slioul.l 

 single best fruit, but to srl.-.-i trui 

 vidual plant. If one is selecting 

 ber of seed he would probably "" 



fewest seeil. H' -ii 'n • 

 trees, and tlo 'i ^ 



which by tho ■ 



show the iiiosi ,l-i li'l 

 lessness. 



Limitation!) of Seleett 

 culturists considered t< 

 factor in the developim 

 some go so far as to i 

 of minor import! 

 however, 



found to contain th( 

 lie the fruit on numerous 

 planting from that tree 

 many fruits is found to 

 il tendency toward seed- 



II. -Selection Is by many horti- 

 have been the most important 

 it of our cultivated plants, and 



sert that all other factors are 



e. Both crossing and selection, 

 definite and distinct places in 



that 



J8«. Aquileeia flowers, illustratine the process ol 



emasculation. 



o matnre bud showing stage which should be selected 



for' emasculation: h. similar hurt with the tips of the 



,'nr..ll-. prie.l aii.irt .mcl the st.imeiis removed: c, a bud 



^ I,, ■[,,,,,,..' ;;.' , 1 t,, 1,1,. I ,t-. 'Ill: rf, a bud of the 



', " , I n-moved to show 



, , , , . ,1 :!■ :is in d, but with 



I , , ,, ^ , , ' ; . I , . , Imt older.at the 

 ,",' v''ii"ii"i"'Mii'''i'ii '"I' ii'Tinillx 1. •! I, r< place: 17. pistil 

 shortly :ift<'r fei-uu.hiticin, the remnants of the stamens 

 having fallen away. 



the crossing of mark- 

 that the breeder must 

 tip oht:iiTiPd combining 



new and novel races it is 1 

 edly ditferent species or raci 

 look. In this way y\:mt-^ iii 

 the good qualities "I t\\oili-- 

 nation of the undi -n:tMi !• ii 

 propagated by vei;.i,iin< p: 

 cuttings, etc., a ckMiable va 

 ing may bo propagated di- 

 rectly without further im- 

 provement. This is the case 

 in apples, pears, oranges, 

 and all orchard fruits. In 

 the case of plants propa- 

 gated by seed, however, a 

 valuable hybrid must be 

 inbred and selected for 

 several generations until a 

 fixed type is produced. 



The process of crossing 

 or hybridizing plants is 

 neither difficult nor mysteri- 

 ous. It is simply necessary 

 to recognize that plants, like 

 animals, bear male and fe- 

 male organs. In plants, 

 however, the male and fe- 

 male elements are most com- 

 monly borne on the same 

 individual and in the same 

 flower. In some cases, as 

 in the castor bean, corn, 

 etc., both sexes are borne 

 on the same plant but in 

 different flowers, while in .. ,j „*„ 



other cases, as in the date palm, hemp, box elder, etc 

 the sexes are on different plants. 

 If the plant to be operated 



1843. Plant of Aauilegia with 

 flowers covered with bags 

 in hybridization work. 



has the stamens and 



When used alone in 

 on depends upon the 

 v:ni:itions through 



.ational system of plant-breeding, 

 the improvement of plants, select 

 adding up of small. in~iL-niiir;iii 

 many generations, wlm li m i h. . n.i nii 1, ^ 



result in marvelous di.M. ;. i- iiv ""^ "• °^ *^« 



breeder has no way to tone the .iKiim-.., :ui.l must be 

 satisfied with slight variation and long-continued selec- 

 tion When marked changes and new creations »rf. 

 desired it is to crossing or to chance sports 

 teution must be directed. 



CT RV Mk 



OP Crossing.— Aside from 

 ■ d the most important role 

 i. ties and races of our culti- 

 ^ obtained are in many cases 

 I lion. In the production of 



buds must be selected and the 

 they burst and discharge the pollen. This is necessary 

 in order to prevent self-fertilization. In some in- 

 stances, as in .1 :i . M- n luml.ine this c_an be 



„o»rt so thLt'tlie ^1 11^ 11- . I" l'"ll'.l off with small 



pincers or forceps. ' I'lo l.u.l .hould then be inclosed 

 in a small paper bag uulil the pistil matures normally, 

 when the bag may be removed and the pollen dusted 

 over the pistil (female organ). After this the bag must 

 again be put over the flower to prevent^other pollen 

 from being broii 

 some cases the- i 

 pistil without in 

 and this is a gri 



However, in ex, , . . ,^ ■» i „ 



lev of the U. S. Department of Agriculture, it has 

 been demonstrated that in some plants the pollination 

 of immature pistils produces injury and thus cannot 

 be practiced in all cases. 



In some instances, as in the apple, pear, cotton, etc., 

 it is difficult to pry the petals apart to remove the sta- 

 mens and in such cases the corolla may be cut oil 

 without in.iurv, in this wav exposing the organs so that 

 the stamens can be easily removed (Fig. 1844). 



In striviiifj to secure a certain combination of the good 

 charaetirs of any two sorts, very numerous crosses 

 between th.-m should be made in order to furnish the 

 breeder greater range of selection. Indeed at every 

 step the success of the plant-breeder depends on han- 

 dling large numbers. True, the desired variation may 

 be secured in a small batch of crosses, but the chance 

 of success is increased in proportion to the n"™ber 

 handled In his experiments Burbank has found that 

 in peaches about one desirable variety of superior ex- 

 cellence is obtained from each 1,000 seed mgs tested, 

 while in raspberries and blackberries only about one 

 sort in 20,000 has proved to be worthy of retention. _ 

 In the crossing of races and species the hybrids in 

 first feneration are usually nearly alike, exhihitmg 

 en.M-il the s.inu- iiitermedi.i'te characters. In the sec- 

 ir,.,,,.r.iiion of ihise hvbrids, however, there is al- 

 t iiiNiii iMv -riMtiT variation, and it is usually from 

 niniis ,1 II I- -ineration that the most valuable 



