26 



SCIENTIFIC AGRICULTURE 



January, 1921. 



types. This is especially the case -R-ith escapes oeeur- 

 ing in colonics. If colonies li\Tng under "wild" con- 

 dirion.s are found for instance of Red Clover in 

 Manitoba, if colonies of Orchard gi-ass are found at 

 Edmonton, then one may be justified in concluding that 

 the colonies in question are likely to represent types 

 that are perfectly hardy for the localities in wihieh 

 tlhey are found, the size of the colonies serving as an 

 indication of the number of years in w/iich they have 

 persisted. It is from such colonies that the most 

 hardy breeding material of tender species may be 

 secured. 



Methods of Breeding. 



Granting that a breeding material, satisfactory in 

 respect to hardiness, has been secured, the breeder's 

 efforts will be directed toward tike fixing of agricul- 

 turally valuable types found in the material available, 

 in other words towards development of superior and 

 constant varieties. The metiiods which may be em- 

 ployed to achieve this object depend primarily on the 

 type of sexual reproduction eharaoteristie to the 

 species worked with. And a? there exist great dif- 

 ferences in the manner in waiich different grasses 

 and leguminous forage plants are sexually repro- 

 duced, different methods are resorted to accordingly. 

 In the following, four types of sexual reproduction 

 found in grasses and clovers will be mriefly dealt vntfi 

 and tie breeding methods applicable to each case in- 

 dicated. 



1. Wrnd-poUinated grasses. — The most common type 

 of poUmatifm iu grasses is, as is well known, wind 

 pollination , i. e., the transportation of pollen from 

 the .stamens to the pistik by means of air currents. 

 In this tj-pe of pollination the pistil of a flower may 

 be fertilized by pollen from the same flower, by pol- 

 len from Oi,aer flowers of the same plant, or by 

 pollen from other plants. Cross-fertilization may con- 

 sequently take place and so it does to a great extent 

 for, if .seed from a wind-pollinated plant growing in 

 company with other plants of the same species is sown, 

 the progeny proves as a rule to be veiy heterogenous. 

 In order to develop uniform varieties, breeding true to 

 type, from such a heterogenous mass of form.s, it is 

 necessaiy to resort to repeated inbreeding, i.e., to self- 

 fertilize' individual plants of desired tjiJe for consecu- 

 tive years until constancy has been reached. 



Tt is obvious that the self-fertilization ooeration-s 

 must be earried on imder t.he best possible guarantees. 

 Ill other words, the breeder must protect the self- 

 fertilized-to-be plants from being pollinated by otiher 

 plants. With this object) in view several isolation 

 methods are being employed. The oldest method, per- 

 haps, consists of enclosing indi^ddual heads, or a few 

 heads together, in paper bags, often oiled so as to 

 allow light to penetrate. T/iis method of course makes 

 it possible to guarantee a perfect exclusion of foreign 

 pollen but it has several drawbacks, the worst, one 

 being tlhat the formation of seed of strong vitality 

 is suffering a serious set back. When paper bags 

 are used, the isolation is perfect and for this very 

 reason there is no chance for the moisture produced 

 by the heads through ph^-siological proces-es to 

 escape. The result is that the atmosplkere inside tJie 

 isolation bags becomes overcharged with humidity, 

 especially as it is often necessary to keep the heads 

 isolated for a week or more. In the atmosp^iere 

 loaded with humidity the formation of seed is ser- 



iously hampered, perhaps not so much beeaiise the 

 excess of moisture prevents the fertilized pistil from 

 developing normally but rather because grass pollen 

 in general is very sensitive to humidity, refusing 

 entirely, as a matter of fact, to germinate under very 

 humid atmospheric conditions. 



As it is essential, in order to .test satisfactorily 

 the con.stancy of a type, to secure hundreds of ger- 

 muiable seeds from each individual plant worked 

 with, the method of enclosing a whole plant in 

 cages of cheese cloth or similar material is commonly 

 employed. With this method it is easy to obtain 

 large quantities of good seed, largely because tlie 

 atmo.spheric conditions inside t;ie isolation cages are 

 more normal. But the method has also its draw- 

 backs, in as much as it does not guarantee, as fully 

 as it should, the exclusion of pollen from outside tlhe 

 cages. Even if the cages are built of double cheese 

 clotli, which is generally the case, t^iere is no abso- 

 lute guarantee against foreign pollen blowing through 

 the meshes of the c)heese cloth. 



Considering the necessity for as normal atmos- 

 pheric conditions as possible in the cages, and con- 

 sidering also t^e necessity of protecting, as much 

 as possible, the isolated plants from pollination from 

 t.he outside, a sort of combination cage was used 

 last year in the timothy breeding block at the Cen- 

 tral Experimental Farm at Ottawa. This cage 

 was made very roomy, allowing for plenty of air. 

 The top and three of the four sides were made of 

 canvas and consequently were pollen proof. The 

 fourth side was made of cheese cloth. By iising 

 cages of this construction absolute protection ag^ainst 

 foreign pollination from tflvee directions was effect 

 ed. and at the same time the nece^ary ventilatrion 

 of the cages was pro\'ided for. By, furthermore, hav- 

 ing all the cheese cloth sides of tlhe many cages in 

 the breeding block facing in the same direction, viz : 

 to tlhe leeward of the prevailing winds, the danger 

 of foreign pollination was minimized as much as 

 possible. 



Seed of good quality in satisfactory quantities was 

 secured from the isolated plants. 



2. Self-fertilized Grasses. — Among the cultivated 

 grasses iJu-re is only one which so far is known to be 

 normally self -fertilized, viz: Western Rye grass {Ag- 

 fopyrum tenermn Vas). This species occurs in a tre- 

 mendously large number of forces in Canada and it 

 was when studying the wild forms with the object 

 of coming to some understanding of their sj^stematic 

 relationship that the writer, in 1913, made the dis- 

 coverj- that self-fertilization regularly takes place. 

 The discovery was made at Edmonton, Alta., where 

 a large number of Western Rye grass forms occur 

 in the greatest profusion. The writer observed, wiaen 

 one day collecting a number of different forms, that 

 the blossoming of the flowers presented some fea- 

 tures, or rather lack of features, which indicated a 

 mode of pollination different from that of other 

 gra.sse5. In tiie first place, it was noticed that, dur- 

 ing the openmg process of the glumes inclosing tihe 

 sexual organs, the .stamens did not protrude from 



*Obser\'ations made by tlie writer during the sum- 

 mer of 1920 have revealed self-fertilization in other 

 species of AgropjTum, viz: A. Richardsonii Schrad., 

 A. biflorum (Brignoli), R.E.S., and A. caninum 

 (L) Beauv, 



