28 



.SCI K X Tl F I (• A (i R [ C U L T U RE 



Jamiarv, 1921. 



Liiocrm' (McdicMjo falccda). In otlior words, conspi- 

 cuous differences in the seed-producing capacity of 

 individual plants are common occurrences in the so- 

 called variegated alfalfas, iucludin<i' Grimm's, Onta- 

 rio Variegated, IJaltie, Cossack, and others. It is 

 difficult, indeed, to explain the existing variations in 

 the seed-producing abilit.y of different types except 

 by assuming that the female reproductive organs in 

 some types are normal while in others they are more 

 or less degenerated or even wholly incapable of func- 

 tion. A c.vtological investigation of the sexual cells 

 of the pistil of different alfalfa types would no doubt 

 be productive of many iutei-esting results. 



While the failure to set seed in many cases may be 

 attributed to lack of sexual vigour in the female 

 organs, it must not be forgotten that failure to pro- 

 duce seed ma.v also be due to impotent or more or 

 less abnormal pollen being ile])0sited on the pistil. In 

 1911, the writer had an opjiortunity to make some ob- 

 servations, for the first time, on tlie character of the 

 pollen in a verj^ large number of different types found 

 in a field of Grimm's alfalfa at the Experimental Sta- 

 tion, Lethbridge, Alta. It was observed that, while in 

 the majority of t.ypes examined the pollen appeared to 

 l)e normal, i.e. heavj', of full colour, and sticky as it 

 generally is in plants pollinated by insect.s, there were 

 quite a few types in which the pollen was abnormally 

 pale, light and almost as dust-like as grass pollen. That 

 latter type of pollen evidentl.v was very inferior to the 

 normal one. Numerous observations of a similar nature 

 have since been made and there appears to be no doubt 

 hut that the male organs in many alfalfa types are 

 imperfectly developed. 



It is obvious, then, that no attempt should be made 

 to fix an alfalfa t.vpe, i.e. to develop it into a constant 

 variety, unless observations on its seed — producing 

 abilit.y and examination of its pollen have shown it tn 

 be sexually normal. 



Granting that a sexuall.v i)erfect plant of a valuable 

 type is selected as mother plant, the breeder's only 

 course in an effort to develo]) it into a constant variety 

 is to resort to inbreeding through self-fertilization. 

 Self-fertilization may be brought about either through 

 self-pollination, effected simjily by tripping the flow- 

 ers by touch, or by tripping the flowers with a suitable 

 instrument on which pollen from another flower of 

 the same plant has previously been deposited. Uoth 

 methods are known to bring results, but it also is well 

 known that the setting of seed in many cases does not 

 materialize. 



The writer is inclined to think that in many cases, 

 when seed formation fails to follow tripping on isolat- 

 ed material, one of the main reasons for the failure is 

 unsuitable conditions for seed fornuition, on account 

 of unsatisfactory isolatio)i methods. The use of 

 paper bags enclosing clusters of flowers has the same 

 drawbacks here as in grasses, and in cages made of 

 cheese cloth it is al.so difficult, at least in the east, to 

 keep the atnu)spheric conditions in respect to heat and 

 humidity, as close to the normal as would be desirable. 



Next year it is planned ta use roomy cages made of 

 wire netting sufficiently open to allow ample ventila- 

 tion, yet .sufficiently close to prevent all insects cap- 

 able of tripping the flowers from entering the cages. 



4. Red Clover.— In the matter of pollination. Red 

 Clover is unlike all the other forage plants which have 

 been dealt with so far. A Red Clover plant is incom- 

 patible to its own pollen, i.e. it cannot produce any seed 

 unless it is fertilized by pollen from another plant. 



This self-sterility was observed alread.y by Darwin and, 

 later, numerous investigators have corroborated Dar- 

 win's findings. Under the circumstances it is evident 

 that it is not ])ossible to develop pure varieties like 

 for instance pure varieties in Wheat and Western Rye 

 grass. Self-fertilization is out of the question and 

 cross-fertilization must be resorted to. 



Although pure varieties in the strict sense of the 

 word can not be obtained, j"et it is possible to develop 

 varieties of a sort exhibiting a rather high degree of 

 uniformit.v in respect to characters particularly bred 

 for. A few examples illustrating the poiBt may be 

 given. 



An ortUnar^' sample of Red Clover seed is, as is well 

 known, ver.v mixed as far as colour is concerned, the 

 individual seed varying from pale yellow to deep 

 purple with all kinds of intermediates. If, however, 

 seed of individual plants is collected aiul examined, it 

 will be found that the ripe seed within each individual 

 plant is of the same general colour. If two plants 

 grown from, for instance, two purple seeds are cross- 

 fertilized, the progeny resulting from the cross will 

 to a large extent consist of individuals having purple 

 seed. And if purple-seeded jDlants from among the 



Figure 4. — Western Rye Grass varieties; differences in yielding 

 capacities indicated by distances between stakes. 



progeny of the original cross are again crossed, the 

 purple seeded plants in the ensuing progeny will be 

 greatl.y increased. It is thus possible to develop a 

 variety of a sort characterized b.v a steadil.v increasing 

 high percentage of purple seed. 



Another example. Red Clover plants with four leaf- 

 lets are frequentl.v found ; more rare are plants with 

 five, six, and seven leaflets, in the order given. If two 

 plants having 4-foliate leaves are crossed, there will 

 appear in the progen.v a certain percentage of 4-foliate 

 plants and perhaps also some odd 5-foliate ones. By 

 keeping on generation after generation to cross plants 

 showing the greatest tendenc.v to grow leaves with 

 more leaflets than three or four it is possible to de- 

 velop a race in which ]ilants having all the leaves 3- 

 foliate are rare. 



From these two examples — and more could be quot- 

 ed — which are taken from papers b.v European in- 

 vestigators dealing exhaustivel.v with iidieritanee of 

 characters in Red Clover, it is apparent that it is 

 possible to develop by means of what may be termed 



