604 
Journal of Agricultural Research 
Vol. XXI, No. 8 
as Virginia. It is an easy matter now to account for the fact that certain 
lots of imported Turkestan alfalfa give comparatively high yields at 
Redfield and other northern points while the yields are comparatively 
low in Virginia and other southern States. 
As a result of Gamer and Allard's 1 discovery of the photoperiod ism 
of plants it appears necessary to change the recommendations commonly 
made in regard to the range and adaptation of alfalfa varieties. Instead 
of recommending the use of southern varieties, such as the Peruvian 
and Kansas, as far north as they are hardy, these varieties should be 
recommended for as far north as the length of day during the growing 
season gives them an advantage over the northern alfalfas that yield 
comparatively better under the relatively long day. There is a differ¬ 
ence between the two types of recommendation, especially along the 
Washington and Oregon coast and in such areas as the Judith Basin, 
Mont., where the winters are not so severe as at some other points of the 
same latitude. Peruvian alfalfa as a rule does not winterkill in the 
former region, and the Kansas seldom winterkills in the latter. Both 
sections have a length of day during the growing season that favors the 
Grimm and its allies. As a matter of fact, the Grimm has given somewhat 
better yields than the Kansas at Moccasin, Mont. The day-night rela¬ 
tion of alfalfa is a much better measure of the adaptability of the varieties 
than their ability to endure cold and unfavorable winter conditions 
generally, as is indicated by the fact that Kansas alfalfa is sometimes 
hardy in the North where the length of the day is less favorable to it 
than to the Grimm and other northern varieties. 
It is believed that by the methods followed by the writers in their 
recent experiments it will be quickly and easily possible to tell within 
reasonable limits from a given lot of alfalfa seed in what sections it will 
give the best yields of hay as compared with other varieties. It may 
even be possible by this method to determine in a measure to what 
extent it is winter hardy. Investigations are now being made in this 
field, and it is confidently expected that a careful study of the day-night 
relations of alfalfa will throw considerable light on the subject of the 
development of regional strains. 
HOW ALFALFAS MAY BE IDENTIFIED BY SEEDLING CHARACTERS 
It is exceedingly difficult if not impossible to identify varieties of 
alfalfa by seed characters. Where identification is important, as it is 
in many cases, any short-time method that will assist in accomplishing 
it is useful. It is generally possible to distinguish between imported 
and domestic seed by the weed seeds and other incidental impurities 
contained in the sample. This is particularly true of imported seed of 
Turkestan alfalfa, but it is practically impossible to distinguish seed of 
1 Garner, W. W., and Allard, H. A. op. cit. 
