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MEDICAGO FALCATA, A YELLOW-FLOWERED ALFALFA. 59 



be obtained. In sections where climatic conditions are reasonably 

 favorable for seed production, hybrid strains could soon be developed 

 by establishing a few plants of Medicago falcata in a field of Medi- 

 cago sativa or in the fence rows and margins of the fields. A hetero- 

 geneous collection of hybrids would develop from this method, but 

 with the assistance of natural eliminating agencies appreciable good 

 would result, especially in sections wher6 drought and winterkilling 

 are important factors. 



DIFFICULTIES IN ESTABLISHING NEW STRAINS. 



The difficulties in establishing a new variety or strain of alfalfa 

 must not be underestimated. There are three important factors that 

 seriously interfere with the maintenance of pure strains of this crop ; 

 namely, the open fertilization of the flowers, the lack of distinct 

 varietal differences in seed and other botanical characters, and the 

 mixing of the seed either as the result of careless or unscrupulous 

 handling. With regard to the first-mentioned handicap it has been 

 suggested that only one variety of alfalfa be grown in a conmiunity, 

 and in this way the chances for the contamination of the strain 

 through the medium of cross-fertilization with other strains would 

 be reduced to a minimum. Under present conditions, this plan is 

 not feasible, since it would be difficult, if not quite impossible, to get 

 farmers to organize properly for such a purpose. 



A wide difference of opinion exists as to the effect on the characters 

 of a given strain of the cross-fertilization that takes place in alfalfa 

 under average field conditions. Brand {13) offers it as an expla- 

 nation for the failure of a certain lot of Grimm alfalfa to survive 

 the winter to the same degree as other lots of this variety tested 

 with it, even though it had been directly exposed to cross-pollina- 

 tion for only one seed generation. Oliver ^ is likewise of the opinion 

 that the cross-pollination that normally takes place in alfalfa is a 

 serious detriment to the establishment of superior strains, and he 

 cites the case of Peruvian alfalfa in the Southwest in this connection. 

 Field observations, however, do not seem to justify the belief that the 

 Peruvian variety will soon lose its identity through cross-fertiliza- 

 tion in the Southwest. In fact, there is no appreciable evidence that 

 deterioration has occurred from this cause. That strains of alfalfa 

 will k>se their distinct characteristics as the result of continued cross- 

 ing with other strains can scarcely be (juestioned, some strains \wv- 

 haps being more susceptible than others. It also appears to be true 

 that it is a mistake to attempt to breed alfalfa along narrow lines. 

 Taking everything into consideration, it is safe to (^onchide that the 

 first of tiie three factors mentioned is the least imf)ortant. 



' In iin mipiilillHhi'd luiix-r. 



