26 CIRCULAR NO. 119, BUREAU OF PLANT INDUSTRY. 



TEMPERATURE REQUIREMENTS. 



Arabian alfalfa is not cold resistant and can be grown successfully 

 only in sections having a mild winter climate. It can not stand zero 

 weather without injury and can be grown successfully only in places 

 where a temperature of 10° F. seldom or never occurs. It stands 

 extremely high temperatures without injury, and only when soil 

 moisture is lacking is it injured by heat. It is less drought resist- 

 ant than ordinary alfalfa. While Arabian alfalfa is less hardy than 

 others, it makes growth at a lower temperature than the more hardy 

 types. During the mild weather of winter in the southwestern United 

 States it makes considerable growth, while ordinary alfalfa and the 

 more hardy varieties, such as the Turkestan and Grimm, make but 

 little. On account of its ability to make growth in cool weather, 

 Arabian alfalfa has a longer growing season than the ordinary or 

 more hardy varieties. It is similar to the Peruvian alfalfa 1 in this 

 respect. 



LOSS OF MOISTURE AFTER CUTTING. 



The rate of loss of moisture after cutting varies decidedly in differ- 

 ent types of alfalfa. The Arabian variety loses its moisture much 

 more rapidly after cutting than the Peruvian and ordinary alfalfa. 

 In Table I the Arabian is compared first with the Peruvian and ordi- 

 nary alfalfa (weight in grams) and afterwards with the Peruvian 

 only (weight in pounds). These data cover the results of experiments 

 at Chico, Cal., in 1911 and 1912. In both years the weighings were 

 made on bright days in the month of June, the first weighing being 

 made as quickly as possible after cutting. The moisture content of 

 the Arabian, Peruvian, and ordinary alfalfa was found to be practi- 

 cally the same for all these varieties when cut at the same stage of 

 maturity. When the plants are in vigorous growth they contain 

 about 85 per cent of moisture if in the bud or first bloom and 75 to 

 80 per cent when one-tenth of the flowers are open. The loss of 

 moisture in curing the Arabian variety is so much more rapid than 

 in ordinary alfalfa that it must be handled more quickly in making 

 hay in order to prevent undue loss of the leaves. The rapid loss of 

 moisture in this variety is very noticeable to anyone handling it for 

 hay. This character is in no way objectionable and would be an 

 advantage in some places, as its rapid drying would render it possible 

 to make it into hay with a shorter period of drying weather than 

 would be the case with other varieties. 



i Brand, C. J. Peruvian alfalfa: A new long-season variety for the Southwest. U. S. Department of 

 Agriculture, Bureau of Plant Industry, Bulletin 118, 1907. 

 [Cir. 119] 



