II. 



CLIMATIC REQUIREMENTS 27 



feet altitude. In the United States the major part of the crop chap. 

 is produced between the 35th and 45th parallels, and 82 per 

 cent of it at an altitude between 500 and 1,500 feet; the 

 proportion grown above 1,500 feet is only 4-4 per cent. 

 Harshberger (1) points out, however, that this is partly 

 due to the absence of large areas of tillable land at an 

 elevation of 2,000 feet, for very fine maize crops are raised 

 in North Carolina at 4,000 feet, between the 34th and 37th 

 parallels. 



23. Temperature. — Careful investigations carried out in the 

 United States fail to show any direct relation between actual 

 temperature and yield of the maize crop. Maize is a tropical 

 plant, susceptible to frost in all stages of its growth ; but 

 being an annual, it can be grown as a summer grain crop in 

 warm-temperate climates, and as a fodder crop (not for grain) 

 even in cool-temperate areas such as the south of England. 



Dwarf, early-maturing sorts have been known to ripen 

 seed in the south of England and even in Norway as far north 

 as 63° 13' {Mueller, 1). Martyn (1) states 1 that maize was 

 cultivated in England in 1562, but that the seeds "rarely 

 ripen in England. . . . Mr. Miller thinks that maize might be 

 cultivated in England to advantage. But it can scarcely be 

 expected to be grown here for the grain, except in favourable 

 seasons and warm soils and situations. Yet as a fodder it 

 might be of considerable service, if it were cut when just 

 opening into ear, and given fresh to the cattle every day " 

 (Martyn, I.e.). Of var. 7 Zea vulgaris, Mill. {Diet., n. 3), he 

 says, " This ripens its grain perfectly well in England in as 

 little time as Barley ". But " Maize is seldom cultivated in 

 England for use" (Martyn, I.e.). 



Eighty-eight per cent of the American crop of 1897 was 

 grown between July isotherms 70° and 80' Fahr. {Brewer, 1). 

 The Argentine crop is grown with a mean January tempera- 

 ture of 7578", while that of the Transvaal Maize-belt is under 

 70° Fahr. The actual highest yields of the United State 

 have been obtained between July isotherms 75" and So Fahr. 

 (Harshberger, 1 ). 



The average temperature of the maize-belt of Argentina is 



given as : — 



1 On the authority of Turner's Herbal, Part II, fol. 58 n. 



s 



