Oct. 15, 1914 



Water Requiremeni of Plants 



31 



Cowpea (PI. VI, fig. i) was the most efficient of the cultivated 

 legumes. The least efficient was purple vetch. The water requirement 

 of the first crop of hairy vetch (PL VI, fig. 2) was 9 per cent less than 

 for purple vetch, the period of growth being the same for both varie- 

 ties. Some of the pots of hairy vetch produced a good second growth, 

 but none of the pots of purple vetch were able to survive the first cutting. 

 The water requirement of the combined crops of hairy vetch was 690^8, 

 or about three-fourths that of purple vetch. Of the soy beans (PI. 

 VI, fig. 3) the wild required 21 per cent more water than the cultivated 

 variety, which in turn required iS per cent more water than cowpea. 

 (See T.able XX.) 



