THE WATER REQUIREMENTS OF FRUIT PLANTS 

 Table 5. — Variations in the Water Content of Apple Sptjrs^^ 



'^ The Water Requirements of Plants in Terms of Dry Weight. — The 



water requirement of any plant is defined as the amount of water used 

 while a unit weight of dry matter is produced. The weights may be 

 measured in grams or in pounds, but the ratio obtained is the same in 

 any easel Table 6 brings together data that have a bearing on this 

 point, as reported by several investigators. 



Table 



-Water Evaporated by Growing Plants for 1 Part of Dry Matter 

 Produced*' 



Lawes and Gilbert 

 (England) 



Hellriegel 

 (Germany) 



Wollny 

 (Germany) 



King 

 (Wisconsin) 



Peas 235 



Barley 262 



Red clover 249 



Beans 214 



Wheat 225 



Peas 292 



Barley 310 



Red clover... 330 



Beans 262 



Wheat 354 



Oats 402 



Buckwheat. ... 374 



Lupin 373 



Rye 377 



Peas 479 



Barley 774 



Maize 233 



Millet 416 



Oats 665 



Buckwheat. . . . 664 



Rape 912 



Sunflower 490 



Mustard 843 



Peas 447 



Barley 393 



Red clover. . . . 453 



Maize 272 



Potatoes 423 



Oats 557 



Though Table 6 does not include figures for fruit plants it is presumed 

 that as a class they do not differ materially from herbaceous plants in 

 this respect. yHilgard"^ states that oaks require from 200 to 300 pounds 

 of water for each pound of dry matter produced, while birches and lindens 

 use from 600 to 700 pounds in producing 1 pound of dry leaves; the 

 figures for beech and maple are intermediate. Hilgard estimates from 



