72 
WATER REQUIREMENT OF PLANTS. 
Table LXII. — Effect of duration of growth on the water requirement of the bush bean at 
Gottingen, according to Fest (1908, p. 34). 1 
Period of growth. 
Condition at harvest. 
Number of 
plants 
harvested. 
Dry mat- 
ter. 
Water re- 
quirement. 
May 28 to June 19 
Third leaf formed 
350 
229 
150 
104 
25 
Grams. 
255.8 
450.8 
438.4 
681.3 
497,8 
June 20 to July 1 
211 
July 2 to July 10 
July 11 to July 25 
Fruit formed 
261 
July 26 to Aug. 18 
304 
1 Twenty kilograms of soil per pot; water content, 70 per cent of moisture-holding capacity. 
von seelhorst's later experiments. 
The results obtained by Von Seelhorst in 1910, already given in 
Table LIX (p. 69), lead to the conclusion that the older growth on 
grassland consumes less water in proportion to the dry matter pro- 
duced than does the younger growth or that following cutting. This 
would indicate that the results previously recorded in this section 
were largely an expression of climatic differences. 
CONCLUSIONS. 
Most of the evidence presented regarding the effect of the age of 
the plant on the water requirement does not seem to be conclusive, 
since the changes in climatic conditions have not been eliminated. 
Von Seelhorst's later work indicates that a nearly matured plant has 
a lower water requirement than a young plant. 
WATER REQUIREMENT OF DIFFERENT KINDS OF PLANTS. 
woodward's experiments. 
Woodward (1699) was the first to show that different kinds of 
plants do not have the same water requirement. His experiments 
with culture solutions (p. 54) included also the determination of the 
water requirement of different plants grown in spring water. His 
results, which are based on green weight, are summarized in 
Table LXIII. 
Table LXIII. — Water requirement of plants in England, according to Woodward (1699, 
pp. 200-201). 
Plant. 
Culture. 
Number of 
determi- 
nations. 
Green 
weight 
produced. 
Water re- 
quirement 
based on 
green 
weight. 
Spring water 
do 
1 
1 
1 
Grams. 
0.97 
3.695 
.227 
170 
65 
...do... 
715 
285 
