WATER-STRESS BEHAVIOR OF PIMA COTTON. 7 
did not receive their first irrigation until June 26. (PI. I.) Through- 
out July and August the plants in plats 1 and 2 continued to grow 
more rapidly and exhibited a more luxuriant growth. This is shown 
in the diagrams in figure 1, which gives the growth in inches per 
plant per week and the average percentage of available moisture 
per week in the upper 4 feet of soil in each plat. 
6 
kc5 
^ Z 
/ 
o 
9 
8 
7 
3 
Z 
/ 
X 9, 
3LE 
we 
■ MC 
V37 
'OKI 
FT. 
r ^£7P 
SO.'L 
«y£-t 
r/c 
A 
/ * 
NX 
/ 
V 
II 
V 
> 
\ 
h 
i 
Is 
k 
\ 1 
v 
y 
\ 
1 
*\ 
/ 
""x 
V 
1 
/ a 
s\ 
/ 
i 
V 
7 
t 
S 
\ 
K 
\ 
\ 
/ J 
\\ 
— * 
V 
s 
--. 
'\ 
. 
!/ 
: i 
i i 
\ 
f 
M 
LT/s 
V& 
COi 
TFF 
<C/£ 
wr 
\ 
J 
\ 
\ 
\ i 
i 
1 
» 
1 
i 
\ 
\ 
i 
i 
» ( 
i 
B 
Ii 
\ y 
1 
t 
\ 
^/ 
k 
\ 
G/?t 
>/T7 
y/A 
'/A/t 
R 14 
^/^ 
vr 
h 
A 
\ 
In 
f ii 
<- 
*« 
r*- 
\ 
h> 
F/.S 
\ 
/ 
w 
1>- 
PL6 
T3 

/ 
/ 
f! 
* > 
* 
% 
V 
*<x* 
——^ 
, 
f" 
i 
s, 
x^: 
;-•< 
^ 
f»-^^ 
t 
YF/ 
?zz 
1 
i 
I 
vfc 
1 
v c5 /O /6 23, J S /$ 2Z 30, v <y /3 ZO 27, g_ /O /6 23 3Q, 
~JUa7£: tJVLY &6/GC/ST <5?£PT£-M3Etf 
Fig. 1. — Average percentage of available moisture per week in the upper 4 feet of soil 
in four plats and the average increase in growth of the main stem of the plants per 
week. 
During periods in the summer when very high temperatures were 
prevailing and when transpiration by the plant was at its highest, it 
was observed that the plants on plat 1 exhibited what might be 
termed a " water stress " in more pronounced degree than those on 
any of the other plats. This stress was made manifest by the wilted 
appearance of plants on plat 1, which occurred more frequently and 
