Journal of Agricultural Research 
Vol. XXI, No. 3 
166 
as those of the green plants. However, the weight of the roots was 
decidedly less in the chlorotic than in the green plants. This agrees 
with the field observations, indicating an association between chlorosis 
and a deficiency of fibrous lateral roots. It will be noted that the 
strongly chlorotic plants in the vigorous class had a root weight con¬ 
siderably less than that of the green plants in the weaker class. While 
the roots of these plants were also somewhat shorter, the weight differ¬ 
ence was distinctly greater. 
The other lack of parallelism between increased chlorosis and de¬ 
creased growth is in the primary leaves. These were nearly as well de¬ 
veloped in the chlorotic plants as in the green plants. This is considered 
significant as indicating that the plants which were decidedly chlorotic 
and lacking in vigor during the second season were not originally very 
different in their growth rate from the others. This relationship is most 
easily seen in the three columns under “ Relative leaf surface ” in Table IV. 
Table III.— Root , top, and terminal bud development of the different type classes of 
2 -year-old seedlings 
UNTREATED WESTERN YELLOW PINE ° 
Type classes. 
Num¬ 
ber of 
seed¬ 
lings. 
Aver¬ 
age 
diame¬ 
ter of 
stem at 
root 
collar. 
Tops. 
Roots. 
Aver¬ 
age 
total 
weight 
of seed¬ 
lings. 
Terminal buds. 
Aver¬ 
age 
length. 
Aver¬ 
age 
weight. 
Aver¬ 
age 
length. 
Aver¬ 
age 
weight. 
Per¬ 
centage 
of seed¬ 
lings 
forming 
termi¬ 
nal 
buds. 
Aver¬ 
age 
length. 
Aver¬ 
age 
diame- 
eter. 
Inches. 
Inches. 
Gtn. 
Inches. 
Gm. 
Gm. 
Inches. 
Inches. 
Vigorous, green. 
IOO 
0.075 
2. 2 
x. 40 
11. 7 
0. 57 
1.97 
9 
0.33 
0.16 
Vigorous, slightly 
chlorotic. 
95 
• 065 
x* 7 
• 77 
9 - 7 
•33 
I. IX 
2 
• 23 
. 12 
Vigorous,strongly 
chlorotic. 
22 
. 062 
x. 6 
• 52 
8.6 
• 20 
• 72 
0 
Weak, green. 
IOO 
. 060 
1.6 
•54 
9.6 
• 26 
.80 
0 
Weak, slightly chlo¬ 
rotic. 
IOO 
00 
«n 
O 
1.4 
•35 
9-3 
. l8 
• 5 2 
0 
Weak, strongly chlo¬ 
rotic. 
IOO 
.045 
z. 2 
• 22 
*6 
• 12 
•34 
0 
UNTREATED DOUGLAS FIR a 
Green. 
50 
.046 
2.8 
•34 
9. 6 
•15 
•50 
IOO 
• is 
.08 
Chlorotic. 
50 
• 038 
2.3 
. 22 
8.2 
.08 
•30 
86 
. 10 
.04 
° The number of chlorotic plants in the treated plots at the end of the season was insufficient to serve as 
a basis for measurement. 
