398 
Journal of Agricultural Research voi. xxvii, no. 6 
Table IX. —The effect of different nutrients in sand cultures started June 14 , ig22, on 
the growth of Haynes Bluestem wheat plants and on the development of stem rust 
caused by biologic Form XXXIII , used as inoculum on July ig,lQ22 
Series 
No. 
Changes in basic nutrient solution. 
Percentage 
of plants 
infected. 
Severity of 
infection. 
Character of 
growth. 
121 
None (control).. 
60 
Medium ... 
Good. 
122 
Phosphate increased by adding 
k 2 hpo 4 . 
20 
...do. 
Medium. 
123 
Nitrate increased by adding KN 0 3 .. 
80 
Severe. 
Excessive till¬ 
ering. 
124 
Nitrate further increased by adding 
twice as much KN 0 3 as in 123. 
90 
...do. 
Do. 
125 
Nitrate decreased to one-tenth; phos¬ 
phate increased by adding 
CaHPO,. 
O 
No infec¬ 
tion. 
Fair; leaves 
narrow ; 
sandy. 
126 
Phosphate decreased to one-fifth, us¬ 
ing CaHP 0 4 ; nitrate increased by 
adding KN 0 3 . 
20 
• 
Medium ... 
Poor. 
127 
FeS0 4 increased by adding 15 times 
as much . 
50 
.. .do... 
Good. 
128 
FeS 0 4 omitted; A 1 C 1 3 added._____ 
(“) 
Very poor; 
plants killed 
by root-rot¬ 
ting fungi. 
a Not inoculated. 
It will be seen from Table VIII that there was no rust on any plants 
except those grown in sand to which considerable nitrogen had been 
added. A single exception was one uredinium which developed on a 
plant in the potassium sulphate series. Table IX shows that in the sec¬ 
ond series the rust developed more abundantly on the plants fertilized 
with a large amount of nitrogen. However, in this series the rust failed 
to develop only on plants receiving a very poor balance of nitrogen and 
phosphorus. 
The plants in the pots receiving excess nitrate tillered more than those 
in the other pots and developed leaves of a different texture. The lower 
epidermis was removed from a leaf of a plant receiving an excess of 
potassium nitrate and compared with that of a leaf from a plant in soil 
deficient in nitrate. (See PI. 9.) The epidermis from the plants sup¬ 
plied with abundant nitrogen is smooth, with few hairs and but little 
bloom, while on plants with a poor balance, or a lack of nitrogen, the 
leaves are rough to the touch, more hairs are present, the bloom can 
readily be seen, and there are fewer stomata. 
The relation of nutrient salts to the type of cell wall and general 
character of the epidermis has been briefly mentioned in the historical 
review. Petermann (40, p. 15-16) states that the cell walls are much 
stronger in wheat plants on a low plane of nutrition, while manures pro¬ 
duced rusted plants, owing to the fact that the haustoria could penetrate, 
more easily. Palladin (38) asserts that cereals grown in soils deficient 
in silicic acid often rust so severely that it is difficult to prevent their 
complete destruction. Russell (46) states that nitrogenous manures 
produce plants with thin walls, easily attacked by fungous hyphae. 
Comes (9) also maintains that organic fertilizers increase the tenderness 
of the plant and favor fungous attack. 
