Potassium to Growth in Plants . 
213 
table shows that delayed additions of potassium had eventually an effect on 
rate of growth, there being after a lapse of time an increase in the daily 
increment. When the addition of potassium was withheld three days the 
increase in rate of growth only became manifest after eighteen days ; when 
the potassium was not supplied until the sixth day, twenty-three days 
elapsed before any change in rate of growth occurred ; when potassium was 
I withheld nine and twelve days respectively, it was thirty-one days before 
the growth-rate improved ; when the potassium was withheld seventeen days, 
no improvement was visible for thirty-six days ; and when potassium was 
not added until the twenty-second day, forty-eight days elapsed before any 
beneficial effect on rate of growth could be observed. It will be noticed 
that after sixty-three days the full nutritive milieu and the milieus which 
received potassium after three, six, nine, twelve, and seventeen days had all 
Table XXIII. Effect of delayed additions of potassium on rate of growth of 
Blue stem Wheat plants in sand culture. 
Measure - 
Potassium 
Potassium 
Potassium 
Potassium 
Potassium 
Potassium 
Potassium 
ments taken 
pre~ent 
added 
added 
added 
added 
added 
added 
Potassium 
after planting from the 
after 
after 
after 
after 
after 
after 
absent . 
of seed . 
beginning . 
3 days . 
6 days . 
9 days . 
12 days . 
1 7 days . 
22 days . 
Days. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
7 
5.0 
5-4 
4-5 
5.8 
5.6 
6-6 
5 -i 
5-7 
10 
6.4 
6.6 
6-o 
7-2 
6.6 
8-i 
6.8 
7 - 1 
13 
7-3 
7 - 1 
6.2 
8-6 
8.4 
10.6 
8-o 
8.4 
16 
9' 1 
8-5 
7.6 
9.6 
10-2 
12.3 
9-6 
10.3 
20 
II *3 
9-5 
8-3 
10.3 
10-7 
12.7 
10.0 
10-7 
25 
13.1 
11.8 
10-0 
10.7 
1 x *5 
i- 3-2 
n -5 
11*2 
30 
14.9 
13-6 
12. 1 
11.9 
12.7 
H-° 
1 2.1 
11. 8 
38 « 
16.1 
17.2 
15-5 
15.0 
1 - 4-5 
J 4-4 
12.2 
1 1*9 
43 
20.3 
20-6 
19.1 
18.4 
17-9 
17-3 
12.4 
12. 1 
49 
23-7 
24.6 
22.4 
22.3 
20.2 
20-9 
1 2.8 
12.8 
55 
26.8 
29-3 
26.3 
27.4 
25.0 
26.6 
16.6 
14.1 
63 
30-1 
33-4 
28.2 
3 i -4 
27.8 
32-3 
21.5 
16.1 
70 
31-4 
35-2 
29.7 
33-7 
30-3 
34 -° 
26- 2 
18.0 
produced plants that were apparently equally vigorous and healthy; but 
that a gradual and progressive falling off in rate of growth occurred when the 
addition of potassium was not made for nine, twelve, seventeen, and twenty- 
two days, though recovery is obvious even when the element is withheld 
twenty-two days. 
When the experiment was discontinued all the plants capable of so 
doing had come to maturity, and the others were drying up. Most of the 
plants had formed heads, except those grown in the absence of potassium, 
but the seed was quite immature in all the plants with the exception of 
those growing in pots No. 1 and No. 1. One effect of absence of potassium 
during the early stages of growth is then to delay maturation, though, as 
will be seen from a consideration of the data given in Table XXIV, the 
production of dry matter is not affected. 
A study of the figures given in the table also shows that when the 
additions of potassium are delayed more than twelve days the effects of 
