Potassium to Growth in Plants. 
195 
other hand, is slightly better in the plants grown in solution A. When we 
study the effect of absence of potassium on growth it makes very little 
difference, therefore, whether we compare the growth of the plants in 
solution B with the growth of those in solution A or solution C, though, 
since solutions B and C are more nearly alike in composition — except 
for the essential difference, absence of potassium — than solutions A and 
B, it is presumptive that the growth obtained in solutions B and C 
more accurately measures the effect of absence of potassium. Plants 
Table V. Green and dry weights of Bine stem Wheat after 21 days 
growth in mitritive solutions A , B, and C. 
Ratio o 
Nutritive solution 
No of 
Total weig 
ht of plants . \ 
Weight 
Weight 
tops tl 
used . 
plants . 
Green . 
Dry . 
of tops . 
of roots . 
roots . 
Grm. 
Grm. 
Grm. 
Grm. 
Grm. 
Nutritive solution A 
5 
5.8102 
0.6256 
0*4704 
0-1552 
3*03 
5 
6.9992 
0.7099 
0-5295 
0.1804 
2-93 
5 
1 o* 1 2 1 2 
0.8659 
0.6159 
0*2500 
2.46 
5 
7.9997 
0-8016 
0*5839 
0-2177 
2.68 
5 
10.9833 
1.0473 
0.7718 
0-2755 
2.80 
5 
9-3301 
0.9029 i 
0-6668 
0-2361 
2*82 
5 
7- 2 533 
* 0.7558 
o *5523 
0.2035 
2.71. 
Mean 
I 
1 
1.6713 
0.1631 
0-1197 
0.0434 
2-77 
Nutritive solution C 
5 
9.6943 
0*9671 
0-7096 
0.2581 
2-75 
5 
1 4*5958 
0-4923 
0-3635 
0*1288 
2.82 
5 
7.9318 
0.9172 
0.6984 
o-2 1 88 
3 -i 9 
5 
11-8819 
1.2601 
0*9534 
0*3067 
3 - 11 
Mean 
1 
1 • 705 2 
0.1819 
0-1362 
0.0456 
2*97 
Nutritive solution B 
5 
1-0468 
0.1522 
0.1264 
0-0258 
4.89 
5 
0.9567 
0-1622 
o-i 347 
0*0275 
4.89 
5 
j 0-8126 
0.1413 
0*1128 
0*0285 
3*96 
5 
0.8394 
0.1445 
0.1197 
0-0248 
4 - 8.3 
1 5 
0.8023 
0.1449 
0.1214 
0-0235 
5.16 
• 
5 
0.9127 
0*1472 
o-i 194 
0*0278 
4*29 
5 
I, 4 II 5 
0.2169 
0*1671 
0-0498 
3*34 
Mean 
1 
' 0-1938 
0*0317 
0.0258 
000*59 
4*48 
growing in the absence of potassium, even over the short period of 
time of twenty-one days, produce between 5*1 and 5*7 times less total dry 
matter than plants growing in a full nutritive solution ; in the case of the 
tops the loss lies between 4 *6 and 5*2, and in the case of the roots between 
7-3 and 7-7. Absence of potassium curtails more markedly the growth of 
roots than the growth of tops. In the full nutritive solutions the ratio of top 
growth to root growth lies between 2-77 : 1 and 2*97 : 1, while in the case of 
the plants growing in the absence of potassium it is 4-48 : 1. 
O 2 
