16,6 Espino: Salt Requirements of Young Rice Plants 49 I 
centration. Another comparison between these two total con- 
centrations is possible, however, from the data of series 15 and 
18, carried out simultaneously in the period beginning May 24, 
and data for this comparison are given in Table 7, which is 
planned like Table 6. For ready comparison, the data for series 
16 and 19 are here repeated from the other table. For each 
series of each period the higher of the two comparable values is 
shown in bold-face type. 
Table 7 . — Highest and lowest yields of tops and of roots (milligrams) in 
the high and in the low groups for the low-medium and high-medium 
total concentrations (series IS, 16, 18, and 19). 
Period beginning May 24. 
Period beginning June 19. 
Series 15 (low- 
medium total 
concentration) . 
Series 18 (high- 
medium total 
concentration). 
Series 16 (low- 
medium total 
concentration). 
Series 19 (high- 
medium total 
concentration) . 
Highest. 
Lowest. 
Highest. 
Lowest. 
Highest. 
Lowest. 
Highest. 
Lowest. 
Tops... 
High group.. 
416 
389 
420 
394 
287 
235 
253 
224 
Do... 
Low group... 
345 
313 
309 
267 
192 
163 
176 
115 
Roots.. 
High group.. 
128 
118 
120 
108 
78 
72 
74 
64 
Do... 
Low group... 
98 
71 
90 
75 
62 
52 
63 
42 
It appears from the upper part of Table 7 that, in three cases 
out of four, both maximum and minimum top values for the 
high group, and also for the low group, are greater for the low- 
medium total concentration than for the high-medium, while 
preference is suggested for the high-medium total concentration 
in the fourth case, that of May 24, of the high group. In this 
case the differences are much smaller than in the others and 
they are too slight to be considered as significant (420 milli- 
grams is not significantly greater than 416, nor 394 than 389). 
It may be added here that the evidence from root yields in the 
lower part of Table 7 points in the same direction, the agreement 
being actually better here than in the case of top yields, for the 
only comparison that gives preference to the high-medium total 
concentration on this basis is that between the two minima for 
the low group, 75 and 71 milligrams. 
From these and other considerations it seems clear that the 
low-medium total concentration (0.0016 gram-molecule per liter, 
or 0.08 atmosphere) is to be regarded as generally more prom- 
ising, for these plants and these non-solution conditions and 
for this 4-salt type of medium, than is the high-medium total 
concentration (0.0038 gram-molecule per liter, or 0.2 atmos- 
phere). The differences are not generally relatively very great. 
