THE VIABILITY OF RADISH SEEDS 
and the subsequent maintenance of approximately the same water 
content for the whole period of heating — due to equilibrium of vapor 
tension — brings the resistance markedly higher. In the seeds of 
Series 3 the water vapor was constantly carried off and consequently 
the seeds lost water throughout the process. 
Attention should be called to the fact that radish seeds heated 
directly in water lose in dry substance. It is necessary to know the 
extent of this loss in order to interpret more accurately the results 
found in Table VI. This experiment was repeated and the loss of 
dry matter determined and recorded as shown in Table IX. 
Table IX 
The. Loss in Dry Weight of Seeds when Heated in Water at 65° C, 80° C, and p5° C. 
Respectively 
3 Min. 
6 Min. 
10 Min. 
15 Min. 
22 Min. 
30 Min; 
Percent of loss at 65° C 
" " " 80° C 
" " " " 95° C 
.21% 
.39% 
.78% 
•4 
.82 
1.6 
.7 
1.4 
2.6 
I 
2.1 
4 
1.4 
3-6 
6.1 
2 
5-4 
7.9 
These results show that there is a gradual loss in dry weight when 
radish seeds are heated directly in water at the temperatures indicated. 
Moreover the higher the temperature of the water the more rapid is 
the loss in weight. The seeds heated at 65° C, 80° C, and 95° C. 
for thirty minutes lost 2 percent, 5.4 percent, and 7.9 percent respec- 
tively. It follows from this that the actual amount of water taken 
up by radish seeds heated directly in water is considerably more 
than the increase in weight as indicated in Table VI. 
Conclusions 
The resistance of seeds of Raphinus sativus L. exposed to high 
temperatures is inversely proportional to the initial water content of 
the seeds at the time of heating. 
At temperatures high enough to be injurious the viability of radish 
seeds of a given initial water content decreases as the temperature 
to which they are subjected is raised. 
The general resistance of Icicle, Black Spanish Winter and Crystal 
Forcing radish seeds exposed to high temperatures is very similar. 
Radish seeds injured by high water content and high temperatures 
are retarded in their germination. This retardation becomes more 
marked as the temperature or water content or both is increased. 
