90 GERMINATION OF SEEDS: SEEDLINGS 
cool, but if Corn or Melons, which have a high temperature re- 
quirement, are planted before the weather and ground are warm 
they will decay and have to bereplanted. In considering tempera- 
ture in relation to germination, three temperatures are usually 
noted; the minimum, the lowest temperature at which germina- 
tion will occur; the optimum, the temperature most favorable 
for germination; and the maximum, or highest temperature per- 
mitting germination. As the following table shows, these tem- 
peratures are very different for different seeds, sometimes differ- 
ing as much as 25° or 30° (Fahrenheit). 
GERMINATION TEMPERATURES (FAHRENHEIT) 
Kind of seeds. Minimum. Optimum. Maximum. 
Deg. Deg. Deg. 
Oats okt haar oa Reese see 32-41 77- 88 88- 99 
Wheat; RYe@ss : cade ghtacewecas mas 32-41 77— 88 88-108 
Pidian CORR Gach csr ican aeechk asa 41-51 99-111 111-122 
Red Clover...... ...........------ 32-41 77- 88 99-112 
PO OSk eas ancosien la act Aais A acimS we eoee e 32-41 77- 88 88— 98 
DUNAOWED. ocean cameoeeaene taza rs 41-51 93-111 111-122 
PUMpRiNensceug ss Kees apeve eae ees 51-61 93-111 111-122 
Musk Melon....................-- 60-65 88- 99 111-122 
Cucumber.................02-0055 60-65 88- 89 111-122 
Germination, which proceeds most rapidly at the optimum 
temperature, decreases in rate as the temperature approaches 
the minimum or maximum as the following table shows in 
case of Corn, in which the time required for the radicle to break 
through, though only 2 days at the optimum temperature, was 
10 days in a temperature near the minimum. In the majority of 
cases, the temperature of the soil in which seeds are planted is 
somewhat below the optimum and, consequently, if the soil tem- 
EFFECT OF TEMPERATURE ON RATE OF GERMINATION 
Germinating Period in Hours. 
Temperature, ° F, 
Indian Corn. Red Clover. 
42 240 180 
55 144 32 
75 56 24 
87 48 24 
102.6 48 24 
112 80 ar 
