156 



T. G. YUNCKER 



65% saturation transpired the greatest amount for both day and 

 night, the plants in the 25% saturation the least, while the ones 

 in the 45% saturation were intermediate. This relation re- 

 mained quite constant throughout the experiment with the least 

 amount of variation occurring in the night periods. A great 

 variation occurred in the amount transpired from day to day, 

 but this was quite constant for the three series and was probably 

 due to variations of those factors which favor transpiration as 



EXP. NO. 



TABLE 1 

 Rates of transpiration at different degrees of soil moisture 



NO. POTS 



10 

 10 

 10 

 20 

 20 

 20 



PER CENT 

 SOIL SATU- 

 RATION 



25 

 45 

 65 

 25 

 45 

 65 



DRY 

 WEIGHT 



gms. 



36.147 

 32.100 

 31.466 

 195.96 

 225.51 

 237.69 



LENGTH OF 

 EXPERI- 

 MENT 



hrs. 



843 



843 



843 



1320 



1320 



1320 



GM'iH 



5.5 

 6.4 

 8.8 

 4.4 

 5.2 

 5.7 



H2O REQ. 



205 

 272 

 330 

 180 

 226 

 261 



AREA 



LEAVES 



sq. cm. 



16,030 

 16,010 

 13,900 

 59,406 

 73,452 

 82,380 



TABLE 2 

 Rates of diurnal and nocturnal transpiration at different degrees of soil moisture 



heat, moisture deficit in the atmosphere, etc. The amount tran- 

 spired increased measurably from day to day for the day periods 

 due to increased growth and consequently transpiratory surface. 

 The increase for the day periods was more than 100%, but in 

 the case of the night transpiration the increase was much less, 

 being not more than 20% for the period. Apparently, there- 

 fore, the plants were transpiring less per unit area during the 

 night periods the larger they became. 



