July 2,1917 Variation of Water in Leaves of Corn and Sorghums 41 



kafir the leaves showed a gain in their leaf water between 1 1 a. m. and 

 I p. m. From i to 3 p. m. the leaves gained in the amount of their leaf 

 water in one-half of the observations of corn and milo and in three- 

 fourths of the observations of kafir, while from 3 to 5 p. m. the leaves 

 of kafir showed a gain in water in all cases. In only four cases did the 

 leaves of milo and corn show a loss of water during this period. In the 

 following discussion the cases of the loss of leaf water only will be con- 

 sidered. 



The average loss of leaf water per square meter of leaf, between 7 and 

 9 a. m. was 4.1 gm. for com, 3.3 gm. for kafir, and 4.2 gm. for milo, while 

 the percentage of loss based on the amount of water in the leaf at the 

 begiiming of the period was 3.5, 2.8, and 4.0, respectively, for com 

 kafir, and milo. During this period the water in the leaves of com and 

 milo decreased in like amount, but the percentage loss was higher for 

 milo than for com. The average loss of the leaf water of the kafir during 

 this period was the least for the three plants, both in percentage and 

 in actual amount. 



From 9 to 1 1 a. m. the water content of the leaves per square meter of 

 leaf decreased 4.8, 3.9, and 2.2 gm., respectively, for com, kafir, and milo, 

 from what it was at the close of the previous period, while the percentage 

 of loss was 4.2 for corn, 3.4 for kafir, and 2.1 for milo. The rate of water 

 loss during this period thus increased markedly for com and kafir, both in 

 percentage and in actual amount, while the loss for milo was only one-half 

 of what it was from 7 to 9 a. m. From ii a. m. to i p. m., the decrease 

 in the amount of leaf water for each square meter of leaf was 3.7 gm. for 

 com, 3. 1 gm. for kafir, and i .9 gm. for milo, while, taken in the same order, 

 the percentage loss was 3.4, 2.8, and 1.9. The rate of loss during this 

 period decreased markedly for com and kafir, while the change in the 

 rate of milo was very slight. From i to 3 p. m. the average loss of leaf 

 water was 3.1, 2.5, and 3.3 gm. for each square meter of leaf for com, 

 kafir, and milo, respectively, while the percentage loss was 2.8 for com, 

 2.1 for kafir, and 3.3 for milo. While the rate of the loss of water in the 

 leaves of corn and kafir continued to decrease, the loss in the leaves of 

 milo showed a marked increase, both in percentage and actual amount, 

 over what it was at the close of the previous period. 



A consideration of the loss of the leaf water during the day shows 

 that from 7 to 9 a. m. the rate of loss was practically the same for com 

 and milo and the least for kafir. From 9 to 1 1 a. m., as the aerial condi- 

 tions became more severe, the rate of loss increased for com and kafir, 

 but decreased almost one-half for milo. During the next two hours the 

 rate of loss decreased for all three plants, but the rate of loss was approx- 

 imately twice as great for corn and kafir as for milo. From i to 3 p. m. 

 the rate of loss continued to decrease, while the rate of loss of milo 

 increased over i per cent. These results seem to indicate that the 



