60 Nebraska Experiment Station Research Bulletin 19 
under adverse conditions. In eastern Nebraska, the average 
optimum planting rate for small varieties is likely to be about 
65 per cent thicker than for large varieties. 
COMPARATIVE TRANSPIRATION OF EASTERN AND WESTERN 
CORN TYPES 
The preceding morphological and histological adaptation 
studies have indicated that the chief adaptive characteristic of 
dry-land short-season corn was a marked reduction in vegetative 
growth. There was no definite indication of favorable structural 
adaptive reaction, tho a somewhat shorter stomatal aperture pre- 
vailed. This was regarded more as a dwarfish correlation, than 
as a directly adaptive feature. If adaptively effective, the 
shorter aperture should be expected to reduce the relative amount 
of transpiration per unit leaf area. This is not the case, as shown 
in Table 30. 
Two native varieties each from western Nebraska, eastern 
Nebraska, and New York state were grown to normal maturity 
during four years, at the Nebraska Experiment Station, in large 
potometers, and the relative use of water determined. The na- 
tive climates of western Nebraska, eastern Nebraska, and New 
York increase progressively in precipitation, and atmospheric 
humidity. Accordingly, this investigation affords an opportun- 
ity to study the adaptation occurring in corn as a reaction to 
moisture shortage. The method for determining the transpira- 
tion is the same as that described in Nebraska Research Bulletin 
No. 6, 1916, pp. 45, 48 and 49. 
The transpiration per square inch leaf area was practically 
the same for corn native to all three regions. For western Ne- 
braska, eastern Nebraska, and New York types it was respec- 
tively: 102, 101, and 100 grams water transpired per square inch 
leaf area. These cannot be regarded as adaptive differences. 
On the other hand the total amounts of water transpired per 
plant were respectively: 85,778, 114,653, and 97,218 kilograms. 
Eastern Nebraska and New York corn transpired respectively: 
34 and 13 per cent more per plant than western Nebraska corn. 
Comparing the two most extreme native Nebraska types tested, 
namely Kimball County and Lancaster County corn, we find 
that the latter used 81 per cent more water per plant, 3 per 
cent less per unit leaf area, and equal amounts per unit dry 
matter produced. The Lancaster County corn plants wen* 51 
per cent taller, had 88 per cent greater leaf area and 79 per 
cent greater dry matter than the Kimball County corn. 
