A BRACHYTIC VARIATION IN MAIZE. 13 



graphically shown in Plate VIII. In addition to the increase in 

 the number of roots due directly to the shortened internodes, there 

 is a further increase of about 15 per cent, due to the fact that the 

 reduced height is accompanied by an increase in the diameter of 

 the culm, thus increasing the periphery of the nodes from which the 

 roots arise. 



This increased root system obtained under ordinary conditions of 

 flat surface tillage is of no mean advantage. In irrigated regions 

 where the flooding system is practiced or even under most furrow 

 systems the taller varieties of maize lodge badly following an irriga- 

 tion, especially if there is a moderate wind. The brachytic plants 

 are thoroughly anchored and by reason of their greatly reduced 

 height would be able to withstand such conditions and remain erect. 



In addition to the increased root system, brachytic plants offer an- 

 other character that may be of advantage for dry-land culture. The 

 reduction in internode length brings the leaves close together, thus 

 effecting a partial shade at the time when the sun is at its height. In 

 this manner transpiration may be reduced at the critical period, and 

 if this reduction is appreciable it should result in a lower water re- 

 quirement for brachytic plants. The feature of partial shade may be 

 desirable also for irrigated regions where, during the bright days of 

 summer, the plants frequently are unable to obtain water from the 

 soil with sufficient rapidity to supply the heavy demands of midday 

 transpiration, even though the soil is thoroughly wet. 



It remains to be determined just how far farm practice can be made 

 to comply with the requirements of harvesting such a crop. Where 

 the practice of hogging off is followed, the ^brachytic plants are ideal, 

 since the ears are brought within easy reach of the animals and little 

 waste should occur. 



As a general rule, the commercial varieties of corn are taller than is 

 necessary to satisfy the physiological requirements for yield of grain. 

 This increased height is due almost entirely to the elongation of the 

 internodes and not to an increase in the number of nodes. An increase 

 in the height of the culm would seem to be a disadvantage unless it is 

 the result of an increase in the number of nodes, as otherwise no addi- 

 tional leaf area results. The brachytic variation affords a means of 

 reducing the stature, with no corresponding reduction in leaf area. 



There is, of course, a physiological limit to the production of grain 

 upon small plants, beyond which it is impossible to proceed. This 

 limit is obviously dependent upon the leaf area available for pur- 

 poses of photosynthesis. The reduction in internode length does not 

 reduce the number of nodes, nor is it accompanied by a reduction 

 in the size of the leaves, and the total leaf area therefore remains the 

 same. The leaves, however, are brought closer together, and possibly 



