Investigations at Peru, Nebraska. 



15 



just beginning to push out from the node, while between these extremes 

 roots of all intermediate lengths were found. They were fairly well branched 

 to the second order; the branches extended in all directions and ranged from 

 0.2 to 2 or 3 inches in length, according to their age. 



A final root examination was made July 4, 95 days after the wheat had been 

 drilled. The plants were 2.2 to 2.8 feet high and averaged two stalks each. 

 The grain was in the stiff-dough stage and the heads had begun to turn 

 yellow. Relative to the other smaller cereals, this plant had a rather meager 

 surface-feeding system at maturity. Usually this consisted of 6 to 8 (rarely 

 more) roots that extended out in an almost horizontal direction (fig. 4 a). 

 They varied in length from 2 to 14 inches and ended only 4 to 7 inches below 

 the surface. They were fairly well supplied with rootlets to the second and 

 third orders. The primary roots, as determined at the previous examination, 

 continued to be the most pronounced portion of the root system. From 

 their points of origin they ran either vertically downward or downward and 

 outward until they reached a distance of 0.4 to 1.3 feet from the vertical, 

 where they turned downward, pursuing a more or less zigzag course. A few 

 of the roots which originated from the node above the old kernel, and which 

 at the second investigation had a course more or less horizontal, had now 

 turned downward and penetrated deeply. All the roots were well supplied 

 with branches from a few millimeters to 3 or 4 inches or more m length. 

 These laterals were rebranched. The soil was especially well filled with 

 roots to the fourth foot; many also occurred in the fifth and sixth foot, and 

 not a few extended even deeper. The maximum depth to which roots ex- 

 tended was 7.4 feet. Due to an attack of stem rust (Puccinia graminis 

 tritici), this wheat yielded at the rate of only 8 bushels per acre. Moreover, 

 there were many shriveled kernels, which made the gram of rather inferior 



^Durum wheat, when grown under the conditions described, has a surface 

 root system of only medium extent, but a large, extensive portion which 

 penetrates very deeply. These studies show clearly, moreover, that the root 

 system develops coordinately with the above-ground parts, for it is only m 

 this way that the increasing demands of the developing shoot for water can 

 be successfully met. 



Marquis Wheat, Triticum ^stivum. 

 The roots of this plant were examined April 25, 20 days after planting. 

 Most of the plants had shown above ground for about 9 days. The tops 

 were 2 to 2.5 inches high and the second leaf had just begun to unfold. Three 

 or four roots had developed. Their courses varied widely. Some had grown 

 almost straight downward, others diverged at wide angles from the vertical, 

 while still others had taken an intermediate position with reference to these 

 extremes (fig. 3 a). The number of roots varied from 3 to 5, but most of 

 the plants had 4. The maximum spread from the vertical was 7 inches; 

 the greatest depth of penetration was 11 inches. The roots ranged m length 

 from 5 to 9 inches. They were fight in color, had a diameter of a millimeter 

 or less, were rather tough, and all their surface, excepting the very tip, was 

 covered with a copious growth of root-hairs. For a distance of 2 to 3.5 

 inches from the base of the longer roots, branches had begun to appear. 

 The longest of these, however, did not exceed 0.5 inch. 



