Investigations at Peru, Nebraska. 13 



6 feet or more, while the maximum depth was 6.8 feet. The soil was well 

 filled with these roots to a depth of 4.6 feet; many reached depths of 5.5 to 

 5.8 feet below the surface. They were profusely branched to the second 

 order; the length of the branches varied from 0.3 to 5 inches. The last 6 to 

 8 inches of the roots were unbranched. 



The superficial system was composed of much finer roots, which ran nearly 

 parallel with the surface or took a sUghtly obUque course. The longest of 

 these were from 1 to 1.3 feet. They were profusely branched and rebranched 

 with fine rootlets, which extended in all directions from the main root. 

 Branches of the first order were sometimes 4 to 5 inches long. In many 

 instances their ends were found just below the dry, dusty surface of the soil. 

 The shallower roots were developed only to a moderate degree at the second 

 examination, but as the time of maturity approached this portion of the root 

 system continued to grow and extend its area markedly. At no time, how- 

 ever, did its extent and density even closely approximate that of the Uni- 

 versity No. 21 variety (c/. figs. 1 and 2). 



Summarizing, this oat is characterized by a well-developed, deeply pene- 

 trating and profusely branched root system. The depth of penetration of 

 so many of the larger roots may be correlated with the luxuriant growth of 

 tops. This brings about a balance between absorption and transpiration. 

 This oat grew rank and produced heavy straw. The plat yielded at the rate 

 of 40 bushels per acre, but the quahty of grain was only fair, because of the 

 presence of many light kernels, due in part to an attack of Pucdnia graminis 

 avena. 



Durum Wheat, Triticum durum. 



The first examination of Durum wheat was made 19 days after sowing. 

 The plants had been above ground about 9 days and had but one leaf un- 

 folded. They were approximately 3 inches tall. The root system consisted 

 of 4 or 5 roots, usually 5, which ranged in length from 1.5 to 8 inches. While 

 some in their descent made only small angles with the vertical, most of them 

 pursued a more obUque course downward, and, compared with their length, 

 spread rather widely from the base of the plant. In some instances the tips 

 of the roots were 4 or 5 inches from the vertical. Secondary branches vary- 

 ing from 2 to 8 in number had begun to appear on some of the older roots 

 along the first 1 to 1.5 inches of their course. They looked Hke tiny white 

 threads only 2 to 3 mm. long. They were rather tough in texture and, with 

 the exception of the extreme tips, fairly well covered with root-hairs. 



The second excavation was made on May 30, 60 days after the date of 

 planting. The crop was from 8 to 12 inches high, and each plant had from 

 1 to 4 shoots. The roots were extremely fine and fibrous and showed more 

 or less distinctly two types — a surface-feeding type and a deeper absorbing 

 one. Regarding the latter, it is of interest to note that Robbins and Rot- 

 mistrov are not in accord as to their point of origin. In discussing the pri- 

 mary roots that spring from the region of the hypocotyl, Robbins (1917 : 91) 

 states: "This whorl constitutes the primary or temporary root system. It 

 usually dies before the plant is full grown." Rotmistrov (1909 : 32), in 

 referring to the smaller cereal crops in general, says: "These primordial 

 rootlets continue to be main roots or roots of the first order during the whole 

 period of vegetation which follows." 



