Investigations at Peru, Nebraska. 



17 



were fairly well branched to the second order with delicate branches that 

 extended in all directions and formed a network (fig. 3 b). 



The part of the root system which penetrated deeper consisted of 3 to 5 

 roots. They originated very near the old kernel. Some of them ran almost 

 straight downward to a depth of 4.8 to 5.5 feet. The maximum depth was 

 5.8 feet. Others wandered off rather obliquely to a distance of 0.6 to 1.3 

 feet and then took a vertically downward course. These roots that spread 

 more widely did not penetrate so deeply, but ended at the 2.5 to 4.5 foot 

 level. All portions of the deeper roots, except the last 6 to 8 inches, were 

 well supplied with fine, often rebranched laterals. The soil was fairly well 

 filled with these main roots and their branches to a depth of from 4 to 



4.6 feet. 



The last examination was made on July 7, 93 days after the planting. 

 The height was from 2.5 to 2.8 feet, and the plants averaged about 2 stalks 

 each. The grain was in the stiff dough and the heads had just begun to 

 ripen. The shallower portion of the root system was not markedly devel- 

 oped; in fact, scarcely more so than at the preceding examination on June 14. 

 It consisted of 9 to 14 roots that took their origin from nodes on the stalk 

 below the soil surface. These either extended laterally quite parallel with 

 the soil surface or took a downward and outward course, thus extending in 

 all directions from the base of the plant. They varied in length from 0.2 to 



1.7 feet (fig. 4 b). While they were quite well supplied with branches from 

 a few millimeters to 3 or 4 inches long, these were not copious. The longer 

 laterals frequently rebranched. The roots that penetrated deeply, usually 

 from 3 to 8 in number, either ran vertically downward from the old kernel or 

 at a depth of 4 to 6 inches took a course obliquely outward to a distance of 

 4 to 16 inches and then turned downward. Of these roots there were gen- 

 erally one or two more than at the time of the second examination. They were 

 well supplied with branches, except the last 8 to 14 inches, where laterals 

 occurred only rarely or not at all. These branches varied in length from 

 1 mm. to 2 or 3 inches. The diameter of the main roots was approximately 

 1.5 mm. The soil was well filled with these roots and their branches to a depth 

 of 3.7 to 4.2 feet. Roots were frequent even at a depth of 5 feet, while 

 some reached a maximum depth of 6.7 feet. 



A survey of these data shows that, while this wheat is provided with a 

 root system fitted to absorb both in the surface as well as in the deeper soil, 

 under the conditions of growth in this experiment the shallower portion was 

 not highly developed. The number and extent of the longer roots, together 

 with their great depth of penetration, is a marked feature and is especially 

 impressive when the extent of the underground parts is compared with 

 height of tops. The yield of Marquis wheat was at the rate of only 3.7 

 bushels per acre. It was planted a week later than the Durum wheat and 

 was somewhat more susceptible to the epidemic of stem rust which swept 

 over much of the Missouri Valley in the summer of 1919. The plants were 

 attacked just before blooming, and by the time the grain was going into the 

 dough stage the surface of the leaves and stems was covered with rust pus- 

 tules. This resulted in very light, shriveled kernels. 



