Investigations at Lincoln, Nebraska. 



49 



The soil area thus inclosed by the developing root system was only fairly 

 well occupied at this time to a working level of about 1.8 feet. 



Barley plants at Peru, 54 days after planting, gave a greater height growth, 

 while maximum root penetration exceeding that of these 63-day-old plants 

 by 1.3 feet. Moreover the differentiation of the root system into two parts 

 was rather clearly marked (p. 18). 



Plants 80 days old were examined on June 19 and 21. They averaged 2.3 

 feet in height, with a maximum development of 2.7 feet. Many plants had 

 no tillers, others had 1 to 7, with an average of about 2 or 3. The crop was 

 just beginning to blossom. A great tangle of well-branched roots spread 

 laterally from medium-sized plants to distances of 7 to 10 inches and occu- 

 pied the soil thoroughly to the working level at 2.7 feet. Even below this 

 level roots were quite abundant for 8 or 10 inches, the longest extending to a 

 total depth of 4.4 feet. Roots were more abundant in the surface 3 inches of 

 soil than were those of either wheat or oats. The development of secondary 

 rootlets was very similar to that of oats and wheat. Wheat, however, was 

 found to be more abundantly supplied with finer rootlets than either oats 

 or barley. 



In the lowland plats, at this time, the crop was about 2.7 feet in average 

 height and had been in blossom for 2 or 3 days. The working depth of the 

 roots was 3 feet, while the longest reached the 4.5-foot level. The greater 

 abundance of surface roots as compared with wheat and oats was clearly 

 evident. 



A final examination of the root system, shortly after the grain was harvested 

 on July 12, showed, as in the case of the other cereals, that the working level 

 was somewhat deeper (2.9 feet), as was also the maximum depth (4.7 feet); 

 The area of soil under the plants was even more completely filled with great 

 masses of finely branched roots, the whole forming an exceedingly efficient 

 absorbing system. On the lowland area the roots of mature barley plants 

 had a working depth of 3.3 feet, while several of the longer roots were traced 

 to depths of 5.4 feet. 



Wheat, Triticum ^estivum. 



The root development of Marquis Spring wheat, growing in an adjoining 

 plat, was determined at the same intervals as the oats. On May 1 the wheat 

 had an average height of 2.5 inches, although many plants were an inch 

 taller. The stand was good and the crop quite evenly developed. The sec- 

 ond leaf was from 1 to 3 inches long in nearly all plants, while some were 

 unfolding the third leaf. The root system, while very similar to that of 

 oats, was somewhat more extensive. The number of roots on the large lot 

 of plants examined varied from 3 to 8, with an average of about 6. The maxi- 

 mum depth of penetration was 15 inches, although most of them were much 

 shorter, so that the working depth was only about 6.5 inches. The greatest 

 lateral spread was 5 inches. The root diameter, which was almost identical 

 with that of oats and barley, was seldom over 0.5 mm. Laterals occurred 

 at the rate of about 5 to 13 per inch. These varied in length from only 2 

 mm. to 1.3 inches. They were entirely unbranched. On the youngest por- 

 tions of the roots practically no laterals occurred, but as a whole they were 

 somewhat more numerous than on the oats or barley (fig. 22). Environ- 



