8 Development and Activities of Roots of Crop Plants. 



I. INVESTIGATIONS AT PERU, NEBRASKA, IN 1919. 



Studies of the root development of plants at Peru were conducted during 

 the season of 1919. The crops used were as follows: two strains of oats 

 {Avena sativa), White Kherson and Swedish Select; two species of wheat, 

 Durum {Triticum durum), and Marquis Spring {Triticum cestivum); Manchu- 

 ria barley {Hordeum vulgare) ; Early Ohio potatoes {Solarium tuberosum) ; and 

 Iowa Silver Mine corn (Zea mays indentata). These were grown on an up- 

 land area of silt-loam soil, which lay near the top of a hill on a gentle western 

 slope. The field, which had formerly been a bluegrass pasture, had been 

 broken three years previously and the plants grown for these investigations 

 were a fourth crop. Potatoes had been grown the preceding year, and the 

 soil was in excellent tilth when the crops were planted. The surface 1 to 1.5 

 feet consisted of a dark-colored silt-loam. This was underlaid by a very 

 mellow loess to a depth of many feet. 



The crops were planted in plats 200 feet long and 30 feet wide, each con- 

 taining approximately 0.14 acre. These extended in an east-and-west direc- 

 tion. Corn and potatoes occupied the plats on the south side of the field. 

 The smaller cereals were planted with a grain-drill at a depth of about 4 

 inches. The rate of seeding in pounds per acre was as follows: University 

 oats 64, Swedish Select oats 48, barley 48, Marquis spring wheat and Durum 

 wheat, 60. The corn was drilled in rows 3 feet apart at a depth of 3.5 inches, 

 the kernels being placed 1.4 feet apart in the row. The potatoes were also 

 planted in rows 3 feet apart, the space between the sUced tubers being 2 feet. 

 They were covered with 3 inches of soil. 



Preparatory to planting, the plats were plowed to a depth of 5 or 6 inches 

 on March 29 or April 4, and immediately harrowed. All of the crops, except 

 corn, were planted at once without further preparation of the seed-bed. The 

 latter was planted on May 9, after the plat had again been harrowed. 



University No. 21 Oats, Avena sativa. 



This is a special strain of the Kherson oats developed and named by the 

 Department of Agronomy at the University of Nebraska College of Agri- 

 culture. It is known especially for its heavy yielding qualities. 



The first examination of this oat was made April 18, 18 days after planting. 

 Each plant had a single leaf, which had been above ground about 8 days and 

 had an average height of 1.5 inches. The number of roots was 3 or 4. In 

 most plants there appeared to be a main root that took an almost vertically 

 downward course. In position it resembled a tap-root, but in structure and 

 appearance was not unlike the others. Its length varied from 4 to 6 inches 

 and all its characters indicated that it was the primary root. The other roots, 

 while taking a general course downward, did not follow the perpendicular 

 so closely. Instead, they descended at various angles from the vertical to 

 a distance of 1 to 5 inches. In some cases they ended 3 inches from the ver- 

 tical and 3 to 6 inches below the surface. No branches had yet appeared. 

 The roots pursued a gently curving course through the loose soil. They 

 were about 1 to 1.5 mm. in diameter and were densely covered with root- 

 hairs to within 5 mm. of the tips. These hairs were borne so profusely and 

 clung to the soil particles so tenaciously that when the roots were excavated 

 and suspended they presented the appearance of small columns of earth. 



