Archive image from page 85 of Development and activities of roots. Development and activities of roots of crop plants; a study in crop ecology . developmentactiv00weav Year: 1922 64 Development and Activities of Roots of Crop Plants. was that of wheat grown at Lincoln. The primary laterals varied in length from to inches, frequently as many as 20 to 27 branches occurring on a single inch. Secondary laterals, to about inch in length, were nu- merous. Even the root-ends were well-branched with rather long laterals (fig. 27). Thus the root system, although largely confined to the
Archive image from page 85 of Development and activities of roots. Development and activities of roots of crop plants; a study in crop ecology . developmentactiv00weav Year: 1922 64 Development and Activities of Roots of Crop Plants. was that of wheat grown at Lincoln. The primary laterals varied in length from to inches, frequently as many as 20 to 27 branches occurring on a single inch. Secondary laterals, to about inch in length, were nu- merous. Even the root-ends were well-branched with rather long laterals (fig. 27). Thus the root system, although largely confined to the surface 2 feet of soil, because of its wide lateral spread and profuse branching, was well adapted to extract water and solutes from these soils of low water- content. The roots in the surface 6 or 8 inches were not at all fleshy, but tough and wiry, and many were at this time drying out. A final examination of wheat was made on July 7, when the plants were 83 days old. They had fully headed out by June 25, and were now in the dough stage. The crop averaged feet in height, with a maximum height of feet. The plants were thin on the ground, and many had no tillers, while Fig. 27.—Wheat roots showing normal differences in branch- ing at Lincoln, L, and Burlington, B. 1, at depth of feet; 2, root-ends. some showed 4 to 6 tillers, but the average total number of stalks in selected meter quadrats was only 201. Most of these did not head out (plate 2 a). When harvested on July 19, the heads were well filled and the grain was of fair quality. The interval since the last examination on June 12 was one of scant water- supply and high evaporation. Rain fell on 11 days, but only 4 showers of more than inch occurred, heavy rains falling on June 18 ( inches) and on July 5 ( inch). A glance at the water-content of the soil given in table 17 is sufficient to show the prevailing drought. During the latter part of the period the crops ripened and dried rapidly. Thre
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