Archive image from page 71 of Development and activities of roots. Development and activities of roots of crop plants; a study in crop ecology . developmentactiv00weav Year: 1922 50 Development and Activities of Roots of Crop Plants. mental conditions during the several intervals of growth have already been given in the discussion of oat. It is of interest to note that wheat planted May 15 was further developed after a growth period of 15 days than were the 31-day-old plants just described. The former were 3 or 4 inches tall, had unfolded 3 leaves, and the roots were developed proportionally.
Archive image from page 71 of Development and activities of roots. Development and activities of roots of crop plants; a study in crop ecology . developmentactiv00weav Year: 1922 50 Development and Activities of Roots of Crop Plants. mental conditions during the several intervals of growth have already been given in the discussion of oat. It is of interest to note that wheat planted May 15 was further developed after a growth period of 15 days than were the 31-day-old plants just described. The former were 3 or 4 inches tall, had unfolded 3 leaves, and the roots were developed proportionally. But even these had not made the rapid root growth recorded by Rotmistrov (1909 : 33). Plants 45 days old were examined on May 15. The crop had an average height of 4 inches, the tallest plants exceeding this by only inch. Some plants had 2 or 3 tillers, the largest of these offshoots having 2 or 3 leaves. The root development again execeded that of oats, with a maximum depth of feet, a general working level of about 10 inches, and an extreme lateral spread of 8 or 9 inches (fig. 23 a). 8 to 10 roots per plant were commonly found; many new roots only 1 or 2 inches in length occurred on the plants that were tillering. In the surface 6 or 8 inches of soil, lateral roots 1 to 3 inches in length and many more shorter ones were found. These had a few very fine second- ary laterals only a few millimeters long. Below 10 inches the main roots became glistening white, larger in diameter, and the laterals very sparse. As a whole, wheat roots are somewhat finer and more thread- like than those of oats or barley. Wheat planted May 5, when 25 days old, showed more advanced growth than these. It had reached a height of 4 or 5 inches, was de- veloping the fifth leaf, and had tillers with 2 or 3 leaves. A third examination of wheat was made on May 29 and 31, when the plants, now 60 days old, had reached an average height of about 8 inches and had grown 4 to 6 leaves. A few plants were
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