File:Development and activities of roots of crop plants; a study in crop ecology (1922) (20269631753).jpg

Title: Development and activities of roots of crop plants; a study in crop ecology
Identifier: developmentactiv00weav (find matches)
Year: 1922 (1920s)
Authors: Weaver, John E. (John Ernest), 1884-1966; Jean, Frank Covert, 1880- joint author; Crist, John W. , joint author
Subjects: Roots (Botany); Plant ecology; Crops and climate
Publisher: Washington, Carnegie Institution of Washington
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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44 Development and Activities of Roots of Crop Plants. The weather for the most part remained cold and cloudy, but no frost oc- curred. The water-content of the soil averaged about 30 per cent. The soil temperatures remained low (minimum 52°, maximum 66° F., at a depth of 6 inches). Air temperatures, recorded by a hygrothermograph, appropriately sheltered and placed with the recording appa- ratus 4 inches above the soil surface in an adjacent prairie, gave an average day reading of about 63° F., while the average night tem- perature was only 53° F. The relative humidity was high. Rotmistrov (1909 :34) states that at the end of 21 days after the appearance of the sprout, not only was the extreme breadth of the root system marked off, but the depth of penetra- tion reached 0.5 meter and roots of the third order were clearly visible, the whole forming a felt-like entanglement. Clearly our plants were developing more slowly. However, oats planted May 4, and examined 26 days later, were further developed than 45-day- old plants just described. They were 5 inches high, had 5 leaves each, and some had tillers. The root growth was proportional. It is interesting to note also the more rapid root penetration of White Kherson oats in the loess soils at Peru. Here plants only 14 days older than those just described had extended their roots into the fourth foot of soil. Fifteen days later, on May 30, the root development was again studied. During this period both roots and shoots had grown rapidly. Although the soil remained quite wet (25 to 30 per cent water-content), it was con- siderably warmer, the average daily temperature during the last week of May reaching 71° F. at a depth of 6 inches. This was higher than the average air-temperature (65° F.) for the same interval. Fewer rains and less cloudy weather occurred during this last half of the month, although the humidity remained high. The average height of the plants was about 9 inches, but some were 3 inches taller. Each plant had 7 to 9 leaves, one or two of the oldest ones being either dead or rapidly deteriorating. About one-tenth of the plants had
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Oata 60 days old.

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