Archive image from page 59 of Development and activities of roots. Development and activities of roots of crop plants; a study in crop ecology . developmentactiv00weav Year: 1922 42 Development and Activities of Roots of Crop Plants. roots, laterals from to 1 inch in length occurred at the rate of 7 to 15 per inch, except near the root-ends, to 2 inches of which were unbranched. All of these laterals were of the first order only (fig. 17). The primary set of roots spread laterally at an angle of about 45 degrees from the vertical; the maximum lateral spread on any side of the plant di
Archive image from page 59 of Development and activities of roots. Development and activities of roots of crop plants; a study in crop ecology . developmentactiv00weav Year: 1922 42 Development and Activities of Roots of Crop Plants. roots, laterals from to 1 inch in length occurred at the rate of 7 to 15 per inch, except near the root-ends, to 2 inches of which were unbranched. All of these laterals were of the first order only (fig. 17). The primary set of roots spread laterally at an angle of about 45 degrees from the vertical; the maximum lateral spread on any side of the plant did not exceed Slnches The slow rate of development was due to adverse growth conditions. In fact, during this period of 31 days, the growth was about equal to that of 18 days at Peru (cf. p. 31). Rotmistrov (1909 : 33) found the roots of oats, wheat, and barley had an average depth of 12 inches only 7 days after the appearance of the sprout. He does not record the environmental conditions of the plants. In our experiment the influence of temperature is clearly shown by the fact that oats planted in the same field on May 15 revealed a much more advanced development of both shoot and root 15 days later than had occurred in a month when the seed was sowed on March 31. Thus, the very slow development of oats is clearly correlated with the unfavorable conditions for growth. Throughout the month of April the weather was cold and wet. Excessive cloudiness prevailed and there was a large defi- ciency m sunshine. The ground was frozen for several days following April 2, and more or less covered with snow from April 2 to 9, while freezing tem- peratures with light snow occurred during the latter half of the month. There were only 6 clear days. The soil was wet and cold. A water-content of about 22 per cent was rather evenly distributed throughout the first 5 feet of soil. Thermograph records from a depth of 6 inches in an adjoining prairie,1 gave an average temperature of about 47° F. fo
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