AMOUNT, DISTRIBUTION, AND SEASONAL TREND OF CERTAIN ORGANIC RESERVES IN THE ROOT SYSTEM OF FIELD BINDWEED, CONVOLVULUS ARVENSIS L

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Abstract
The root system of undisturbed field bindweed was arbitrarily divided into lateral roots and the primary (original) and secondary vertical roots to study the distribution and seasonal trend of organic reserves. The 2 types of vertical roots were each divided into the 1st, 2d and 3d foot portions, which with the permanent lateral roots gave a total of 7 portions. The total N, protein N, reducing sugars, total sugars and starch-dextrin fractions were detd. From these data 2 other fractions, the nonprotein N and the readily available carbohydrates were computed. All data are reported as % dry wt. and as grams in 100 lineal ft. of each of the 7 portions at each of the 14 sampling dates, Apr. 1 through Nov. 1, 1937. The general trend of the N fractions in practically all portions showed an early season rise to Apr. 15, followed by a decline to a low point during the interval May 15 to June 15. Marked fluctuations then occurred in many of the portions, succeeded by a 2d low interval, Aug. 15 to Sept. 1. Additional fluctuations followed. All of the carbohydrate fractions, except the reducing sugar fraction, reached low points in all of the root portions during the interval of Apr. 15 to June 15. In many instances this was the low point of the season for that fraction in that portion. The total sugars attained a seasonal max. Nov. 1 in the lateral roots and in the first foot portion of the 2 types of vertical roots. In the other portions there was a tendency to attain a high point on or before July 15 and a max. later but prior to Nov. 1. The starch-dextrin and the readily available carbohydrate fractions were similar in their trends attaining a max. in the lateral roots and the 1st foot portion of the 2 types of vertical roots on Oct. 1. In the 2d foot portion the starch-dextrin fraction reached high points in both types of vertical roots and the readily available carbohydrate fraction reached high points in the primary vertical roots on Aug. 15 and on Oct. 1. Both fractions reached a max. in the 3d foot portion of both types of vertical roots and in the 2d foot portion of the secondary vertical roots during the interval of Aug. 15 to Sept. 1. Certain of the differences in the various fractions between comparable portions of the 2 types of vertical roots are statistically significant, some to a high degree. The total N fraction and the readily available carbohydrate fraction are considered more reliable indices of the reserves of the plant than any of their component parts, the readily available carbohydrate fraction being the more reliable of the 2.