Growth Patterns of Irrigated Sugarbeet Roots and Tops1

Abstract

AbstractElectronic growth sensors were used in the field near Amarillo, Texas, to obtain continuous records on strip chart recorders of the root and top growth of irrigated sugarbeets (Beta vulgaris). The purpose of the study was to characterize the typical diurnal variation in growth rate of the crop and to determine its growth response to variations in ambient atmospheric and soil conditions. The growth sensors were potentiometers, either constructed in the form of slidewire discs or adapted from commercial linear transducers. The root sensors were operated by a pulling action of a noose surrounding the root. The height sensors were rotating slidewire discs attached with fine wires to leaf tips.The growth patterns of sugarbeet roots and tops were very similar with most of the growth occurring at night. The main difference was a decrease in size of roots during the daytime that did not occur with leaves.On a typical day with few clouds in July or August and with the plants under a moderate moisture stress, the growth rate of roots and tops accelerated suddenly about an hour before sunset and reached a peak or maximum point around sunset. Growth continued at a high rate during the night. The growth rate of roots usually reached a secondary peak between midnight and sunrise. The growth rate of roots and tops decreased rapidly after 7 to 8 A.M. and little or no growth took place during the middle of the day. The normal dear−day growth pattern was altered by high moisture stress as well as by cloudiness and rain showers.