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Sugarbeet Response to Irrigation as Measured with Growth Sensors 1
Author(s) -
Johnson Wendell C.,
Davis Ronald G.
Publication year - 1973
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1973.00021962006500050035x
Subject(s) - irrigation , agronomy , environmental science , growing season , dns root zone , moisture stress , water content , field experiment , soil water , irrigation scheduling , biology , soil science , geology , geotechnical engineering
Most research with sugarbeets ( Beta vulgaris L) under natural field conditions has been concerned with longterm effects of moisture or fertility levels on overall yield and sugarbeet quality. Variations in ambient conditions under which experiments have been conducted, together with the interrelationships of these variables with each other and with plant factors, have resulted in variable and sometimes contradictory results. There is, therefore, a need for more information on the effects of microclimatic and soil conditions on plant growth. In the study herein, root growth sensors that provide a continuous record of sugarbeet root growth were used to study the short‐term growth response of sugarbeets to irrigation and to variations in ambient meteorological and soil conditions. The continuous growth records of two typical irrigated sugarbeet roots were compared at Bushland, Texas, during a 48‐day period, June 25 to August 11, 1970, in a record dry season when there was little interference from rainfall on the effect of irrigation on root growth. The roots received 10 cm of irrigation water on staggered dates so that the growth record of a root not being irrigated at a particular time might be used to interpret the growth response to irrigation of the second root. The soil was slowly permeable, requiring an average of about 3 days for free water to disappear after an irrigation. A slowgrowth period of about 3 days in length occurred after each. irrigation during which time the irrigated root grew more slowly than the unirrigated root. When moisture stress was not extreme at the time of irrigation, a temporary decrease in growth rate actually occurred after irrigation. In general, root growth occurred at night. In the daytime, growth ceased or a shrinkage in circumference occurred which was proportional to the degree of moisture stress. As the need for moisture by the plant increased between irrigations, the increment of nighttime increase in circumference became progressively smaller and that of the daytime shrinkage, progressively greater. By the time the plant showed visual signs of a severe need for irrigation, the net daily growth had approached zero. Some daytime root shrinkage, however, was also noted during the slow‐growth period when the soil moisture content was very high. Although the reasons for the slowgrowth period after each irrigation were not directly determined in this study, logical explanations based on the literature of plant and soil‐water relationships are poor aeration and/or cooling of the soil.