Abstract
Development of tobacco root systems was characterized under controlled environmental conditions by use of morphometric root analysis. According to the classification scheme of this system, roots terminating in apical meristems are defined as first-order roots. Elements of second-order roots begin where two first-order roots merge, and so forth. Growth of root systems was similar for susceptible and resistant tobacco cultivars in nonautoclaved and autoclaved soils. During 15 days of growth subsequent to transplanting of 2-week-old plants, relative multiplication and extension rates of first-order and second-order roots were constant. Apparent unit extension rates of first-order and second-order root elements increased through 15 days of root system growth. Classification of tobacco root systems by the morphometric scheme provided a useful means of partitioning susceptibility of tissues to infection byPhytophthora parasitica var.nicotianae. Zoospores applied at the tips of first-order roots were most successful in causing infections; 73.3% of the roots inoculated with 16 zoospores per root tip became infected. Percentages of infections after inoculation of first-order root tissues 2 cm behind root tips or after inoculation of second-order roots were 10 and 4.3%, respectively.
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Florida Agricultural Experiment Station, Journal Series Paper 8106.
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English, J.T., Mitchell, D.J. Use of morphometric analysis for characterization of tobacco root growth in relation to infection byPhytophthora parasitica var.nicotianae . Plant Soil 113, 243–249 (1989). https://doi.org/10.1007/BF02280187
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DOI: https://doi.org/10.1007/BF02280187