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Cytology and Histology

Environmental and Host Effects on Colony Development of Puccinia recondita f. sp. tritici. J. R. Tomerlin, Formerly agricultural research technician, U.S. Department of Agriculture, Agricultural Research Service, Department of Plant Pathology, Kansas State University, Manhattan 66506, Present address: USDA-ARS, Field Crops Laboratory, Plant Genetics and Germplasm Institute, Beltsville Agricultural Research Center, Beltsville, MD 20705; M. G. Eversmeyer(2), C. L. Kramer(3), and L. E. Browder(4). (2)(4)USDA-ARS, Department of Plant Pathology, Kansas State University, Manhattan 66506; (3)Division of Biology, Kansas State University, Manhattan 66506. Phytopathology 74:225-229. Accepted for publication 31 August 1983. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1984. DOI: 10.1094/Phyto-74-225.

Plants of near-isogenic wheat lines Thatcher (TC), LR16(TC), and LR18(TC) were inoculated with urediniospores of culture UN02-64A of Puccinia recondita f. sp. tritici at seedling, heading, and anthesis stages. Following inoculation, seedlings were maintained at temperatures ranging from 15.6 to 29.4 C, and plants inoculated at heading or anthesis were maintained at temperatures ranging from 21.1 to 29.4 C. Rate of growth of colonies and uredinia was generally fastest at moderate temperatures on cultivar TC and on seedlings. Temperatures below 21.1 C greatly reduced fungal development on seedlings of LR18(TC). Colony growth was linear with time within each temperature at each growth stage. The number of urediniospores produced per unit area of uredinium was not a satisfactory way to evaluate environmental, host age, or host resistance effects. The number of urediniospores produced per unit area of colony was slightly more useful in evaluating those effects.