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Inoculation of Detached Cotyledons For Screening Soybeans Against Two Races of Phytophthora Megasperma Var. Sojae 1
Author(s) -
Morrison R. H.,
Thorne J. C.
Publication year - 1978
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1978.0011183x001800060049x
Subject(s) - cotyledon , biology , inoculation , phytophthora megasperma , hypocotyl , botany , pathogen , phytophthora sojae , phycomycetes , horticulture , damping off , phytophthora , seedling , microbiology and biotechnology
A non‐destructive method was used to evaluate the resistance of soybean ( Glycine max (L.) Merr.) to Phytophthora megasperma . Drechs. var. sojae Hildeb. based on the reaction of detached cotyledons inoculated with the pathogen. Cotyledons from soybean seedlings were placed on moist filter paper and inoculated with an agar culture homogenate of the pathogen using a hypodermic needle. Disease reactions were determined 72 to 96 hours after inoculation. Cotyledons of resistant genotypes showed only a slight discoloration at the inoculation site; cotyledons of susceptible genotypes became severely necrotic. Similar results were obtained with cotyledon and hypocotyl inoculation when soybean genotypes differing in their reaction to races 1 and 3 were tested. The same plant could be tested simultaneously with both races by using a mixture of races, or by inoculating each cotyledon with a single race. The method was effective for greenhouse and field grown plants. Cotyledon inoculation is non‐destructive so that susceptible germplasm may be conserved and field‐grown plants can be tested without introducing the pathogen into an area.