Heritability of Tolerance to Phytophthora Rot in Soybean1
- A. K. Walker and
- A. F. Schmitthenner2
Heritability estimates would be useful in determining breeding strategies for tolerance to phytophthora rot caused by Phytophthora megasperma Drechs. f. sp. glycinea Kuan and Erwin in soybean [Glycine max (L.) Merr.]. The objectives of our study were to determine the heritability of tolerance to phytophthora rot in three soybean crosses and to determine what effect majorgene, race-specific resistance has on tolerance. Parents and F3-derived lines from three soybean crosses were evaluated for tolerance to phytophthora rot using the greenhouse, mycelium-inoculum-layer method. Also, each F3-derived line was tested for race-specific resistance. Herltability estimates for tolerance were determined for susceptible lines, resistant lines, and combined lines for each cross using the components of variance method. Heritability estimates ranged from 79 to 87% on an entry-mean basis and from 49 to 63% on a plot basis. Herltability estimates were not affected by major-gene resistance. However, lines carrying major-gene resistance had a higher mean tolerance rating than lines which did not carry genes for race-specific resistance. This suggested that major-gene resistance and tolerance were not completely independent. The high heritability estimates indicated that considerable genetic gain should be expected from selection for tolerance in crosses where genetic variability is present.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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