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Penetration of Soybean Roots by Soybean Cyst Nematode at High Soil Water Potentlals
Author(s) -
Johnson A. B.,
Scott H. D.,
Riggs R. D.
Publication year - 1993
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/agronj1993.00021962008500020045x
Subject(s) - soybean cyst nematode , loam , heterodera , soil water , agronomy , penetration (warfare) , water potential , potato cyst nematode , cultivar , inoculation , chemistry , biology , nematode , horticulture , mathematics , ecology , operations research
Soil water is an important factor in the movement and development of soybean cyst nematode ( Heterodera glycines Ichinohe). Plant growth and soybean cyst nematode (SCN) population density were measured to determine the effects of soil water potential ( Ψ 8 ) on root penetration by SCN of ‘Essex’, a suspectible cultivar of soybean [ Glycine max (L.) Merrill]. Soybean seeds were planted in growth containers and subjected to constant Ψ 8 of −5, −10, −20, −30, −40, and −50 kPa at SCN levels of 12 000 eggs and second‐stage juveniles (J2) per kg soil or no SCN for the controls for 16 d. The soil used was a Captina slit loam (fine‐silty, mixed, mesic Typic Fragiudult) with 23, 68, and 9% sand, silt, and clay, respectively. Soybean was inoculated with eggs and J2 at the cotyledon growth stage (VC). Average soil temperature during the study was 25.5 °C. Leaf water potential ( Ψ 1 ) and soil oxygen diffusion rate (ODR) were significantly affected by Ψ 8 < ( P > 0.01) after 16 d of exposure to SCN. In the infested treatments Ψ 1 was reduced at a more rapid rate with decreasing Ψ 8 than in the non‐inoculated controls. The increase in SCN penetration of the soybean root system corresponded positively to the increase in soil ODR and corresponding decrease in Ψ 8 . Recovery of SCN from the soil decreased with a decrease in Ψ 1 . A mechanistic, nonlinear mathematical model was used to describe the relationship between Ψ 8 and SCN penetration of soybean roots. A quadratic regression model was used to describe the relationship between Ψ 8 and SCN recovery from the soil.