Soybean Cyst Nematode Effect on Soybean Grown at Controlled Soil Water Potentials
- L. D. Young and
- L. G. Heatherly
Soybean [Glycine max (L.) Merr.] grown in fields infested with soybean cyst nematodes (SCN), Heterodera glycines Ichinohe, produces lower yields when soil moisture is deficient than when soil moisture is adequate. The relative contribution of moisture and nematode stress to decreased yields has not been determined. The objective of this study was to determine the effect of SCN on soybean grown at controlled soil water potentials (SWP) in the upper profile. Upper-profile (0 to 0.30 m) SWP in a Vicksburg sandy loam soil (coarse-silty, mixed, acid, thermic, Typic Udifluvents) was maintained at wet (−20 to −40 J kg−1) and dry (−60 to −80 J kg−1) levels in outdoorain-sheltered microplots and in greenhouse pots that were either infested or noninfested with SCN. Wet plots yielded more seed than dry plots and noninfested plots had greater seed yield than infested plots. Soil water potential and SCN effects on seed yield appeared independent. Number of pods and leaflet area at R5 were reduced by both lower SWP and presence of SCN. Soil water potential effects on SCN numbers at harvest were inconsistent. Lower soybean yields in SCN-infested fields during years of deficient rainfall are apparently due to both drought and nematode stress.
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