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This article in CS

  1. Vol. 41 No. 2, p. 493-509
    Received: Oct 25, 1999

    * Corresponding author(s): jspecht1@unl.edu
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Soybean Response to Water

  1. J.E. Specht *a,
  2. K. Chaseb,
  3. M. Macranderc,
  4. G.L. Graefa,
  5. J. Chungd,
  6. J.P. Markwella,
  7. M. Germanne,
  8. J.H. Orff and
  9. K.G. Larkb
  1. a Dep. of Agronomy, Univ. of Nebraska, Lincoln, NE 68583-0915
    b Dep. of Biology, Univ. of Utah, Salt Lake City, UT 84112
    c Pioneer Hi-Bred, 4405 Winsor Court, St. Joseph, MO 64506
    d Dep. of Agronomy, Agric. College, GyeongSang National Univ., 900 Gaza-Dong, Chinju City, Geyong-Nam, South Korea, 660-701
    e Bio Nebraska, 3820 N W 46, Lincoln, NE 68524
    f Dep. of Agronomy and Plant Genetics, Univ. of Minnesota, St. Paul, MN 55108


Soybean [Glycine max (L.) Merr.] yield, when regressed on water needed to replenish 0 to 100% seasonal evapotranspiration (ET), generates an estimate of season-specific water-use efficiency (WUE). The impact of unpredictable water deficits might be lessened if high-yielding genotypes had a smaller beta. Our objective was to determine the genetic basis of beta and carbon isotope discrimination (CID), a theorized indicator of transpiration efficiency (TE). A ‘Minsoy’ × ‘Noir 1’ population of 236 recombinant inbred lines (RILs), genotyped at 665 loci, was evaluated in six water treatments (100, 80, 60, 40, 20, and 0% ET) for 2 yr. Water stress was mild in 1994, but high temperatures and no rainfall in 1995 led to a drought so severe that the 100% ET treatment required 41 cm of irrigation. The 1995 yield-to-water regression was highly linear (28 kg ha−1 cm−1). Genotype × water (G × W) interaction was due to genotypic heterogeneity in beta The CID vs. beta correlation was low (r = 0.26), so selection for better leaf TE may not improve crop WUE. Selection of low beta (less sensitivity to drought) will be difficult, given the yield beta vs. yield correlation (r = 0.71). The major quantitative trait loci (QTL) for yield beta, yield, and CID were coincident with maturity and/or determinancy QTLs, except for a CID QTL in linkage group U09-C2, but it had no effect on beta Genetic improvement of soybean yield performance under drought would be better achieved by coupling a high-yield grand mean with a high- (not low-) yield beta

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Copyright © 2001. Crop Science Society of AmericaPublished in Crop Sci.41:493–509.