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Agronomy Journal Abstract -

Soybean Water Extraction, Leaf Water Potential, and Evapotranspiration During Drought1


This article in AJ

  1. Vol. 71 No. 1, p. 45-50
    Received: May 5, 1978

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  1. D. C. Reicosky and
  2. D. E. Deaton2



Soil water is often the most limiting factor in soybean production in the southeastern US. To increase wateruse efficiency in soybean production, it is necessary to characterize the plant's response to the evaporative demand and to soil water stress when the root distribution changes with depth. ‘Davis’ and ‘McNair 800’ soybean cultivars (Glycine trim (L.) Merr.) were grown in a field experiment conducted on Norfolk sandy loam (Thermic Typic Paleudults) to evaluate the effect of irrigation on soybean yields and to determine the combined effects of soil matric potential and evaporative demand on evape transpiration (ET) in nonimgated and irrigated treatments. Water was applied to the irrigated treatment when the matric potential at the 15cm depth was −0.2 bar. Leaf water potential was measured using the pressure chamber technique and ET was measured using a portable chamber during a 34day drought. Only small differences in the midday leaf water potential were found between the two cultivars, whereas ET on the nonirrigated treatments was about two-thirds of that on the irrigated treatments 25 and 32 days into the drought. Soil matric potential data indicated significant water extraction at the 153-cm depth in the nonirrigated treatments near the end of the drought. The maximum incanopy air temperature during the drought in the nonirrigated Davis was 6.7 C higher than in the irrigated treatment. Irrigation resulted in a 351- and 364-kg/ha increase in Davis and McNair 800, respectively. Even though the nonirrigated plants exhibited severe wilt symptoms during the drought, the resultsgint out the importance of the root distribution and su oil water in partially meeting the evaporative demand during drought.

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