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This article in AJ

  1. Vol. 69 No. 2, p. 231-233
     
    Received: Apr 20, 1976


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doi:10.2134/agronj1977.00021962006900020009x

Soil Water-Root Relations in Wheat: Water Extraction Rate of Wheat Roots that Developed under Dry and Moist Conditions1

  1. R. B. Sharma and
  2. B. P. Ghildyal2

Abstract

Abstract

Prior investigations have reported modifications of various root characters of plants Drown under relatively dry soil conditions, but there is a lack of information on the effect of these modifications on the capacity of root systems to extract soil water. This study was therefore conducted to investigate whether the root systems of wheat (Triticum aestivum L.) grown under different soil water conditions differed in their capacity to extract water from the soil.

In a greenhouse experiment the water extraction rate per unit root volume was measured for two wheat (Triticum aestivum L.) genotypes grown for 60 days after sowing in pots maintained under three different soil water tension regimes of 0.3 to 0.8, 2.0 to 2.5, and 4.0 to 4.5 bars. The two genotypes under study were one gene dwarf Sonalika RR-21 and three gene dwarf UP 301. The soil used was silty clay loam of the Mollisol order. Beginning on the 60th day after sowing the transpirational losses under different soil water tension regimes were measured for a period of 12 days by covering the pots with polyethylene sheet and weighing them intermittently. At the end of this 12-day period volume, length, and dry weight of the roots were measured. The water extraction rate per unit root volume was calculated assuming that the transpirational loss was the amount of water extracted by the roots in a linear proportion to the root volume. The water extraction rate per unit root volume increased significantly with increasing soil water tension regimes. It varied from 7.91 cm3 H2O cm−3 root day−1 for UP 301 under the wettest regime of 0.3 to 0.8 bar to 9.11 cm3 H2O cm−3 root day−1 for Sonalika RR-21 under the driest regime of 4.0 to 4.5 bar tensions. These findings suggest that root systems that developed under relatively dry soil conditions were capable of extracting greater amount of soil water on a unit root volume basis than those developed under moist conditions.

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